U. S. COMMISSION OF FISH AND FISHERIES,
GEORGE M. BOWERS, Commissioner.
MANUAL OF FISH-CULTURE,
BASED ON THE
METHODS OF THE UNITED STATES COMMISSION
OF FISH AND FISHERIES,
WITH
CI1AFTE118 ON THE CULTIVATION OF OYSTERS AND FROGS.
E.E~viSE]D EiDimoisr.
WASHINGTON:
GOVERNMENT PRINTING OFFICE.
19 00.
HAROLD B. LEE LIBRARY
BRIGHAM YOUNG UMii^ERSITY
PROVO, UTAH
TABLE OF CONTENTS.
Page.
I'retWe to revised edition vii
Preface to first edition ix
The Salmons of the Paritic Coast 1-15
The Allantie and Landlocked Salmons 17-60
The Rainbow Trout 61-79
The lirook Trout 80-90
The Lake or ^lackinaw Trout 91-105
The Cfraylings 106-108
The Whitefish 109-1 20
The Shad 1 21-145
The Black Ba^sses, Crappies, and Kock Bass 147-163
The Pike Perch or Wall-eyed Pike 165-179
]Miscellaneous Fresh-watei Fishes 181-193
Minor Trouts 181
Lake Herring and other Whitefishes 182
Muskellunge 183
Yellow Perch 184
Striped Bass and White Perch 187
Alewives » )r Hi ver Herrings 188
Smelt 190
Golden Ide 190
Sturgeons 191
The Cod 195-209
The Mackerel 211-215
The Flatiish or Winter Flounder 217-220
Sand-dab and Four-spotted Flounder 220
Miscellaneous Salt-water Fishes 221-228
Tautog 221
Spanish Mackerel 222
Haddock, Pollock, and other Gadida; 224
Cunner 225
Scup 225
Sea Bass 225
Squeteagues 226
Sheepshead 226
Sea Herring 227
The American Lobster 229-238
The Transp(jrtatiou of Fish and Fish Eggs 239-243
Spawning Seasons of Fishes Propagated, Character of Fish Eggs, Period of
Incubation, etc 245-247
Notes on the Edible Frogs of the United States and their Artificial Pr()i)a-
gation 249-261
Oysters and Methods of Oyster-culture 263-338
Notes on Clam-culture 339-340
HI
LIST OF ILLUSTRATIONS.
Plate. Page.
Salvclin Ksj'ontinalis, Brook Trout, Specklod Trout Frontispiece.
1. Cliickamas. Oregon, Pnlniou Station VII
2. Figure of a Fisli showing the Location of Parts usually referred to in Descriptions X
3. OitcorhyncliHS tschawytscha, Quinnat Salmon, Chinook Salmon, King Salmon 1
4. Oncorhynchus nerka, Blueback Salmon, Redfish 5
5. Oncorhynchus kigitlch, SiWer Salraon. Breeding male, with Distorted Jaws 7
6. Salmo nairdncri, Steelhcad 7
7. Rack for stopping Ascent of Salmon, at Battle Creek, California 8
8. Taking Salmon Eggs. Fertilizing Salmon Eggs. Salmon in Strait-jacket 10
9. Pens for holding Ripe Fish, and Stripping Platform, at Battle Creek, California 12
10. Interior of Hatchery at Battle Creek, showing Salmon Basket 14
11. Salnio salar, Atlantic Salmon 17
12. Entrance to Dead Brook Inclosure for Salmon. Inclosure for Salmon, .showing Pens 20
13. Salmon Live-car used in transporting Fish. Salmon Live-cars en route with Fish 22
14. Salmon Rearing-troughs, Residence and Barracks in Background, Craig Brook Station 30
15. Examining Fish for Stripping. Stripping Female Salmon 34
16. Picking out Dead Eggs. Packing Salmon Eggs. Handling Egg-trays 10
17. Fungus on Salmon Eggs 54
18. Taking Spawn of Landlocked Salmon at Grand Lake Stream, Maine 56
19. Sdliiio iriihus. Rainbow Trout gl
20. Wytheville Station, Virginia— New Rearing-ponds 62
21. Spawning-pond 61
22. Interior of Wytlieville Hatchery, showing Men picking out Dead Eggs 66
23. Rearing-pond 70
21. Wytheville Station, Virginia— Spa wning-pond, .><howing Raceway 72
25. Plan of Station at Spearfish, South Dakota, showing typical arrangement of Trout Ponds ... 78
26. Hatchery and Rearing-ponds for Trout at Manchester, Iowa 80
27. Selecting and Stripiiing Rijjc Trout, Northville, Michigan 84
28. Interior of Northville Hatchery 86
29. Removing Green Eggs from Shipping-trays, Northville. Packing Eyed Eggs, Northville ... 88
30. Criniivomcr namaycush, Lake Trout 91
31. Collecting Lake-trout Spawn on Fishing Stoamer in Lake Michigan 96
32. ThyniaUiis tricolor inuntaii its, Montana Grayling 106
33. Corcf/onus cliipeiforiiii.<, Common Whitefish 109
34. Hatching Battery at Put-in Bay, 1899 112
35. View of Battery for hatching Whitefish 116
36, 37, 38, 39. Development of the Whitefish Embryo. 118
40. Alosa sapidissima. Common Shad 121
41,42,43. Embryology of the Shad 124
44. Main Deck of the Steamer Fish Hawk, equipped for hatching Shad 128
45. Battery Station Hatchery, Havre de Grace, Maryland 130
46. Interior of Hatchery at Battery Station, equipped with Hatching-jars 110
47. Micropteriis galmoidcs and dolomieii, Large-mouth and Small-mouth Black Bass 147
48. Ba.ss Ponds at Neosho Station 152
49. Bass Ponds at San Marcos Station 1,56
50. Plan of San Marcos Station, Texas, showing typical Arrangement of Bass Ponds 160
")1. Stiz(»:tcdioa vitraim, Pike Perch or Wall-eyed Pike 105
52. Photo-micrographs showing Phases of Cannibalism among Pike-perch Fry 170
53. Salmo mykigg, Black-spotted Trout l,si
54. Gndiis callarias, Cod I95
•55. Stripping Cod on Vessel 198
06. Hatchery at Gloucester, View from Gloucester Harbor 200
57. Interior View of Gloucester Hatchery, showing Cod Boxes in Operation 201
•58. Chester Boxes 206
■59. Scomber scombriis. Common Mackerel 211
60. Pseudopleuroneclcs americanuf. Flatfish or Winter Flounder 217
61. Taiduga onitis, Tautog 221
62. HonuiruA auicricanu!<. American Lolister 229
63. Laboratory, Hatchery, Acjuarium, Mu.seum, and Residence, Woods Hole, Mass 234
6-1. Views of Car No. 3 239
V
VI
LIST OF ILLUSTRATIONS.
Plate.
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
XII.
XIII.
XIV.
XV.
XVI.
XVII.
XVIII.
Page.
Anatomy of tlio Oyster 27(5
Snlinometer and Salinomoter Cup 282
Ground-plan and Section of Ponds for Spat-eulture ;i2S
Details of Filter for Ponds used for Oyster-culture 330
Inner and Outer Faces of Shell of Typical American Oyster 340
Views of Valves of Pacific Oyster 340
Development of Oyster 340
Views of Oyster Embryos 340
Set of Oysters on Shell, showing crowding 340
Oyster Spat, 2 or ;^ weeks old, on inside of Oyster Shell 340
Oyster Spat about 2 months old, on a Stone '. 340
Oysters, 1, 2, and 3 years old 340
Oysters 4 and 5 years old 340
1 , Photo-micrograph of Diatom. 2, Food of South Carolina Oyster 340
1 , Urosalpiiix cincrca. 2, Mytilus cdulis. 3, Sabcllaria vulgaris. 4, Falgur carica 340
Starfish attacking Oysters 340
Bunch of Oysters, showing Growth of Mussels and Barnacles 340
1, Crcpidula fornieata. 2, Crcpidula plana. 3, Crcpidula convcxa. 4 and 5, Anowia
glabra. 5, Pecten irradians. 7, Oyster attached to pebble 340
FIGURES IN TEXT.
Page.
Gravel Filter 27
Wire Filter 29
Trough arranged for Eggs 39
Longitudinal section of case of Atlantic
Salmon Eggs 42
Atlantic Salmon recently hatched 44
Troughs arranged for rearing 4.5
Stand of Troughs for rearing Atlantic
Salmon 46
Hatching-troughs, Guard-screen, etc 68
Cross-section through box after it has been
packed and closed 74
Egg-tray 74
Foundation-board 74
Ice-hopper 75
Egg-trays packed and cleated 75
Outside Case 76
Floating Box 95
Clark-Williamson Trough 98
Pans used in cleaning Eggs 136
Shad-hatching Table 137
Automatic Shad-hatching Jar 138
Egg Funnel 139
ripe
PagK
142
149
149
150
182
185
185
204
Application of a Measuring Scale
Pomoxix aminlaris, Crappie
Poraoxis sparoidcs, Calico Bass
AmhlopUtcs rupesiris, Rock Bass
Argyrosomus artcdi, Lake Herring
Ovary of Yellow Perch with nearly
Eggs
Part of a recently laid mass of Yellow Perch
Eggs
Diagram of Tidal Cod Hatching-box
Spring Frog or Leopard Frog {Sana vires-
ccns) 255
Green or Spring Frog ( Rana claynata ) 256
Figures illustrating relative size of the
Tympanum in the two Sexes 257
Common Bullfrog ( Rana catcsbiana) 258
Western Frog {Rana 2>rdiosa ) 259
Western BuWhog {Rana aurora) 259
Anatomical figure of the Oyster 278
Tangle and Tackle 315
Drill-dredge in position for work 316
Drill-dredge open for emptying 317
Receptacle for Cultch 324
Digitized by the Internet Archive
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Fish Manual, (To face page Vll.)
Plate 1,
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PREFACE TO REVISED EDITION.
The Manual of Fish-Culture, issued in 1897 as an appendix to the
annual report for that year, proved a very useful and popular work,
and the edition was soon exhausted. The continued demand for this
volume and the increasing interest in the artificial propagation of food-
fishes have warranted the preparation of a new edition, the printing
of which has been authorized by concurrent resolution of Congress.
Several of the chapters have been revised in order to exhibit the latest
facts and most approved methods, and a number of new illustrations
have been inserted. The cultivation of the pike perch having been
resumed on Lake Erie, a chapter on that important species, prepared
by Mr. J. J. Stranahan, has been added. At tlie Uozeman station in
Montana the artificial propagation of the grayling has recently been
inaugurated, and the superintendent, Dr. James A. Henshall, has con-
tributed an article on that subject. Others who have furnished infor-
mation for this edition, in addition to those named in the first edition,
are Mr. W. De C. llavenel, in charge of the division of fish-culture, and
Mr. John W. Titcomb, superintendent of the Government hatchery at
St. Johnsbury, Vermont. Hon. A. IS^elson Cheney, of the New York
Fish Commission, has also supplied data regarding some of the fishes
propagated in that State.
Since 1897 new stations of the Commission have been established at
the following ])laces: Nashua, New Hampshire, and Spearfish, South
Dakota, for the propagation of trout; Erwin, Tennessee, and Bulloch-
ville, Georgia, for trout and basses; Baker Lake, Washington, for
blueback or sockeye salmon and other salmonoids; and Eden ton. North
Carolina, for shad and basses. The station at Fort Gaston, California,
has been abandoned.
Geo. M. Bowers,
Commissioner.
Washington, D. C, April 16, 1900.
VII
PREFACE TO FIRST EDITION.
The -^vork of tlie United States Commission of Fish and Fisheries
is carried on at twenty-five stations or hatcheries located at suitable
places throuj;hont the country. At Woods Hole and Gloucester, Massa-
chusetts, cod, inacikerel, lobster, and other important marine species are
propagated and the fry are deposited on the natural spawning- grounds
along the coast. At Battle Creek, Baird, and Hoopa Valley in Califor-
nia, at Clackamas in Oregon, and Little White Salmon Eiver in Wash-
ington, the eggs of the Pacific salmon are collected and hatched, and
the fry are planted on the spawning-beds in the neighboring streams.
The Atlantic and landlocked salmons are cultivated in Maine at Craig
Brook and Green Lake to restock the depleted streams and lakes of
New England and northern New York. On the Great Lakes at Cape
Vincent, New York; Put-in Bay, Ohio; Alpena, Michigan, and Duluth,
Minnesota, the work is with whitefish and lake trout, in order to sustain
the great commercial fisheries conducted for those species. Hatcheries
in the interior at St. Johnsbury, Vermont; Wytheville, Virginia;
North ville, Michigan ; Manchester, Iowa; Bozeman, Montana; Neosho,
Missouri; Quincy, Illinois; San Marcos, Texas, and Leadville, Colo-
rado, are devoted to the important work of maintaining in the inland
lakes and streams the supply of brook trout, rainbow trout, black bass,
crappie, and other fishes. During the spring, on the Potomac, Dela-
ware, and Susquehanna rivers, shad are hatched and are distributed
in suitable streams along the Atlantic Coast.
For the distribution of fisli and eggs the Commission has four cars
specially equipped with tanks, air-circulating apparatus, and other
ap])liances.
In the prosecution of marine work three vessels are used, the steamers
Albatross und Fish ITawJi^nml a schooner, the Gramims. The Albatross
is fitted with appliances for deep-sea dredging and collecting work, and
is used for surveying and exploring ocean bottoms and investigating
marine life. The Fish Haicl- is in reality a floating hatchery, and is
engaged in hatching shad, lobsters, and mackerel, in collecting eggs,
and in distributing fry, besides making topographic surveys of fishing-
grounds, etc.
The necessity for a handbook describing the manner of propagating
the different fishes reared by the United States Commission of Fish
and Fisheries has long been felt in the Coiumissiou, and it is thought
IX
X REPORT OF COMMISSIONER OF FISH AND FISHERIES.
that such a numual will be of vahie to all persons interested in fish-
culture. The material for the present work has been furnished by
experienced tish culturists connected with the Commission, who have
treated of the subjects with which they were especially familiar. Owing
to the interest showft in the cultivation of oysters and frogs, special
reports on these subjects have also been incorporated.
The following is a list of the contributors and their subjects:
Charles G. Atkins, Superintendent U. S. F. C. Station, Craig Brook, Maine.
The Atlantic and Landlocked Salmons.
V. M. C'bamberlain, Assistant, U. S. Fish Commission, Washington, D. C.
Edible Fro(js and their Artificial Propagation.
Frank N. Clark, Superintendent U. S. F. C. Stations in Michigan.
The Brook Trout and the Lake Trout.
J. Frank Ellis, Superintendent of Car Service, U. S. F. C, Washington, D. C.
Transportation of Fish and Fish Eggs.
H. F. Moore, Assistant, U. S. Fish Commission, Washington, I). C.
Ogstera and Methods of Oyster-Culture.
William F. Page, Superintendent U. S. F. C. Station, Neosho, Mo.
The Black Basses, Crappies, and Rock Bass.
George A. Scagle, Superintendent U. S. F. C. Station, Wytheville, Va.
The Rainbow Trout.
Livingston Stone, Superintendent U. S. F. C. Station, Baird, Cal.
Tlie Salmons of the Pacific Coast.
J. J. Strauahan, Superintendent U. S. F. C. Station, Put-in Bay, Ohio.
The Whitefish.
Stephen G. Worth, Superintendent U. S. F. C. Station, Washington, D. C.
The Shad.
The chapters on most of the minor fishes were furnished by Dr.
Hugh M. Smith.
Valuable information on marine fishes was also furnished by Lieut.
Franklin Swift, U. S. N.,C. G.Corliss, E. E. Hahn, Alexander Jones, and
E. F. Locke, of the United States Fish Commission, and on the quinuat
salmon by J. P. Babcock, of the California State Fish Commission.
In order to increase the usefulness of the work to the general reader,
a technical descriiition of each important fish is given, together with
brief information regarding its geographical distribution, habits, move-
ments, size, growth, food, natural spawning, etc.
While the operations described are essentially those of this Com-
mission, they are usually the same as those employed by the State
commissions and individual fish-culturists, although, in some instances,
excellent work is done by other methods. The propagation of the
various marine species is carried on only at the Government hatcheries.
The methods described for hatching Salmonidcv, while differing in
minor particulars, are practically interchangeable, and may be used at
the discretion of the fish-culturist.
John J. Brice,
Commissioner.
Washington, D. C, September 1, 1897.
Tish Manual. ( fo face page X.)
Plate 2.
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Fish Manual. (To (aco page 1 .)
Plate 3.
THE SALMONS OF THE PACIFIC COAST.
There are five species of salmon on tlie Pacific coast which belong
to the genus Oncorhynchus, namely, the chinook or (luinnat salmon
{Oncorhynchu.s tschawytsclM), tlm red or blueback sahuon {Oncorhynchus
nerka), the humpback sahnon [Oncorhynchus yorhusclia), the silver
salmon [Oncorhynchus Msutch), and the dog salmon [Oncorhynchus keta).
The features which separate the Pacific salmons from the Atlantic salmon
are not marked and consist chiefiy m a larger number of rays in the
anal fin, and more branchiostegals, gdlrakers, and pyloric coeca.
The characters noted in the following key will usually be sufticient to
distinguish the difierent species of Pacific salmon :
Quinnat salmon: Scales in longitudinal series from 135 to 155, aver-
aging about 145; pyloric cctca liO to 185; gillrakers comparatively
short and usually 23 in number, 9 being above the angle; rays in anal
fin 1(5; branchiostegals 15 to 19. Body robust; head conic; eye small;
caudal fin deeply forked. Color above dusky, sometimes with bluish or
greenish tinge; sides and belly silvery; head dark, with metallic luster;
back and the dorsal and caudal fins with numerous round black spots.
Blueback salmon: Scales in longitudinal series about 130; pyloric
cuica, 75 to 95; gillrakers comparatively long and 32 to K) in number;
rays in anal fin 14 to 16; branchiostegals 13 to 15. Body rather slen-
der; caudal fin much forked; anal and dorteal fins low. Color, above
bright blue, sides silvery, no spots.
Humpback salmon : Scales very small, 210 to 240 in longitudinal series;
pyloric cfcca very slender, about 180 in number; gillrakers short, about
28, 13 being above angle; anal rays 15; branchiostegals 11 or 12.
Color, bluish above, silvery on sides; hind part of back, adipose fin, and
tail with numerous black spots, largest and of oblong form on tail.
Silver salmon : Scales large, 125 to 135 in longitudinal series ; pyloric
c(Bca comparatively few and large, 45 to 80 in number; gillrakers long
and slender, 23 in number, 13 below angle; anal rays 13 or 14; branchi-
ostegals 13 or 14. Body long; head short, conic; snout blunt; eye
small; fins small, caudal deeply forked. Color bluish green, sides sil-
very, finely punctulated; spots few and obscure on head, bapk, dorsal,
adipose dorsal, and upper rays of caudal.
Do(j salmon: Scales of medium size, 138 to 155 in lateral line; pyloric
ccBca 140 to 185; gillrakers short and few, 9 above and 15 below angle;
13 or 14 rays in anal fin ; branchiostegals 13 or 14. Form of (jninnat,
but head longer and more depressed. Dusky above and on head, paler
on sides; very fine spots on back and sides, often wanting; tail plain
dusky or finely spotted, with black edge; other fins blackish.
1
2 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
These salmons are the most important gronp of fishes entering the
rivers of North America. The steelhead {Salmo f/airdneri), technically
a trout, but i)oi)ularly regarded as a salmon, also inhabits the waters ot
the Pacific coast and adds to the importance of the salmon tribe.
In recent years the annual catch of salmon in the Pacific States and
Alaska has been over 1()0,()()(),()00 pounds. In 1899 the quantity of
salmon canned was 2,450,000 cases of 48 one-pound cans. The weight
of the fresh fish re})resented by this pack, together with the large
quantities sold Iresh, salted, and smoked, was about 175,000,000 pounds,
with a value, as placed on the market, of nearly $9,000,000.
THE QUINNAT SALMON.
The quinnat salmon {Onrorhynchus tschawytscJia) is known by a
number of other common names in various parts of its range; among
them are chinook salmon, king salmon, Columbia salmon, Sacramento
salmon, and tyee salmon. The quinnat is the most important of the
sabuons. It is not only superior in food qualities, but attains a vastly
larger size, has a wider geographical range and a greater commercial
value than any of the others. When fresh from the ocean it is a very
handsome, res])lendent, well-formed fish, greatly resembling the Atlan-
tic salmon {Salnio salar), although its form is less symmetrical and its
outlines less graceful. It is of a uniform rich red color, becoming paler
or streaked upon the api)roach of the spawning season. Its value for
canning purposes is largely enhanced by the persistence of the red color
of the meat after cooking.
In size no other salmon in the world compares with it. In the Yukon
Eiver, Alaska, it reaches a weight of over 100 pounds, and in the
Columbia Kiver there are well-authenticated cases of its weighing
more than 80 i)()unds. Farther south, it runs smaller, although in the
Sacramento individuals weighing 50 or 60 i)0unds are not rare; 22
pounds is a fair average weight in the Columbia River and 16 pounds
in the Sacramento.
Its known range is practically from Monterey Bay (latitude 36i) to
the Yukon Eiver, but individuals have been seen in Norton Sound,
somewhat north of the Yukon, and as far down the coast of California
as the Ventura River. Since itthrives well in very cold water it is likely
that its range extends to and possibly within the Arctic Ocean.
While in the sea quinnat salmon probably do not wander very far
from the mouths of the rivers they have left, and for this reason usually
return to spawn in the rivers in which they were hatched. They prefer
the larger rivers, like the Sacrameuto, the Columbia, the Nushagak,
and Yukon. They are very persistent in ascending the rivers to spawn,
and have been seen crowding up the rivulets which form the head
waters of the Sacramento until nearly half their bodies were exposed
to the air. No matter how far the headwaters of a river are from the
ocean, some of the salmon will ])ress forward until stopi)ed by impassable
obstructions or water too shallow for them to swim in. On reaching
MANUAL OF FISH-CULTUIIE. 6
the headwaters they remain for a week or two before proceeding to the
spawning grounds. Their rate of i)rogres8 varies with the season, and
l)robal)ly depends to a great extent on the rainfall and the state of the
river, rain, roily water, and high water always hastening their progress.
When they first come from the ocean the sexes are almost identical
in api)earance, but as the time for spawning approaches a ditterence is
noticed between the males and the females, which during the spawning
season be(;omes more marked. The fully developed ova of the female
give her a round, plump api)earaiu'e, while the male grows very thin.
Jlis head flattens, the upper Jaw curves like a hook over the lowu^r, the
eyes become sunken; large, i)owerful, white, dog like teeth appear on
both Jaws, and the fish acquires a gaunt and savage appearance. As
soon as they reach fresh water their appetites grow less, their throats
begin to narrow, and their stomachs to shrink. This does not at first
entirely prevent them from feeding, but it changes them enough to
enable them to overcome the temjjtation to return to tlieir well-stocked
feeding-grounds in the ocean, and the longer they remain iu fresh water
the greater are the changes, and the desire to turn back for food is
correspondingly lessened. This change comes about gradually, increas-
ing day by day from the time they leave tide water until at the near
approach of the spawning season their throats and stomachs become
entirely incapacitated for receiving food, and the desire and ability to
feed leave them entirely. The great reserve of flesh and blood which they
bring with them from the ocean enables them to keep the vital organs
active until their mission up the fresh-water streams is accomplished.
Quinnat salmon that spawn a long distance from the ocean do not
return to it again, but die on or near their sjiawning grounds. This
singular fact has been disi)uted, but its truth has been proved repeat-
edly and conclusively. After spawning they rapidly deteriorate, the
flesh shades oft" to a light, dirty pink and_ tliey become foul, diseased,
and much emaciated. Their scales are wholly absorbed iu the skin,
which is of a dark olive or black hue, and blotches of fungus appear on
their heads and bodies, and in. various places are long white patches
where the skin is i)artly worn oft". Their tins and tails become badly
mutilated, and in a short time they die exhausted.
The (piinnat salmon first appear on the Pacific coast at Monterey Bay,
where many are caught with hook and line as early as the second week
in .lanuary, and are next seen in the Sacramento River in numbers in
February. In the Columbia Kiver they appear m March, but are not
abundant until A])ril or May. They arrive in southern Alaska in
May and farther north in June, while it is probable that it is still later
betbre they aocend the Yukon, wliere the running season is very short
and may not exceed a month or six weeks. The early runs in the
Columbia River are usually from one to three weeks passing from the
mouth of the river to Clifton, about -JO miles. They first appear &i
The Dalles, 200 miles uj) the river, in the middle of April, and are found
4 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
in great quantities at this point about the middle of June, two months
after they appeared in large numbers at the bar. This would indicate
that they ])ro('eed up the Columbia at the rate of 100 miles a month.
In the later runs tliey probably travel faster.
The spawning season of the quinnat varies in different rivers and,
considering the entire coast, lasts at least six months. In July the
summer run is spawning at the headwaters of the McCloud and Sacra-
mento rivers in California; in August and September, farther down
tliese rivers. In October the fall run has begun in the McCloud and
below and this run continues spawning through November into Decem-
ber. In the Columbia the spawning begins at the headwaters in
June; at Clackamas, ll'a miles from the mouth of the river, it begins
about the middle of September and continues until November.
A few days before they are ready to spawn the salmon hollow out
elongated cavities with their heads and tails m the gravel beds of the
river where there is some current, and here in due time the eggs and
milt are deposited. The eggs drift into the crevices in the ])ile of stones
thrown up below the hollow, sink to the bottom, and remain in that pro-
tected position during incubation; here, also, the young remain until the
umbilical sac is absorbed. The eggs and young are liaV)le to destruction
by freshets, but are comparatively safe from other injurious influences.
The quinnat is not so prolific as the Atlantic salmon, 300 or 400 eggs
to each pound weight of the parent fish being a fair average.
In view of the enormous annual catch of this salmon for commercial
purposes the necessity for its propagation became manifest at an early
period in the history of the Pacific fisheries. Fortunately it is readily
susceptible of artificial propagation on a large scale, otherwise the
supply in the western rivers would have materially fallen off'. Since
the work began in 1873 on the McCloud Eiver it has grown to large
proportions, and engages the attention of all the coast States as well as
the General Government, and is now more extensive than ever before.
As the salmon ascend the rivers they are caught by gill nets, fyke
nets, pounds, weirs, seines, wheels, and other devices, but in the Sacra-
mento and Columbia the greater numbers are caught with gill nets
drifting with the current or tide as they head upstream. In the
rivers they are comparatively safe from enemies except otters, ospreys,
and fishers, but immense numbers are destroyed at the mouths of the
streams by seals and sea lions.
The quinnat salmon has been introduced into Japan, Australia, New
Zealand, and Europe, but efforts to acclimatize it on the Atlantic coast
of the United States have so far been unsuccessful.
THE BLUEBACK SALMON.
Considering the entire west coast, this species {OncorhyncJms nerJca)
is probably more numerous than all the other salmons combined. It is
known in different regions under the names blueback, redfish, red
salmon, Fraser Kiver salmon, and sock-eye or saw-cjui. It ranks next
Fish Manual. (To face page 5.)
Plate 4.
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to the Chinook in commercial valne, being especially important in the
Columbia and Fraser rivers and in Alaska. For <'annin<;- ])urposes it
is but little inferior to the chinook, the color of the flesh being a rich
red. Avhich persists after canning. Largeciuantities are canned in Kritish
Columbia and in Alaska, particularly on Kadiak Island, and its com-
mercial importance to that Territory is indicated by the fact that nearly
half of the entire salmon pack of the world comes from Alaska and the
majority of the fish there canned are of this species. Comparatively
few red salmon are sold fresh in the United States.
It is next to the snuillestof the salmons, the maximum weight being
about 15 pounds, but it rarely weighs over 8 pounds and the average
is scarcely 5 pounds. In various lakes this fish weighs only half a
pound when mature, and is called the little redfish.
It ranges from Humboldt Bay, California, to the far north. In gen-
eral it ascends only those rivers which rise in cold, snow-fed lakes. No
more is known of its ocean life than of the quinnat. It appears in the
Columbia with the spring run of the quinnat. In southern Alaska and
at Kadiak Island it comes in numbers in June; the heaviest run is in
June and July, the spawning occurring in August and September. In
the Idaho lakes, which may be considered typical spawning-grounds
for tins fish in the United States, the height of the si>awning season is
from August 25 to September 5, altliough ripe eggs have been found as
early as August 2, and fish with eggs in them as late as September 11.
In the numerous affluents of the Fraser Kiver the spawning extends
from September 15 to November 15, a few stragglers spawning as late
as November 30. They deposit their eggs on gravel in rather shallow
water, usually in the inlets of the lakes. The eggs average about 1,000
to 1,200 to the fish.
Except in the breeding season the color of this fish is a clear bright
blue above, with sii/ery sides and belly. At the spawning period the
back and sides become red, and the male develops an extravagantly
hooked upper jaw.
THE HUMPBACK SALMON.
The humpback salmon {Oncorhyiichiis (forhuscha) is the smallest of
the Pacific salmons; its average weight is only 5 jwunds, and it rarely
reaches 10 pounds. Its range is from San Francisco probably as far
north as the ^Mackenzie Eiver, and it is also common on the Asiatic
coast. It is the most abundant and generally distributed salmon in
Alaska, but in the Pactific States it does not ordinarily occur in great
abundance, although there is sometimes a noteworthy run in the Puget
Sound region.
In food (iualities the fresh-run humpback is scarcely inferior to any
other salmon. While the fiesh has a very fine flavor, it is paler than that
of other red salmon, and the species has consequently been neglected
by canners; but it is i)robab]e that it will eventually be utilized for
canning purposes, and its excellent (qualities when fresh are undoubtedly
6 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
destined to <j;ive it a jireat cominercial value. Its chief consnniption
now is by Alaskan natives, who <aire large (juantities for winter use.
The humpback salmon o<^nerally seeks the smaller streams for the
purpose of spawninj^ and deposits its eggs a short distance from the
sea, sometimes within only a few rods of the ocean. At Kadiak Island,
Alaska, where it is often very abundant, it arrives in the latter part of
July, the run continuing only a few weeks. Spawning takes place in
August.
There are only a few hundred eggs to each fish, the eggs being
SMialler than those of the quiunat but larger than those of the redfish,
and paler in color than the eggs of either of those species.
When this salmon first comes from the ocean it resembles a small
quinnat, but as the spawning season advances it develops a very Lirge
and prominent hump on its back. This, with the distortion of the jaws,
gives the fish a very singular appearance. The extreme enjaciation and
the extensive sloughing of the skin and fiesh, which are incident to
spawning, result in the death of all the fish, either on the spawning-
ground or after being swept out to sea by the current.
THE SILVER SALMON.
The silver salmon {Oncorhynclnis Msutch) is also known as silversides,
skowitz, kisutch, hoopid salmon, and coho salmon. It is a beautiful
fish, having a graceful form and a bright silvery skin. Its flesh, which
is fairly good, usually has a bright red color, but as this fades on
cooking it is not highly regarded for canning purposes, though large
quantities are thus utilized on the Columbia Eiver, Puget Sound, and
the short coast streams of Oregon and Washington. Its average
weight in tlie Columbia and Puget Sound is 8 pounds, but in Alaska it
averages nearly 15 pounds; it rarely reaches 30 pounds. Its range
is from San Francisco to northern Alaska, and as far south on the
Asiatic coast as Japan. It runs up the rivers to spawn in fall or
early winter, when the waters are high, but usually does not ascend
great distances from the ocean. The average number of eggs to a fish
is about 2,000.
THE DOG SALMON.
The dog salmon {Oncorhi/nchus keta) is the least valuable of the
Pacific salmons, although it is dried in large quantities by the Alaskan
natives. Its average weight is V2 pounds and the maximum is about
20 pounds. It is found from San Francisco to Kamchatka, being
especially abundant in Alaska. The enlargement and distortion of
the jaws give the species a very repulsive look, and the large teeth
give to it its common name. When just from the ocean, the flesh has
a beautiful red color and is not uni)alatable, but it deteriorates rapidly
in fresh water. It spawns in shallow rivers and creeks. Larger quan-
tities are utilized in Puget Sound than elsewhere in the Pacific States,
and it is also used considerably by the natives of Alaska.
Fish Manual. (To face page 7.
Plate 5.
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THE STEELHEAD.
Another anadromons salinonoid fish fouiid on the Pacific; coast, popu-
larly regarded as a salmon, is the steelhead {Sahno (jairdneri), known
also as hardhead, winter salmon, square-tailed trout, and salmon trout.
It resembles in form, size, and general appearance the salmon of the
Atlantic coast, and is distinguished from other Pacific coast salmon by-
its square tail, its small head, round snout, comparatively slender form,
light colored flesh, and its habit of spawning in s])ring. It is more
slender than the (luinnat and consequently not so heavy for its length.
Its average weight in the Columbia is about 10 pounds, although it
sometimes reaches 30 pounds.
Its range is very extended, reaching from Santa Barbara on the
southern coast of California to the Alaska I'eninsula, and perhai)s to
the Arctic Ocean, and it is found in almost all the streams of the
Pacific States which empty into the ocean. It begins to enter the
Columbia in the fall, and is then in prime condition. From this time it
deteriorates until the following spring, when, between the months of
February and May, spawning occurs. Its movements in other rivers
on the coast are not materially different, though perhaps it enters the
southern rivers earlier and northern rivers later than the Columbia.
Like the chinook, the steelhead ascends rivers for long distances, and it
has been found almost as far up the tributaries of the Columbia as the
ascent of fish is possible. Its eggs are much smaller than those of the
chinook and average 3,000 to 5,000 to the fish.
As the greatest quantities of steelheads are caught in the spring,
when they are spawning and are in a deteriorated condition, they are
not generally esteemed as food; but when they come fresh from the sea
and are in good condition, their llesli is excellent. As the demand for
salmon has increased, steelheads have been utilized for canning and
they have formed a noteworthy part of the canned salmon from the
Columbia Kiver for a number of years past, as well as from the short
coast rivers of Washington and Oregon. Their consumption fresh has
been increasing yearly and considerable quantities have been sent to
the Eastern States in refrigerator cars.
ARTIFICIAL PROPAGATION.
The chinook being the principal salmon that has been propagated
artificially, the present chapter relates almost entirely to this species.
The discussion of the ai)paratus and methods has special reference to
the hatcheries of tlie Commission on McCloud liiver and Battle Creek,
tributaries of the Sacramento, although cognizance is also taken of
the work at the stations in the basin of the Columbia liiver and on
the short coast rivers of California and Oregon.
In 1809 the number of eggs of this fish collected by the Commission was
48,043,000, from which about 43,775,000 fry were hatched aiul i)lanted.
The collections of steelhead egfs numbered 415,000, which produced
85,035 fry.
8 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
CAPTIRING ADULT SALMON.
The eggs used for artificial i)ropagation are obtained from salmon
taken on their way upstream to the natural spawning-grounds. The
ascent of tlie fish is stopped by a heavy wooden rack or barricade and
below this obstruction their capture is effected by various means
dei)ending on the natural conditions. At Baird station, on the McCloud
River, the most practical method of collecting them in large numbers
is with drag or sweep seines. These are from 120 to 170 feet long,
made of about 28-thread twine, and are 20 feet deep in the middle,
tapering down to about 6 feet at the ends; they are double-leaded on
account of the swift current of the river, and have a 4-inch mesh.
In the rack are built large wooden traps, in which at times (especially
during a rain storm accompanied by a marked rise in the river) large
numbers of salmon are taken, but there is never more than a small
percentage of spawning fish thus secured. The trap is simply a square
inclosure of vertically placed slats, with an entrance similar to that of
an ordinary pound net. The fish, in their eager efforts to pass upstream,
go through the V-shaped mouth of the trap, and having OTice entered
are not able to find their way out. Boards are placed over the top of
the trap to prevent the fish from leaping out.
The trap is quite a valuable auxiliary to the seine, but although it
will secure many unripe fish, the ripe ones, which are the ones wanted,
finding an obstruction in their way, are apt to settle back to spawning-
grounds below and remain tliere. This may be obviated by building a
second rack below the first, which, while permitting the ascent of the
fish, is so constructed as to prevent their return.
Large di^) nets have been used occasionally at Clackamas station, in
Oregon, the fishermen standing on the rack at night and dipping below
it. Toward the end of the season this method secures a considerable
number of ripe fish, but it involves much labor and expense, and most
of the spawning fish taken with the dip nets would probably have been
captured in the regular course of fishing. There being no satisfac-
tory seining-grounds at Clackamas, and the river just below the rack
being shallow, an Indian method of Ashing is used. The aversion of
salmon to heading downstream is well known, but when they are very
much frightened they will turn around and rush downstream at their
utmost speed. The Indians take advantage of this fact and build a
dam of rock or wickerwork, or anything that will present an obstruc-
tion to the frightened fish. It is shaped like the letter V, with the angle
downstream, and at the angle is a large trap into which the fish are
driven. This was nt one time the i)rincipal method of capturing the
breeding salmon at Clackamas, and it worked very satisfactcn-ily. Fyke
nets and other fish-(;atcliing devices have been employed from time to
time, but have been rejected as unsatisfactory.
At Baird, before the rack was emi)loyed permanently, seine fishing
was usually begun after dark and continued throughout the night, but
Fi'.f Manual. ^ To face p.i>^e
Plate 7.
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MANUAL OF FISH-CULTURE. i)
since the rack has been in use the seine has been hauled more or less
in the daytime with perfectly satisfactory results, the fishing generally
commencing about 4.30 a. m. and continuing as long as the results war-
rant it. The work is resumed again about 5 o'clock in the afternoon
and continued as long as it meets with success.
CONSTRUCTION OF THE RACK.
This obstruction consists of a fence placed across the river and sup-
ported by piers heavy enough to prevent the force of the current from
pushing them out of position. Log stringers, from 8 to lo inches in
diameter, are laid from ])ier to pier, to which they are securely pinned,
and posts, from 2 to 4 inches in diameter and of the required length,
are driven obliquely into the bed of the river, the lower ends being 3
or 4 feet upstream, the upper ends resting on the stringers. Against
these posts is laid the rack, which is made in sections, each C to 10 feet
long, the slats which form them being IJ inches thick and 3 inches
wide, and securely braced at top and bottom. The slats are set 1^
inches apart, and are beveled on the upper side in order to present less
resistance to the current. The space between the slats allows ample
room for water to go through, but prevents any salmon from ascending.
A wider space between the slats would be i^referable, as creating less
obstruction to the current, but it would allow a considerable percent-
age of small grilse (the young salmon after its first leturn from the sea)
to get by the rack, and unless the older males are quite plentiful the
grilse are likely to be needed when the spawning season arrives.
The piers, when first made, are hollow triangles of heavy logs, each
layer of logs being firmly pinned to the one below it, until the required
height is reached, the apex of the triangle pointing upstream. They
are afterwards filled with rocks and are very substantial. Those on
the ^IcCloud have been able to withstand the tremendous momentum
of the current, even in the highest water.
TAKING AND IMPREGNATING THE EGGS.
After salmon are secured by the seine or other means, they are, for
convenience in handling, placed in pens or live boxes made for this
purpose, the ripe or nearly ripe males and females being kept separate.
Where the eggs are taken on a large scale, it is desirable to have
separate com]>artments for ripe males, ripe females, nearly ripe females,
and males partially spent that it may be necessary to use again, and
one or two spare compartments are found to be convenient where large
numbers of fish are handled.
Stripping the fish is usually done every day, as the eggs of the females
confined in the pens are likely to be injured within the fish, which is a
serious objection to keeping the parent fish in confinement any longer
than is absolutely necessary.
Of the signs that usually accompany ripeness in a female salmon,
the separation of the eggs in the ovaries is the surest, but the spawn-
10 KEPORT OF COMMISSIONER OF FISH AND FISHERIES.
taker relies rather on a jieneral ai)i)earance which is neither color,
shape, nor condition of organs, but which shows at a glance that the
fish is ripe and can be appreciated only by experience.
Spawning operations are conducted upon a floating platform, beneath
which are compartments for retaining the ripe fish, and which are
accessible through hinged covers set in the plank flooring. Projecting
beyond this platform is another, upon which the actual work of strip-
ping the fish and caring for the pans is performed.
When taking the eggs, one or two men stand ready with dip nets to
hand the females to the spawn -taker, and one or more perform the same
office with the males. After the salmon are taken from the pens they
are held suspended in the net until their violent struggles are over,
after which they become (piiet enough to be handled and the eggs and
milt can be expressed easily.
All methods of taking salmon si)awn are very much the same, there
being only slight differences in details, chiefly in the manner of holding
the parent fish and impregnating the eggs. Where there are plenty
of assistants and the salmon are of medium size, the most expeditious
way is for the man who takes the spawn to hold the female in one
hand and press out the eggs with the other, another in the meantime
holding the tail of the fish. The male is handled in the same way.
The above method is employed at Baird, but on the Columbia River,
where the salmon are larger and are harder to manage, the "strait-
jacket," as it is called, is used; this is a sort of a trough made about
the average length of the salmon and hollowed out to fit its general
shape. Across the lower end is a yermanent cleat, and at the upper end
is a strap with a buckle. The fish, when manipulated, is slid into the
trough, the tail going down below the cleat, where it is securely held,
and the head is buckled m at the upper end with the strap. It is now
unable to do any harm by its struggles and the eggs can be pressed
out at leisure. The strait-jacket is almost indisi)ensable with the very
large salmon and is a very great convenience when the operators are
limited in number.
In impregnating the eggs the main object is to bring the milt and
the eggs together as quickly as possible after they have left the fish.
By some persons a little water' is considered desirable to give greater
activity to the milt, but if left more than a minute in the water there
is a decided loss of fertilizing power. The eggs do not suffer so quickly
from immersion in water. The absorbing property which they possess
when they first leave the parent fish, and which attracts to the
micropyle the spermatozoa, lasts several minutes, but it is not prudent
to leave the eggs in the water a moment longer than is necessary before
adding the milt.
The addition of the water is not essential to a good impregnation;
in some instances better results are secured without the use of water
and, after all, if the main object is secured, of bringing the milt and
Fish Manual I To face page 10.'*
Plate 8.
TAKING SALMON EGGS AT LITTLE WHITE SALMON STATION.
FERTILIZING SALMON EGGS
SALMON IN STRAIT-JACKET.
MANUAL OF FISH-CULTURE. 11
the cjigs together with the slightest possible delay after they leave the
fish, it makes very little diflereiice whether water is used or not.
The milt retains its fertilizing power several days when kept fi'om air
and water, and impregnation can be effei^ted between fishes widely
separated by merely forwarding tlie milt properly sealed. At Baird
impregnation by the dry method, which has always been followed there,
has resulted in the fertilization of about DO per cent of the eggs so treated.
The llussiau or dry method of impregnating eggs consists simply in
taking both the eggs and the milt in a moist pan. It may be urged as
an objection to this method that the eggs will be injured by striking
against the pan, but it is a fact that although the same eggs would be
destroyed by the concussion a week later, or even 24 hours later, they
do not suffer in the least from it at the moment of extrusion from the
fish.
It was at one time considered an important question whether the
eggs or milt should be taken first, but with the dry method it makes
no dilference, as, either way, both eggs and milt remain operative long
enough for all practical purposes of impregnation.
Various methods of treating the eggs in the pan after impregnation
has taken place have been tried. Some operators leave the eggs in
the pans as first taken with the milt for two or three minutes and then
add water, after wiiicli they are left to stand in the pan until they
separate, when tiiey are washed clean, taken to tlie hatching-house, and
placed in the troughs. Others i)our the contents of the several pans —
eggs, milt, and all — into a large can after the eggs bec^ome impregnated,
and when the eggs separate the contents of the can are poured into the
hatching-troughs, trusting to the current in the troughs to wash the milt
from the eggs. At Baird, water is ])oured on the eggs a few moments
after they become impregnated, after which they are left perfectly quiet
until they separate, which in water of the temperature of the McCloud
River in September, 52° to 53°, takes about an hour. The pans, in the
meanwhile, are put in a trough filled with river water to keei) them
from becoming too warm. After the eggs separate they are carefully
washed and are carried in buckets to the hatching-house, where they
are measured and placed in the hatching-trays.
The methods of taking and fertilizing eggs atClackamas are as follows :
The female fish to be operated ui)on is taken from a fioating pen and
is placed in the spawning-box or " strait-jacket''; a male fish is then
caught and tied with a small ropearound its tail to some part of the corral
where he can be quickly caught when needed. One man presses the
eggs from the female securely held in the spawning-box, the pan for
receiving these being held by another. As soon as the eggs are taken,
the male is drawn from the pen by the rope and held by one man, who
takes it by the tail with his left hand, its head between or across his
knees. With his right hand the milt is then pressed from the fish
into the pan containing the eggs as soon as jwssible after they are taken.
12 REPORT OF COMMISSIONER OF I< ISH AND FISHERIES.
The eggs are taken in a pan without any water and milt enough is
used to insure its coining in couta(;t with each egg. After the eggs and
milt are obtained the pan is gently tilted from side to side and the mass
of eggs and milt stirred with the fingers until thoroughly mixed. The
pan is then filled about two-thirds full of water and left until the eggs
separate, the time varying from 1 to li hours, according to the number
of eggs and the condition of the atmosphere.
The eggs of the quinnat salmoti are of a deep salmon-red color and are
heavier than water. In size they average about n; or ,% of an inch,
from 12 to 18 being covered by a square inch. The number in a (]uart
is about ,■^,700. Probably 90 per cent of the eggs taken are impregnated
on an average, though the results vary with different seasons, places,
and methods of handling.
HATCHING APPARATUS AND METHODS.
The hatching apparatus generally emi)loyed on the Pacific coast in
salmon ])ropagation consists of a combination of troughs and baskets.
The troughs in common use are the so-called " Williamson troughs,"
which aie IG feet long, 1'2 or 16 inches wide, and (ii inches deej). The
troughs are arranged in pairs, and usually two or three pairs are placed
end to end on difl'erent levels. The fall of water in each trough is 1^
inches. The troughs are divided by double partitions of wood or metal
into compartments just enough longer than the baskets to enable the
latter to be raised and lowered and to be tilted slightly. The essential
feature of these troughs is that at the lower endof each compartment a
partition, extending entirely across the trough, reaches from the bottom
almost to the toj), and another similar partition at the upper end of the
compartment reaches from the top almost to the bottom of the trough,
each set of partitions being about an inch apart. The water is conse-
quently forced to fiow under the upper partition and over the lower
l)artition, and to do this it must necessarily ascend through the tray
of eggs. The troughs are x>rovided with canvas covers stretched upon
light frames, and made sunlight proof by saturation with asphaltum
varnish, and their interiors are thickly coated with asphaltum.
The egg receptacles are wire trays or baskets about 12 inches wide,
24 inches long, and deep enough' to project an incsh or two above the
water, which is 5 or 0 inches deep in the troughs in which they are
l)laced. Into each of these baskets 2 gallons of salmon eggs, equiva-
lent to about 30,000, are poured at a time. The eggs suffer no injury
whatever from being packed together in this manner, the water being
supplied in a way that forces it through the eggs, ])artially supporting
and circulating through them. The meshes are too small to permit the
eggs to pass through, although the fry are able to do so.
The advantages of this apparatus aiul method are:
(1) The top of the tray or basket is out of the Writer and always
entirely dry; consequently, in handling it, the hands are kept dry.
F's*^ M-in'j^!. ( T" f=irp p^iee 1 ?, ^
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MANUAL OF FISH-CULTURE. 13
(2) By tiltinii' one end of the tray up and down a little or by lifting
it entirely and settling it gently back again in its place the bad ('Hix^
will be forced to the top; thus a feather is not required in picking over
the eggs and the injuries very often inflicted with it are avoided.
(3) The top of the tray being above water, the eggs can never run
over the top nor escape in any way, which is a great advantage over
the shallow form of tray.
(4) There is economy of space; 30,000 to 40,000 eggs can be placed
in each basket, i)r()vided a sulticient (piantity of water is available.
Two troughs. 1(5 feet long and 1 foot wide, will by this method carry
about 500,000 salmon eggs. The deep trays may be filled at least half
full of eggs, and thus ten times as many eggs can be hatched in the same
space and with the same supply of water as by the old method. A
good bui gentle circulation is continually maiiitainerl through the eggs.
(5) The dee!)-tray system is admirably adapted to getting rid of nuid
that has collected on the eggs, for all sediment ac(!unnilating about
them can be easily removed by gently moving the tray up and down a
few times in the water; but if the deposit of mud on the troughs
becomes so excessive as to be unmanageable, a false l)ottom of wire
cloth or perforated zinc can be placed in the troughs at a suitable
distance al)Ove their real bottom, leaving a space of about 1 or l.j inches
between the wire cloth and the trough bottom. By this means the mud
that comes into the trough will sift down into the space below the wire
ch)th entirely out of the way of the tisli, the movements of the tish
themselves helping very much to produce this result. Should the
ac(;unuilation of mad in the space below tlie false bottom of the trough
become too great, it can easily be sluiced out in various ways.
When (luinnat-salraon eggs are simply to be matured for shi])ment,
hatching trays with i or i inch square mesh will answer the purpose,
but when the eggs are to be hatched in them, every alternate strand
of wire running lengthwise, or, better still, every second and third
thread should be left out in order to form an oblong mesh through which
the newly hatched fry, after separating themselves from the unhatched
eggs, can escape from the hatching trays into the trough below.
AtBaird eggs kept in water averaging about 54° F. hatch in 35 days.
The allowance of 5 days' difference in the time of hatching for each
degree of change in the water temperature is approximately correct.
For the first few days the eggs of the (juinnat salmon are very hardy,
and at this time they should be thoroughly picked over and the dead
ones removed as far as possible before the delicate stage during the
formation of the spinal column comes on, so that during that critical
period they may be left in perfect quiet. As soon as the spinal column
and the head show plainly, the eggs are hardy enough to ship, but when
there is time enough it is better to wait a day or two until the eye-spot
is distinctly visible, after which time the eggs will stand handling and
may be safely shipped if properly packed.
14 KEPOKT OF COMMISSIONER OF FISH AND FISHERIES.
PACKING EGGS FOR SHIPMENT.
The packing-box used in sluppinji- salmon eggs is made of i-inch
pine, 2 feet square and 1 foot deep. At the bottom is placed a thick
layer of moss, then a layer of raos(iuito netting, then a layer of eggs,
then mosijuito netting again, then successive layers of moss, netting,
eggs, netting, and so on to the middle of the box. Here a firm wooden
partition is fastened in and the packing renewed above in the same
manner as below. The cover is then laid on the top, and when two
boxes are ready they are placed in a wooden crate, made large enough
to allow a space of 3 inches on all sides of the boxes. This space is
tilled with hay to protect the eggs against changes of temperature, and
the cover being put on the eggs are ready to ship. In the middle of
the crate an open space about .4 inches in depth is left, between the
two boxes of eggs, for ice. As soon as the crates arrive at the railway
station this space, as well as the top of the crate, is filled in with ice.
Eecent experiments show that salmon eggs can be packed and safely
transported to considerable distances when they are iirst taken.
CARE OF THE FRY.
The eggs of quinnat salmon, like those of the other SalmonidcB, hatch
very gradually at tirst, only a small proportion of tish (;oming out the
first day; but the number increases daily until the climax is reached,
when large numbers of young burst their shells in a single day. At
this time gieat care and vigilance are required. The vast numbers of
shells rapidly clog up the guard-screens at the outlets of the troughs,
which should be kept as free as possible by thoroughly cleansing them
from time to time.
In the deep trays the newly hatched fish are mixed with unhatched
eggs, and the advantage of the oblong mesh in the bottom of the trays
be(;onies api)arent. This mesh is too narrow to allow the eggs to fall
through, but the hatched fish, being comparatively long and narrow,
easily slip down through the long meshes into the space below. They
should be assisted by gently raising and lowering the tray at intervals,
care being taken not to raise them out of the water, as at this tender
age a slight i»ressure against the wire of the tray will often produce
fatal injuries. On this account too much caution can not be exercised
in regard to handling them out of water during the first stages of the
yolk-sac period, for the injuries can not be seen at first, and often the
death of the fry is the first warning that they have been injured.
After the eggs are all hatched and the young fish are safely out of
the trays and in the bottom of the troughs, their dangers are few and
they require comparatively little care. Almost the only thing to be
guarded against now is suffocation. Even where there is an abun-
dance of water and room, with a good circulation, they often crowd
together in heaps or dig down under one another until some of them die
from want of running water which is not an inch away from them. The
best remedy in such a case is to thin them out.
Fish Manual. (To face page 14.)
Plate 10.
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MANUAL OF FISH-CULTUHE. 15
Eifiht thousand {jallous of water an lionr is sufficient for ten lines of
troujihs G4 feet in length, containing altogether a little over 1,000,()()0
young salinous iu the yolk-sac stage. This gives in round numbers
800 gallons of water to each 100,000 fry every hour, or 16| gallons per
minute, which is a safe minimum.
FEEDINCI AND PLANTING THE FRY.
When the yolk-sac has become nearly absorbed the fish rise from
the bottom of the trough, where they have previously remained, and
begin swimming. They are now almost ready for food and must be liber-
ated unless artificial food is i)rovided. As a rule the fry are planted
about the time the yolk-sac is absorbed. This is regarded as the best
practice, and moreover the amount of space required renders the rearing
of fry iu large numbers impracticable. They have, however, been suc-
cessfully retained in troughs in small numbers from the time they begin
to feed in February until the middle of May, when on account of the
rising temperature of the water they are liberated. They show when
they are ready to feed by darting to one side or the other when small
particles of food are dropped in the water iind Hoated past them. From
this time, for several weeks, the necessity for care and vigilance never
ceases. For the first few weeks they should be fed regularly and as
often as six times a day, and the earlier iu the day the feeding begins
and the later it continues at night the better. Two hours after feeding
the}^ will be found to be ravenously hungry, and they grow much faster
for frequent feeding and get that growth in their infancy which is
indispensable to their ultimately attaining the largest ])ossible size. If
not fed sufficiently they will bite at one another and cause more or less
mortality among themselves.
The best food for salmon fry is some kind of meat, finely pulverized.
Boiled liver is especially good for this purpose, partly because it is
inexpensive and easily obtainable, and also because it can be separated
into very fine particles. Raw liver is also excellent and may be reduced
into as fine particles as the cooked liver by grinding or chopping aud
then properly straining it through a fine-mesh screen. The yolk of
boiled eggs is also suitable, but is much more expensive than liver and
is not so good for the fish as liver, unless largely mixed with it.
As the fish grow older they continue to thrive best on meat food, but,
it that is not always obtainable in sufficient quantities or on account
of its expense, a very good substitute is a mixture of shorts or corn
meal with the meat. This is prepared as a mush by stirring shorts or
middlings into boiling water, a little at a time, so that it will not cook
in lumps, but become more of a paste. After it has thoroughly cooked
it is allowed to cool aud harden. The best proportion is 30 pounds of
shorts to 25 gallons of water with 3 or 4 pounds of salt. The per-
centage of liver to be used in this mixture should be regulated by the
age of the fish, feeding the very young fry upon almost a simple meat
diet aud gradually increasing the proportion of mush.
Fish Manual. (To face, page 17.)
Plate 11,
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THE ATLANTIC SALMON.
DESCRIPTION OF THE FISH.
The body of the Atlantic saliuoii {Salmo solar) is moderately elongate
and but little compressed; tlie greatest depth is about one-fourth the
total length without the caudal fin. The length of the head is about
equal to the body depth. The mouth is of moderate size, the maxillary
reaching just past the eye, its length contained 2i or 3 times in the
head. The scales are comparatively large, becoming embedded in adult
males; the number in the lateral line is about 120, with 23 above and
21 below that line. The dorsal fin has 11 rays and the anal 9 rays. The
pyloric coeca number about 05.
The color, like the form, varies with sex, age, food, and condition.
The adult is brownish above and silvery on the sides, with numerous
small black spots, often x or xx shaped, on the head, body, and fins,
and with red patches along the sides in the male. Young salmon (parrs)
have about 11 dusky crossbars, besides black and red spots.
RANGE.
The salmon native to the rivers of the northeastern United States is
specifically identical with the salmon of Europe and all the affluents of
the North Atlantic. Its original natural range in America appears to
have been from Labrador or Hudson Bay on the north to the vicinity of
New York on the south. Within these limits, at the ])roper season of the
year, it ascended, for the purpose of reproduction, nearly every river
except those that did not attbrd the requisite facilities for depositing
spawn or were inaccessible by reason of impassable falls near their
mouths.
In American rivers frequented by Atlantic salmon they were found
successively in all parts from the mouth upw ard, their migrations extend-
ing nearly to the headwaters of all the branches so far as they were
accessible and adapted to their necessities. The one exception is the
liver St. Lawrence, where it seems probable, from such evidence as is
available, that few if any salmon entering the river from the sea ever
ascended as far as Lake Ontario, and that the salmoninhabiting that lake
and its tributaries have always, as a rule, made the lake their sea and
the limit of their downward migrations. Within or partly within the
limits of the United States there can be enumerated twenty-eight rivers
that were beyond doubt naturally frequented by salmon, beginning with
F. M. 3 17
18 REPORT OF COxMMlSSIONER OF FISH AND FISHERIES.
the St. Joliii and ending" with the Housatonic* In the greater part
of these the species has been exterminated by civilized man, and in
the few in which it still i^ersists its numbers are fiir below the estimates
which the earliest records warrant us in making for those days.
In certain lakes of Maine and northward this fish is i^erfectly land-
locked and has somewhat different habits and coloration, but no distinct
specific characters. Similar landlocked varieties occur in Europe.
LIFE AND HABITS.
Salmon eggs are deposited on coarse gravel on some rapid, generally
far up toward the sources of a river, late in October or early in Novem-
ber, when the water is perhaps about 44° F. and the temperature is
falling. The Ggg is impregnated at the moment of its deposit, and the
independent life of the salmon begins to develop at once. In a few
weeks the embryo becomes sensitive, but the extreme cold of the water
retards its development to such an extent that it does not burst the
shell of the egg until spring. In the rivers of New England it is prob-
able that nearly all tlie eggs naturally deposited hatch very late in
Aj^ril and early in May. At this time the embryo salmon has a slender
half-transparent trunk, less than an inch in length, carrying, susjiended
beneath, an immense ovoid sac — the " yolk-sac." For about six weeks
jifter hatching it hides in crevices among stones, keeping up an inces-
sant fanning with its i)ectoral fins. During this period it takes no food,
but is supported and nourished by the yolk-sac, the substance of which
is gradually absorbed into the rest of the body, and not until the sac
has nearly disappeared does the salmon really look like a fish and begin
to seize and swallow food. It now i^uts on a mottled coat, with several
heavy dark bars across its sides, and bright red spots, larger and fewer
than those of a trout, looking therefore very unlike the adult salmon
but much like a young trout. In this stage it is termed, in Scotland
and England, a '' parr," and it was formerly thought to be a wholly
different species from salmon.
The parr stage lasts a year or two in British rivers, and the few
observations made in America indicate that it is more likely two years
than one in our rivers. The parr, at first but little over an inch in
length, is provided with good teeth and a good appetite, and beginning
to feed at a season of the year when the water is almost crowded with
small insects and other more minute creatures, it grows rapidly, jjrob-
ably increasing its weight thirty or forty times the first summer. In
two years it reaches the length of 6 or 8 inches, and its bright red
spots and dark bars have given place to a silvery coat like the adult
salmon. It is now termed a "smolt" and is ready to go to sea, which
it does with little delay, and passes out beyond the range of man's
*The Hudsou River is by some believed to have been a natural salmon river. Its
discoverer, IlcDdrik irnd-^oii, reported having observed them there, and there is
nothing inherently improbable in it, but the evidence is perhaps insufficient.
MANUAL OF FISH-CULTUKE. 19
observation, but to a region where it finds a rich feeding-ground and
rapidly increases in size.* In northern rivers, tlioseof New IJrunswick
and beyond, as in those of northern Europe, the salmon returns from
the sea when it has attained a Aveight of 2 to 0 pounds, and is tlieu
termed a "grilse."
In the rivers of Canada, in general, grilse occur in great numbers,
coming in from the sea at a later date than the adults, but ascending
like them to the ui)per waters, mingling freely with them, rising to the
same fly, and caught in the same weirs. The mesh of the nets is limited
by law to a size that takes the adult salmon, but allows the grilse to
slip through. To this circumstance it is in part owing that by the
time the fish have reached those portions of the rivers suitable for
angling there is commonly, if it be late enough in the season, a great
preponderance of grilse, so that more of the latter than of the former
are taken by the angler. In Nova Scotia many grilse are taken in the
Shubenacadie River from August until late in the fall. On the Mirami-
chi, in New Brunswick, grilse nuike their appearance about July 1, and
from the middle of that month till the end of August they (constitute
the main body of the salmon entering the river. Some sportsmen
report that the grilse caught exceed the adults in the ratio of 5 to 1.
In the month of August, in the Nepissiguit, Restigouche, and St.
John of (raspc, grilse have been found in some years to exceed the
adults m the ratio of 3 to 1. They run into the Nepissiguit mostly
between July 25 and September 1. Their scarcity during the early part
of the angling season, or say i)revious to July 20, is attested by numer-
ous fishing scores. A series of scores of salmon fishing in the Godbout
River, on the north side of the St. Lawrence, shows that previous to
July 15 or 20 the adult salmon taken with the fly in that river exceed
the grilse in the ratio of 10 to 1 or more.
In our rivers grilse are seldom seen, and only 3 or 4 are taken per year
in a weir in the St. Croix, which takes about 70 adults. In the Dennys
River the ratio of grilse to salmon caught is not more than 1 tooOO, and
in the Penobscot they are quite as rare. Adult salmon running in this
river several weeks earlier than in those of eastern New Brunswick, we
* There has been considerable disciissiou ou this point, and the conclusions of some
observers arc at variance with the above statement. In Scotland many years ago it
seemed to be well established l)y tlie observations of Biiist that a portion of the young
salmon ]tut on the silvery coat and went to sea at the age of one year, but that otiiers
of the same broo<l did not get readj' to go until two years old. American observa-
tions, however, tend strongly to the conclusion that tiie young salmon passes two
whole summers in the river, going out to sea in tbe autumn following its second
summer or the next spring. It is not probable that the seaward migration is
restricted in any river to any exact jieriod of a few weeks duration, but that it
extends over many mouths, some of tlie young salmon, by reason of 8uj)crior native
vigor of growth or from other e(iually efficient cause, attaining the migratoi'y stage
months earlier than others of the same brood.
It is the ojjinion of one .\iueri<;m observer that salmon fry remain in the streams
until October of the second year before going to sea, and that they do not go down
until the spring of the third year; i. e., wlieti they are two years old; though some
may go down the fall of the second year; and that the salmon do not return until
they are four years old.
20 REPOKT OF COMMISSIONER OF FISH AND FISHERIES.
should naturally exi)e(tt the advent of grilse early in July in considerable
nunibeis; but some of the weirs are often kept in operation until the
middle or last of July, and sometimes even through August, when they
take menhaden; but no grilse enter them. During the latter ])ait of the
summer the water at the several falls between Bangor and Oldtown is
generally at a low stage, and the attempt of grilse, even in small num-
bers, to ascend the river could hardly fail to be frequently detected.
A similar state of things exists in the Kennebec. There is no escaping
the conclusion that the great run of grilse, which is so prominent a fea-
ture in the history of the salmon of northern rivers, is almost entirely
wanting in the rivers of the United States. It by no means follows from
this that our salmon do not pass through the same phases of growth, or
that the growth is more rapid, but merely that when in the grilse stage
they generally lack the instinct that impels their more northern relatives
to seek fresh water.
Of the characteristics of grilse, as ascertained in the rivers they
frequent, it will be sufficient to say that they exhibit to a great degree
the characteristics of the adult; that the main external differences
are a shorter head, slenderer form, and a difference in the color and
markings; that they are remarkably active and agile, leaping to great
heights; that the male is sexually well developed and mates with the
adult, but that the female is imnmture, and that, like the adult, they
abstain from food and consequently lose flesh during their stay in fresh
water.
The next stage of life of the fish is that of the adult salmon, and this
is the stage at which, with the exceptions indicated above, the Atlantic
salmon first ascends the rivers of the United States. Assuming that it
relinquished the rivers for the sea at the age of two years, being then
a smolt, it has been absent two years, and it is now four years or a little
more since it burst the shell. Tins estimate of age is based on the
observations made by the Massachusetts commissioners of fisheries
on the return of salmon to the Merrimac River, which plainly estab-
lished the fact that the entire period between the hatching of the fry
and the return of the adult to the rivers is about four years., Whether
the same rule holds in other New England rivers can not as yet be
established, owing to deficient data, but the presumption is in favor of
that conclusion. In Canadian rivers the same period of growth appears
to be the universal rule, at least as far north as the St. Lawrence River.
Statistics of the catch of salmon for many years in eighteen separate
districts, showing many fluctuations, exhibit a remarkable tendency of
the figures to arrange themselves in periods of five years; thus, the
year 1875 having been a year of small catch of salmon, it also appears
in most of the districts that the next year of abnormally small catch
was 1880. Now, the eggs laid in 1875 would hatch in 187(5, and the
young hatched at that time would be grown m 1880, requiring thus
four years from hatching to maturity, just as on the Merrimac. It
would seem no other interpretation can be put upon tlie statistics.
Fish Manual. (To face page 20
Plate 12.
ENTRANCE TO DEAD BROOK INCLOSURE FOR SALMON.
DEAD BROOK INCLOSURE FOR ATLANTIC SALMON, SHOWING PENS.
MANUAL OF FISH -CULTURE. 21
EARLY SALMON-CULTURE ON THE PENOBSCOT RIVER.
The movement for the reestablish meiit of tbe fisheries for salmou,
shad, and other aiiadromous species iu American rivers originated in
the action of the legislatures of New Hampshire and Massachusetts,
having in view ])rimari]y the fisheries of the Merrimac and Connecti-
cut rivers. The course of the Connecticut lies partly in the State of
Connecticut, while many of its tributaries are in the State of Vermont,
and these two States were therefore early interested in the project, and
their action soon led to a similar movement on the part of Rhode Island
and ]\Iaine. The rivers within the borders of these six States are the
only ones in the United States known to have been frequented by the
seagoing ISalmo salar, except possibly the Hudson and certain rivers
tributary to the St. Lawrence, in the northern part of New York.
The commissioners to whom the governments of the above States
confided the task of restocking the exhausted rivers turned their
attention at once to the two most important of the migratory fishes, the
salmon and the shad. The utter extermination of salmon from most
of the rivers comi)elling the commissioners to consider the best mode of
introducing them from abroad, eggs were obtained for a time from the
spawning- beds in the rivers of Canada and hatched with a measure of
success. After a few seasons permits for such operations were discon-
tinued, and it became essential to look elsewhere for a supply of salmon
ova. In 1870 attention was directed to the Penobscot lliver, in the
State of ]\Iaine, which, though very unproductive compared with Cana-
dian rivers, might yet, perhaps, be made to yield the requisite quantity
of spawn. The fisheries are all in the lower part of the river and in
the estuary into which it empties, Penobscot Bay, and there the supply
of adult salmou could be found with certainty, but they must be obtained
from the ordinary salmon fisheries in June and held in durance until
October or November, and the possibility of confining them without
intei'fering seriously with the normal action of their reproductive func-
tions was not yet established.
This plan was finally adopted, and in 1871 this method of breeding
salmon was first attempted. For the purpose of the experiment, a
point at the mouth of Craig Brook, which is by water nearly 9 miles
distant from the mouth of the Penobscot River, more than half the
route being through brackish water, was selected as the most conven-
ient fresh-water stream which offered facilities for confining the salmon
and maturing their eggs. After some unsuccessful trials means were
found of safely conveying a few live salmon in floating cars from the
fishing-grounds to the station, where they were held till the spawning
season, when their eggs were taken and impregnated.
From 1872 to 1870 operations were conducted on a larger scale, with
a fair degree of success, and, after a suspension, were resumed in 1879
at Craig Brook hatchery, while the retaining inclosures were located
in Dead Brook, about '2 miles distant. The disadvantage of this
22 KEPORT OF COMMISSIONER OF FISH AND FISHERIES.
distance between tlie hatchery and retaining-ponds was oiftset by other
advantajijeous conditions.
lintil 1<S8() no attenii)t was made to rear salmon, and witli unimpor-
tant exceptions the work was confined to the collection of salmon eggs,
their development during the earlier stages, and their transfer in winter
to other stations to be hatched. Tn 1889, however, the United States
Fish Commissioner decided to establish a permanent station at Craig
]'rook, and in anticipation of the i)urchase of the premises, which was
concluded the following year, the rearing of salmon to the age of six or
seven months was undertaken as the leading work of the station.
WATER FOR A SALMON HATCHERY.
The first requisite for a salmon hatchery is an ample supply of suit-
able water, on a site where it can be brought comjiletely under control
and the requisite fall secured. In this matter there is quite a range of
choice. The very best is the water from a stream fed by a clean lake of
considerable depth, taken a short distance below the outlet of the lake,
with an intervening rapid. Craig Pond may be taken as an examjde of
such a lake. It has an area of 231 acres, an extreme depth of G9 feet,
and a depth of 25 feet within 500 feet of the outlet. The depth directly
intiuences the temperature and, other things being equal, a deep lake
will afford water more uniform in temperature than a shallow (me — cooler
in summer and warmer, though never too warm, in winter. Such water
is commonly quite even in volume and temi)erature, and comi)aratively
pure. It IS cold in winter and warms up slovvly in spring, assuring a
slow, normal development of the eggs, which is more conducive to
health and vigor than a quicker development. The passage down a
rapid will further improve this water by charging it highly with air.
After this, the water of a brook is to be chosen that is fed largely by
springs, so as to insure constancy in the supply and some moderation
of the temperature on warm days, but it is better to have the water
flow a long distance in an open channel before using, and, if possible,
over a rough and descending bed, that it may be well aerated, and in
cold weather somewhat cooled down from the temperature with which
it springs from the ground.
The next best is pure spring wat6r; but in all cases where this is
used a cooling and aerating pond is necessary, that the original warmth
of the water may be subdued by the cold of the air before it reaches
the hatching troughs, and that it may absorb more or less air by its
wide surface.
Lastly, choose ordinary river or brook water, as clean as possible.
These are inferior to spring water by reason of liability to floods,
drought, muddiness, and foulness of other sorts, and in cold climates
to anchor ice.
Between these different sorts there is of course an infinite number of
gradations. If lake water can not be obtained it would be of some
Fish Manual. (To face page 22.)
Plate 13.
SALMON LIVE-CAR USED IN TRANSPORTING FISH FROM WEIRS TO DEAD BROOK.
SALMON LIVE-CARS EN ROUTE V^'ITH FISH.
MANUAL OF FISH-CULTURE. 23
advantage to liave a su])ply of hotli spring water and brook water,
depending for ordinary use on the brook water or a mixture of tlie two,
and on the spring water for emergencies, such as the freezing, drying,
or excessive heating of the brook, Hoods with accompanying niuddiness,
etc. Water coming from boggy and stagnant ponds and marshes is
objectionable; for though excellent water, capable of bringing out the
nu)st vigorous of fish, may sometimes be had in such places, yet when
not sui)plied by springs it is dependent for its freshness and good qual-
ities on rainfalls, and if these fail, as they are liable to, the water nmy
become foul and unfit. It must be borne in mind that these remarks
about the selection of water for fish-cultural purposes apply only to the
culture of Atlantic or landlocked salmon, in a climate like that of the
State of Maine.
It is best to select a site for a hatching establishment in time of
extreme drought, and if it then has an ample supi)ly of pure, sweet
water the first requisites are fulfilled. It is well also to visit the place
in time of flood and, if in a cold climate, in severe winter weather,
to learn the dangers to be guarded against on those scores. The
volume of water necessary will depend mainly on the i)roposed capacity
of the establishment, the temperature of the water, its character as to
aeration, and the facilities existing for the aeration and repeated use
of the water. With water of the highest quality and low temperature,
and with unlimited facilities for aeration, possibly a gallon a minute,
or even less, can be made to answer for the incubation of 100,000 eggs
of salmon. As the temperature rise^ or the facilities for aeration are
curtailed a larger volume becomes necessary. In case of spring water,
cooled only to 40° and aerated only by exposure to air in a pool of about
a square rod surface, with no facilities in the house for aeration, and
with the eggs and fry crowded in the troughs at the rate of 4,000 per
square foot, 4 gallons a minute is the least that can be allowed, while
6, 8, or 10 gallons per minute are better. While the minimum is, as
stated above, possibly less than a gallon a minute, it is not advisable
to trust to less than 3 gallons per minute for each 100,000 eggs under
the most favorable circumstances.
If the water supply is drawn from a small brook or spring, it is neces-
sary to measure the volume approximately, which is easily done, in the
following manner: With a wide board I inch thick, having a smooth
inch hole bored through the middle, a tight dam is made across the
stream so that all the water will have to How through the hole. If the
water on the upper side rises just to the top of the hole, it indicates a
volume of 2.3 gallons per minute; a rise of half an inch above the top
of the hole indicates a volume of 3.5 gallons per minute; 2 inches rise, 5
gallons per minute; 3 inches, G gallons per minute; 6 inches, 8 gallons
per minute; 13 inches, 12 gallons per minute. If two 1-inch holes are
bored, the same will, of course, indicate twice the volume. The volume
of water flowing through holes of different sizes is in proportion to the
24 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
squares of their diameters; thus a 2-iucli bole permits the passage of
four times as much as a 1-inch hole. A tube whose length is three
times its diameter will allow 21> per cent more water to i)ass than a hole
of the same diameter through a thin plate or board.
SITE.
After a satisfactory supply of water is found a site for the hatching-
house must be selected that affords facilities for creating a head of
water to provide for the reijuisite fall into and through the troughs,
security against inundation, security against too much freezing if in a
cold climate, and, finally, general safety and accessibilit}'. The fall
re(iuired in the hatching-house can hardly be too great. The minimum
is as low as 3 inches, but only under the most favorable circumstances
in other respects will this answer, and even then it is only admissible
where there is an ample sui)pl3^ of aerated water and the troughs are
very short and there is absolutely no danger of inundation; and this
fall has the disadvantages of the impracticability of introducing any
aerating apparatus and the necessity of having the troughs sunk below
the floor of the hatching-house, Avhich makes the work of attending the
eggs and fish very laborious.
A fall of 1 foot will do fairly well if there is entire safety from inun-
dation, as this will permit the troughs being placed on the floor, which
is a better ])osition than below it, though still an inconvenient one,
and some of the simpler aerating devices can be introduced. Better is
a fall of 3 feet, and far better a fall of G feet. The latter ])ermits the
placing of the lowest hatching-troughs 2 feet above the floor and leaves
ample room for com])lete aeration. The necessities of the case are
dependent largely upon the volume and character of the water, and
if there is plenty of it, well aerated before reaching the hatching-house,
there is no occasion, in a small establishment, of additional aeration in
the house, and therefore no need of more than 3 feet fall.
Inspection of the premises at time of floods will suggest the safe-
guards necessary to provide against inundation. If located by a brook-
side, the hatching-house should not obtrude too much on the channel,
and below the house there should be an ample outlet for everything that
may come. By clearing out and enlarging a natural watercourse much
can often be done to improve an originally bad site.
In a cold climate it is an excellent plan to have the hatching-house
partly under ground, for greater protection against outside cold. When
spring water is used there is rarely any trouble, even in a cool house,
from the formation of ice in the troughs; but water from lake, river, or
brook is, in the latitude of the northern tier of States, so cold in winter
that if the air of the hatching house is allowed to remain nuich below
the freezing-point ice will form in the troughs and on the floor to such
an extent as to be a serious annoyance, and if not watched will form
in the hatching-troughs so deeply as to freeze the eggs and destroy
MANUAL, OF FlSlI-CUl/rURE. 25
them, stoves are needed in sucli climates to warm the air enough
for the comfort of the attendants; but the liouse sliouhl be so located
and constructed that it may be left without a tire for weeks without
any dangerous accumulation of ice, and if the site does not permit of
building the house partly under ground the walls nuist be thoroughly
constructed and banked well with earth, sawdust, or other material.
In warmer climates no trouble will be experienced from this source.
DAMS AND CONDUITS.
The reciuisite head of water can often be had by throwing a dam
across the stream and locating the hatching-house close to it. The
dam will forni a small pond wliich will serve the triple purpose of cool-
ing, aerating, and cleansing tlie water. But unless the bed and the
banks of the stream are of such character as to preclude any danger
of undermining or washing out the ends of the dam, it is best not to
undertake to raise a great head in this way. With any bottom except
one of solid ledge there is always great danger, and to guard against
it when the dam is more than 2 feet high may be very troublesome. If
there is a scarcity of water, or if it is desirable, for aerating or other
purposes, to secure a considerable fall, it is better to construct the dam
at some distance above the hatching-house, on higher ground, where a
very low dam will suffice to turn the water into a conduit which will
lead it into the hatching-house at the desired height.
A sciuare conduit made of boards or planks, carefully jointed and
nailed, is in nearly all cases perfectly satisfactory, and for an ordinary
establishment a very small one will suffice.
The volume of water that will flow through a pipe of a given form
depends upon its size and the inclination at which it is laid. A straight
cylindrical pipe, 1 inch in diameter, inclined 1 foot in 10, conveys about
11 gallons of water per minute. The same pipe, with an inclination
of 1 in 20, conveys 8 gallons per minute; with an inclination of 1 in
100, it conveys 3i gallons per minute; with an inclination of 1 in 1,000,
it conveys 1 gallon per minute. A 2-inch pipe conveys about 5^ times
as much water as an inch pipe; a 3-inch pipe nearly 15 times as much.
A 1-inch ])ipe, with an inclination of 1 in 1,000, conveys water enough
for hatching 25,000 eggs; with an inclination of 1 in 50, enough for
100,000 eggs; with an inclination of 1 in 20, enough for nearly 200,000
eggs. A square conduit conveys one-quarter more water than a cylin-
drical pipe of the same diameter. If there are any angles or abrupt
bends in the pipe, its capacity will be considerably reduced. It should
be remembered that if the water completely tills the aqueduct it is
entirely shut out from contact with the air during its passage, whereas
if the pipe is larger than the water can fill, the remainder of the space
will be occupied by air, of which the water, rushing down the incline,
will absorb a considerable volume and be greatly imi)roved. It is
therefore much better to make the conduit twice or thrice the size
26 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
deinaiided by the required volume of water. If tlie bottom and sides
are rougli, so as to break ui) the water, so much the better, and the
wider the conduit is the more surface does the water i)resent to the air.
AERATION.
The water which fishes breathe is but the medium lor the conveyance
of air, which is the real vivifying agent, without which tish and eggs
will die, and with a scanty supply of which the proper development of
the growing embryo is imi)0!^sible. Water readily absorbs air when-
ever it conies in contact with it, and the more intimate and the longer
continued the contact the greater the voluiue it will absorb. The ample
aeration of the water to be used in the hatching-house has already been
mentioned as a desideratum of the first importance, and some of the
devices by which it is to be secured have been alluded to.
Water from either a brook or a river that has been torn into froth by
dashing down a steep bed has absorbed all the air that is needed in 10
or 20 feet of hatching-trough, and demands no further attention on this
score; but if the water is taken from a lake, a spring, or a quiet brook
it contains less air, which may be so reduced before it gets through the
hatching- house as to be unable to do its proper work. It is therefore
desirable to adopt all practicable means of reinforcing it. If the site
of the hatching-house commands a fall of 5 feet or more, the object
may be attained by contriving in the conduit outside the house, or in
the hatching-troughs themselves, a series of miniature cascades.
The broader and thinner the sheet of water the more thoroughly it is
exposed to the air, and if, instead of being allowed to trickle down tlie
face of a perpendicular board, it is carried off so that it must fall free
through the air, both surfaces of the sheet are exposed and the effect
is doubled. When circumstances permit, it is best to aerate in the
conduit, whi(;h, as already suggested, may be made wide and open for
that i)uri)Ose.
If aeration can not be effected outside the house it may be done
inside by arranging two long troughs side by side, leveled carefully,
so that the water is received in one of them and poured over into the
other in a sheet the whole length of the trough. In the hatching-
troughs themselves there is an opportunity for aeration, either by
making short troughs with a fall from one to another or by inclining the
troughs and creating falls at regular distances by partitions or dams,
each witli its cascade, after the fashion already described. The only
serious difficulty is encountered where the ground is very flat, so that
tlie requisite fall can not be obtained, and in this case the best that
can be done is to make a very large pool, several square rods at least,
outside the house, and make all the conduits as wide as possible, so
that the water shall flow in a wide and shallow stream.
It will of couise be borne in mind that the better the aeration the
smaller the volume required to do a given work, and ou the other hand
MANUAL OF FISH-CULTURE.
27
it is equally true that the greater the volume the less aeration is
necessary. When so large a volume as 6 gallons ])er minute for every
100, 00 eggs is at command, a comparatively small amount of aeration
will answer. But, so far as known, the higher the degree of aeration
the better the result, without limit, other things being equal, and it is
therefore advised to make use of all the facilities existing for this
purpose.
FILTERING.
Before the introduction of wire or glass trays for hatching fish eggs
it was customary to lay them on gravel, and it was then absolutely
necessary to filter all but tlie i)urest water. Even ordinary spring
water deposits a very considerable sediment, which might accumulate
upon the eggs to such an extent as to deprive them of a change of
a, cordnit from brook.
b, gate, swiiigiug on pivot at c, to change
direction of water.
d, direct branch of conduit.
f, reverse branch of conduit.
/,/, etc.. a single long compartment for untiltered
water.
g, g, etc., compartments occupied by gravel.
Gravel Filter.
/i, a .single long compartment for tiltered water.
i,j, racks to hold gravel in place.
i is in 5 sections, movable, and can be taken out
when gr.arel is to be renewed.
k, I, sluices near bottom for cleaning out.
m, wasteway.
n, aqueduct to hatchery.
water and smother and destroy them. When, however, eggs are depos-
ited on trays arranged for a circulation of water beneath, as well as over
them, as described below, even though their upper sides are covered
with sediment, tliey are clean and brigiit underneatli and remain in
communication with tlie water beneath the tray, though of course the
circulation of the water through the tray is not perfect. It is not,
therefore, deemed necessary to introduce any considerable devices for
filtering water which is naturally very pure, like lake and spring water
when not subject to intermixture with surface water during rains; but
where it is necessary to use water subject to constant or occasional
turbidness some method of filtering is indispensable.
In the majority of cases at least a portion of the water supply is
obtained from an open brook, lake, or pond, and measures must be taken
28 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
to get rid of the leaves and other coarse rubbish brought down by the
stream or conduit. A great deal of such material is encountered in a
stream at all seasons of the year, but during the fall and early winter
it is especially abundant, and to secure entire vsafety from a stoppage of
the water, and consequent loss, a screen on a generous scale must be
provided.
A description of the means adopted at this station for providing a
temporary extra water service of several hundred gallons per minute,
taken from Craig Brook, will serve as an illustration : A tank or vat,
12 feet sq[uare and about 2 feet deep, is built in the bed of the brook
with a tight dam of stones, gravel, loam, and leaves (these to stop
small leaks) running asliore on either side, so that the entire volume of
the brook passes over the tank. The bottom and sides are tight and
strong, and both bottom and top are inclined about G inches down the
stream. The cover is of si)ruce lumber sawed 1^ inches scpiare and
nailed on in the direction of the current, with interstices open half an
inch ; when in operation the water fills the tank and runs over the lower
edge, which is raised enough to maintain a depth of several inches over
nearly the whole tank. All leaves and other materials floating near the
surface of the water are carried over, together with most rubbish which
floats deep. At one of the lower corners of the tank, near the bottom,
is a gate about 15 inches square, which is hung by hinges on its upper
side. It opens inward, and is closed tightly by the pressure of the
water : but it can be easily" opened by pushing with a pole from without,
and then serves as a floodgate, whereby the tank may be thoroughly
cleaned out.
At the other lower corner is a conduit, G by 9 inches, which takes
from this "leaf-screen" a supply of water not entirely free from rubbish,
but so nearly so that a filter of moderate capacity can co^je with what
remains. A very useful adjunct would be a second horizontal screen
of similar construction, through which the water that has passed down-
ward through the first screen, as described, should next i)ass upward
through the second; the first screen would remove floating debris, the
second such as is heavier than water.
The filter, situated about 70 feet from the leaf-screen, consists of a
wooden flume, 12 feet long and 4 feet deep, divided lengthwise into three
comi)artments, of which the central contains fine gravel held in i)lace
by a rack on either hand, of which the interstices are i inch wide and
1^ inches apart. The water from the leaf-screen is introduced into one
of the lateral com])artments, and filters through the gravel into the
opposite compartment, from which it is taken by a plank aqueduct, G
by G inches, to the hatchery. Under the conditions described, and with
a fall of about 1 foot from supply to discharge, this filter discharges
over 300 gallons of watei' per minute into the aqueduct — water not abso-
lutely pure, but sufficiently free from coarse dirt for the purpose.
In many cases, where small qjiantities of water are used, it is custo-
MANUAL OF FISlI-CUl/rUHE.
29
mary to filter through thinnel screens iu the hatchery, and such filters
do very good service. They can be introduced into (he egg-troughs,
or by running them lengthwise of a trough a very large volume of
water can be filtered.
PLAN.
n n □ CI
;■■'■■■ -I
Scale of feet.
Wire Filter.
A form of filter that has given good satisfaction at the Craig Brook
station through five years of service consists of a series of graduated
wire screens, through which the water passes upward, first through
the coarser and tlieu tlirougli the finer screens, with provision for the
30 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
reversal of the curreut for cleaning purposes. By refereuce to the cut
on page -59, it will be seen that the water is brought to the filter through
a i)lank eonduit, and is aihnitted to the filter through either of two
gates that swing on hinges, one for the direct fiow and the other for the
reversal. The direct flow is first into a receiving chamber, which
extends under the screens, then upward through the whole series and
out at the top, overflowing into a catch-trough, from which it is dis-
tributed as desired. In cleansing, the supply-gate is closed and the
other one opened, and at the same time the sluice-gate at the bottom is
opened; the water then flows in fnll volume upon the screens and down
through them, carrying all the intercepted debris into the lower cham-
ber and out through the sluice-gate.
The wire filter illustrated has to pass some 500 gallons of water per
minute, and has three screen -boxes, each of which carries 5 to 7 screens
about 2 feet wide and 4 feet long; the meshes are from 2 inches down
to j^ inch s<iuare, and therefore intercept all coarse debris.
It is but the work of a few moments to reverse the current and
thoroughly cleanse the screens; when the autumn leaves are falling
this must be done several times a day, but at other seasons some days
elapse between the cleanings. The wire— even galvanized — rusts out
in two or three years, and lately the coarser screens have been n)ade
of slender rods of oak, which will undoubtedly prove more durable.
Noueof the filters described will intercept the finest sediment, and
the water is finally passed through a capacious wooden reservoir, 30
feet loug, S feet wide, and 5i feet deep, before it reaches the troughs.
This answers the i)urpose well for the amount of water supplied by the
filter last described (about 500 gallous per minute) and is regarded as
well worth having, though even this will not insure limpidity in the
water when the brook is swollen by rains.
It may be mentioned that this reservoir is kept brimful at all times,
so that all portions of the woodwork, except the railing surrounding it,
are kept continuously wet and thus insured against decay for a very
long period of years.
CRAIG BROOK HATCHERY AND ITS EQUIPMENT.
The Craig Brook hatchery derives its water supply from the brook,
which has its source in Craig Pond, but which receives iu the lower
part of its course many copious springs. This spring water has some
advantages, but i)ossesses the serious disadvantage of such higli tem-
perature in winter as to unduly hasten the development of the eggs,
causing them to hatch early and necessitating shipments of eggs iu
December.
Accordingly, an aqueduct from a point on the brook above the springs
brings to the hatchery a supply of cold water for winter use, in which
eggs taken the first of November will not hatch until the following
April. This is important, as, if the product of the season's hatching
is to be liberated as fry, the late date of hatching will bring them
to the feeding stage about the time when suitable food abounds in
Fish Manual. (To face page 30.)
Plate 14.
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MANUAL OF FISll-CULTURE. 31
open watervS, and if they are to be reared it is well to shorten up
the sac-stage and to have the early feeding stage fall at a date when
the temperature of the water is rapidly rising, which will get the fish
(piickly through that most difficult of all stages of growth.
The aqueduct is about l,(iOO feet long, with a bore 4^ inches, and has
a nearly uniform descent and total freedom from depressions, and is
from end to end one single piece of cement concrete. It delivers to the
hatchery about 100 gallons of w^ater per minute, which is sufficient for
the development of 4,000,000 eggs, and i)Ossibly many more. It was
built in place around a slightly tapering core, which was drawn forward
as fast as the mortar set, and it has now done good service for seven-
teen years. By this means the temperature of the hatchery water is
maintained 3° below that of the brook modified by the springs. During
the five months from November 1, 1S95, to April 1, 1890, the mean tem-
perature in the hatchery was SG.O.jO p_
COLLECTION OF STOCK SALMON.
The only salmon fisheries available for the purpose of supplying Craig
Brook station with breeding fish are those carried on by weirs about
the mouth of the Penobscot. Arrangements are made early in the
season with weir fishermen to save their salmon alive and deliver them
daily to the collecting agent of the station, who makes the rounds of
the district about low water with a small steamer, which tows the cars
containing the fish on the flood-tide to Orland village, where they are
passed through the lock about high water and taken by a crew of oars-
men to the inclosure at Dead Brook.
In anticipation of this work, the fisherman places the floor of his
weir a little lower than he would otherwise do, so that at low water the
salmou may have water to swim in instead of being left high and dry
by the retreating tide, in case of an accidental delay or failure to visit
the weir at the usual hour. It is, however, the ordinary practice to
take the salmon out at each "fish-tide," i. e., low water, and place them
in a car. Cars enough are stationed among the fishermen to bring one
at least in each neighborhood, and in most cases the car is brought
alongside and the salmon transferred to it directly from the weir,
though in some cases it is necessary to ])lace the salmon first in a box,
in which it is carried by a boat to the car. The car employed is made
from the common dory, divided transversely into three compartments.
The central one, which is much the larger, is occupied by the fish, and
is smoothly lined with thin boards and covered with a net to prevent
the fish jumping out or being lost by the car capsizing, which some-
times occurs, while to guard them from fright and the rays of the sun
a canvas cover is drawn over all.
The first cars of this form had iron gratings to separate the central
from the forward and after compartments, the water being admitted
through the forward and discharged through the after coni[)artment,
but this Avas objectionable because the salmon were constantly seeking
32 KEl'OllT OF COMMir-;SIONER OF FISH AND FISHERIES.
to escape lluough the forward grating, and often injured themselves by
rushing against it. Smooth wooden gratings were afterwards used and
for many years cars were emi)h)yed in which the compartments were
separated by tight board partitions, the openings for the circulation of
water coninuinicating through the sides of the boat directly with the
fish compartnient and being, of course, grated. This was a very satis-
factory form, but when it was fouud desirable and practicable to use
ice in transportation, the forward compartment became the ice-room,
and it was necessary to perforate the partition again to admit the cold
water to the fish. Finally, stout woolen blanket cloth was substituted
in the j)artitions, with eyelet holes to afford passage to the water.
This is the form now in use, in which the water is admitted through
openings in the sides to the ice-room, from which it passes through the
fish-room to the after room, whence it is discharged.
The car is ballasted so that the rail is Just above water or, in case
of an unusually large load of fish, a little below it. j\\\ the openings
communicating with the outside are controlled by slides, which can be
closed so as to let the car swim high and light when it is towed empty.
The boxes used for the transfer of salmon hold about J)0 gallons each,
and are 2 feet wide, 2 feet deep, and 3 feet long, with a sliding cover,
in the center of which is an inch auger-hole for ventilation. Such boxes
were used at Bucksport from 1872 to 1S74 to convey the salmon on
drays from the cars to the inclosure, a distance of a little over a mile;
six or eight salmon were taken at once, the box being filled brimful
of water, which was brackish and generally clear and cool. Though the
largest fish could not lie straight in the box, and the time occupied
in transit was commonly twenty minutes, they as a rule arrived at the
pond in good condition.
To avoid injury to the fish in transferring them to the cars, fine dip
nets, lined with woolen flannel of open texture, are used. The bow on
which the net is hung is 22 inches in diameter, and to secure a net of
ample width three ordinary nets, 36 inches in depth, are cut open down
one side quite to the bottom, and then sewed together, giving thus
three times the ordinary breadth without increasing the depth.
The collection of salmon is begun each season usually from the 2()th
of May to the 1st of June, but as the maximum temperature that the
fish fresh from the weirs will endure is about 75° F., the temperature
of the water through which the cars are towed must be taken into
consideration, and the collection not be postponed until too late in the
season. If the collection is prolonged, this difficulty is obviated by
using ice, as it has been found that by moderating the volume of water
passing through the car and introducing it all through the ice compart-
ment it is possible to keep a uniform temperature in the compartment
in which the fish are held several degrees below that of the water in
the river, thereby insuring the safe transfer of the salmon.
The principal sources of Dead Brook are two snuiU lakes, and on
some of the tributaries there are consideiable springs. While the
MANUAL OF FISH-CULTURE. 33
water is slightly purer than that of ordinary brooks, it is by no means
so transparent as that of Craig l>rook, and the bottom can hardly be
be seen at the depth of 4 feet. This (!ircuinstance is regarded as favor-
able. The inclosure is located on the lower stretches of the brook, not
more than half a mile from its mouth, with low banks on either hand
and a very gentle curreitt flowing over a bed that is for the most i)art
gravelly but in ])art consists of a peaty mud that supports a luxurious
growth of aquatic vegetation. The general depth is less than 4 feet,
but two of the pools are 8 feet deep and another is G feet deep. The
width of the stream is from 20 to 80 feet. The inclosure occupies the
entire stream for a distance of 2,200 feet, embracing an area of about
2i acres. At either end is a substantial barrier, consisting of wooden
racks, which obstruct the current very slightly but confine the salmon
securely. The lower barrier is provided with a gate, which swings open
to admit boats, and at the upper barrier are the spawning-house and
watchman's camp and a small storehouse.
The temperature of the water during the summer months generally
ranges between CA)° and 70° F., but the surface temperature occasionally
rises to 76°, 80°, and even 84°. During sultry weather the temperature
at the bottom has been observed and in the deeper i)ools has been
found to be notably lower than at the surface. Thus a temperature of
75° at the surface has been found to be accompanied by 08° at the bot-
tom : 78° by 74° ; and 81° by 72°. It is probable that to the existence
of these deeper pools the survival of the salmon through extremely hot
weather may be ascribed.
After their liberation in the inclosure the salmon are at first quite
active, swimming about and often leaping into the air. This continues
for several weeks, after which they become very quiet, lying in the
deepest pools and rarely showing themselves until the approach of the
spawning season.
Most of the deaths occur during the first few weeks of their impris-
onment, doubtless in consequence of injuries received in capture or
during transfer, though high temperatnre in the inclosure itself about
the time of the introduction of the salmon may be one of the causes of
mortality. Fish that escape the dangers of June appear to become
acclimated and able to endure the high temperatures of July and August
without injury.
Notwithstanding salmon enter the rivers in spring or early summer,
ascending at once to their ui)per waters and there, in fresh water,
awaiting the spawning season, fresh water is not essential to the activ-
ity of their reproductive functions. At the Canadian fish-breeding
station of Tadoussac, where salmon are almost the only fish cultivated,
it has for many years been the prac^tice to hold their brood fish in an
inclosure supplied with salt water, which flows and ebbs through the
barrier confining the salmon, and the development of eggs and milt is
in no wise unfavorably affected.
34 REPORT OF COMMISSIONEK OF FISH AND FISHERIES.
THE EGG HARVEST.
The natural deposit of spawn by the Atlantic salmon in the rivers of
the United States occurs during the months of October and November.
In artificial operations at Dead Brook it has rarely been necessary to
begin spawning before October 22, or to close later than ]S"o\ember 15.*
Dead Brook is commonly at a very low stage in August and Septem-
ber, but it rarely fails that before October 20 there is a very material
increase in volume. Whenever a sudden rise occurs, even in August
or Sei)tember, imprisoned salmon are at once excited to activity, and
any aperture in the upper barrier sufficient to admit the body of a
salmon is sure to lead to loss. As the breeding season approaches the
sensitiveness of the fish to such in tluences increases, and a rise about
October 20 is followed by a general movement of the salmon upstream
in search of spawning-grounds. Advantage is taken of this circum-
stance to entrap them at the upper barrier, where a small pound with
a board Hoor and a barbed entrance, like that of a weir, is constructed a
few days in advance. The success of this trap depends on the stage of
the water, and it is always the case that a portion of the fish fail to
enter it, so that the final resort is to a seine, with which the recalcitrant
salmon are swept out of pools where they are wor.t to lie.
The fish are dipped from the trap or from the seine with soft bag-nets,
such as are used in collecting them at the beginning of the season,
assorted according to sex and condition, to facilitate manipulation, and
placed in floating wooden pens, which are moored to the bank in front
of the spawn-house. These pens are about 12 feet long and 4 feet wide,
with grated sides and floors, afibrding sufiflcieut circulation of water,
and, although indispensable for the convenient manipulation of the fish,
the confinement in such narrow quarters leads to considerable chafing
of noses and tails, and if long continued affects the development of the
sexual functions of the female unfavorably, retarding the maturity of
the eggs and even affecting their quality. The capture of the fish
from the brook is therefore delayed to the point of risking the deposit
of some of the earliest eggs in the brook rather than the possible
injuries in the pens.
The spawn-taking operations begin as soon as any females are ready
to yield their eggs. A scarcity of males in breeding condition has never
yet occurred at this station at the beginning of the season, and hardly
ever at its close. Among the earliest captures there are always a few
unripe fish, but invariably by the last day of October all are ripe.
The spawning-house consists of a single, plain room, with two doors.
From one of the beams hangs a steelyard and a bag, in which salmon
are weighed. At one end is a stove, in which a fire is built in very
cold weather. At the other end is a graduated board, upon which the
* In Cauadian rivers the dates arc but a little earlier. Thus at the Gasp<= hatchery,
in the rroviuce of Quebec, in 1891, the work of spaAvning began Octoljer 10 and closed
Movcmber 2.
Fish Manual. (To face page 34.)
Plate 15.
Ripe female salmon. Male salmon.
EXAMINING FISH FOR STRIPPING.
STRIPPING FEMALE SALMON.
MANUAL OF FISH-CULTURE. 35
fish are laid for measurement. At tlie front is a narrow table, on wliicli
the eggs are washed; and at the rear the entire side of the room is
occui)ied by a series of shelves, on which the eggs are placed after
fecundation and washing.
The spawn taker, clad in waterproof clothing and wearing woolen
mittens, sits on a stool or box, and on a box in front of him is a clean
tin ])an holding about 10 (piarts, which has been rinsed and emptied
but not wiped out. A female salmon is dii)ped up from one of the
floating i)ens and brought to the operator, who seizes her by the tail
with the right hand and holds her up, head downward. If unripe, the
hsh is returned to the pens; if ripe, the spawn will be loose and soft
and will run down toward the head, leaving the region of the vent
loose and flabby, and the operator, retaining his hold of the tail with
his right hand, places the head of the fish under his left arm with the
back uppermost, the head highest, and the vent immediately over the
pan. At first the fish generally struggles violently and no spawn
will flow; but as soon as she yields the eggs flow in a continuous
stream, rattling sometimes with great force against the bottom of the
pan. Shortly the flow slackens and must be encouraged and forced by
pressing and stroking the abdomen with the left hand. It is better to
use the face of the palm or the edge of the hand rather than pinch
between the thumb and finger; the latter action, especially when work-
ing down near the vent, is apt to rupture some of the minor blood
vessels, with the result of internal bleeding, and it is better to leave
some of the eggs behind to be taken another day than to run the risk
of such ruptures.
If the fish in.hand is fully ripe, nine-tenths of the eggs are obtained
at the first trial. When the o])eration has api)arently gone far enough
for the first day, the fish is laid in the weighing bag, and as soon as the
weight is recorded is stretched upon the measuring board, whence she
is returned to the water, after a stay of 10 or 15 minutes in the air,
which results in no permanent injury. Both the weight and length of
the fish and the weight of the eggs are recorded, together with anything
remarkable connected with fish or eggs.
Large salmon endure transportation and confinement less success-
fully than smaller ones, and tlie lecord therefore shows large numbers
of salmon from 29 to 31 inches in length, weighing, in eluding eggs, from
9 to 12 pounds, and yielding 2^ to 3 pounds of spawn (6,000 to 8,700
eggs), with now and then a fish 35 or 40 inches in length, yielding, in
some cases, as many as 10,000 to 20,000 eggs.
As soon as the s])awn of a single female is taken, a male is brought
to the spawn-taker and the milt expressed upon the eggs. The pan is
then swayed and shaken violently until the milt becomes well dis-
tributed and in contact with every egg. If the quantity of spawn
exceeds 3 pounds it is divided and fecundated in two pans instead of
one, as it is diflicult to secure a good result if the eggs lie in too great
36 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
masses. The eggs are passed over to the washer, who repeats the
swaying and the shaking, and, liaving weighed them, pours in a small
quantity of water and goes through the mixing process for a third
time. After this the eggs are immediately washed by pouring in an
abundance of water and turning it off, and repeating the operation
until the water appears quite clear, when the eggs are placed on the
shelves in the rear of the apartment, to await the process of swelling.
When the egg first comes from the fish it has a soft and velvety feeling
to the hand, and the outer shell lies loose and slack against the yolk.
The presence of water excites the shell to action ; its pores absorb water
with such force that any foreign object coming in contact is sucked
against it, and in consequence of this suction the eggs stick to the pan
and to each other. In the course of 20 or 30 minutes this process is
completed, the shell is swollen to its utmost extent and is firm to the
touch, the space between the shell and the yolk is now filled with water,
and adhesion to outer objects ceases.
The eggs can now be laid upon trays and carried to the hatchery.
No serious harm would ensue if the eggs should be disturbed during
the process of swelling, but it is better not to spread them upon trays
until they have attained full size and ceased to adhere to each other,
and they are left on the shelves until the spawning for the day is over,
when all are carried to the hatchery together. After the absorption of
water the eggs must be handled very gently, as they are now suscep-
tible to injury from sudden shocks, such as might ensue from pouring
them from pan to pan, or setting the pan containing them down roughly
upon a wooden table, and to guard against such injuries the tables and
shelves are covered with old nets or other soft material.
CONDITIONS AFFECTING FECUNDATION OF EGGS.
While the spawn of a salmon is, with very rare exceptions, in normal
and healthy condition and capable of fecundation within the limits of
the spawning season, occasionally a fish is found whose eggs are in
some way defective. Sometimes they are developed unevenly, the
ovaries containing eggs in various stages of growth, some mature and
some rudimentary; sometimes all the eggs of a fish are abnornuilly
small, and sometimes all have defects which render them incapable of
fecundation. But among the thousands that have been mani])ulated
at the station not 1 in 300 has had defects involving as many as 20
per cent of her eggs, and in the spawn deemed of normal quality there
can hardly be more than 1 defective egg in 400. Among the males no
instance has occurred where there was reason to suspect the milt of
being of defective quality if secured from a living iisli.
In 1872 experiments were made bearing on the duration of the
capacity for fecundation of the eggs with interesting results. From
eight lots of eggs taken from dead fish, the rates of impregnation ranged
from 92^ per cent down to zero. From a fish that had been dead 2
MANTTAL OF FISH-CULTIIRE. 37
hours 4,400 eggs wore obtaiued, of which only 58^ per cent were capable
of fecundation. In one instance eggs taken from a dead fish and kept
until the morrow before milting remained so ftir in normal condition
that 12| per cent were fecundated. In another case 400 eggs from a
fish that had been dead 15 hours failed totally; and the same result
was obtained with 2,200 eggs taken from four specimens killed two days
before.
The same experiments afford evidence as to the result of keeping eggs
for various periods of time after they are taken from the fish, and
eggs exposed to the air and guarded against contact with water appear
to keep better than in the organs of a dead fish. Thus, 200 eggs were
kept in a pan without water for 12 hours after they were taken from
the fish, and the application of milt then resulted in the impregnation
of 90 per cent; of 200 eggs kept in the same way for 30 hours and then
treated with fresh milt, 87^ per cent were impregnated; and of 100 eggs
kept 4 days and then treated with fresh milt, 12 were impregnated.
Milt taken from a living male and kept in an open dish for several
hours retains its powers fully, but experiments with milt from dead fish
have given almost wholly negative results. Numerous exi)eriments
show that if eggs are merely covered by water, without eftbrt to secure
intermixture or the washing off of the mucus that envelops them when
pressed from the organs of the mother fish, their susceptibility to fecun-
dation may not be seriously affected by immersion 5 or 6 minutes; but
if the eggs are stirred, so as to facilitate the washing off' of the mucus
and the access of pure water, immersion for 1 or 2 minutes may pre-
vent impregnation.
When thoroughly diluted with water the milt speedily loses its
power, the effect being very marked at the end of 30 seconds ; diluted
with the mucus that accompanies the egg, it will remain effective for a
long i)eriod. Where water has been carefully excluded, milt has been
used successfully after the lapse of 12 hours with landlocked salmon,
and this would probably hold with eggs of all kinds of salmon and
trout. This i)roperty of the mixed mucus and milt has been utilized
in impregnating masses of eggs when there is a scarcity of males, as
sometimes occurs toward the close of the spawning season. In strain-
ing the mixed mucus and milt from the pan of eggs, the lower strata,
which are richer in milt than the upper, should be especially secured
and the mixture kept in a convenient receptacle. The upper strata of
the mixture should not be used, as the milt settles to the bottom.
Fresh milt should always be preferred when obtainable.
The eggs are washed as soon as the milt is thoroughly diffused among
them, and this can hardly be done too speedily for the milt to act. A
careful record of certain lots of eggs that were washed in special haste
for experimental purposes shows that they were as well impregnated
as those exposed to the action of the milt for a considerable i)eriod.
Prolonged exi)osure to the milt has been found to affect the health and
development of the embryo unfavorably.
38 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
TRANSFER OF EGaS TO THE HATCHERY AND THEIR CARE.
From Dead IJrook the eggs are transferred to the hatchery at Craig
Brook station, about 2 miles, and spread on trays in the spawning-
house. The trays are placed in frames, inclosed in boxes which are
padded within to guard against concussion. In spite of all i)recautions
some of the eggs are occasionally killed, though the trays are placed in
pans of water and the eggs poured from the spawn ing-paiis with the
greatest care. The frames or " stacks " containing the eggs are placed
at once in the troughs where they are to be developed.
The trays are 12^ inches square, and constructed by attaching iron
wire-cloth to light wooden rims with blocks at the corners, so that when
piled up, one above another, there are narrow interstices on all four
sides, through which water circulates freely. The rims of the trays
are very slender, in order that they may never have buoyanc^y enough
to float, which would necessitate some means of holding them down and
increase the trouble attending their manipulation. Southern poplar
(whitewood) is commonly used, and a rim ^ inch wide and =1 inch deep
answers the purpose well, provided the wire be not very light. The
corner pieces are ^ inch thick, and give the interstices just enough
width to provide an ample circulation of water, but not enough to
allow the escape of salmon eggs, which are nearly ^ inch in diameter.
Eusting is prevented by varnishing the wire-cloth with several coats of
asphaltum varnish, which works better if made very thin by the use of
a large proportion of spirits of turpentine. The same varnish gives a
clean and glossy surface to submerged woodwork, and the varnishing
is extended to the rims of the trays, the "stack -frames," and interior
surfaces of the troughs themselves. Material subject to rust should be
used only with great caution. Wire or other metallic forms galvanized
with zinc vary in quality. Total loss of eggs has been known to result
from the use of galvanized wire-cloth when unvarnished. Careful
experiment should precede the use of any particular brand. Tinned
wire cloth is better, but whether sufiiciently to warrant the extra
expense is the question.
In developing eggs, in order to economize room, the trays are piled
up 10 or 20 deep in frames that conline them only at the corners and do
not hinder the free passage of Avater horizontally through the -'stack."
About 2,000 Atlantic salmon eggs are placed on a single tray, and a
trough of the ordinary length, lOi feet, therefore carries 110,000 to
280,000 eggs, with suitable free space at either end. It is therefore an
exceedingly compact apparatus and has the further advantage that it
can be used in a very plain trough which can, with a few minutes' work,
be transformed into a rearing-trough for young fish. For 10-tray stacks
the trough is made of pine boards, 123 iudies wide and 0 inches deep
inside, and is set up level, with the top about 30 inches Irom the floor of
the room.
MANUAL OF FISH-CULTURE.
39
The water is fed into one eud through a wooden or rubber tube
guarded by a wire screen, and is regulated by a simple swinging-
gate. The outlet is either over a wooden dam or through a hollow
plug, either of which determines the height of the water in the trough,
which is always maintained just at the top of the covering tray or au
eighth of an inch above it.
Scale effect.
Troiigh Arranged for Eggs.
Fig. 1, plan. Fig. 2, lougitudiual section.
a, supply-trougli
6, screen.
d, 8ui)ply-pipe.
/, egg-trough.
j, down- spout.
r, cleats.
*, stacks of egg-trays.
(, waste-pipe.
u, screen.
V, outlet.
w, wooden dam.
X, water surface.
For the regular picking and cleaning, and for other examinations, the
stacks are removed from the trough to a table, where the trays can be
taken out one by one, set over into an empty frame, and returned to
the trough. This can be performed with ordinary caution at any stage
of the development of the embryo, without doing the slightest injury,
and after the delicate stage is passed the trays and their burden of
eggs can be washed at the same time in a pan of water.
WINTER CARE OF EGGS.
The eggs pass the winter in the stacks. They are regularly picked
over and the dead ones removed once or twice a week — twice during the
first few weeks, on account of the comparatively high temperature then
prevailing and the consequent rapid development of decay and growth
of fungus. It depends, to a considerable extent, on the water tempera
ture; the water at the beginning of the spawning season varies from
50O to 55° F., and maintains a mean of 43° to 45^^ F. during the mouth
of November.
The color of a good egg, or of an unimpregnated egg that still retains
its vitality, is a translucent salmon pink, with some variations in shade.
40 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
It is possible, by i)laciug it in a favorable light, to get a fairly good
interior view, including the detailed anatomy of the embryo. When
the egg dies it turns chalky white, becomes wholly opaque, and in a few
days, depending on the temperature, decay sets in, and sometimes a
white water- mold or fungus begins to grow upon it. The mere decay
of the egg would foul the water, thereby injuring the neighboring eggs,
and the fungus established on the dead eggs may spread to the living
ones. It is therefore essential that the white eggs be removed before
they have time to do any injury.
For egg-i)icl\ing a homemade pair of tweezers, about 6 inches long, is
used, made of any convenient wood and tipped with a pair of wire
loops of a size to conveniently grasp the egg. The operator lifts the
stack of trays carefully from the trough and, to save dripping, carries
it on a wooden waiter to a well-lighted table of convenient height, on
which stands an oblong pan, 14 by 18 inches, holding about an inch of
water.
The stack of eggs to be picked is placed at one end of the pan and
at the other end is an empty stack-frame. The trays are examined one
by one, dipped in the pan of water, picked (or cleaned by agitation
when the eggs are in condition to endure the disturbance), and placed
in the empty frame. The air of the room is kept at a low temperature
during this process, and the water in the pan is often changed.
The eggs when first impregnated are very sensitive to rude shocks and
are handled with great care. Within a few hours the germ begins to
develop; in 10 days, at a temperature of about 40° F., the germ-disk
appears as a ring of color on the upper side of the yolk. At this date
the unimpregnated egg presents the same appearance and does not
change much until its death, however long that may be deferred. In
the impregnated egg^ however, the germ-disk continually enlarges upon
the surface of the yolk; the ring of color that marks its edge advances
before it, passing quite round the yolk, and closing uj) on the posterior
side.
As early as the thirteenth day the difference between the impregnated
and unimpregnated egg is quite plain to the unaided eye after a very
little experience, and three or four days later the good egg is marked
by a distinct line of color passing around the very middle of the yolk,
a phenomenon never appearing in an unimpregnated egg. During
this stage, while the embryonic disk is spreading around the yolk,
the egg grows constantly more and more delicate, and liable to rupture
of its tissues ^md consequent death on very slight disturbance; but
later the tissues grow stronger, and when, about the thirty-fifth or
fortieth day, the eyes of the embryo have assumed enough color to
appear as two dark dots, the egg has attained hardiness enough to
endure rougher handling. Thenceforward, until the near approach of
the time for hatching, the work consists simply in picking out the dead
ones, occasionally rinsing out the sediment, and sometimes removing
the unimpregnated eggs.
Fish Manual. (^To face page 40.)
Plate 16.
rJ^
i o ■
'fi^^^
P^ .
1 C
^ 1
PICKING OUT DEAD EGGS.
PACKING SALMON EGGS.
HANDLING EGG-TRAYS.
MANUAL OF FISH-CULTURE. 41
The latter pioccduie is attended to for the entire stock of eggs, but
is of special importance in case of those that are to be transported. It
may be performed any time after the good eggs become hardy — that is,
after the eyes become black — but becomes easier late in the season. The
unimpregnated eggs, which were at first fully equal in hardiness to the
imi)regnated, lose in that respect as time passes, and finally are readily
killed and turned white by a shock which does no injury to the impreg-
nated eggs. When this time has arrived, the eggs are turned from the
trays into spawning-pans with a moderate quantity of water, and
poured from pan to pan back and forth a dozen times, each time falling
a foot or more, and striking the bottom of the pan with considerable
force, giving each egg a severe shock. They are then returned to the
trays and troughs and as soon as convenient are picked, and if the
operation has been thorough almost every unimpregnated egg has
turned white and is picked out, while the eggs in which the embryos
are developing have not suffered at all.
PACKING AND TRANSPORTINa.
Eggs may be safely transported as soon as the eyes have become
thoroughly colored, and until within a few weeks (five or six in cold
weather) of the date for hatching. In shipments made too late the shells
burst on the way and the embryos i)erisli. The method of packing eggs
at Craig Brook is to put them in layers alternating with wet sphagnum
moss in shallow wooden boxes, placed in cases of a size to afford on
all sides of the inner package a space of 2.^ or 3 inches, which is filled
with some light, porous material that will form a good nonconductor
of heat.
The eggs are thrown from hatching-trays into a large rectangular
pan, from which they are poured with water into tin measures which
hold 2,500 each. A thin layer of moss is phiced in the bottom of a
packing-box. A little flue snow is sifted upon the moss, and on this is
spread a piece of mosquito netting that has been soaked and rinsed in
clean water. A measure of eggs is now poured on and spread out and
covered by folding over the edges of the netting, which now comijletely
envelops them. Xext a layer of moss is spread, followed by snow,
netting, and eggs, as before, and the series is repeated until the box is
full. The moss must be sutticiently wet, so that with the melting of the
snow it shall have all the moisture it will hold, and no more, as it is
very desirable to avoid the wetting of the outer i^acking. If the
moss is too dry, the eggs may dry to the extent of becoming indented,
and the same result may come from crowding the moss in too hard on
the eggs, though it should be pressed in so tightly that the eggs wiU
not slide out of place if the case is turned for a moment on its side.
The temperature of the packing-room is below 50° F., and packing
materials are kept in a place which is cool, yet not nuich below the
freezing-])oint. Salmon eggs packed as above commonly go a three
days' journey without comi>lctely melting the snow that was sprinkled
42
REPORT OF COMMISSIONER OF FISH AND FISHERIES.
uutler the eggs, and ou several occasious eggs of landlocked salmon
have been carried across the Atlantic in prime condition, withont
repacking or special attention.
The packing-boxes are made of thin i^ine or flr, 12 inches wide and 15
inches long — |iuch thick boards being used for the end pieces and
^-inch for the other parts — and hold in a single layer, without crowding,
2,500 eggs. The deepest are 3.^ inches deep and take four layers, or
10,000 eggs, in a box. To make up a shipment of 40,000 eggs, four boxes
are i)iled up and secured together by tacking strips of wood against
the ends, with a cover ou the upper box, and this package placed in
the case. For a shipment of 80,000, two of the 40,000 packages are put
side by side in a larger case, and the i^roportions selected for the inner
boxes are such that the case required is of convenient form.
■^
n=^
' > l^^:^S'^sstS^^i^iJni^^^^^^i^^0^^9S9^^^!&^j>^^
/./jjJJtL^XiC-.-J^^-
^
/ // t
py77/7//Zvy/7?//7y7Zv7//7>////////7//
Loiigitudiual section of a case of Atlantic Salmon eggs.
Different mosses can be used for packing, but none are so good as
the sphagnous moss that can be found in swamps and bogs in most
regions of high latitude or considerable elevation. Fresh moss is
preferable for a bed lor the eggs, though dead, dry moss may be moist-
ened and used with good results.
The moss is gathered in August or September, dried on tlie ground,
and stored in sacks or in bulk until wanted. It retains its freshness
through the following winter, not heating like most organic materials.
It is exceedingly liglit, and the best nonconductor known, with the
possible exception of asbestos. It is used dry in the outer i)acking
mainly to save weight, but when protection against freezing is all that
is sought, wet moss is better, as frost penetrates wet moss more slowly
than dry. When moss can not be had, there are many substitutes
which may be used for the protective envelope, such as dry forest
leaves, chaff from a haymow, chopped hay, or even crumpled paper;
but the latter should not be allowed to become wet.
MANUAL OF FISH-CULTURE. 43
HATCHING.
As the time for liatcliiug draws near, the eggs are placed on trays
provided with legs or some other support to keep them up from tlie
bottom of the trough. Brass nails driven into the under sides of the
tray rims are good temi)orary legs, and after the hatching is over they
are readily removed and the necessity of a special set of trays for
hatching is avoided. When there are plenty of troughs, these trays
stand singly on the bottom of the trough, but when it is necessary to
economize room two or even three are disposed one above anotlier.
When no necessity exists for economy of space, 4,000 eggs are allowed
a whole trough, which is at the rate of 400 to the square foot; 2,000
or even 5,000 to the square foot may be carried through liatching and
the entire sac stage, but the latter number involves risky crowding.
The hatching is sometimes expedited by giving eggs that are just at
the hatching point a decided shock, similar to that given at an earlier
date to kill the unimpregnated ones; also by the temporary stoppage
of the water supply. But at Craig Brook it is the custom to lay the eggs
out in good season and allow them unlimited time in which to hatch,
sometimes a week, sometimes two weeks. The earliest lots commonly
batch the latter part of March, and it is not often that any remain
unhatched after April 20. The mean duration of the egg stage is
therefore about 157 days, during which the mean temperature of the
water has been ab(mt 37° F. While hatching is progressing, the outlet
screens are closely watched to keep the empty shells from clogging
them up; for when a considerable part of the screen is clogged the
force of the current through the open spaces is greatly increased, and
the soft and yielding sacs of the tish are liable to be drawn through
the meshes.
THE SAC STAGE.
When the shell breaks, though it has been coiled iip in a space less
than ^ inch in diameter, the trunk of the newly hatched salmon at once
straightens out to a length of about f inch. The yolk, scarcely dimin-
ished from its original size, hangs beneath and constitutes the greater
part of the bulk of the fish. The young salmon is for a while more
unwieldly than a tadpole. When frightened he sculls about with great
energy, but makes slow progress and is fain to lie on his side on the
bottom of the trough or crowd with his (jompanions into a corner. The
sac is a store of nutriment, which is gradually absorbed into the other
parts of the fish; and so long as it lasts the young salmon will not eat.
The interval between hatching and total absorption of the sac varies
with the temperature, the mean at Craig Brook in April and May being
about six weeks.
As time passes the embryo fish grows more and more to resemble the
adult, his body acquires strength, and his tins assume form and become
more effective as organs of proi)ulsion. At last his digestive systeuj
44
REPORT OF COMMISSIONER OF FISH AND FISHERIES.
assumes its fiiiictioiis and rouses the desire for food. Until this time,
intent only on hiding', the fry have clung obstinately to the bottom and
to the dark corners, but now they scatter about through the water,
with lieads upstream, watching for prey. This indicates that they
must be fed. During this period of his growth it is simply necessary
to see that the young fish has plenty of water, that there is no hole or
crevice into which he can be drawn by the current, and that he is pro-
tected from enemies, such as large fishes, minks, rats, kingfishers, and
herons. If not in a house, well- fitting covers must be provided to the
troughs and impassable screens command both ends. The screens are
of fine wire-cloth, 12 or 14 meshes to the linear inch, and present a sur-
face of 14 square inches to each gallon of water passing through them
each minute. Thus, if there are 4 gallons of water passing through the
trough each minute the portion of the screen beneath the surface of the
water must measure as much as 56 square inches, and if the screen is
12 inches wide the water must be 4f inches deep on the screen.
Atlantic Salmon, recently hatclied.
REARING.
The leading feature of the work of the station is the rearing of fry to
the age of six or eight months. The fishes reared are mainly Atlantic
salmon, but landlocked salmon, American brook trout, European brook
trout, rainbow trout, steelhead trout, American lake trout, Swiss lake
trout, Scotch sea trout, and saibling have also been handled. The fish
are fed wholly on artificial food from about June 1 till October or
November, Avhen they are mostly liberated. To a limited extent they
are kept in artificial i)onds, but troughs of the same form and dimen-
sions as those already described for use in developing the eggs and in
hatching have given satisfactory results and have been adopted for tlu
most part. Each trough is provided with a changeable outlet screen
and below the screen discharges the water through a hole in the bottom,
into which is fitted a hollow plug, the height of which determines the
depth of water in the trough. The hollow plug inlays an important part
in the daily cleaning of the trough, which will be referred to further on.
The use of the troughs in the open air, which, in the absence of com
modious buildings, is a necessity, comj^els the constant use of covers to
kee]) out vermin ; and wooden covers in i)airs, i-unning the whole length
MANUAL OF FISH-CULTURE.
45
of the trough, hinged to its sides, and, when closed, assuming the form
of a roof at an angle of 45°, were finally ad<)[)ted. These covers are
made of thin boards, § inch thick, sawed in narrow pieces, which are
put together so as to leave in each corner two cracks open ^ inch wide
for the admission of light when the covers are closed. When ojjcn tliey
may be fixed in an upright position, thus increasing the height of the
sides and guarding against the loss of lish by jumping out.
T : Ti^-l
i
a
h
r 9 ^
e
I 1 '
i
o
r »
p
JJ
ri|.2.
r
v<<v""''"""''"'''''''''''''''"'''''<'^""'''''"'"''''''a{/^'''''''"''''''''"''''"'''j''''''''^''''//ju
0
Fi|.3,
Kg. 4.
\
Hg.5.
I \-!
55^i
;;il,-
Scaleoffcet.
-'''"--
' f— 1
Troughs arrauged for Rearing.
Fig
with r
a,
f,
/■
h.
1, plan. Fig. 2, lonjjitudiual section. Fig. 3, cross-aection near fool of tiougli.
ocking gate. Fig. ."), elovation of lower end.
Fig. 4, inlet,
supply trough.
screen.
rocking gate.
supply-pipe.
watcr-ljoanl (to .spread the water and throw it down).
lisli-trough.
gripe, to prevent sproadinj; of sides.
outlet screen.
i, hoUow outlet l>lug.
j, down-spout.
k, supports.
Z, cover. •
7/i, cover open (hanging).
«, cover open (ui)right).
p, cover closed.
</, end boards (closing aperture).
Water is furnished through rubber or wooden pipes \ inch in diame-
ter, and the bore of the hollow plug at the outlet is 1;^ inch or larger.
The inflow is regulated by an oscillating or rocking gate, which is set
to admit the desired volume of water. The trough is set with the
upper end an inch or two higher than the other, to facilitate cleaning
out, and the water is kept during the summer about 4 inches deep at
the lower end.
46
REPOKT OF COMMISSIONER OF FISH AND FISHERIES.
The troughs are supported by a suitable framework at a convenient
height from the ground and arranged in pairs with their licads against
a long ieed-trough, constructed of pine boards and perforated on the
side by the feed-pipes, over each of which is a capacious screen to pre-
vent clogging by leaves or other floating debris, A frame 6 by 12
inches, covered on its outer side by wire-cloth of ^ inch square mesh,
answers the x^urpose of a screen so well that water from an ordinary
brook can be admitted to the feed-trough without previous filtering or
screening and with little or no danger of a stoppage of water in any
of the fish troughs. Such screens over the feed-pipes might be made
tiie sole dependence, were it not that the labor attending their cleaning
Avould be greater than that required by a separate filter or screen.
?
*^. ^
Conduit to lower- l^vet.
n
■^ FisK trough
FisK trough.
\'.o
rl
;;o
-I
1
t
^
Scul*; offset.
(I
E
"Stand of Troughs for Rearing Atlantic Salmon.
Tiie system represented here b}^ 12 troughs in two series may be
extended to many hundreds of troughs in four (or more) series, each
series on a different level and receiving water from the series next
above, the fall from one to another being about 4 feet. In the drawing
the series of 6 troughs on the left is supplied with water directly from
the upper "feed-trough" (i. e., supply-trough), and they discharge into
a catch-trough, from which the water is carried to the supply-trough
("feed-trough") of the lower level. If the aqueduct sui)i)lies more
water than the upper series of troughs can use, the surplus passes by
way of the "overflow" directly to the catch-trongh and thence to the
supply-trough of the second series. With a fall of 4 feet, the catch-
trough and the conduits that lead from it are below the walks which
give access to the troughs on both sides and at the lower end.
The number of fish assigned to a single trough is ordinarily 2,000,
and the volume of water given them is commonly 5 gallons per minute.
Generally the water is used but once in troughs and is discharged
MANUAL OF FISH-CULTURE. 47
into conduits leadiiift' to ponds wlierc larger fish are kept; but a stand ot
100 troughs has hitely been set up with the design of using all the
water twice; and for manj' years there lias been one system of 52
troughs, arranged in four series, which use in succession the same
water, the young salmon thriving quite as well in the fourth series as
in the first.
On one occasion a few of them were maintained for several weeks in
the warmer water of a neighboring brook, where a trough was set up
and stocked with 100 young salmon taken from one of the troughs at
the station July 30. The temperatures observed between 1 and 4 p. m.
in the fish-trough on successive days from July 30 to August 14, not
including August 1 or 10, were as follows: 79°, 75°, 77°, 79°, 82°, 82°,
78°. 7CP, 7GO, 70°, 74°, 74°, 74°, 74°, F.
The fish were fed the same as the lot out of which they were taken,
except that they received food only once a day instead of twice, and
were returned to the station October 7 without a single loss during the
experiment. Moreover, they were all weighed October 10 and found
to average 100.6 grains, while those of the original lot that had remained
at the station, with a temi^erature between 50° and 71° F,, averaged
only 5(>.l grains. While the greatly increased weight of the fish kept
in the stream was owing in part to more space, as the 100 had as large
a trough as 1,505 at the station, the higher temperature was undoubt-
edly one of the factors that contributed to the gain in weight, and it is
at least plainly shown that the warm water was not unhealthful.
Though small ponds, excavated bj^ the former j)roprietor, were in
existence at the station and used to some extent for rearing young fish
in their first summer as far back as 1888, and older fish have been kept
in small ponds each season since that, it was not until 1896 that enough
pond work was done to furnish data of importance.
The ponds for rearing Atlantic salmon are among the series known
as the ''south ponds," occupying a smooth piece of ground sloping
toward Alamoosook Lake at a grade of 1 in 8. Formerly it was mostly a
swale, watered by a copious spring at its head. This series comprises 19
ponds of rectangular form, about 50 to 90 feet long and 15 feet wide, with
a depth of 2 or 3 feet. The water supply of those used for Atlantic sal-
mon is derived from Craig Brook by an aqueduct tapping it at a point
where two parts of Craig Pond water are mingled with one part spring
Avater, being substantially the same as the water supplying the most
of the rearing-troughs. From 5,000 to 10,000 fish that have been fed in
troughs during the early part of the feeding season are placed m each
pond, and for the remainder of the season are fed the same food that is
given to the fish left in the troughs; and the results indicate that the
stock of fish might he safely increased.
While the greater part of the salmon reared at Craig Brook are
liberated in October, wlien about seven months old, in 1891-92 about
16,000 were carried thiough the winter, most of them m tanks sunk
in the ground, and nearly as many have been wintered some other
48 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
seasons. Fish may also be kept all winter in trouglis in the open air
by occasionally si^reading blankets over them in exceptionally cold
weather, and keeping the conduits carefully covered.
The fish surviving the summer season are generally counted and
weighed in October, in the following manner: A large number of them
are dii)ped up from a trough in a small dip net made of cheese-cloth,
and from this, while it is hanging in the water in such a manner that
the fish can not escape, they are dipped out a few at a time, in a small
dipper or cup, counted, and placed in another bag net until a sufficient
number (generally 200) are counted, when they are lifted out of the
water, held a moment in the air to drain, and all turned quickly into
a pail of water which has previously been weighed. With care no
appreciable amount of Avater goes with the fish, and the increase in the
reading indicates their weight with a fair approach to accuracy, and
with care and celerity of action it is quite safe for the fish.
The size attained by the fish varies greatly, being affected by the
water, the space allowed, the feed, and perhaps by hereditary influences;
but when seven months old a trough-reared salmon is generally from
2J to 3 inches long and weighs from 35 to 100 grains, the maximum being
about 130 grains and the minimum as low as 7 grains, the general
mean for 1890 being 45.8 grains. Salmon reared in i)onds have been far
more thrifty, their general average in 189G being 101 grains.* The
losses in ponds from July to October were rather heavy, being 11.7 per
cent, owing to depredations of frogs, birds, and cannibal fish. The
losses in the troughs during the entire season were 9.1 per cent, but
most of these were in the early stages of fryhood. After July losses in
troughs are always very light.
MATERIALS FOR FISH FOOD.
At Craig Brook station there have l)eon used butchers' offal, flesh of
horses and other domestic animals, fresh fish, and maggots. Experi-
ments have also been made with pickled fish, blood, fresh-water
mussels, mosquito larva?, miscellaneous aquatic animals of minute size,
*A very interesting comparison between the results of rearing in troughs and
ponds is afforded by the record of two lots of steelhcad trout during the season of
189(5. All the fry of this species that were devoted to rearing were fed in troughs
until July 22, when some of them were trausl'erred to a pond which has an area of
about 1,100 8(|uare feet and another lot was kept in a trough. The two lots were fed
exactly alike, about one-sixth of their nutriment beinj:; live maggots, and Hve-sixths
chopped meat, liver, aud other butchers' oftal. November 7, the lot in the trough
was oxerhanlcd, and the 7G2 survivors found to Aveitrh 10 itounds 4 ounces, or an
average of 94 grains. Three days later the pond fish Avere seined out and the 7,398
survivors found to weigh 235 pounds 10 ounces, an average of 223 grains. It is not
believed that natural food occurring in the pond contributed much to this result, and
it would appear that the controlling factor in the case was the space afforded the
fish. Leaviug out of tlu) account the diflerence in dei)th, in the ])()nd there were less
than 7 fisli to each square foot of area, while in the trough, whicli liad an area of
about 11 square feet, there were to ea(;h scpiaro foot 6!) fish. A similar illustration
was furnished by 41 rainbow trout of the hatching of 1896 that got astray in one of
the ponds and were taken out November 11, weighing 480 grains eacli. rhose
of fhe same age, reared in troughs, attained during the season only a weight of 136^
grains each.
MANUAL OF FISII-CULTURE. 49
flour, and middliugs. The butchers' ofial comprises livers, hearts, and
lij^hts, which are collected from the slaughter-houses twice or thrice
weekly, and preserved in refrigerators until used.
The tlesh of old and worn-out horses has been used each year since
1892 in the same way as the butcher's ofifal, witli very satisfactory
results; the parts that could be chopped readily have been fed direct
to the fish so far as needed, and other parts have been used in the
rearing of maggots.
Next to chopped meat maggots have constituted the most important
article of food, and their systematic jiroduction has received much
attention. A rough wooden building has been erected for this branch
of the work, and one man is constantly employed about it during the
summer and early autumn months. The maggots thus far used are
exclusively flesh-eaters, mainly those of two undetermined species of
flies; the first and most important being a small, smooth, shining green
or bluish-green fly, occurring in early summer and remaining in some-
what diminished numbers until October; and the other a large, rough,
steel-blue fly that comes later and in autumn becomes the predomi-
nating species, having such hardiness as to continue the reproduction
of its kind long after the occurrence of frosts sufficiently severe to
freeze the ground.
To obtain maggots meat is exposed in a sheltered location accessible
to flies during the day. When well stocked with the spawn of the flies
it is placed in boxes, which are set away in the " fly-house " to develop;
when fully grown, the maggots are taken out and fed at once to the fish.
Stale meat, parts of the butchers' oflal and of the horse carcasses not
adapted to chopping; fish, fresh, dried, or pickled; fish pomace from
herring-oil works, and any animal refuse that comes to hand, are used
to entice the flies and aftbrd nourishment for the maggots. Fresh fish,
when not too watery or oily, like alewives and herring, is very attract-
ive to the flies, and in proper condition may serve as well as fresh meat.
Fish dried without salt or smoke and moistened before using is, when
free from oil, a superior article. Its preparation presents some difli-
culties, but in winter it is easily effected by impaling whole fishes on
sticks and hanging them up under a roof where they will be protected
from rain without hindering the circulation of the air; in this way
many flounders and other refuse fish from the smelt fisheries have been
dried.
It is usually necessary to expose meat but a single day to obtain suf-
ficient fly spawn; thelarvic are hatched and active the next day, except
in cool weather, and they attain their full growth in two or three days.
To separate them from the remnants of food the meat bearing the fly
spawn is placed on a layer of loose hay or straw in a box which has a
wire-cloth bottom, and which stands inside a slightly larger box with a
tight wooden bottom. When full grown, the maggots work their way
down through the hay into the lower box, where they are found nearly
free from dirt.
F. M. 1
50 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
When young siilinon or trout first begin to feed they are quite unable
to swallow lull grown maggots, and small ones are obtained for them by
[)utting a large (piantity of fly sjjawn with a small (juantity of meat,
the result being that the maggots soon begin to crowd each other and
the surplus is worked off into the lower box before attaining great size.
No attempt is, however, made to induce the young fish to swallow even
the smallest maggots until they have been fed a while on chopped
liver.
IMaggots are produced and used in considerable numbers, sometimes
as many as a bushel in a day. The fish eat them eagerly, and appear
to thrive on them better than on dead meat. Having great tenacity of
life, if not snapped up immediately by the fish they remain klive for a
day or two, and, as they wriggle about on the bottom, are almost cer-
tain to be finally eaten, which is a great gain in cleanliness and economy,
as the particles of dead flesh falling to the bottom are largely neglected
by the fish and begin to putrefy in a few hours and foul the troughs.
As the growth of maggots can be controlled by regulation of the tem-
perature, they may be kept all winter in a pit or cellar and used as food
for fish confined in deep tanks not easily cleaned.
In the rearing of maggots the offensive odors of decaying flesh may
be iiartly overcome by putting it away in boxes, after the visits of the
flies, and covering it with i)ulverized earth. Only flesh-eating maggots
have yet been tried, and the trouble may i)ossibly be rectified by culti-
vating the larva; of other species, such as the house-fly, the stable fly,
etc., or a little white maggot known to grow in heaps of seaweed, if
their rate of growth is found to be satisfactory.
Occasional use has been made of fresh fish for direct feeding, but when
thrown into the water after chopping it breaks up into fibers to such
an extent that it is not satisfactory, unless in a coarsely chopped form,
for the food of lai^ge fish. A few barrels of salted alewives have been
used, and, if well soaked out and chopped, they are readily eaten by the
larger fish and can be fed to fry, but are less satisfactory with the latter,
and, like fresh fish, break up to such an extent that they are only to be
regarded as one of the last resorts.
Fresh-water mussels, belonging almost wholly to a species of Unio,
have been occasionally gathered with nets or dredges in the lake close
to the station and opened with knives and chopi)ed. The meat is
readily eaten by all fishes and appears to form an excellent diet. It is
more buoyant than any other article tried, sinks more slowly in water,
and gives the fish more time to seize it before it reaches the bottom;
but the labor involved in dredging and shelling is a serious drawback.
During the seasons of 1886 and 1888 some use was made of mosquito
larvfe, collected from pools of swamp water by means of a set of strain-
ers specially devised for the purpose and from barrels filled with water
disposed in convenient places near the rearing-troughs. The larva' (or
pu})ie) were strained out and led to the fisli. No kind of food has been
MANUAL OF FISH-CULTURE. 51
more eagerly devoured, and apparently uo other food lias contributed
more to the growth of the lish; but the time exi)ended in (collecting is
out of all proportion to the quantity of food secured. Perhaps a series
of breeding-tanks arranged in proximitj' to the fish-troughs, into which
the water containing the larva? might be drawn when desirable by the
simple opening of a faucet, would reduce the labor involved.
Middlings and Hour have been tried in combination with blood from
the shambles, but did not appear to satisfy the fish so well as the vari
ous forms of meat, and their use has, therefore, not been continued.
They were fed in the form of a pudding comijosed of two parts blood
and one part flour or middlings, cooked carefully to avoid burning,
and the mixture was then passed through a meat-chopper and ladled
out with a spoon, like other chopped food.
The growth of live food in the ponds themselves in which the fish are
maintained has been the subject of study. Ponds several years old
and well stocked with vegetation were at one time devoted to these
exi)eriments. They had been empty during the preceding winter, and
in the spring were fertilized with various sorts of animal and vegetable
refuse. They were stocked witli different species of Crustacea native
to the region, including shrimps {G((mmarns) and entomostraca, of the
genera Daplinia^ Cerioihiphnia, Sida, CyelopH, I'oli/jjhemiifi, etc., which
were systematically collected from open waters by nets and other appa-
ratus and placed in the' ponds. These forms all multiplied there, some
of them enormously, but no means was found of inducting continuous
or frequent reproduction of them, and the young fish soon exhausted
the supi)ly.
In serving the food the attendant carries it with the left hand — in a
2-quart dipper if chopped meat, in a larger vessel if nuiggots — and,
dipping it out with a large spoon, strews it the whole length of the
trough, being careful to put the greater portion at the head, where the
fish nearly always congregate. Finely chopped food, for very young
fish, is slightly thinned with water before feeding.
It is usual to feed tlie meat raw except the lights, which chop better
if boiled first; but occasional lots of meat, on the point of becoming-
tainted, are boiled to save them. All meats fed directly to the fish are
first passed through a ch()})piug machine. To fish just beginning to
eat, food is given four times a day, or in some cases even six times, but
as the season progresses the number of rations is gradually reduced
to two daily. In winter su(;h fish as are carried through are fed but
once a day. •
CLEANING THE TllOUGHS.
The troughs are all cleaned daily. When the hollow plug is drawn
the water rushes out rapidly and carries most of the debris against the
screen. The fishes are excited, and, scurrying about, loosen nearly all
the dirt from the bottom; what will not otherwise yield is started with
a l)riish, but after the lirst few weeks the brush has rarely to be used
52 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
except to nil) the debris through tlie outlet screen. Owing to the incli-
nation of the trough, the water recedes from the upper end until the
fishes lying there are almost wholly out of water, but, althougli they are
left in that position sometimes for 10 or 15 minutes, no harm has ever
been known to result.
TRANSPORTATION AND LIBERATION OF YOUNG SALMON.
The salmon produced at the station have, with few exceptions, been
liberated in the Penobscot River or its tributaries, and more than 90
per cent of them in small tributaries within 10 miles of the station.
They have been spread about in streams and lakes, at all accessible
points. They are transferred in tin cans, holding about 8 gallons, with
an extreme height, including neck, of 17 or 18 inches, and a body 15^
inches in diameter and 10 inches deep, making a very broad and low
can, well adapted to the use to which it is put. Its great width favors
aeration at the surface, and a good deal of dashing about of the water
when on the road. The cans are filled to within about an inch from the
shoulder, giving opportunity for the water to swash about and aerate
itself. Into such a can are put from 200 to 400 Atlantic salmon seven
months old, more or less, according to the size of the fish, the tempera-
ture of the air, and the weather. The ordinary load is about 300 when
the temperature of the water is 52° to 54° F., making 37 fish per gallon.
Such loads are entirely safe for the conditions attending the work.
The motion of the wagon in which they are carried keeps up the aera
tion of the water, so that the fish can not exhaust the air. Should the
cans stand still a very long time aeration is effected by a force-pump
which draws the water from the can and returns it through a tube so
that it strikes upon a deflector by which it is broken and scattered in
spray. The suction hose is covered with a roomy wire strainer, so that
the fish are not drawn in.
DISEASES.
Salmon in all their stages of growth are subject to a variety of dis
eases. White spots sometimes occur on the eggs attached to the shell>
but have no hold on the embryos, so that when the shell is torn off" the
white spot is seen as a cluster of globular white masses on its inner
surface. These appear to be vegetable parasites, perhaps fungoid in
their relations, and are never seriously abundant. Other white spots
are connected with the yolk-sac itself. These are more serious, but
while they result in the deatl^of many embryos, they are by no means
always fatal. In 189G there were hatched at the station some rainbow
trout that were badly spotted on the sac. A portion of the fry were
divided into three lots for experiment: (a) Without spots; (b) moder-
ately spotted; (c) badly spotted. They were kept separate through the
season, and a fair percentage survived, as follows: Of lot a, 55 per
cent; of lot />, 50 per cent; of lot c, 43 per cent. In the fall they were
MANUAL OF FI8IT-CIJLTURE. 53
all weighed, and it was found that lot <■ had made a slijihtly better
growth than lot <(.
One of the most uncontrollable diseases attacks salmon fry midway
in the sac stage, and linishes its work before the complete absorption
of the sac. The most evident symptom is the ai)pearance of scattered
white spots in the sac; the fish cease to try to hide, but lie scattered
about on the bottom of the trough; the spots increase in size, coalesce,
and finally occupy large areas, especially in the tip of the sac, which
becomes quite white. Soon after this the fish dies. The attack on a
lot makes rapid progress; for instance, a lot of 2,000 in which, up to
April 22, the losses had been from 1 to 9 daily, showed 17 dead on the
23d, and five days later 300 died in a single day. In 1890 this epi-
demic attacked especially the fry of Atlantic salmon, destroying about
a third of them; it also destroyed many landlocked salmon, and some
other si^ecies suffered heavily about the same time. In 1891 there was
not a trace of it. In 1892 it returned again, and out of 305,353 fry of
Atlantic salmon it left but 3,874, and these were by no means healthy;
but it attacked only Atlantic salmon. Salt and mud were tried as
remedies, but though the progress of the disease appeared in some
instances checked thereby, no permanent benefit resulted from their
use.
In 1890 this epidemic appeared to run in families. There was evi-
dence tending to show that all the eggs coming from a particular mother
would have a common degree of liability to the disease — sonie families
being exterminated by it, some only decimated, and others able to resist
it altogether. It did not appear to be infectious, as several lots of fry,
separated by screens, would occupy a single trough, and in some cases
those at the head of the trough would be totally destroyed, or nearly so,
and those below them escape from attack.
The only other diseases of Atlantic salmon that demand notice here
are connected with the so-called fungus, belonging to the group of
water molds called Sajyrolegniw, and probably to the genus Saprolegnia^
one species of which, S.fcrax, is noted as the cause of very destructive
epidemics among the adult salmon of Scotch and English rivei's. The
species that attacks fish eggs is well known to every fish-culturist as
a fine white growth of a cottony or woolly appearance that forms upon
dead eggs, and when neglected spreads out so as to envelop in its
threads a great many of the living eggs surrounding it. It is by no
means certain that all such growths belong to one sj^ecies or even to
one genus, but they are nuich alike in structure and growth and live
upon animal and vegetable matter, either as j)arasites attacking living
matter or as saprophytes attacking only dead and decaying matter.
There has never been serious trouble with this fungus at Craig Brook
station, and great loss from it can only occur in consecjuence of neglect
of the duty of picking cmt the dead eggs. An instance of its attacking
a living egg except by reaching out from a dead one is unknown. Fish
54 HEPOliT OF COMMISSIONER OF FISH AND FISHERIES.
several months old are sometimes afflicted with a similar growth, which
may possibly be not the origiual cause of the disease, but only an
attendant symptom. Such an attack was experienced at Craig Brook
in July, 1888. The fry of Atlantic salmon were the sufferers and the
mortality was considerable, but it yielded promptly to a salt bath.
The occurrence of fuugus on wounds, even on such as result from
the abrasion of the skin or the loss of a scale, is very common, but such
cases are rarely fatal, though no remedy be applied. The only serious
attack of fuugus on adult salmon occurred during the experimental
work at Craig Brook in 1871. The first inclosure made to receive the
breeding fish was a small and shallow one, made by damming the brook
itself at a point where its volume consisted of about 30 per ceut of
spring water. The fish had suffered considerably from the handliug
necessary in bringing them so far and from the rough character of the
experimental cars in which they were transported. The first of them
were placed in the inclosure June 8. On the 12th 2 of them died, on
the 13th 2 more, and by the 17th 14 were dead out of 41 received; by
the 20th the mortality had increased to such a point that it became
evident that not a single salmon would survive unless some change was
made in the mode of confining them, and they were all removed and
placed in other quarters. ]N^ine of them, already so badly diseased as
to be considered hopeless cases, were turned loose in Craig Pond, and
part of these recovered and spawned in the autumn following on a
gravelly shore, where some of them were taken and found to bear the
well-healed scars of their ugly sores.
The symptoms noted were sluggishness and heedlessness; an inclina-
tion to swim near the surface of the water; a white, filmy appearance
of the eyes, which seemed to be accompanied or followed in many cases
by blindness; a white fungoid growth on the abraded tips of the fins
and wherever the scales had been rubbed off; white blotches breaking
out on all parts of the body, even Avhere there had been no mark of
injury, particularly on the head, proving on examination to be patches
of white fungus, which, on the parts of the body covered by scales,
grew underneath the latter and pushed them from their i^laces.
Experiments in confining salmon in other waters the same season
turned out successfully, and it seems that the most important condi-
tions in the case were these: The area of the fatal inclosure was about
a quarter of an acre; the water was partly from springs and was so
exceedingly transparent that a pin dropped into it could be readily
seen at a depth of G feet, so that there was practically no protection
from the rayft of the June sun ; the fish had been transported in a com-
mon dory with holes bored in the bottom to admit water, a very inferior
sort of car com])ared with those now in use; they had been transported
a long distance and passed throe sei)arate locks and had finally been
hauled in a tub on a cart over rough ground from Alamoosook Lake to
the inclosure.
Fish Manual. (To face page 54.)
Plate 17.
^yhikA^AJ!''/ A
FUNGUS ON SALMON EGG
(Enlarged 9 tinnes.)
FUNGUS ON SALMON EGG, BEARING REPRODUCTIVE ORGANS.
(Enlarged 9 times.)
REPRODUCTIVE ORGANS OF EGG FUNGUS.
1 Enlarged 150 times.)
MANUAL OF FISH-CULTURE. 55
The conditions at Craig Pond, where some of the worst cases recov-
ered, wore these: An area of 231 acres; a luaxinuun depth of (59 feet;
exceedingly pure and transparent water, like that of the inclosure.
At two of the other iuclosiires tried that summer, where there was
no attack of fungus, the water was brown and dark, like that of ordi-
nary brooks and ponds, and in the remaining one it was intermediate
in character.
These facts point strongly to the character of the water as the cause
of the fatality of the disease, and especially to its pellucid character,
which exposed the salmon to an extraordinary glare of light, whereby
the growth of the pest was greatly encouraged. The recovery in the
transparent water of Craig Pond was rendered possible by the great
dej)th of the water, through which but a small fraction of the light of
day could penetrate. No doubt the salmon liberated there at once took
refuge in the deeper parts. The suggestion naturally arises that arti-
ficial shade might be useful in the treatment of such diseases, whether
the attacking fungus be identical with that observed in the above in-
stances or a related one.
It is certain, from the promptness with which dead animal matter
becomes the prey of saprophytic growths, that the si^ores of these
water-molds are well disseminated throughout fresh waters, everywhere
ready to seize upon an opportunity for germination and growth, and
that as a general rule these spores are quite unable to seize upon any
animal substance which is not already dead or in a diseased condition.
A growth of Saprolegnia ferax once established on the body of a
salmon is able to extend itself uijon and into the living tissues around
it, Avhich it seizes upon and destroj^s. Growing upon a dead egg, it not
only ensnares the neighboring living eggs, but sometimes pierces their
shells and establishes itself on the internal parts. In one instance the
fungus had gone so far as to attach itself to a living embryo, which, on
removal from the shell, was found to support on the sac quite a tuft of
growing fungus, though neither on the sac nor any other part of the
fish was a trace of dead substance discernible.
It has been ascertained that the Saprolegnia which attacked the
living salmon can be communicated by contact to dead flies, and that
Saprolegnia found growing in the ordinary way on dead flies in water
can be communicated in its turn to living and healthy dace and may
so flourish on them as to cause their death.
The impression has prevailed that the Saprolcgnia which infests the
eggs in hatching-troughs originates in or is encouraged by bare wood
exposed to water, and that special effort is necessary to prevent its
forming; but experience at this station does not show that attacks of
fungus on either eggs or fish could be traced to bare wood, and, on the
other hand, eggs aiul fish in troughs carefully varnished with asphaltum
are no freer from fungoid or other disease than those in neighboring
troughs from which long use had worn almosi the last vestige of varnish.
56 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
Tlie best precaution against this growth is the careful picking out of
dead eggs before there is time for the fungus to grow on them, and in
case of a serious attack on fry or older fish to treat them with an exterior
application of salt, whicli, wliile not a cure-all, is very efficacious in
cases of fungous diseases, and, if prudently used, a safe remedy for fish
that have reached the feeding stage.
To apply this remedy to fry in the troughs a saturated solution of
salt in water is made — that is, the strongest brine that can be made with-
out heating the water. The flow of water in the trough to be treated
is then stopped, which leaves it from 3 to 4 inches deep, when enough
brine is poured in to make the water in the trough about as salt as com-
mon sea-Avater, about 1.028 specific gravity. The fish are left in this 20
or 30 minutes, unless they exhibit uneasiness, and tben fresh water is
turned on. Precaution is taken to dilute the brine with an equal quan-
tity of water, to distribute it the whole length of the trough, actively
stirring the water to secure an even mixture ; and before turning on the
usual water snpply a large quantity of fresh water is likewise poured
in, distributing it the whole length of the trough and stirring as before,
to guard against a too sudden change.
Such precautious are especially necessary in the application of salt
to very young fish. A large number of salmon in the sac stage was
once destroyed by i)ouring in a little brine without stirring it; it ap-
peared to sink to the bottom and spread out in a layer by itself among
the fry, and all exposed to it died.
ENEMIES OF YOUNG SALMON.
The young salmon are subject to the attacks of many animals and
birds, such as the mink, mole, star- nosed mole, common rat, muskrat,
kingfisher, great horned owl, great blue heron, sandi)iper, and fish-
hawk, besides frogs and all large fishes.
At Craig Brook the mink has caused serious loss. As a protection
some of the ponds are covered with galvanized poultry netting, and
traps are kept constantly set in the avenues by which this animal is
apt to approach. The mole burrows through embankments and thus
sometimes causes trouble. The star-nosed mole is known to steal dead
eggs, and is snspected of taking live ones. The rat sometimes takes
young fish from the troughs. The muskrat burrows in embankments
and sometimes eats fish.
The different fish -eating birds occasionally steal fish from the ponds
or troughs, but if a careful watch is kept the danger is not great.
Frogs may be exceedingly destructive to young salmon, and must be
caught out of the fish-ponds.
To avoid loss from cannibalism among the fishes it is necessary to
feed them well and to take great care that no large fish get in among
the small ones.
Fish Manual. (To face page 56.)
Plate 18.
TAKING SPAWN OF LANDLOCKED SALMON AT GRAND LAKE STREAM. MAINE,
THE LANDLOCKED SALMON.
The landlocked salmon was formerly regarded as specifically distinct
from the seagoing form, but it is now generally considered only a
variety. The tisli lound in Sebago Lake and other localities in the
United States is known as Salmo salar sehago, and the Canadian form as
Sahno salar ouananiche. From the fish-culturist's point of view, how-
ever, the marked difference between the landlocked and the seagoing
salmon in habits and growth must separate them as widely as any two
species of the same family.
Landlocked salmon are known to exist only in some of the lakes in
Sweden, besides the lakes of eastern North America. They are native
to most of the lakes of eastern Labrador, including the waters tribu-
tary to Ungava Bay, and find their western limit in Lake St. John and
vicinity, on the Saguenay River. Those of the latter district have been
much written about under the name of ^^ ouananiche.''^
Doubtless the absence of the seagoing instinct is at the bottom of
most of the variations from the normal type of Salmo salar which the
landlocked salmon exhibits. Its lower tone of color, less permanent
sexual marks, and greater liability to ovarian disease, as well as differ-
ent habits of feeding, may perhai)S be referable to the same general
cause. There are some other peculiarities, how^ever, which are not so
easily explained. For instance, the eggs of the landlocked salmon are
considerably larger than those of the sea salmon, and the very young
fry are correspondingly larger.
The growth of the young of the Sebago landlocked salmon seems to
be more rapid than that of the anadromous salmon, for some specimens
more than a foot long still bear on their sides dark, transverse bands,
characteristic of young salmon; but it may be that the landlocked fish
simply retain the marks of the immature stages to a later period of life.
This view is supported by the fact that the dark bands are never com-
pletely obliterated from the sides of the landlocked salmon, being always
very distinct, even in adult specimens, on the under side of the skin, a
character absent among migratory salmon.
The landlocked salmon is smaller than the anadromous salmon, but
its fiesh is fat and rich and of a very delicate flavor. In game qualities
it is, for its size, quite the peer of the larger salmon, and affords keen
sport to the fly fisherman. It is, therefore, much sought after, and
ranks in public favor among the foremost fresh-water species.
57
58 REPORT OF COMMISSIONER 01' FISH AND FISHERIES.
The iiiitnral range of the lancUocked salinon in the United States is
much restricted. Leaving out of the question the salmon formerly
frequenting the rivers tributary to Lakes Ontario and Champlaiu, the
extent of whose migration is a matter of doubt, we find them only in
four limiteddistricts, all in the State of Maine, namely, the Presumpscot
Kiver (including Sebago Lake) in Cumberland and Oxford counties, the
Sebe(; liiver (a tributary of the Penobscot) in Piscataquis County, the
Union River in Ilancock County, and the St. Croix Eiver in Washing-
ton County. Tiiere are some minor differences between the iish of these
several districts, of which, perhaps, that of size is most notable. The
Sebago and Tnion Kiver fish are much larger on the average than those
of the Sebec and St. Croix. The Sebago salmon average at the spawn-
ing season 4 or •') pounds weight for the males and a pound less for the
females, while specimens of L2 and 14 pounds weight are not rare, and
there is a record of one of 25 pounds. The Union River fish are about
the same size, The St. Croix fish vary in the matter of weight in dif-
ferent parts of their range, but the average weight of either sex at
Grand Lake Stream is a little less than 3 pounds; specimens of over 6
pounds are rare, and none is on record of over 10 pounds.
After attempts to collect eggs of landlocked salmon in each of the
four regions mentioned, it was found that Grand Lake Stream in the
St. Croix district afforded excellent facilities for this work. A hatching-
station at that place was operated from 1875 to 1892, and has been
recently reopened.
The following notes on fish-cultural methods have special application
to Grand Lake Stream:
The landlocked salmon of the St. Croix, though originally well dis-
tributed through the lakes tributary to that river and still inhabiting
a great many of them, finds in some a much more congenial home
than in others, its favorite abode being (irand Lake on the Schoodic
River. This body of water is of irregular shape, about 12 miles in
length and 4 in extreme breadth, fed almost wholly by short streams
that form the outlets of other lakes, and from this cause, as well as
from the fact that it drains a gravelly country and is girt with clean
rocky shores, it is one of the purest of the Maine lakes. Its greatest
depth is believed to be little more than 100 feet. Its outlet is Grand
Lake Stream, a shallow, rapid, gravelly stream, about 3 miles long, to
which the salmon go in October and November to deposit their eggs.
Comparatively few of the salmon of this lake resort to the streams
tributary to it.
The operations with landlocked salmon necessarily differ from those
with migratory salmon. Being at home in fresh water and having there
their feeding-grounds, they continue to feed until the close approach
of the spawning time, and hence they could not be penned up in the
sunnner without some provision for an artificial supply of food, which
would probably involve a great deal of expense and trouble. More-
MANUAT> OF FISH-CULTUKE. 59
over, the necessity of collecting- breeding fish early in the summer does
not exist, because they are at no time more congregated and easy to
catch than at the spawning season.
Their capture is easily effected by stretching a net across the outlet
of the lake and leading them through a tunnel-formed passage into an
iuclosure of netting. There happens to be at this point a wide surface
of smooth bottom, with water from 1 to 3 feet in depth, affording an
excellent site for s])acious inch^sures, not only for entrapping but for
assorting and storing salmon during the spawning season. Nets are
generally stretched across the stream (to keep the fish back in the lake)
immediately after the beginning of the close season, September 15.
The earliest of them begin to spawn before the end of October, but the
actual inclosing of the breeding stock is deferred until the early days
of November. The taking of spawn generally begins about November
6 and continues two or thi'ee weeks. Commonly by November 20 or 22
this work is completed, and the breeders are carried a mile or two up
the lake and liberated.
The method of manipulation is the same as at the Craig Brook station,
and does not differ materially from that adopted by all the American
breeders of Salmonida'. The results in the impregnation of the spawn
are not so uniformly satisfa(;tory as with sea salmon. Ovarian dis-
ease seems more prevalent among landlocked than among migratory
salmon. The occurrence of white eggs among the normally colored
and healthy ones, as they are yielded by these fish, is very common,
and occasionally the entire litter is defective. It is not improbable
that some eggs are incapable of impregnation, though exhibiting no
visible signs of disease. However, the general result is satisfactory,
the ratio of impregnated eggs being from 93 to 05 per cent.
The facilities for developing and hatching the eggs at Grand Lake
Stream are rather poor. No good site could be found by the side of
the stream, no suitable brook could be found near enough to the fishing-
grounds, and the neighboring springs lacked either volume or facilities
for utilization. Of three hatcheries, two use spring water exclusively,
and one of them lake or stream water exclusively. The lake water is
preferred, but unfortunately it can only be used for the slow develop-
ment of part of the eggs, circumstances connected with the floating of
timber down the stream compelling the evacuation of that hatchery in
March. The main hatchery is well located except that the water is from
springs, and this unfavorabhi circumstance is well counterbalanced by
the facilities for aeration, which are very good and very fully emi)loyed.
The eggs are placed upon wire-cloth trays in stacks or tiers, ten deep,
and arranged for a free horizontal movement in the water.
The egg shipments are made in January, February, and March, and
sometimes in April. The eggs hatched are selected from those that have
been retarded in development; the fry reach the age for liberation in
June, when their natural food is believed to be abundant.
60 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
Experience at Green Lake has supplied some interesting data. Here
we find the breeding- grounds of the salmon both in the affluents and in
the effluent of the lake, but, unlike (xrand Lake, mainly in the affluents.
Great Brook, the largest tributary, is most resorted to, and on this
stream is located a station for the propagation of this species. The
most of the breeders are taken in a trap in the brook, which they
readily enter when seeking to ascend to their natural breeding-grounds
just above. The trap is constructed of wood, and close to it, also in tke
bed of the brook, are numerous pens of the same nuiterial, in which the
fish are assorted and held during the spawning season. On the bank,
snug by the pens, is the spawn-house, and a few rods away is the
hatchery. The hatchery is supplied with water from Kooky Pond, the
source of Great Brook, by a wooden flume 7,050 feet long, supported by
wooden trestles, at some points elevated many feet above the ground.
In cold weather the water cools oft" 1^ degrees in passing down this
flume; in warm weather it warms up lA degrees. Though the summer
temperature during the early years of the station was sometimes over
80° F. and some other species succumbed to the heat, the landlocked
salmon endured it safely, and the only notable effect on them was that
at 75° and upward the adults reared in the station ponds refused to eat.
As at Grand Lake Stream, among the adult wild salmon caught for
breeding each year are many more females than males. In 1881) the
proportion was 3 females to 2 males; in 1893 it was 0 to 4. The size of
the Green Lake salmon is remarkable; the mean of 69 full-roed females
in 1889 was 7.8 pounds in weight and 25.5 inches in length ; the males
the same year averaged 5 i)ounds in weight and 22.3 inches in length;
one female weighed 11 pounds 9 ounces, and measured 30 inches;
another, 11 j)ounds 0 ounces in weight, was 30i inches in length; one
male, 31 inches long, weighed 13 i)Ounds 8 ounces. The number of eggs
yielded by the females is about 4,000 each.
Fian Manual. (To face page 6 1 .)
Plate 19.
'-,■':* >
THE RAINBOW TROUT.
DESCRIPTION OF THE FISH.
The body oftlie rainbow trout {Salmo irideus) is comparatively short
and deep, and is more elongate in males than in females. The average
depth is contained about three and four-fifths times in the body length.
The short head, which is obtusely ridged above, is about one-fourth the
total length. The mouth is smaller than in other species of Salmo, the
maxillary reaching scarcely beyond the eye, which is rather large, and
is contained five times in the side of the head. The caudal fin is dis-
tinctly but not strongly forked. On the vomer are two irregular series
of teeth. The dorsal rays number 11 and the anal 10. In the typical
species there are about 135 scales in the lateral series, Avith 20 rows
above and 20 below the lateral line; in the several subspecies the
number of rows of scales along the side is from 120 to 180. The color is
variable, depending on sex, age, and character of water. Typical adult
fish are bluish above, silvery on the sides, profusely and irregularly
dark-spotted on the back and sides, the spots extending to the vertical
fins, with a red lateral band and blotches and a nearly plain belly. The
sea-run fish are nearly plain silvery. The chief distinguishing color
characteristics of the varieties are in the number and position of the
spots.
RANGE AND VARIATION.
The rainbow trout is not indigenous to eastern waters, its original
habitat being the Pacific coast of the United States. It is especially
abundant in the mountain streams of California. A few specimens,
however, have been taken in saltwater, audit is not nnlikely that some
find their way through the rivers into the sea.
The species is subject to considerable variation in form and color in
dift'erent parts of its range, and the following varieties have received
recognition by ichthyologists: The brook trout of western Oregon and
Washington [Sulmo irideus masoni), which rarely weighs as much as a
pound and is locally abundant in the streams of the Coast Range from
Puget Sound to southern Oregon; the McCloud River trout {kSalmo
irideus. shast<(), which attains a large size, is abundant in the streams of
the Sierra Nevada Mountains from Mount Shasta southward, and is the
rainbow trout which has received most attention from fish-culturists;
the Kern River trout {Salmo iridens gilberti), which attains a weight of
8 pounds and is found only in Kern River, California; the nosliee or
nissuee trout {Salmo irideus stonei), Avhich inhabits the Sacramento
basin and reaches a weight of 12 pounds; the golden trout of Mount
Whitney (Sahno irideus aqua houita), which inhabits streams on both
sides of Mount Whitney, California.
61
62 REPORT OF COMMiaSlONER OF FISH AND FISHERIES.
Tn the extensive section of the West in Avhich the fish abonnds its
name varies in different localities; red sides, monntaiu troiii, brook
trout, and gohlen trout, besides rainbow trout, are some of the popular
appellations, while in the States east of the Mississippi Kiver it is verv
generally called rainbow trout or California trout.
TRANSPLANTING.
The rainbow trout has been successfully transplanted in many of t iu'
mountain streams in different parts of the United States, where it
grows and multiplies rapidly, as is shown by the many favorable
reports. The best results, however, seem to have been obtained from
plants made in streams of Michigan, Missouri, Arkansas, throughout
the Alleghany Mountain ranges, and in Colorado, Nevada, and other
Western States. It was iutroduced into eastern waters by the United
States Fish Commission in 1880, but it is possible that specimens of it,
or its spawn, had been brought east prior to that time by some of the
State commissions or by private enterprise.
It is believed that this species will serve for stocking streams for-
merly inhabited by the brook trout {Snivel ini(sj'ontinalis), in which the
latter no longer thrives, owing to the clearing of the lands at the
sources of the streams, which has produced changed conditions in and
along the waters not agreeable to the brook trout's wild nature. The
rainbow is adapted to warmer and deeper waters, and is tlierefore
suited to many of the now depleted streams which flow from the moun-
tains thiough the cultivated lands of the valleys.
Kainbow trout differ widely from brook trout and other pugnacious
fishes, in that they feed principally upon worms, larva', Crustacea, and
the like, and do not take readily to minnows as food. They should be
planted in spring or early summer, when their natural food is abundant,
as they will then grow more rapidly and become accustomed to life in
the stream, and when worms, larvae, etc., are no longer to be found,
their experience and size will eiuible them to take a minnow or any-
thing that may present itself in the shape of food.
Fry should not be planted in open waters until they are several
months old, and then not until the temperature of the streams begins
to rise; but tish hatched in December and January can safely be planted
in Ai^ril and Maj.
SIZE AND GROWTH.
The size of the rainbow trout depends upon its surroundings, the
volume and temperature of the water, and the amount of food it con
tains. The average weight of those caught from streams in the East is
probably less than a pound, but some weighing 6| i^ounds have been
taken. In the Ozark region of Missouri they are caught weighing 5 to
10 pounds. In some of the cold mountain streams of Colorado their
average weight is not more than 6 or 8 ounces, but in lakes in the
same State, where the water becomes nu)derately warm in summer
and food is ])lentitul, they reach 12 or Impounds, tish of this size being
from 25 to 28 inches long. In the Au Sable Kiver, in Michigan, they
Fish Manual. (To face page 62.)
Plate 20.
MANUAL OF FISH-CULTURE. 63
attain a weight otT) to 7 imunds. In their native streams of California
they are often eaujiht ranging from 3 to 10 ponnds, bnt average from
1 to 2 pounds. The largest specimen ever i)roduced in the ponds at
Wytheville, and fed artificially, weighed OJ pounds, but many others in
the same ponds weigh from 1 to 3 pounds.
The average growtli of the rainbow trout under favorable artificial
circumstances is as follows: One year old, from i| to 1 ounce; 2 years
old, from 8 to 10 ounces; 3 years old, from 1 to 2 pounds; 4 years old,
from 2 to 3 pounds. They grow until they are 8 or 10 years old, the
rate diminishing with age. Some grow much faster than others under
the same circumstances, but the rate of growth is largely a question of
food, temi)eratnie of water, and extent of the range. In water at 00°,
with plenty of food, lish 1 or 2 years old will double their size several
times in a single season; Avhile in water at 40°, with limited food, the
growtli is scarcely perceptible.
The rainbow, like the brook trout, will live in water with a compara-
tively high temperature if it is plentiful and running with a strong
current, but sluggish and shallow water, even with a temperature of
70° F., is dangerous for brook trout. Rainbow trout will live in warmer
water than brook trout, and are found in swift, rapid streams at 85° F.,
especially where there is some shade, but in ponds that temperature is
dangerous even with shade and a good current. In its natural condi-
tion this trout is usually found in water varying from 38° F. in winter
to 70° F. in summer, and in selecting a site for a trout liatchery spring-
water with a temperature of 42° to 58° is required.
The rainbow trout is a superior game fish, a vigorous biter, and fights
bravely for liberty, though in the East it is somewhat inferior to the
brook trout in these respects.
In the following pages is described the manner in which this fish is
l)ropagated artificially at Wytheville, together with the design and con-
struction of the ponds and apparatus, and such other information is
given as is suggested by experience at this station. It may be observed
that the methods would be equally api)licable to the propagation of the
brook trout.
SPAWNING-PONDS.
In constructing ponds, one of the first considerations is to place the
fish absolutely under the control of the fish-culturist, that he Tuay be
able to handle them without delay or inconvenience. At Wytheville
they are constructed entirelj^ of wood, about 15 by 50 feet and 3 to 3^
feet deep, and sha])ed as shown in plate 21, and have been found very
satisfactory. Excellent water circulation is obtained in all jiarts, and
there are no corners for refuse to lodge in. The bottom of the j)ond is
built with a gradual elevation, in the direction of the upper end, of 2
inches in the entire length of the pond. This makes it practically self
cleaning; nearly all of the foul matter will pass of!" and any remainder
can be disposed of by drawing the water down low for a short period
and then flushing the pond with fresh water. This method obviates the
necessity of handling the lisii, which is very important, especially when
near the spawning time.
64 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
A guard-rack made of thin, narrow slats is arranged on an incline of
about 4r)0, as shown at C If the water is to be used again in ponds
below, a receiver is built underneath the bottom of the pond at the
lower end, between the foot of the guard-rack and the dam-boards,
and the floor of the pond immediately over the receiver is cut away and
fitted with a grating. This allows matter to fall through the receiver
and from there it is washed through the sluiceway, which taps the
receiver by drawing the gate shown at D. The sluiceway, E, is
covered and leads off to a general waste-ditch.
The pond is provided with a spawning-race about a foot deep, 4 feet
wide, and 25 feet long, placed at the upper end of the pond, as shown
at H. Three division boards (shown at F), about 12 feet long and of
suitable width to come within 1 or 2 inches of the surface of the water
when the pond is filled, are firmly fixed at the bottom. The object of
these boards is to form four avenues leading to the raceway, so that
one or two pugnacious fish can not command the ai)proach and keep
back spawning fish inclined to enter. There is a dam across the race-
way about 4 inches high (shown at G) for the purpose of bringing the
water to that depth in the lower end, so that when the trout enter they
will find sufficient water in which to swim freely, and not be inclined
through fear to return to the pond.
The water in the pond is of sufticient depth to bring its surface
within G inches of the top of the dam in the raceway, which will give
the fish, in entering the raceway, a jump of 7 inches, allowing 1 inch
for the de[)th of water on the dam in the raceway. This distance has
been found more satisfactory than any other, and spawning fish alone
will go up. If a jump of less than 7 inches is given, other fish can
enter the raceway without much exertion, and will ascend and disturb
the breeding fish, which, when spawning, should be kept strictly by
themselves.
There is no rule regarding the supply of water that applies to a
spawning-pond at all times and in all places. It is necessarily gov-
erned by the temperature of the water, size and shape of the pond,
size of the fish to be supported, the amount of shade, etc. For a
pond such as has been described, where water is plentiful, at least 200
gallons per minute should be provided, with not less than 75 gallons
per minute as a minimum, even where the temperature is from 50 to
55 degrees and all other conditions are favorable. While the former
amount is not absolutely necessary for the support of the fish, i'
insures the pond being kept clean and the fish are more inclined to
enter the raceway at spawning time. In order to maintain an even
temperature in the pond the earth is banked against the sides and
ends, covering the framework shown on plate 21, and the embankments
are made broad enough on top to admit of a good footway around the
ponds.
Such a pond as this can accommodate from 1,000 to 1,500 breeding
fish. Fish must not be overcrowded, and in estinuiting the capacity of
Fish Manual. (To face page 64.)
Plate 21,
Z- w c; o '£ o c o
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MANUAL OF FISH-CULTURE. G5
a pond several luodityiiig conditions must be considered, such as the
size of tlie fish, water sui)ply, temperature, and sliade. In stocking the
spawning-pond a good proportion is two females to one male. The
breeding stock is selected carefully every year; only sound and perfect
fish are retained for the next season, and the blind and emaciated
fish of both sexes are destroyed.
TAKING TDE SPAWN.
The spawning season varies with the locality and the temperature of
the water. It is usually two to four weeks later in the streams than
where the tish are kept confined in spring water. In the ponds at
Wytlieville the spawning fish may be found any time after the 1st of
November; the season is well started by November 15, and generally
closes about the 1st of March. December and January are the best
months. In California the season extends from the 1st of February to
May, and in Colorado begins early in May and continues until July.
The natural nests of these fish are made on gravelly bottoms, and
are round or elongated depressions about the size of a dinner plate.
After the eggs have been deposited and fertilized they drop between
the pebbles of the nest, where they lie protected until hatched.
Where spawning-ponds are provided with suitable raceways the fish
will ascend from the ponds into them, seeking a place to make their
uests, and may then be taken out and stripped of their spawn. To take
the fish from the raceway, a square net (I, plate 21) is dropped in on
the cleats nailed against the side walls in the approach, shown at J, the
dam in the mouth of the raceway is raised, and the fish driven back
into the net. The net is then lifted out of the water, and if it contains
too many fish to handle conveniently a landing-net is used to take out
part of them before the square net is moved. The ripe fish are then
placed in tubs or other vessels provided for the purpose. If too many
fish are put in the tub at one time they become restless and sick before
they can be stripped of their spawn.
There are two methods of taking and impregnating the spawn of
fishes, the "wet" and the "dry" methods. By the "wet" method the
eggs are taken in a pan containing sufficient water to cover them and
allow them to mix freely with the nult, which is immediately added.
After the contents of the pan have been stirred for a few seconds with
a feather, the eggs are set aside and left undisturbed during fertiliza-
tion. The "dry" or "Russian" method is nowin general use; the eggs
and milt are taken in a moist pan and it makes little difference which
is taken first, but one should immediately follow the other, and the
contents of tlie pan be thoroughly mixed.
After the eggs and milt have had time for (;ontact, and before the
eggs begin to adhere to the bottom of the pan, water is added to
the depth of about an inch, the eggs being kept in gentle motion, by
turning the pan, to prevent adhesion. After 2 or 3 minutes the milt
F. M. o
66 REPOHT OF COMMISSIONER OF FISH AND FISHERIES.
is poured off and clear water is put in the pan, in which the eggti are
allowed to remain until they separate, which will be in from 15 to 45
minutes, depending on the temperature of the water. It is preferable
to take the eggs to the hatcherj^ before the milt and water are poured
off, and there rinse them off" and place them directly on the hatching-
trays (previously arranged in the troughs) and then allow them to
separate. In freeziug weather it is advisable to strip the eggs in water
or to use two pans, one set in the other, with water in the bottom pan
to prevent the eggs from being chilled.
In taking spawn the manipulation of the tish without injury is a very
delicate and exacting task, full knowledge of which can only be
acquired by experience, as it is difficult to siiueeze the spawn from the
fish without injuring or even killing it. In taking hold of the fish in
the spawning-tub the operator catches it by the head with the right
hand, the back of the hand being up, and at the sajne time slips the
left hand under the fish and grasps it near the tail, between the anal
and caudal fins. A fish caught in this way can be easdy turned over
as it is brought out of the water, so that its abdomen is up and in the
proper position for spawning by the time the spawning-pan is reached.
If the fish struggles it must be held firmly, but gently, until it becomes
quiet, and when held in the right position it will struggle only for a
moment. A large fish may be held with its head under the right arm.
"When the struggle is over the right hand is passed down the abdo-
men of the fish until a point midway between the pectoral and ventral
fins is reached, then with the thumb and index finger the abdomen is
pressed gently, and at the same time the hand is slipped toward the
vent. If the eggs are ready to be taken they will come freely and
easily, and if they do not, the fish is put back in the pond until ready to
spawn. If the eggs come freely from the first pressure the operation
is repeated, beginning at or near the ventral fin.
After the first pressure has been given, by holding the head of the
fish higher than the tail, all of the eggs that have fallen from the
ovaries and are ready to be expressed will fall into the abdomen, near
the vent, so that it will not be necessary to press the fish again over
its vital parts, the eggs having left that portion of the body. All of
the eggs that have fallen into the abdnmen below the ventral fin can
be easily ejected without danger of injury to the fish, caused by unnec-
essary pressure over its important organs after the eggs have left that
part of the body. If these directions are judiciously and carefullj^ fol-
lowed but little, if any, damage will result; and, as an illustration, it
may be mentioned that fish have been kept for 14 years and their full
quota of eggs extracted each season during the egg-producing term,
which is normally from 10 to 12 years. The male fish is to be treated
very much in the same manner as the female, except the milt must not
be forced out, only that which comes freely being taken.
After strii)ping, the fish are not returned to the spawning i)ond. but
spent females are placed in one pond and tlie males in another. The
FUh Manual. (To face page 66.)
Plate 22.
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MANUAL OF FISH-CULTURE. (17
iiKiics are very puj»nacioiis at this season, and sometimes finiit for an
hour or more at a time, until they are entirely exhausted; they run at
each other with open mouths, lock their jaws together, and in that
position sink to the bottom of the pond, where they lie for a short time,
each holdin,i;' the other in his grasp until rested, when they rise and
resume the eombat. As their teeth are abnormally long, they scar
each other and even bite pieces of skin and tiesh from the cides of their
antagonists.
The males are good breeders at two years old, but very few females
produce eggs until the third season, when they are from 30 to 3G months
old. At Wytheville hatchery about 1 per cent of the females spawn at
2 years of age; about ")() per cent at 3 years, and about 85 percent
each season after that. About 15 per cent of the fully matured females
are barren eacli season. It was at one time thought that the same
individuals were barren each year, but experience has shown that
such is not the case, as fish which were barren one season have been
held over, in a separate pond, until the following year, when a large
portion, if not all, produced eggs. This sterility may be the result of
injuries which were received the previous season, during the progress
of spawning.
EGGS.
The number of eggs produced in a single season depends upon the
size and age of the fish. The maximum from one 3 years old, weighing
^ to 1^ i)Ounds, is from 500 to 800; from one 6 years old, weighing 1' to 4
pounds, it is 2,500 to 3,000. The eggs vary in size from 4.i to 5 eggs to
the linear inch, and are of a rich cream color when first taken, changing
to a pink or tiesh color before hatching.
THE HATCHING-TROUGHS AND TRAYS.
The eggs are incubated on trays ])laced in troughs of various sizes and
shapes, which at Wytheville are set in pairs, as shown on page (58.
They are made of the best pine lumber, dressed to li inches thick, and
are 15 feet long, 14 inches wide, and 8 im;lies deep. Fourteen inches
from the lower end inside is a guard-screen of perforated tin or wire
mesh, fastened on a frame exactly fitted across the trough. Tin with
perforations of -^ inch for very young fry, and larger ones as the fish
grow, is ])referable to wire. The screen is arranged to slide vertically
between beveled cleats, that it may be kept clean easier. A plain
board, 3^ inches wide, is placed 4 or 5 inches from the lower end of the
trough to serve as a dam.
In the upper end of the trough horizontal screens (B,page G8), made
of perforated tin, are used. These are so constructed that they can be
slipped forward or raised up (as shown in the illustration) in feeding
the fry or cleaning the troughs, and the water falling on a small wooden
block in the center of tlie screen is thoroughly aeiated before entering
the trough. This arrangement possesses many advantages over the old
method, w^here the screens were vertical, or nearly so, as it i)ermits the
68
REPORT OF COMMISSIONER OF FISH AND FISHERIES.
fisli to ascend to tliehead of the trougli and receive tlie water as it falls
from tbc screen, which is very beneficial. Its use not only keeps the fry-
clean even in muddy water, but also reduces the loss of fry from suffo-
cation in the early stages, caused by their banking around the vertical
screens, and obviates the necessity for trough covers to prevent jumping,
as trout rarely jump where the horizontal screen has been adopted.
f
I
1
A. Guardscroeii.
B. Horizontal sliding-screen.
C. Hatchiugtray.
U. Position of liatching-trays.
E. Tin tray for use in muddy \\ a'er.
F. Block for water to fall on.
G. Brackets.
H. Feet.
suDiNG scfesw,
J =-... 0 o 0 - 0_ ^ ° -P—
LONGITUDINAL SECTION OF HATCHING TROUGH.SHOWNG POSITION OF HATCHING THAYS, DAM, ETC.
llatching-trouglis, Guard-screen, etc.
Hatching-trays (C), made about twice as long as wide, i. e., 28 by
13i, are convenient to handle and adjust in the troughs. The sides
of the frame are made of good pine lumber, dressed, 1 inch square;
the ends are dressed i by 1 inch, and are cut into the sides to form a
smooth surface on the bottom for the wire filling. The wire used on
the trays is woven with 8 threads to the inch, with a mesh \ inch long,
and should be well galvanized after it is woven, in order to prevent
rusting at the laps.
MANUAL OF FISH-CULTURE. 69
Four lijitc'hinj^'-trays are placed in each trough and are secured by
keys or wedges, and should be from 1 to 2 inches lower at the end next
to the head of the trough, as shown at U, D, D, D, page 68. If placed
in this way, each tray will hold from 12,000 to ir),000 eggs with safety.
jVIuddy water during the hat(;liing season necessitates the use of a tin
tray with a i)erforated bottom (shown at E, page 68), which is i;>i^ inches
wide and 32 inches long. This sets inside of the hatching-trough on
feet raising it an inch above the bottom of the trough. The hatching-
tray containing the eggs is placed inside and rests on the brackets
shown at G. The fish, as they hatch out, fall from the hatching-tray
upon the perforated bottom of the tin tray, and by their movements
work the sediment through, leaving them on a clean bottom and in no
danger of being smothered. The tin trays are also useful in counting
fish, or in holding small lots of fish of different species in the same
trough. Where supplementary trays are not used, the fry fall directly
into the troughs.
Troughs 15 feet long will admit of four hatching-trays in a single
row, each of which will safely carry 12,500 eggs, making 50,000 to a
trough; this is enough to work easily, but if it is necessary to make
more room a double row of trays may be put in, one tray resting on
the top of the other. Thus the trough could contain 100,000 eggs as
its full capacity. The troughs will carry this number up to the time
of hatching by placing the trays lower at one end than the other, as
previously described.
When the hatching stage arrives, two trays of 12,500 eggs each are
as many as should be left in one trough ; with this number, by using the
horizontal sliding-screen in the upper end, there is but little danger of
the alevins congregating and smothering in any part of the trough. If
it is necessary to hatch a much larger number than this in one trough,
the sliding-screen is so arranged that the water falls well up against
the end of the trough. This is done by raising the screen and turning
it back against the reservoir, or by putting in a wedge-shaped block for
the water to fall upon, turning the thin side of the block toward the
upper end of the trough. Fifty thousand trout have been hatched in
one trough prepared in this way without loss from suffocation, but it is
not advisable to hatch such a large number together.
The amount of water necessary for hatching and rearing depends
upon the temperature and the manner in which the water is applied.
The water should receive as much aeration as possible before entering
the compartments containing the fish and eggs. At Wytheville, where
there is an even temperature of water of 53° in the hatchery, about the
following quantities are used in the troughs containing fish and eggs:
100,000 cfffTs dnrinjr incubation, 12A gallons jxn- minute.
100,00(1 fisb hatchiu'r to time of feeding, .SO gallons per minute.
100,000 fish from 1 to i months old, 50 gallons per minute.
100.000 (isli 1 to G months old, 100 gallons per minuto.
100,000 lish from 6 to 12 months old, 200 gallons per minute.
70 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
These amounts are ample, and probably even lialf would suffice if it
were necessary to economize in the use of water. In rearing-ponds
more water is required, as the circulation is not so good and the out-
door exposure causes the temperature to rise. If water is plentiful,
double the amounts stated Avould be advisable for pond-culture.
During the last two seasons at Wytheville 80 to 85 per cent of the
eggs taken produced tish, of which about 70 per cent were raised to
three months old and 55 per cent to yearling fish. The loss in eggs
was almost entirely due to failure in impregnation, very few bemg lost
from other causes.
CARE OF EGGS AND FRY.
After the eggs are placed on the trays, the only attention necessary
until the hatching begins is to keep them clean; the dead eggs, which
may be known by their turning white, must be picked out at least once
each day. After the eye-spot can be plainly seen it is well to run a
feather through the eggs for the purpose of changing their position
on the trays, and to disclose any foreign matter or dead eggs that
may be hidden underneath. The greatest care should be exercised in
handling the eggs at anytime, particularly from the first or second day
after collection up to the a])pearanceof the eye-spot, and then only when
absolutely necessary. During this period, the eggs are very delicate,
and even passing a feather among them may cause a heavy loss.
The time required for hatching depends mainly upon the temperature
of the water. Kainbow trout eggs will hatch in water at 50° in from 42
to 45 days, each degree colder taking 5 days longer, and each degree
warmer 5 days less; the difference increases as the temperature falls
and diminishes as it rises.
After the fry hatch they require but little attention until the umbil-
ical sac is absorbed and the time for feeding arrives. They are exam-
ined each day, and the dead fish and decayed matter removed from
the troughs, which are kept perfectly clean, and if possible provided
with a thin layer of coarse white sand on the bottom, to keep the tish
in healthy condition. As the fish grow they should be thinned out in
the troughs, from time to time, as their size may require. When they
first begin to feed, 12,000 to 15,000 fish to the trough are not too many;
but by the time they get to be 1^ to li inches long they must be divided
into lots of 8,000 to 10,000 to each trough; while with fish averaging 3
inches in length, 3,000 to 4,000 are as many as one trough will accom-
modate. It is advisable to give as much room as is j)racticable.
REARING-PONDS.
Ponds for rearing trout are from 8 to 12 feet wide, and of any desired
length up to GO feet, which, for convenience in drawing them off and
in feeding the fish, is about the extreme limit. The size, shape, and
arrangement of the i)onds must depend upon the ground on which
they are to be constructed. If practicable, it is best to build them on a
Fish Manual. (To face page 70.)
Plate 23.
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MANUAL OF FISH-CULTURE. 71
liillsiile, one above the other, Avith earth and piling cnibanknients on
the lower vsidcs and at the ends, A pond of this kind is shown in
plate 23, and is the one here described. Various materials may be used
for damming- the water. The embankments may be made altogether
of earth or lined with stone, brick, cement, or timber, according to
circumstances. Where the ground is of a porous or loose formation it
is necessary to use ])iling or cement for the inside of the embankments
and possibly cement for the bottoms, but earth bottoms are best where
the nature of the ground permits. The water enters the pond at one
end and discharges from the lowest opposite corner. The bottom is
graded as shown in the cross-section, plate 23, with a slope toward the
outlet, so that when all the water is drawn out the fish are led into the
receiving-trough (C), the top of which is flush with the earth bottom in
that part of the pond.
The outlet for the water is an L-shaped pipe, shown at F, and is
jilaced in the corner of the pond, the long end passing through the
piling and underneath the pond embankment; the short end, called
the standpipe, stands close to the inside corner of the pond, in an
upright position. The standpipe has two or more holes cut through
(G) on the side next to the receiving-trough, to let the water pass out
in drawing down the pond. The size of these holes is in proportion to
the size of the standpipe, which, in turn, is governed by the si/e of the
pond. The holes may have blocks of suitable size tacked over them to
allow the pond to fill with water, or, what is more convenient, covered
with blocks arranged to slip down in grooves, one block resting on the
other. Surrounding the standpipe is a crib, the front of which is 15
inches or more from the pipe and coi\tains an opening for a guard-
screen, v/hich is 14 to 10 inches wide and made with copper or galva-
nized wire cloth, the size of the mesh depending on the size of the fish
in the pond. In the bottom of the pond is a receiving-trough (C) for the
fisb, built in i)roportiou to the size of the pond; 10 feet long, 10 inches
wide, and 0 inches deep is a satisfactory size for a pond like the one
described. Tins trough extends to and connects with the standpipe,
and the guard-screen is arranged to fit down on the inside. Every
l)art is made secure, to i)revent fish from escaping when drawing off the
water. The supply-trough or pipe is arranged to keep the fish from
jumi)ing into it from the pond, as shown at A.
STOCKING THE REAKINfl-POND.S.
The rearing-ponds at Wytheville are stocked gradually, oOO to 1,000
fish being placed in the pond and trained to take food before more are
added, as that number can generally find enough natural food to sub
sist upon until they learn to take artificial food. When they have been
accustomed to hand-feeding another 1,000 fish are added, and in about
ten days 2,000 more, this i)ractice being continued until the pond is
stocked with the desired number. .When fish are first released in ponds
72 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
tliey are wild and run away from the food given them ; hence the neces-
sity of teaching a few lish to eat before more are added. The number
offish that a pond of a given size can support depends upon tlie amount
of water and shade and the temperature of the former. Ten thousand
fish are amjjle for a pond 10 by 50 feet, with water deepening from 3
inches to 3 feet.
FOOD FOE FRY.
Beef or sheep liver, ground or chopped to a pulp, seems to be the
most satisfactory artificial food for young trout. Fresh, hard-boiled
eggs, grated fine, are good, but expensive. Efforts have been made to
produce a natural or living food, such as insect larvai and small crus-
taceans, and this may yet be accomplished for late spring and summer
feeding, but for feeding the fry during the first three or four months of
their lives, which is in the winter season, there is nothing better than
liver. Shad and herring roe, put up in sealed tin cans, have been used
to a limited extent with satisfactory results, and it is believed that they
will furnish a wholesome and natural diet.
The manner of feeding young fry is very important, as the losses from
im])roper feeding are greater than from all other causes combined. If
there is undue haste the water becomes polluted, or the food is so
distributed that some fish are prevented from getting their j)roper share.
Polluted water is very injurious to the young fish, being apt to produce
inflammation of the gills and a slimy, itching condition of the skin,
which often causes heavy mortality.
The fry are ready to take food as soon as the sac is absorbed, the
time required for this depending upon the growth of the fish, which is
governed by the temperature of the water. Where the temperature is
regular at 53° they will take food in about 30 days after hatching, and
the time to commence feeding may be closely determined by watching
the movements of the fish. Before the sac is entirely absorbed they
will begin to break up the school on the bottom of the trough and
scatter through the water, rising higher and higher from the bottom
each day, until they can balance themselves gracefully in a horizontal
position, all heading against the current and swimming well up in the
water. By dropping some small bits of cork or the naj) from red flannel
on the surface of the water it can be determined if they are ready for
food; if they strike at the pieces as the current carries them down it
is evident they are hungry.
The liver is prepared by chopping it very fine and, if necessary,
mixing it with water, in order that it may be distributed evenly. It
should be given to the fish by dipping a feather into the liver and
gently skimming it over the surface of the water. After the fish grow
to be 1| to 1.^ inches long they begin to take up tlie food that settles
on the bottom of tlie trough; it is then not necessary to mix the food
with water, and it can be given by hand. The young fry are fed five
or six times a day and the food given slowly and sparingly. After they
Fish Manual. (To face page 72.)
Plate 24.
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MANUAL OF FISH-CULTURE. 73
learn to take their food from the bottom of the trough it is necessary
to feed them only three times daily, but more food must be given at
each meal.
FOOD OF ADULT FISH AND YEARLINGS.
In domestication the rainbow trout is preferably fed upon a meat
diet altogether, if it can be had plentifully and sufficiently cheap;
otherwise a mixture of liver and mush may be used advantageously.
The mush is made by stirring wheat shorts or middlings in boiling-
water until the mixture becomes thick; it will keej) for several days,
even in warm weather, if put in a cool place. The liver is ground
or chopped fine and mixed thoroughly with the mush in any desired
proportion up to four fifths of the whole, but it is better to mix
only as needed. This mixture has been used satisfactorily for many
years.
A meat-chopper may be obtained for grinding liver which will do the
work in an excellent manner, leaving no strings or gristly chunks to
choke the fish. There are several sizes of the machine made, with extra
perforated plates having difierentsized holes, from one-twelfth to one-
fourth of an inch in diameter, so that the meat may be prepared coarse
or fine, to suit the size of the fish to be fed. For small fry it is neces-
sary to use the plate having the smallest holes and to grind the food
over several times until fine enough to use.
The practi(;e of throwing food into the pond in handfuls causes the
fish to come together in great numbers and in a violent manner; and
struggling with open mouths to get a bite of the food, they often hurt
each other, injure one another's eyes, sometimes even jducking them
from the sockets. This is probably one of the main causes of blindness
among pond-fed fish.
The most approved method of feeding is to walk along the pond its
entire length to the up[)er end (the fish will soon learn to follow to that
point), then scatter a handful of food along the surface of the pond so
that it will fall to pieces. The fish follow and take up what has been
thrown out and then return to watch for the next handful, and the
operation is repeated until sufficient food is given. This manner of
feeding induces all the fish to head in the same direction while eating,
thus reducing the danger of injury.
The amount of food for a given number of trout dei)ends upon the
size of the fish and the temperature of the water, as fish will not take
food as freely in water of a low temperature as in warmer water. With
water from 50° to GO^ a daily ration for 1,000 yearling fish ranging
from .') to ") inches in length is about f of a pound; while for the same
number, 8 to 12 inches long, about 12 pounds per day are recpiired.
As the fish increase in size the amount of food should be increased
proportionately. Tliey are fed twice a day at regular hours, morning
and evening, giving half of the daily allowance each time. This keeps
them in a thrifty and growing condition.
74
REPORT OF COMMISSIONER OF FISH AND FISHERIES.
I
Cross-section through Box after it has been packed and closed.
PACKING EGGS FOR SHIPMENT.
In packiug trout eggs for shipment they are usually i)lacetl on trays
aud packed iu wet moss and the eggs divided into from five to ten equal
parts, according to the size of the shipment, using trays of suitable
size to hold each part. If 30,000 eggs are to be shipped, ten trays are
used large enough to contain 3,000 eggs each 5 if 15,000 eggs, ten trays
A. Egg-tray.
B. Foundation-board.
containing 1,500 eggs each ; 10,000 eggs, eight trays of 1,250 each, etc.,
and if over 30,000 eggs are to be shipi)ed the sliipment is made in
more than one lot. In a i)ackage of more than ten trays, esjx'cially if
the trays are large, the eggs on the lower trays are liable to be crushed
MANUAL OF FISH-CULTURE.
75
C. Ice-hopper.
by the weight above, aud if less than five trays are used in a shipment
the package is liable to become dry, and the eggs reach their destina-
tion either dead or in a shriveled condition.
The frames of the trays are made of light, soft wood dressed to -^ by
-J- of an inch, with a soft canton-iiannel bottom tightly stretched and
well tacked on. Thetrays
are made large enough to
contain their proportion
of the eggs, with an allow-
ance of f of an inch be-
tween the eggs aud the
frame of the tray. A foun-
dation-board (B) is made
with the same outside di-
mensions as the tray, with
a strip nailed around the
edge on the upper side to
form a cushion of moss
for the bottom tray. A
hopper for ice (C) is used
on the top tray. The out-
side case (E) is made 7 to
8 inches larger on the
sides (inside measure)
and 5 inches deeper than
the outside dimensions of
all the trays after they
are cleated together, in-
cluding the hoi)i)er and
the foundation-board, as
shown at D.
The trays having been
prepared, the eggs are se-
lected, those being taken
which show eye-spots and
are not too old to reach
their destination before
the time for hatching.
Allowance is made for
changes in temi^erature
on the road which would
cause them to hatch too
soon.
D. Egg-trays packed and clenteil
The eggs are taken from the hatching-trays in pans, well cleaned of
all sediment, and given a slight concussion by allowing water to fall on
them from a small spout or sprinkling pot, which causes the dead and
unfertilized eggs to turn white, when they are carefully removed. The
7G
REPORT OF COMMISSIONER OF FISH AND FISHERIES.
eggs are then accurately weighed or measured (1 ounce may be weighed
and counted, or the eggs for one tray counted and then weighed) and
the required number phiced in a single layer in the middle of the tray,
leaving an empty space all round next to the frame.
The trays are then placed one above the other on the foundation-
board, after each is covered with a piece of mosquito netting, which
should be at least 2 inches larger each way than the tray, and the
E. Outside case.
tray is filled with wet moss, the part immediately over the eggs in a
loose manner, the emi^ty space around the eggs packed tight. This
gives support to the next tray above and prevents the eggs from com-
ing in contact with the wood and becoming dry and shriveled.
After all the trays are thus arranged the hopi)er is placed on to]) and
the whole cleated together, as shown at D, They are then ready to be
placed in the box or outside case (E). Diy sphagnum moss is placed
MANUAL OF FISH-CULTLTRE. 77
in the bottom of the box to a depth of about 3 inches and the crate
of trays phiced as near the center of the box as possible. The sides
are well packed to hold it firmly in position, and when the top of the
liopper is reached witli the packing it is well filled with ice, the remain-
ing space in the box being filled with moss. Wet moss or wet packing
of any kind should never be used for the cushion around the egg-crate,
as it does not preserve an even temperature and is liable to freeze solid
if exposed to a low temperature in transit. A cross- section of the
box thus packed is showu on page 74.
The box containing the eggs should be provided with handles to
facilitate moving during transportation, in order that the liability to
injury from jarring or concussion may be reduced. For a long journey
the lid of the box is provided with hinges and hasp and staple, so that
the ice may be easily renewed. Eggs packed as described above have
been shipped with safety to all parts of the United States and to for-
eign countries.
DISEASES OF FRY AND ADULTS.
The most common diseases of trout fry are the inflammation of their
gills and a slimy skin disease, which may be caused by impure water;
the food itself may produce it, especially if stale liver is used, but it
generally follows fouling of the water while feeding. By watching
the n'lovemeuts of the fish, the symptoms of disease can generally be
detected before it reaches an alarming stage. If the gills are afiected
the fish will usually swim high in the water in an uneasy, restless man-
ner, as if gasping for breath, and when this is observed the gills must
be examined to see if they are becoming inflamed and swollen. If a
skin disease is attacking the fish, they generally indicate it by rubbing
themselves on the bottom of the trough or against anything that may
be convenient, or by diving down and giving themselves a quick, twist-
ing motion against the bottom of the trough. If the progress of dis-
ease is not promptly checked, it will soon reach a stage where nothing
can be done, and the fish grow weaker every day until they begin to
die in alarming numbers. One of the best remedies for both diseases
is salt sprinkled through the water after the ponds are drawn low, and
for a bad case of skin disease a half pint of salt for every gallon of water
in the trough is used, or about that proportion. The fish should be
watched closely and allowed to remain in the salt water until they
become restless and begin to turn on their sides. Then, as fresh water
is turned on and the trough fills, a slime will arise and float on top of
the water, like a white scum. Coarse sand should be kept in the trough
for the fish to rub themselves against. Salt is also good for the dis-
eased gills and will free them from adhering sediment.
Fungus, "blue swelling," and other diseased conditions sometimes
occur, but the most serious diseases of the fry are those just described.
Parasites sometimes attack the fish, but if the water is pure and the
fish in a healthy condition, they are not troublesome. To keep the fish
78 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
that are raised in troughs and tanks in a healthy state, it is Avell to give
them a salt bath occasionally, and a small quantity of salt in their food
will at times do them good. A little sediment from the reservoir, or
such as collects on stones in the streams, is beneficial to fish if mixed
with their food. It seems proper that they should have something of
this nature, since all or nearly all of their natural food contains more
or less sediment of the kind,
A very serious disease among adult rainbow trout shows the follow-
ing symptoms: The afflicted fish refuse to take food, and very dark
spots, from ;| to 1 inch in diameter, appear on different parts of the body,
varying in number from two or three up to twentj' or thirty on each
fish affected, a light spot about the size of a green pea appearing on
the head immediately over the brain. The fish become restless and
seek the shallow water in the corners of the pond, hiding among the
plants, and begin to die within twenty- four hours from the time the dis-
ease is noticeable. They jump and dart around in the water in a
frightened manner, settling back on their tails and sinking to the
bottom of the pond in their last struggles. This disease made its
appearance at Wytheville in December, 1S95; it was first observed
among a lot of 637 yearling Von Behr or brown trout that had been
delivered at the station on November 29. The first sign of the disease
was noted about the 5th of December, and by the 12th of the month
455 of the G37 fish were dead.
These fish were in the nursery during the first stages of the dis-
ease. The water in which they were held passed from them through an
empty pond into a second one containing about 1,000 large rainbow
trout that had recently been stripped of their spawn. On the morning
of December 23 the disease made its appearance among the latter, and
by 4 o'clock in the afternoon of the same day 50 of them had died.
Salt was applied and the water in the pond was drawn down to about
300 gallons, and 150 pounds of common salt were sprinkled evenly
through it. The fish Avere allowed to remain in this brine about 15
minutes, when they showed signs of weakening by turning on their
sides ; then fresh water was turned on freely. Good results were at
once noticeable, the fish became quiet and appeared to rest more easily,
and steadily improved, another application not being necessary. The
final result was that 70 per cent of the adult rainbow trout that had
been treated with salt were saved, while of the yearling brown trout
that were not thus treated nearly 71i per cent died.
Foul ponds cause disease, and if the fish become sick from this reason,
they must be removed to a clean pond at once and given a saltand-
clay bath, which is applied as follows: While the salt bath, before
described, is being given, 2 or 3 bushels of clay are placed in the
reservoir or supply-trough, and when the fresh water is turned on after
salting, the reservoir is flushed for 30 minutes with roily water from the
clay, and after the latter is washed away an increased amount of fresh
water is turned on for ten days or more.
Fish Manual. (
Plate 25.
<3
Nos. 1 to 12
.' 13 to 21
1899
MANUAL OF FISH-CULTURE. 79
Adult fisli are very liable to be affected with fun,£?us, which generally
appears atter a bruise or liurt, or when the tish are in an emaciated
condition. If the trouble results from an injury, it can often be cured
before it spreads to the sound flesh, but if fungus spreads like a slimy
web all over the tish, it is fatal. Fish must be handled very carefully
during the spawning season to j)revent scarifying the body in any way,
as they are especially susceptible to fungus at that period. Should it
occur, the tish must be caught at once, rubbed with salt on tlie affected
part, and then released in a pond or tank by itself, Miiere it can be
caught for further treatment in a day or two, while those affected ail
over the body should be killed and thrown out at once.
"Glassy eggs" may be the result of overretentiou of the eggs on the
part of the parent tish. If the eggs are not delivered within a reason-
able length of time, say from 30 to 48 hours after they fall from the
ovaries into the abdomen, they are surrounded with a thin watery fluid,
having a glassy appearance, which if allowed to come in contact with
water will change to a milky white, and the eggs absorbing this fluid
become hard and " glassy," after which fecundation is impossible.
Many thousand eggs have been lost annually on this account, and many
brood fish lost or rendered worthless from the same cause. The tish in
captivity will not spawn of their own accord unless they have access
to gravel or earth in which to make nests. If attention is not given to
the spawning tish and their eggs taken when ripe, they soon become
very dark in color, the abdomen swells, and sometimes the head will
enlarge, causing the eyes to protrude. Under these conditions the tish
will die in a few days, but with free and easy access to the raceway
they will not often be thus affected.
THE BROOK TROUT.
DESCRIPTION OF TIIK FISH.
The brook trout or speckled trout {Salvelinus fonthialis) is one of the
most beautiful, active, and widely distributed of the American tronts.
It prefers clear, cold, rapid streams, and belongs to that group of trout
known as charrs, characterized by the presence of round crimson spots
on the sides of the body. Other members of this class are the saibling
or charr {S. alpinus) of Europe and Greenland; the Sunapee trout {S.
aJjnnus ai(rcolus), found in parts of Mew Hampshire and Maine; the
blueback trout (-8'. oquassa) of the Kangeley Lakes iu Maine, and Dolly
Yarden trout, red-spotted trout, or bull trout {8. malma) of the Paciiic
States and Alaska. The lake trout also belongs in this group.
The general form of the brook trout's body varies considerably, some-
times being elongated and sometimes rather short, but the usual depth
is about one-fourth or one-fifth of the length. The head is large and
blunt, and is contained 4i times in the body length. The large terminal
mouth is provided with teeth on the jaws, tongue, and palate bones, and
also with a small patch on the vomer. The eye is placed high iu the head ;
its diameter is about one-sixth the length of head. The gillrakers on
the first arch number about 17, of which 11 are on the lower arm. The
scales are very small and numerous; about 230 are in the lengthwise
series, and 35 above and 35 below the lateral line. The dorsal and
anal rays are 10 and 9, respectively. The tail is square or slightly
lunate in the adult, forked in the young.
There is considerable variation in the color of this trout, dependent
on local conditions, sex, and age. The head, back, and sides of the body,
dorsal and caudal fins are of a grayish or greenish color ; the back, head,
dorsal, and base of caudal are mottled with dark green or black. In
the male there is a reddish band along side of belly. Along the middle
of the side are numerous round light-red spots surrounded by whitish
or light-brownish circular areas. The lower fins are dusky, with a pale
or cream-color anterior border bounded by a black streak; remainder
of fin often red in breeding males. The brook trout may be distin-
guished from the other charrs by the dark-brown or black marblings on
the back and the general absence of spots on the back.
The parr-marks, which are always present in young trouts and sal-
mons, are often found in large brook trout, and may even be permanent
in aquarium or pond specimens and in wild fish with a restricted environ-
ment. These marks, which in the brook trout are about 8 in number,
are large, dark, ^'ertical blotches or bars extending along the sides.
Persisting i)arr-marks are shown in the accompanying colored illustra-
tion of an artificially hatched aud reared brook trout. (See frontispiece.)
80
Fish Manual. (To face page 80.)
Plate 26.
MANUAL OF FISII-CULTUUE. 81
FOOD, SIZE, ETC.
The brook trout has a voracious appetite and takes advantage of
every opportunity to satisfy it except in the spawning season, when it
takes no food at all. It is strictly a carnivorous fish, its food consisting
chiefly of Crustacea, niollusca, and various forms of insects and worms.
When pressed with hunger it does not hesitate to devour its own kind.
The size of these fish varies iu different localities, usually in propor-
tion to the abundance of natural food and to the size of the body of
water in which they are found. They seldom, however, exceed 2 pounds.
The Au Sable Eiver trout will rarely run as large as 2^ to 3 pounds, but
in other rivers of Michigan larger examples are occasionally found. In
southern Xew York they seldom weigh over 2 pounds, while iu the
Eangeley Lakes, of Maine, they have been caught weighing 10 pounds.
The rate of growth also varies with the surrounding conditions and is
more rapid in water of higher temperature and with a i)lentiful supply
of food. Under favorable circumstances an average growth for the
first year is from f to 1 ounce, in two years 8 to 10 ounces, in three years
about 1 pound.
While not of any considerable commercial importance, the brook
trout is highly esteemed as a table delicacy on^account of the flavor
and quality of its flesh, and, as it is very game, it is much sought after
by sportsmen. Those from clear, swiftly flowing streams do not grow
so large as those found in quiet and deeper waters, but are superior in
quality and appearance.
RANGE, SPAWNING, ETC.
The natural range of the brook trout in the Fnited States is from
Maine to Georgia and westward through the Great Lakes region to
Minnesota, and in Canada from Labrador to the Saskatchewan. Owing
to its hard}' nature and ability to adapt itself to new snrroundings, it
may be successfully transplanted into suitable streams, and has been
extensively introduced into waters to which it was not native, iu Mich-
igan, Wisconsin, and Minnesota, many of the waters of the Rocky
Mountains and the Pacific Coiist, the Eastern States, and the creeks
and rivers of the Alleghany range of mountains. With the possible
exceptions of the rainbow trout and steelhead it is the hardiest mem-
ber of the salmon family and will make a brave struggle for existence
even with adverse snrroundings. All streams can not be successfully
stocked with this si)ecies; the temperature of the water must not be too
high nor the flow too sluggish, although an unfavorable temperature is
no serious obstacle if the speed of the current is great enough to insure
a sufficient aeration of the water, or if there are creeks fed by springs
flowing into the main stream to which the fish can run. The best
streams are those with a gravelly bottom, clear shallow water, and a
steady current, and waters to be stocked must contain a sufficient
amount of natural food and suitable places for spawning.
F. M. 6
82 RFPORT OF COMMISSIONER OF FISH AND FISHERIES.
The Micliigan streams exemplify the practical results attained in
the introduction of brook trout in new waters. The Au Sable Eiver
was long thonght to be esi)ecially adapted for this species, but it
abounded witli grayling, and until this beautiful fish began to disappear
no movement was made toward introducing- the brook trout. The
lumber interests of that section made it necessary to use the river for
conveying logs to various points downstream, and, as the log-driving
could be done only during the spring freshets, it came just at the time
when the grayling were on their spawning-beds. They were driven
away and the beds destroyed by the jdowing of logs through the
river bottom each year, till the fish gradually began to disappear.
The brook Iroiit was suggested as the proper substitute, because its
spawning season is in the autumn when the river is undisturbed, and
the Michigan Fish Commission began the work by planting 20,000 fry
in the year 1885. Though additional plants were made from time to
time, both by the Michigan and United States Commissions, no results
were observed for some years, and it was thouglit that the work had
been a failure. But the natural instinct of the tish had caused them
to push from the main river into the small tributaries, where they
nuiltiplied and grew during these years till they finally crowded down
into the river itself. ' Here they found as suitable a home as in the
small streams, and their numbers gradually increased till now the
strean) is completely stocked.
In the autumn of 181)5 a camp was established for the United States
Fish Commission 9 miles below the village of Grayling for the purpose
of taking spawn from wild fish. The work was confined to rod-and-line
fishing until the spawning season opened, when it was found necessary
to adopt some other plan, as at this time the trout refuse to feed.
During the five weeks, in which the rod was used exclusively, 3,000
spawning fish were taken. A snuill seine was then used for capturing
the fish, by hauling it at right angles to the current of the river, directly
across the spawning-beds, which thickly dotted the river bottom in
vsonie i)laces. I>y this method a tubful of trout at one haul was often
taken, and during the period the fish were running between 8,000
and 10,000 were obtained. This illustrates the abundance in which
this species is found in a river to which it has been transplanted. A
conservative estimate would place the number of trout taken from
this stream in the season of 1895 at 100,000, perhaps 25 per cent being
rainbow trout. Other waters of the State have been successfully
stocked, so that the northern half of lower Michigan now contains a
network of trout streams, made by introducing this fish into waters
where it was not indigenous.
In its native haunts, whether in lake or stream, the brook trout is
usually found in the same clear, cold, spring water, and prefers brooks
or streams flowing swiftly over gravelly bottoms. It pushes from the
rivers into the small streams, seeking the headwaters, searching out
MANUAL OF FISH-CULTURE. 83
deep pools and eddies where it can lie concealed beneath the shelter of
grassy banks or logs, and see withont being seen. Under artificial con-
ditions it endnres greater temperature than in its native waters, where
it is seldom found in water over 00'=^ to 05^'. It thrives at much higher
temperature in swift, well-aerated streams than in sluggish waters.
The brook trout spawns in autumn during the falling of the water
temperature. The season, which usually lasts about two months, begins
earlier in northern latitudes, in the Lake Superior region in September
or even August, while in New York, New England, and lower Michigan
it commences about the middle of October.
As the spawning time approaches the fish push up toward the shal-
lower waters where the female selects a spot near the bank of the stream
and prepares her nest by washing out the sand with her tail and pushing
aside the gravel with her nose. After forming a slightly concave depres-
sion she deposits a part of her eggs on the newly cleansed gravel, and
the male — which up to this time has been playfully swimming around
the nest — emits milt upon them almost simultaneously. The female
then covers the eggs with loose gravel. The spawning, impregnating,
and covering are repeated continuously until the eggs are all laid.
After the spawning-ground is once selected it is hard to drive the fish
away, the female especially returning to the same spot at the earliest
opportunity. A female has been taken from her nest and marked and
then returned to the water a mile down the stream, and the next morn-
ing was again found on the same bed.
The eggs vary in size, but are usually one-sixth of an inch in diameter.
The number yielded by one fish depends on its size and age, yearlings
usually producing from 150 to 250, two-year-olds 350 to 500, and older
fish 500 to 2,500. The time necessary for developing the eggs is depend-
ent on the temperature of the water, varying from about 125 days in
water at 37° F. to about 50 days in water at 50° F.
TROUT-CULTURE IN AMERICA.
The first attempt at artificial trout-culture in America was made in
Ohio in 1853 with marked success. Further satisfactory trials were
made in 1855 and 1859 in Connecticut and New York, and in 18G4 a
hatchery was established in New York which carried on the work on a
large scale. Somewhat later the work was taken up by the State and
United States governments and is now very extensively conducted in all
parts of the country. The methods described in the following pages are
those which have been found advantageous at the Northville Station
and are there i)ursued.
SPAWN-TAKING.
Eggs are obtained from brood-fish held in ponds and from wild fish
obtained at a field station located on a tributary of the An Sable
Iiiver near its junction with the river. As the spawning season
approaches, the brood-fish at the station are sorted according to age
and size and transferred to spawning-ponds, which are seined once a
84 KEPORT OF COMMISSIONER OF FISH AND FISHERIES.
week for ripe iisli in tbe early part of the season and later on three
or four times a week. Oreat care is used in niaiiipnlating the seine,
and when its ends are drawn up on the bank the fish are transferred
with dip nets from the bag of the seine into tubs, care being taken not to
overcrowd tlie tubs. The fish are then examined ; those which are not
ready are returned to the pond, while the ripe males and females are
placed in separate tubs or buckets. A good spawn-taker can tell at a
glance if a female is rii)e, and only in such condition should an attempt
be made to take her eggs. As soon as these fish have been stripped
and the eggs fertilized, the spent fish are liberated in a separate pond
to avoid rehaudling them during the season.
After the males and females are se[)arated, an ordinary milk-pan
coated with asphaltum i)aint on the inside, to prevent rust, is dipped
in water and allowed to drain, leaving only the water that clings to the
inside. Taking a female from the tub, the spawn-taker holds her as
quietly as possible till all struggles cease, and then pressing gently
with the thumb and forefinger a little above the ventral fins, passes his
hand down the belly to the oviduct, repeating the operation till all the
eggs are extruded. The eggs are immediately impregnated with milt,
obtained from the male in a similar manner, except that more force is
necessary and the pressure is made at a point about midway between
the ventral and anal fins.
The contents of the pan are next lightly stirred with a feather to
insure impregnation of all the eggs possible. They now present a
milky appearance and are washed in as many changes of water as is
necessary to thoroughly cleanse them from milt and refuse, when the
pan, half-filled with fresh water, is placed in running water to keep
the eggs at a low temperature. In 30 to GO minutes, according to the
temperature of the water, the separation of the eggs ensues,
THE HATCHING APPARATUS.
The apparatus at Korthville is arranged as follows: A tank 15 feet
long, with a partition running its entire length, is so placed that its
lower end rests upon the upper end of a similar one 13 feet long, which
differs from the upper one only in that it contains two boxes less. Nine
partitions, placed crosswise of the tank, form, with the lengthwise
partitions, a double row of eight compartments, each of which is lOJ
inches long and 15i inches wide, and is provided with a waste-water
channel or sluiceway leading into the next compartment. In these
compartments are placed Clark hatching-boxes.
The Clark box is 18 inches long, 14 inches wide, and 9i inches deep,
and is made from f -inch dressed whitewood lumber. On its under side
the box is provided with feet, 1^ inches square and '} inch thick, to allow
a free circulation of water under it and to prevent it from resting upon
any sediment or refuse that may be deposited on the bottom of the
tank ; and on the inside in each bottom corner is fastened a block, f inch
thick by li inches square, to support the trays. Five circular openings,
J inch in diameter, permit the escape of water from the box. A slot is
Fish Manual. (To face page 84.)
Plate 27.
m
o
z
t/i
z
CD
O
c
2
c
X
1-
o
MANUAL OF FISH-CULTUKE. 85
cut in one end of the box so that water from the compartment above
can not tiow into the one below without falUng into and passing through
this box. Upon the feet or risers inside the box rest 0 trays, i)laced
one upon tlie otlier, the end of tlie box whicli contains the slot fitting
snugly against the upper end of the compartment, in which is litted a
tin overflow. The whole is held in place by a crossbar or binder, which
fits in |-inch grooves cut in both sides of the tank. The binder, resting
on the box, keeps it from rising in the water, and is provided with feet
so placed as to prevent the trays from floating in the box itself. The
trays are perforated zinc or line wire netting, tacked on a frame 10
in(;hes long and 7 inches Avide inside measurement, made from finch
pine 1^ inches wide.
CARE OF THE EGGS.
The eggs after separating are placed in troughs, the bottoms of which
are covered with half an inch of gravel, and here they remain till the
eye-spots begin to appear.* During this interval of about 30 days the
principal care consists in sorting out bad eggs, and, with a feather,
gently changing the position of good ones to prevent sediment from
collecting on them. At theexpiiation of this period they are ready for
transfer to the hatching-boxes. They are drawn oft* the gravel by means
of a siphon into a tub or bucket which has been half filled with water
to preserve them from injury and then carefully dipped into a glass
graduate, measured, and placed on the hatching- trays. The trays are
arranged in the boxes in stacks of nine, and 5,000 eggs are allowed to
each tray except the top one, which is left empty and serves only as a
cover. The eggs from domesticated brook trout measure 350 to 450 per
fluid ounce, depending on the age of the fish. Eggs from wild trout
collected in the Au Sable River measure 450 to the fluid ounce.
At intervals of from 3 to 6 days during the period of incubation, in
order to remove the bad eggs, the trays are taken from the boxes and
l>laced in a shallow picking-trough through which a stream of not more
than 3 gallons per minute is flowing. This trough is only wide enough
to allow perfect fieedom in handling the trays when putting them into
or removing them from it, and only of sufticient depth to allow the eggs
to be fairly covered. Nailed to the bottom on each side is a i-inch strip,
li inches wide, and running the entire length of the trough. Tliese
strips permit the free passage of water beneath the trays, as otherwise
the water would flow over the tops and a great many eggs would be
lost. The bad eggs are removed with tweezers, the labor being usually
performed by girls, who become so expert that one girl will often remove
100 bad eggs per minute.
After tlie incubation has reached a stage where the fish are begin-
ning to break their shells, the hatching- box is taken out and reversed,
*The practice of holdiiij; tlio new p<;g.s on gravel until the eve-spots bej^in to
appear is pursued at Xorrliville with eminent success, hut at the other trout hatch-
erics oT the CoMuuissiou, where etiuaily good results are obtained, it is customary
to transfer the e;igs to the iiatchinj; tra.vs as soou as they are impregnated, as is
described in the chapter on the rainbow trout.
86 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
the open end being fixed smigly against the lower wall of the compart-
ment. The closed end of the box being thus placed upstream, tlie
water is prevented from entering except through its former exit, the
holes in the bottom of the box, and is thus forced up through the box,
M'ith an exit at the top which prevents the sacs of the hatching fish
from being forced, by pressure from above, down through the screen,
as would be the case if the box were left in its former position.
When the i)rocess of hatching is nearly com])leted the trays are
removed and emptied into a large pan filled with water, where tlie dead
shells and other refuse, being of low specific gravity, rise to the top
and can be easily poured off. This is called washing the fish. The fish
are then replaced upon the trays and returned to the hatching-boxes,
where they remain until the food-sac is nearly absorbed, a i)eriod of from
25 to 40 days, according as the temperature varies from 50° to 38° F.
The young fry, deprived of their food supply by the absorption of
this sac, must soon be placed where they can get their sustenance else-
where. They may be planted in waters suitable to their nature, or
reared for breeding or other purposes at the station.
THE FIELD STATION.
The egg-collecting station previously referred to is on a tributary
of the Au Sable, flowing about 1,000 gallons per minute. A dam is
thrown across the stream and 100 feet above is a screen to prevent the
fish from escaping in tliat direction. The dam is simply constructed
by banking up mud, sand, and turf, and has a frame sluiceway 3 feet
long, 2 feet wide, and 2 feet deep. In the sluiceway is inserted a
double screen of ^-inch mesh wire netting, two screens being necessary
to keep the overflow clear and reduce as low as possible any loss of
fish through this outlet. The iuclosure accommodates about 10,000
lish. Fish are obtained with rod and line, until they begin to run from
the deep pools upon the spawning-grounds, when much better results
are obtained with nets. With an ordinary seine at the approach of
the spawning season, the fish can be taken in large numbers from their
spawning beds. As the season advances and too raauy fish are caught
that have already spawned, of>erations are suspended.
As soon as ripe fish are found among those caught on the spawning-
beds, the inclosure is hauled with a seine and the fish are looked over
twice a week until the eggs are taken. When the season is fairly open
the spawn may be taken from most of the fish immediately after they are
caught, thus obviating the diificulty of transferring them from the point
of capture to the inclosure, in some cases a distance of 3 or 4 miles.
For holding the eggs two pairs of troughs are placed on standards
driven into the bed of the stream, with a passage between them wide
enough to a<lmit a man. The water is received through two 1-inch
orifices in a bulkhead about 9 feet long, situated at the head of these
troughs and fed by a roughly constructed raceway leading from a small
spring about G rods distant on the hillside. The water from each of the
Fish Manual. (To face page 86.)
Plate 28.
MANUAL OF FISH-CULTURE. 87
openings feeds two tious'lis, so placed that the lower end of the u[)i)er
one rests upon the head of the other, thus creating a fall of nearly the
height of the troughs. Each trough is 14 feet long, o inches deep, and
consists of a double row of boxes, each box 17 inches long, 15 inches
broad, and 2 inches deep, giving a capacity of from 8,000 to 10,000 eggs.
SHIPPING GREEN EGGS.
Green eggs can be safely moved at any time up to and including the
eighth day. They are shipped from the Held station to the hatchery
in cubical boxes constructed from .]-inch pine lumber, just large enough
to admit, with a surrounding air space of i-inch, 19 canton-tiannel trays,
18 inches square on the inside, the frames of which are made from
J-inch square white pine. The eggs are siphoned from the gravel
boxes, as described above, and, using a graduated dipper for the pur-
pose of ascertaining approximately the number of eggs necessary to
make them about two deep on the tray, the packer i)onrs them upon
the tlannel and spreads them as evenly as possible with a feather.
The tray is then placed in the box and the operation repeated until
eighteen trays are filled with eggs. The nineteenth, or toj) tray, is
usually left emi)ty, but if the weather is very warm it is filled with fine
ice. The cover is then ftistened down, the box marked, and the eggs
are ready for shipment to the hatchery.
PLANTING THE FRY.
In their natural state, as soon as the weight of the food-sac has
diminished by absorption enough to permit their rising, the fish begin
to take food, and by the time the sac is entirely gone they are probably
taking it regularly. When very young fry are transferred to outside
waters where there is natural food only, it should be done 8 or 10 days
before the sac is entirely absorbed, for, if delayed till after the sac dis-
appears, many will die before they become ac(;ustomed to finding food
in their new home.
Brook-trout fry are usually transported in ordinary round-shouldered
cans of 10 gallons capacity, the number of fish per can depending
entirely upon the distance they are to be carried and the fiicilities for
taking care of them en route, such as opjiortunities for changing the
water, supplying fresh ice, etc. For a short trip of from 5 to 10 hours
duration, between 4,000 and 5,000 are carried in each can, but where
they are to be on the road from 1 to 5 days, it is hardly safe to attemi)t
carrying more than 2,500. The Conmiission distributes fry by means of
its cars, built especially for the purpose, in which either running water
is kept upon them or fresh air introduced into the water to make it life-
sustaining. Small shipments are made by a special messenger in a
baggage car, the railway companies usually offering every available
opportunity for changing water, etc. The fish, upon arrival at the rail-
way point nearest their destination, are carried thence by wagon to the
stream where they are to be planted, by distributing them in small lots
in difierent places where there is shallow water and a good bottom.
88 KEPORT OF COMMISSIONER OF FISH AND FISHERIES.
REARING AND FEEDING.
If tlie fry ai'e to be reared for breeding, one week before tlie food-sac
is absorbed they are cliauged from the trays to a large pan and removed
to tlie rearing-troiiglis. Gravel should not be used in these troughs,
as the unconsunied food works down into it and, becoming fnngussed
there, causes a greater spread of disease and increases the labor of
caring for the fish.
The time to begiu feeding the fry is readily ascertained by trial. If
they rise to minute particles of food thrown upon the water, they are
then ready for regular feeding. The time and frequency of feeding
young fish, tlie kind of food, audthe manner of feeding them, are of the
greatest importance. Liver gives better results than any artificial
food, and its i)reparation is very simple. Beef livers are ground by a
meat-chopper and then strained through a fine-nieshed screen, a thick
pudding being made by the addition of water. A small portion, only
such an amount as the fish will readily eat at a time, is spread upon
the surface of the water with a feather, and they are fed as often as six
or eight times per day until they become used to the new diet. As
they grow older the quantity of food may be increased but the fish are
fed less frequently. At this stage the young fish have such a i)reca-
rious hold ui)on life that too much attention can not be given to their
care. Not more than 20,000 can be held with success in a feeding or
rearing trough, and a regular stated supply of water is kept flowing
through to prevent disease, and the fish are properly thinned out in
order to prevent loss by suffocation when they increase in size. About
30 gallons of water per minute are suflicient for 20,000 fry, though this
quantity is increased as the fish grow stronger and are able to breast a
heavier current.
In the spring season, when the water begins to grow warm, the fish
require more room than the feeding-troughs afibrd, and it is then nec-
essary to transfer them to ponds. The Northville rearing-ponds are
5 feet by 20 feet, made from 2 inch pine boards and provided with a
gravel bottom. A pond of this size .accommodates from 10,000 to 20,000
fry till the middle of the summer, when the number is reduced to as
low as 5,000. It is advisable to place not more than 5,000 in the pond
at first to avoid the labor of reducing the number of fish at different
times, and also because crowding into too small a space retards their
growth.
At first the fish require coaxing to induce them to eat, as the change
to their new abode has frightened them, and a great deal of patience is
necessary in their treatment. They are fed at regular intervals three
times per day. As their appetites are poor for the first few days, the
liver will fall to the bottom and foul the pond, if great care is not exer-
cised, and three fourths of an hour is not too long for feeding 5,000 fry.
The time occupied in feeding is diminished and the amount of food
increased accordhig to the judgment of the fish-culturist; but their
appetites should never be completely satisfied.
Fish Manual. ^To face pa^e 88.)
Plate 29.
REMOVING GREEN EGGS FROM SHIPPI NL^- TKAYS NORTHVILLE.
PACKING EYED EGGS, NORTHVILLE.
MANUAL OF FISH-CULTURE. 89
Bj' early winter tliej' will have grown to a lengtli of from 3 to G inches,
necessitating- a change to a larger pond. The Northville breeding-
ponds are 20 by 75 feet, and are constructed in the same manner as
the rearing-ponds. One of these larger ponds accommodates 10,000
yearlings, 5,000 two-year-olds, and about 3,000 fish from three to five
years old. By the time the fish are three years old and over, less care
is re(iuired in the preparation of their food, as the liver may be given
to them in pieces half an inch in diameter.
PACKING EYED EGGS FOR SHIPMENT.
Eyed eggs prepared for shipment in the following manner have been
sent from Northville to all parts of the United States with practically
no loss: The trays upon which the eggs are to be shipped are made
from the same materials as those upon which green eggs are carried,
but are usually much smaller. Fewer eggs are placed upon a given
surface than is the case with green eggs. For example, 10 trays, 12
inches by 12 inches, will carry 50,000 eggs; 8 trays, 10 inches by 10
inches, 32,000 eggs; and 5 trays, 8 inches by 8 inches, 12,500 eggs; or
5,000, 4,000, and 2,500 eggs per tray, respectively.
The trays are allowed to stand in cold water till thoroughly soaked,
and are then drained off and taken to the packing-room. After the dead
eggs have beeu removed from a box, the trays are taken out, drained,
and removed to the packing-room. A f inch wooden frame, made to tit
tlie inside of the canton-flannel tray, is then inserted, the eggs are
carefully brushed with a feather from the wire trays and spread as
evenly as possible upon the flannel. The eggs have been previously
measured at the time when they were removed from the gravel to the
hatching-box, so the number to be placed upon each tray can be easily
determined. After the eggs are spread upon the flanyel, the inside
wooden frame is taken out, leaving a | inch margin around the inside
of the tray. A square of mosquito netting large enough to lap over on
all sides of the tray is laid upon the eggs and tucked down tlrmly along
the insider Sphagnum moss is scattered to a depth of about J inch
upon this netting. The moss is prepared by removing sticks and other
foreign matter; it is soaked in water a short time and then run through
a clothes-wringer. In spreading it upon the netting the moss is i)icked
apart and made as light and flufl'y as possible, to give the eggs plenty of
oxygen.
AYhen tlie required number of flannel trays are packed they are
l)laced one upon another and cleated together on all sides, with boards
at the bottom and top. This crate is usually placed, if possible, where
the temperature of the air is below freezing, so that the moss may be
slightly frosted before the crate is put in the shipping-case.
A case is made large enough to allow a 4-inch space above, below,
and around all sides of the crate when it is placed in position. Its
bottom is filled with fine shavings, 4 inches deep, and the crate placed
upon them as nearly as possible in the center of the case. Shaviugs
90 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
are packed tightly around the crate, a few being thrown in and pounded
down securely before more are added. This must be well done, as the
shavings are the only means of preventing a change in the position of
the crate. The top of the crate is then covered with closely packed
shavings and the cover of the case screwed on. By means of rope or
iron handles the case may now be moved about with ease, and is ready
for shipment.
REFRIGERATOR BOX FOR SHIPMENTS ABROAD.
A double box is used for this purpose. The inside one is 2i inches
larger on all sides than the crate of trays, and the outside one large
enough to make a 5-inch space on all sides when the smaller box
is placed within it. The trays of eggs are prepared as in ordinary
shipments, and when crated are placed in the snudler box upon a frame
which is constructed from a ^-inch strip, 2^ inches wide, tacked at right
angles to the inside and bottom of this box. In the chamber thus
formed between the crate and the box is packed finely chopped ice, an
exit for the water resulting from its melting l)eing provided by a half
dozen openings in the bottom of the box. This box is now packed
according to the same plan as that followed with the shipments for a
short distance. Where there is an opportunity, it is well to have the
case unpacked en route and new ice added.
Eggs have been sent in this manner to England, jMexico, ^ew Zea-
land, Japan, and South America.
Fish Manual. (To face page 91.)
Plate 30.
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THE LAKE OR MACKINAW TROUT.
DESCRIPTION OF THE FISH.
This baudsome species {Cristivomer namaycush), tlie largest of the
trouts, is classed with the charrs. It has an eloiij>at('d body, the length
being about 4i times the depth. The head is large, flat above, and about
as long as the body is deep. The mouth is large; the maxillary bone
extends beyond the eye and is half the length of the head; the jaws
have strong teeth. A peculiarity of the vomerine bone distinguishes
this fish from the genus ^alvelimis ; it has a crest provided with teeth
extending backward from the shaft of the bone. On the hyoid bone the
teeth are in a cardiform band. The eye, placed near the top of the head,
is contained about 4i times in length of head. The caudal fin is well
forked. Both the dorsal and anal fins contain 9 to 11 rays. In the straight
lateral line there are about 200 scales. Brauchiostegals 11 or 12.
The coloration is quite variable in fish from different localities. The
general color is usually dark gray. The body, head, and fins are
covered with small discrete rounded spots, usually of a pale color, but
often tinged with reddish. On the back and top of head there are fine
vermiculations, as in the brook trout. Exami)les from some lakes of
Maine and eastern Canada are nearly black, and Alaskan examples
are often very dark; others are quite pale.
That variety of the lake trout known as the siscowet {Cristiromcr
namaycush siscoivet), found only in deep water in Lake Superior, is
shorter and paler than the typical fish and has weaker teeth and a shorter
head; it is, however, chiefly characterized by an excessive fatness, which
greatly reduces its food value.
Tlie present chapter is devoted to trout of the Great Lakes and the
methods of i)ropagation employed at the station of the United States
Fish Commission at Korthville, Michigan.
RANGE, FOOD, ETC.
Tlie lake trout is found throughout the chain of the Great Lakes, and
the inland lakes of northern New York, New Hampshire, and Maine;
the headwaters of Columbia and Fraser Kivers, streams of Vancouver
Island, and even waters within the Arctic Circle are said to contain
this species. With the exception of the whitefishes, it is perhaps the
most numerous food-fish of the Great Lakes, and formerly none ex(;eeded
it in weight excei)t the sturgeon. Instances are cited by fisliermen and
others of lake trout weighing as high as 12.') pounds, and its average
weight has been given at from 20 to 30 pounds, but of late tliey are
rarely found exceeding 18 or 20 pounds. Possibly, if unmolested by
91
92 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
man, tliey might again reach the enormous weight of early citations,
their sluggish movements and voracity being conducive to such a result.
The nature of their environments has a decided influence on the
characteristics of this species; the temi)erature of the water, food, and
character of bottom entirely changing the marking and peculiarities of
these fish in their various habitats.
Until recently it was commonly thought that the principal food of the
lake trout was the young whitefish, and for this reason the fishermen
of the lakes were generally unfavorable to its artificial propagation.
The error of that belief, however, is now generally conceded, though
no doubt quite a number of young whitefish become food for trout
during each season. But as the habits of the lake trout take it to
deep water immediately after spawning, while the young whitefish
remain in shallows, the few which are destroyed in this manner are
either stragglers from shoal to deep water or taken by trout aimlessly
wandering from their natural range. The lake trout is an omnivorous
feeder and has a ravenous appetite. It greedily devours all fishes
possessing fins of flexible character, and jackknives, corncobs, and
other articles equally indigestible have been found in its stomach.
The spawn and fry of lake trout suffer from the same enemies as the
young of all fishes, but the mature fish are too formidable for other
species to prey upon. They are troubled with a few parasites. Oc-
casionally individuals, very thin in flesh and sickly-looking, known as
"racers" by fishermen, are found swimming near the surface; no
sufficient cause has been discovered for this condition, as they are no
more afflicted with iiarasites than healthy fish.
IMPORTANCE AND ABUNDANCE.
The trout fisheries, of the Great Lakes are second in importance
commercially, the whitefish ranking first. At one time trout were so
plentiful that they did not command a price at all proportionate to their
edible qualities, but as the fishing continued the catches decreased,
until about the year 1886 the market price of trout became equal to
that of its more delicate rival. At this time it became evident to the
Federal and State governments, as well as to those dependent upon
this industry for a livelihood, that decisive steps ought to be taken
toward providing against the extermination of this valuable food-fish.
Artificial hatching was commenced that year with the object of restock-
ing the Great Lakes. The work progressed only in a limited way up
to 1892, when the output of both the United States and ^Michigan Fish
Commissions reached something like its present proportions. During
the season of 1895 the United States Fish Commission station at
Northville secured over 11,()00,()()0 lake-trout eggs. As indicative of
the success attending the plants of lake trout, it may be remarked that
for a short period daring the season of 189G the fishing-boats, which
had been working to their fullest capacity', ceased oi)erations, the
market being glutted and the remuneration not being commensurate
with the labor, hardship, and capital invested.
MANUAL OF FISH-CULTURE. 93
The method of capture is by gill uets, pound nets, liook and line,
and in winter by spearing through the ice. The majority, however,
are taken from gill uets operated by steam tugs. These boats are titted
out with the most approved appliances of their trade and have (quar-
ters on board for the men employed, usually a crew of 8 or 10. Some
of the tugs carry 5 or (> miles of nets and catch in one lift from 1,000
pounds to 4 or 5 tons of trout. Fishing is done from the time the ice
breaks up in the spring until late in the fall or early winter, the work
ceasing only when the weather and ice no longer permit operations.
In some localities the water becomes so warm during summer as to be
detrimental to the nets, and consequently at sucli points there is a
lull in the work for a few weeks. Lake trout spawn on the reefs and
liv^e in deep water during the remaining time, and their migratory
habits govern the movements of the tags, the fishermen necessarily
moving from one point to another. The small gill-net boats, carrying
sails and handling a few hundred feet of nets, confine their operations
to more shallow water and fish only during the spawning season. At
Detour, Lake Huron; at some points in Lake Superior, and on the
north shore of Lake Michigan pound nets are in use, but usually these
net-* are not used for the capture of lake trout.
NATURAL SPAWNING.
Spawning commences the last of September in Lake Superior and
later in the lower lakes, since the water does not become sufiiciently
cool here as early as in the headwaters. In Lakes Huron and Michi-
gan the height of the season is in tlie early ])art of November, and
8[)awniug continues to the first of December. The spawning-grounds
are on the reefs of '' honeycombed" rocks, 10 to 15 miles from shore,
and during the reproductive period vast numbers of fish visit these
places, spawning in a depth of from 1 to 20 fathoms. Owing to the great
depth of water, the shyness of the fish, and the severity of the weather
at this time, nothing definite has been determined as to the fish's
maneuvers while si)awning. The supposition is that the female lies
over an indentation of the rocks and allows her eggs to settle into the
"honeycomb" cavities; fragments of the rock with the cavities filled
with eggs having been hauled in by fishermen when lifting their nets.
No doubt the general characteristics of the Salmonidcc are carried out
by the lake trout as far as the conditions in which they exist permit.
An instance has been known of a Mackinaw trout of 24 pounds weight
containing 14,943 eggs; but not over 5,000 or 6,000 eggs are commonly
found, and 1,000 eggs to the pound of fish may be accepted as a general
rule, after the trout have attained maturity, at three years of age.
A much smaller variety, called the shoal trout, is found in Lake
Huron in the vicinity of Alpena, and in Lake Michigan near Charle-
voix and Northport, but its weight compared with its length is greater
than that of the true Mackinaw trout, and the markings and appearance
of the two also ditier. The shoal trout spawns in September, about a
94 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
month eai'licr than the lake trout, on a cobble, bowlder, or gravel
bottom, and in from 2 to 8 feet of water.
OBTAINING THE EGGS.
During the spawning season men are employed by the different
lalce-trout hatcheries to accompany the tugs to their fishing-grounds
and strij) tlie ripe fish as they are taken from the nets. These "spawn-
takers," or "strippers," must i)ossess strong constitutions to withstand
the many hardships to which they are subjected. Wfiere very exten-
sive nets are operated by a boat and fishing is exceptionally good, two
men are detailed to the same ground, one as spawn-taker, the other as
helper. Pans, pails, and dippers are taken on board and made ready
by the time the nets are reached. As the net is lifted the men disen-
tangle the trout and throw them on deck, where the spawn-takers sort
them over, taking the eggs from ripe females and imi)regnating them
with milt from the males. During very severe weather the fish are
thrown into the hold instead of on deck and the work is done there.
The manner of taking the eggs is similar to that used in taking
spawn from other fronts and salmon. First, the female is taken and
the eggs, if mature, are gently stripped into an ordinary railk-i^an and
then impregnated with milt from the male. This operation is repeated
until the pan is about half filled, when the eggs are "washed up" and
poured into a 5-gallon jjail. The "washing-up" process is performed
by filling the pans with water and then allowing it to run off", repeating
the same until the water which is poured off no longer appears milky;
as the specific gravity of the eggs jirevents their rising to the surface
this can be done without loss if ordinary care is exercised. The pans
are refilled and emptied in the same manner until the pail is half or
three-fourths full, when it will contain about 75,000 eggs; other pails
or buckets are brought into use as often as necessary. To keej) the
eggs from dying, the water is changed in the large pails every hour
until the eggs are taken from the boat and transferred to fiannel trays or
floating-boxes. All pans, pails, and other metallic apparatus are coated
with asphaltum paint to prevent rusting, as rust is fatal to the eggs.
When the weather is so cold that there is any chance of eggs
freezing to the pan, two pans are sometimes used. The outside one is
partly filled with water, upon which floats the pan that is to receive
the eggs as they are stripped. The pan of water protects that part of
the inside pan where the eggs rest and in that way their temi)erature
is kept above the freezingi^oint.
SHIPPING EGGS TO THE HATCHERY.
When spawn-takers are operating at a distance the eggs are held at
field stations located at convenient points, whence they are sent to the
hatching-house as soon as possible, but if the stations are at isolated
l)oiuts on tlie lakes it is often necessary to hold the eggs for several
days, and occasionally weeks, before means of transportation can be
obtained. In such a case the eggs are held in floating-boxes, which
are made 2^ feet by 1| feet by 1 foot, with the ends rounded up about 6
MANUAL OF FISH-CULTURE. 95
inches; tlie sides and ends are 1-incli pine and the bottoms ^ inch-mesh
iron wire cloth, which is continued over the rounded ends. Cleats are
nailed on the sides, one end somewhat lower than the other, to give the
box a tilt whcu placed in water. Each box carries safely about 180,000
eggs, and when it is filled is anchored either in running water or in a
sheltered cove of the lake. In the former case a current of water is
kept passing thrcmgh the box, while in the latter the eggs are given a
slight motion by the action of the waves upon the surface of the water.
Floating-box.
When eggs held in floating-boxes are to be shipped they are dipped
into pails and taken to a place arranged for packing them, located
at no great distance away, where a table upon which to place the
trays may be improvised from any material at hand.
The trays for packing the eggs are constructed by making a frame of
finch square pine, 18 inches square, inside measurement, with white
canton tiannel tacked on one side. A case to contain the trays is made
of ^-inch pine, large enough to hold 19 of these trays one over the other,
allowing for a surrounding air-space of half an inch. Half-inch cleats
are nailed on the bottom and at the corners of the box on the inside, so
that the trays are securely held in position. A hinged door is at the top,
handles are at the sides, and the whole is painted and of neat appearance.
For transferring the eggs from pail to tray a graduated dipper is
used, which has a capacity of about 10,000 eggs, the number usually
placed upon each tray. Thus, in a case containing 18 trays 180,000
eggs may be stored. A dipperlul is placed upon each tray. The canton
llannel holds water for some time, and if a little is poured upon the
eggs, which are at first bunched in the center, they settle and spread,
and by a slight dexterous movement, ac(piired by practice, are evenly
divided over the tray. Ten thousand eggs on a surface 18 inches by 18
inches are about two deep, and if kept at the proper temperature and
handled carefully the^' may be carried a long distance. After the eggs
96 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
are spread upon tlie tray it must be drained before being- placed in the
case, for eggs slightly moistened Avill live for a longer time in open air
of the right temperature than in dead water. The tray is easily
drained by slightly tipping it, so that the water will run out at the
edges where the flannel is tacked on the frame. The trays are then
placed in the case, eighteen tilled, the top one empty.
If the case is to pass through a varied air temperature, moss is
packed in the space between tlie trays of eggs and the sides of the
shipping-case for protection against abrupt changes in the weather.
When necessary to hold eggs on the trays for any length of time, as
is often the case, each tray must be taken out and sprinkled with water
at least every 24 hours. When they are held for a longer period than
4 or 5 days they must be taken from the trays and placed in a tub of
water and there washed in the same manner as described in taking
spawn. When adding water, care is taken that it does not strike tiie
eggs with such force as to injure them, the dipper either being held down
in the eggs or the water i)oured against the side of the tub a little above
the surface of the spawn, which gives them a steady whirling motion
and at the same time does them no injury.
The manner of -transferring eggs from trays to a tub is very simple.
After filling the tub with water to about a third of its capacity, the
tray is placed in water at an angle of about 45° with its surface. INIost
of the eggs will slide down this incline into the tub, and what few
remain may be washed down by pouring a little water on the uppermost
side of the tray. After the eggs have been given a good washing they
are replaced on the trays and returned to the cases, as described above.
The eggs are shipped in charge of a messenger, if possible, to see that
the cases are not roughly handled or tilted and the contents jarred or
bunched while being placed in the baggage car. While on the road
they must be kept in the coolest place on the car, i)roviding that the
temperature is not below 28° or 30°.
It can be readily seen that the percentage of lake-tront eggs hatched
can not be so large as with other species of trout. Tbe rolling and
pitching of the tugs and other boats upon wliicli the spawn-taker is
operating prevents the eggs from separating naturally. The time during
which this should take place Avould be, approximately, within the first
30 minutes after they are taken, and as the boats are out from 5 to 24
hours or longer, when shore is reached the time is long past when
quiet is of any value. Besides, the temperature often falls far below
freezing, and all the precautions that can be taken will not prevent a
considerable percentage of the eggs becoming chilled, although there
may be no ill effects discovered until after they reach the hatchery.
Other losses often occur through accident and the carelessness of those
handling the cases while en route to the hatchery. Taking everything
into consideration, it may be considered excellent work if an average
of 70 per cent of eyed eggs and fry is turned out. In exceptional cases
as high as 00 per cent have been hatched.
F sh Manual. fTo i^co page 96.)
Plate 31.
MANUAL OF FLSH-CULTURE.
THE HATCHERY.
The liatchiug-trongh or tank in use at Xorthville combines the prin-
ciples of both the Clark aiul the Williamson hatching apparatus and
is therefore called the Clark-Williamson hatching-box. It possesses
more advantages than any other in use for the development of a large
number of eggs; a thorough circulation is obtained for thousands, the
apparatus is simple, and the eggs may be readily handled for picking,
cleaning, etc. It consists of a trough of any length according to the
number of fry to be held, 18^ inches wide inside and 1 foot deep, with
partitions to divide it into compartments, and is ooustructed as follows:
Only the best l.;^-inch pine is used, all planks containing knots, heavy
pitch, etc., being rejected, and the sides and ends are each made of but
one piece of lumber. The t)ottom is made first, the strips of different
widths plowed and tongued securely, and all joints laid in white lead.
- deferring to figs. 1 and 3, page 98, three-quarters of an inch down
from the top of the sides is a f-inch groove (A) running the entire length
of the trough. The partitions, dividing the trough into compartments,
18i^ inches by 9f iucTies by 12 inches, are mortised ^ inch in the sides;
the first and each alternate partition (B) is fixed i inch from the bottom
of the trough to allow the water to pass under it; the second and each
alternate partition (C) is mortised into the bottom, and at the top is cut
out so as to leave a space 14f inches long by li inches deep for the
water to pass over. In the bottom of the boxes thus formed a i-inch
strip (D) ^ inch wide is nailed to the sides; upon these the bottom trays
rest. A crossbar (E), with g-inch block (F) to hold the trays securely
in place and prevent them from rising in the water, is made to fit in the
grooves at the sides of the trough.
The capacity of the troughs may be doubled by the addition of a
second row of boxes, one side of the first tank acting as a partition
between the two rows. Each box holds eleven trays (G). Ten of these
are filled with eggs, the eleventh, or top one, acting merely as a cover
to prevent the eggs on the tenth tray from being carried off by the
current. The trays are made of ^inch mesh galvanized wire cloth,
tacked upon frames 16 inches long, 7 inches wide, and f inch thick.
Both the trays and tanks are given three coats of asphaltum paint
before being used, and one coat at the beginning of each succeeding
season. Eleven of such trays, in the box described, will till the com-
partment to within | inch of the groove in the sides of the tank; then
the crossbar with the g-inch feet holds them securely in place. The
tanks are set upon iron standards cemented in the floor, and are given
a pitch of i of an inch to the foot. The height of the tank from the
floor is a matter of convenience to the operator, depending on the fall
of water available.
The water enters through a 1-inch pipe at the head of the tank, flow-
ing down through the first division, up through the second, and so on
to the lower end. W^here water is scarce, two troughs mav be made to
F. M. 7
98
REPORT OP COMMISSIONER OF FISH AND FISHERIES.
utilize the same supply by placing one after another, the upper end of
the lower trough being from 8 to 12 inches lower than the overliow of
the upper trough ; this gives a good aeration and will be found to answer
Clark-Williamson Trough.
nearly as "well as though fresh water "was conducted to the tank.
►Should the supply be taken from a creek, lake, or other reservoir ex-
posed to changes of weather and drainage from the surrounding land,
MANUAL OF FISH-CULTURE. 99
or if it abounds with aquatic insects, it is quite essential to have some
kind of filtration, otherwise the eggs may be injured by animalculae
or coated with sediment, the trays clogged with refuse, the circulation
stopped, and in the end a majority of the eggs lost. Many filters
have been devised, all of which are good, but a simi)le aiul effective
contrivance is made by tacking medium-weight fiannel to wooden tray
frames and placing them at the head of the tank directly beneath the
head of water, the number used at one point being governed by the
amount of sediment or other foreign matter present.
At Northville, as a convenience in caring for eggs, a shallow "picking-
trough" is used, 40 feet long, 10 inches wide, and 2.] inches deep, with
a i-inch strip, ^ of an incli wide, nailed along each side of the bottom,
upon which the trays rest, to give a good circulation while the eggs are
sorted over. The trough has a fall of not more tlian ^ inch throughout
its entire length, and it is fed by a flow of about 2 gallons of water
per minute. A dam at its lower end raises the water 1| inches, not
entirely covering the trays. This is a point that must not be over-
looked, for if the water flows over the tops of the trays many of the
eggs and fry will be apt to escape through the waste-pipe.
CARE OF THE EGGS AND FRY.
Upon their arrival at the hatchery the eggs are taken from the
shipping-cases and turned into tubs, whence they are removed to the
hatching-troughs. In removing eggs from the flannel shipping-trays
to the tub the same method is followed as in washing eggs that have
been held in cases for several days. The transfer should take place in
ft temperature not higher than 45° or 50° F., and if the eggs are held
in the tubs for any length of time they are given a change of water
every 30 minutes.
Great care is necessary in transferring eggs to the hatching-trough
in pails. To guard against any shock, the i)ail is partially filled with
water, and the eggs are carefully taken in the dipper, which is lowered
into the i)ail in such a way that tlie eggs will glide into the water and not
fall upon it. The pail when filled is placed upon the trough as near as
possible to the box for which the eggs are intended, and by means of a
perforated dipper with a capacity of 20 ounces, or 4,000 eggs, they are
transferred to the hatching boxes. A tray is i)laced in the water and
a dipperful of eggs is i)()ur('(l upon it; then another tray, i)laced on top
of the first, is served iti like manner, and this is repeated until ten trays
are filled. The eleventh, or cover tray, is left empty, and the whole
ai)paratus is held in place with a crossbar or binder. In two double
troughs, containing 04 boxes and occupying a floor space of 10() sijuare
feet, 2,500,000 eggs may be safely carried with 22 gallons per minute
of good spring or lake water, well aerated.
To estimate the number of eggs laid down, a fractional portion of a
quart is counted several times until a satisfactory average is arrived at;
this has given 200 to the fluid ounce, or 6,400 to the quart.
100 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
For the first few weeks after the eggs liave reached the liatchery
close attention must be given to prevent the growth and spread of
fungus throughout the tank. The eggs must be carefully luind-i)icked,
and the trays and boxes kept thoroughly cleansed from slime and other
impurities. If a heavy rain should wash dirt, refuse, etc., into the
supply reservoir and thence to the hatchery, the eggs must be cleaned
to i)revent their smothering. Ko filter, practical for use in a hatchery,
has been invented that will entirely remove injurious substances.
To remove the egg-trays from the boxes for sorting, the binder is
first slipped out from the groo\^es and the trays taken out separately,
each rising to the surface as the one above it is removed. All the
trays are taken out of one box and i)laced one after another along
the picking-trough. The dead eggs and "ringers" — the latter not
appearing until in the later stages of incubation — are then picked out
with small metal tweezers. The eggs will turn white when dead, and
if allowed to remain upon the trays a fungus will soon appear upon
their surface and spread its growth until all the eggs witliiu a short
radius are affected; these in their turn will be smothered and become
fungussed in the same manner.
When it is necessary to change the position of the eggs in order to
bring those at the bottom to the surface a soft feather is used, and if
manipulated carefully it will have no injurious effect. After the eggs
have been carefully sorted the trays are again placed in the hatching-
box. The eggs are looked over at least every three days during the
first five or six weeks; at the end of that time, in a water temperature
of from 40° to 45° F., the eye-spots will show up plainly, and from this
stage to the breaking of the shell less labor need be expended in this
direction, for the eggs are not so susceptible to fungus, etc., as in the
early stages. At this period unimpregnated and imperfectly developed
eggs are easily distinguished and taken out at one picking, leaving
practically only those that will ultimately hatch as perfect fry.
For washing the eggs when coated with sediment a large galvanized-
iron i)an, about 2^ feet long. If feet wide, and 4 inches deep, is used;
this is nearly tilled with water and a tray floated on its surface. The
eggs are gently moved about with a feather, and by submerging and
quickly raising the tray the eggs will be left as clean as Avhen first
taken. It is necessary to be very careful to give no sudden jar or
shock to the eggs, for up to the time the eye-spots begin to appear they
are very delicate and must be handled accordingly. It is better to
allow a small amount of dirt to remain on the eggs than to under-
take washing them, which should only be done when the coating of
sediment becomes dangerously heavy. The boxes may be washed when
the trays are in the picking-trough, but to wash the trays is difficult,
yet very necessary in case they become covered with slime.
The eggs may be transferred to a clean tray without serious harm
by placing the clean tray face downward upon the dirty one, and by a
quick movement reversing their positions, submerging both trays in a
MANUAL OF FISH-CULTURE. 101
pan of water. This will deaden the fall of the eggs from one tray to
the other and free what few adhere to the first tray.
In a water temperature of from 40° to 45° F., hatching will begin in
from 75 to 90 days. The dark hue of the egg as a whole, the distinct
outline of the fish, and its convulsive movements show the approach
of the hatching period. If the weather is clear and cold these indica-
tions may continue for some time, but with the advent of a single warm
day more than 50 per cent of the fry are apt to break their shells.
As the total number of eggs received at the hatchery has decreased,
in order to determine the number of fry that will be hatched they are
now measured again by first emptying the eggs in the large pan
described above, and then placing 4,000 each upon trays, in this case
made of wire cloth with a -,\-inch mesh. Should the temperature
remain uniform the hatching will cover a number of days, but a sudden
rise or fall in the temperature will have a marked effect in either
advancing or retarding the further development of the eggs.
The dead shells from the hatching fish must be removed or they
will clog the trays and stop the circulation of water. To provide
against this, one box of trays is emptied into a pan of water and the
eggs stirred with a feather ; the shells rise to the top and can be easily
j)Oured off, and by repeating this operation several times the hatching
fish are entirely freed from this refuse. In returning the fish and eggs
to the trays they sliould be divided as equally as possible among the
ten trays. The necessity for this depends on the rapidity of hatching
and perhaps a single box need be served in this manner only three
or four times during the hatching period.
The care of the fry from this time to their distribution, if distributed
before the absorption of the food-sac, is somewhat similar to the treat-
ment described for eggs. JMoustrosities, " blue-sacs," and dead fry are
picked out as soon as they are discovered. The yolk-sac attached to
the fry will be gradually absorbed and the fry so increase in size that
4,000 overcrowd one tray, and when the sac is about half gone, which
is in about three or four weeks after the fish are hatched, it is necessary
to reduce the number upon each tray to 2,000.
DISTRIBUTION OF THE FRY.
Lake trout should either be planted while the food-sac is still visible,
or not until they possess the vitality of the yearling. Trout planted
when the food-sac is within one or two weeks of complete absorption
have sufficient nourishment to sustain life until they are acclimated to
their surroundings, as well as the natural impulse from the beginning to
take the minute particles of food which they find. As from 2,000,000 to
4,000,000 lake trout are hatched at I^orthville annually, it is impossible,
with the present facilities, to hold them all in rearing-troughs and ponds
until they become yearlings, and the fry are usually distributed direct
from the hatching-boxes.
102 REPORT OP COMMISSIONER OF FISH AND FISHERIES.
Til slnp])ingtliem to tlieir destination, 10-gallon round-shouldered cans
are filled to witliin a foot of tlie tof) with the water used in hatching.
One trayful, or 2,000 fry, is put in each can, and as soon as it is filled,
enough ice is added to bring the temperature down to 38° or 40° F. If
the fry are to be planted in the Great Lakes, the cans are transferred
from the car, upon its arrival at its destination, to a fishing-tug and
conveyed to the reefs or natural spawning-grounds of the lake trout;
here the cans are lowered into the water and the fry allowed to escape
and in a few moments they disappear from the surface and sink to the
bottom.
PACKING EYED EG^GS FOE SHIPMENT.
When the eye-spots are plainly visible, the eggs can be packed and
successfully shipped to any part of the world, if kept at a uniform
temperature. The trays used for this purpose are made like those used
in shipping green eggs from the field station to tlie hatchery. For
100,000 eggs 16 trays, 18 inches by 18 inches, are required; for 50,000,
8 trays, 16 by 16; and for 5,000 eggs, 5 trays, 8 by 8. After they are
l^acked, the trays are placed one upon the other and crated together by
nailing a cleat on each side from the foundation to the top board. The
packing-case is made large enough to admit of an air-space of 1 inches
around the top, bottom, and four sides of the crate, when it is placed
in position. Eope handles are inserted at the sides.
The temperature of the packing-room should not be higher than 40°
nor lower than 26°. A temperature of from 28° to 30° is preferable.
The canton flannel trays are first soaked in water, drained, and then
placed upon a table to receive the eggs. Wooden frames of finch
square strips, made so as to fit inside the frames of the packing-trays,
are then inserted. A box of eggs, previously picked and cleaned, is
taken out, drained, and carried to the packing-room. The eggs are
carefully brushed from the wire trays upon the flannel trays with a
feather and spread evenly over the surface. To divide the eggs among
the flannel trays is not difficult, as there are 40,000 in the hatching-
box, or 4,000 to the tray. Tlie inner wooden frame is now removed,
leaving a f-inch margin on all sides between the eggs and the tray
frame, and a piece of damp mosquito netting is laid over the eggs,
extending IJ inches beyond the sides of the frame. This netting is
pressed down at the inside corners of the tray and all along next to
the frame, in order to hold the eggs in position and avoid their coming
in contact with the wooden frames. Over this netting is scattered
sphagnum moss, ^ to f of an inch deep. This moss is gathered in the
fall, and is prepared by being soaked in water and wrung out with a
clothes-wringer. It must be free from all sticks and decayed matter
and thoroughly wrung out, picked apart, and made fluffy, for if used
upon the eggs in a compact mass, the supply of oxygen would not be
sufficient for their maintenance while en route. It should be moist, but
not so wet as to drip on the eggs.
MANUAL OF FISH-CULTURE. iU3
When packed the egg-trays are placed upon a foundation-board, made
the same size as the trays and covered with moss. At the top another
board of the same dimensions is hiid. Cleats are nailed on all iour
sides and fastened to the top and foundation boards, making a hrm
crate, which can be handled without danger to its contents.
If the temperature of the i)aoking-room is not below freezing, the
trays are placed out of doors before they are crated, to allow the moss
upon the eggs to become slightly frosted. Eggs at this period may be
subjected to a very low temperature without injury — in fact, may be
enveloped iu a thin coating of ice, and if shii)meuts are made when
the weather is too warm for frosting the results are not so good.
A packing-case, provided with rope handles, is prepared large enough
to admit of an air-space of 4 inches around the top, bottom, and four
sides of the trays. The bottom is tilled 4 inches deep with fine shavings,
the crate of eggs is placed upon them, and more shavings packed all
around between the trays and the case. The packing is carefully done,
a few shavings being thrown in and pounded down before more are
added, in order that the trays may be held securely in the center of
the case. Shavings are filled in on top, the cover screwed on, and the
box is ready for shipment.
In transit the eggs must be kept in a cool place, though not allowed
to freeze; and if this precaution is taken, and they are not unneces-
sarily jolted, they will be found in good condition when unpacked.
Hundreds of thousands of eggs have been thus shipped from North-
ville during the past few years, the eggs arriving in fine condition and
with practically no loss.
For foreign shipments a double box is used. The inside one is made
2^ inches larger on all sides than the crate of trays, and the outside
one large enough to make a 5-iuch space on all sides when the smaller
box is placed within it. The trays of eggs are prepared as in ordinary
shipments, and. when crated, are placed in the smaller box upon a
frame which is constructed from a ^-inch strip, 2J inches wide, tacked
at right angles to the inside and bottom of this box. In the si)ace
thus formed between the crate and the box is packed finely choi)ped
ice, water from the melting ice being drained oil' through a half dozen
small openings in the bottom of the box. This box is now packed
according to the same plan as that followed with shipments for a short
distance. Where there is an opportunity it is advisable to have the
case unpacked while en route and fresh ice added. Eggs have been
shipped in this manner to England, Mexico, Xew Zealand, Japan, and
South America, and have reached their destinations with little loss.
FEEDING AND EEARINd LAKE TROUT.
Lake trout fry held for rearing are kept in troughs until they are large
enough to be transferred to ponds. These troughs at Northville are
12 feet long and 2 I'eet 7 inches wide, with a 1 inch partition running
through the middle its entire length, thus forming two troughs, each
104 REPORT OF COMMISSIONER OF FISH AND FISHERIES,
1 foot 2 inches -wide. At intervals of 18 inches, cleats If inches high
are mortised across the bottom, and in the sides of the trough, at
the ends of the cleats, grooves are made to admit the placing of a fine-
meshed vertical screen, which can fit tightly to the i)artition at the
bottom. Everything is coated with asphaltum paint. The trough lias a
fall of one-fifth of an inch to the foot, the overflow being at the end
through a tin spout. Another trough may be set at the lower end of
the first, provided, as with hatching-troughs, a sufiflcient fall is given for
aeration.
A week or ten days before the disappearance of the yolk-sac, which
will be absorbed in five or six weeks, with water at a temperature of 40°
to 45°, the fry intended for rearing should be transferred to the troughs.
In a single trough of the size described, 15 gallons of spring water per
minute, with a temperature ranging from 45° to 50° F., will support
8,000 fry during the first few weeks they are held. Ui) to this time it is
not necessary to insert the vertical screens except at the head and out-
let, but as the fry increase in size they become restless, snapping at each
other and crowding together in a mass at the head of the trough, and
then it is necessary to thin theni out and separate them by subdividing
the troughs, holding an equal number of the fry in each of the compart-
ments. The action of the fish determines when this should be done.
The use of warm water hastens the development of the fry, the same as
it does with the eggs.
For the first four weeks the fry are fed four times per day on finely
chopped beef liver, ladled through a close screen to remove all lumps.
The liver is diluted with water and the mixture fed to the fry with a
feather. For some days they do not appear to take their food, but the
routine is continued, and as soon as the sac is entirely consumed they
commence feeding. No rule can be laid down prescribing a definite
amount of food, but the fry are fed till their appetites are appeased and
every fish has obtained a morsel. Some days they disjjlay more hunger
than usual, a warm day especially increasing their appetites. After
they begin to feed well the liver may be given to them but three times a
day, more being thrown in at a time.
The troughs must be cleaned out daily by turning on an additional
supply of water — not so much that the fish will be carried against the
screen — and the foul matter stirred up' from the bottom with a fi-ather
and worked through the wires with a small sponge. Twice a week the
sides and bottom are sponged off.
Three months after being transferred to the feeding-troughs, trout
will take food well and be from 1 to 2 inches long. They are then ready
to go outside to the rearing-ponds. These ponds are about 32 feet long
by 5 feet wide, with from 10 to 20 inches of water, and have a mininmm
water supply of 20 gallons per minute. The bottom is graveled and
the sides constructed of planks or cobblestones, and on the sides where
the sun strikes the warmest during the day a board shades the trout
MANUAL OF FISH-CULTURE. 105
from the direct rays. A pond of this description will accommodate
lO.OOO hike trout three or four months ohl. As they increase in size
this number may be diminished, a great deal dei)ending upon the
quality and temperature of the water.
The temperature of the water should never be higher than 65°;
preferably from 48° to 58°.
As when kept in rearing-troughs, the fish are now fed the amount
they seem to desire, being neither overfed nor starved. The liver, not
so finely cho])ped as before, is thrown in with a spoon. At the first
feeding the fish may be somewhat wild and scatter over the pond, but
after one or two days they will collect at one point and take the food
greedily. After four weeks' time they are fed only twice per day, and as
they increase in size, coarser liver is given to them. Food is thrown
in slowly, and no more given at one time than the fish can eat, for
waste matter soon becomes foul, and unless drawn off will speedily
cause sickness.
In from 10 to 12 mouths after hatching, lake trout artificially reared
measure from 4 to 8 inches in length and are ready for planting. This
is done in the same manner as with fry, 100 fish being placed in each
can for transportation.
DISEASES.
The diseases to which lake trout are susceptible are those common to
all other trout. They are caused bj^ impure water, poor food, injuries
received, and the attempted cannibalism of then* neighbors. The first
three of these causes can be guarded against, but the last is much more
difficult to prevent. At the first sign of cannibalism the fish must be
thinned out, and, if feeding well, transferred to the rearing-pond, where
they will have greater range for development. In fact, for any of the
diseases this will prove of more benefit than anything else.
It is beneficial to treat the fry witli salt twice a week by shutting
off the water and sprinkling salt in the trough until a weak brine is
formed. The fish must be watched closely, and as soon as they show
any signs of "turning up'' a full head of water must be turned on
until all the brine is washed off, after which the supply may be reduced
to the regular amount. A small quantity of swamp earth should be
scattered in the tanks about once in two weeks, merely enough to dis-
color the water for a few moments, and allowed to wash off gradually
with the current of the water.
THE GRAYLINGS.
The graylings of America comprise Thymallns tricolor of Michigan,
TJiymallus tricolor montanus of Montana, and Thymallus sif/nifer of
Ahiska and the Mackenzie Eiver region. They are closely related to
the Salmonidw in habits, general appearance, etc., but ditler in the
character of the skeleton.
Only the Montana grayling at present receives the attention of lish-
culturists. Its body is elongated, compressed, the depth contained
4J times in the length. The subconic head is of moderate size, and its
length is one-fifth that of body. The dorsal outline, from snout to tail,
is a uniform gentle curve, highest at the beginning of the dorsal fin.
The mouth is oblique, terminal, and of moderate size; rather feeble
teeth, of uniform size, occur on jaws, palatines, and vomer. The short
and stiff gillrakers number 17. The eye is large, exceeding length of
snout, and is contained 3i times in length of head. From 82 to 85
scales are found along the lateral line, with 8 rows above and 10 rows
below the line. The dorsal fin is long and high, and contains 18 to L'l
rays; both its length and height equal the depth of body. The caudal
is strongly forked. The coloration is gorgeous. The color of the back
is gray with purplish reflections; the sides of head and body are lighter,
with purplish and silvery iridescence; the belly is i)ure white; there
are a few V-shaped black spots on the anterior part of the body; a
dark heavy line, most distinct in males, extends along upper border
of belly from ventral to pectoral fins. The dorsal fiu is richly varie-
gated with a rosy border, 4 to G rows of roundish rosy spots in whitish
areas, with dark blotches forming lines between the spots. The ventral
fins have three rose colored branching stripes along the rays. The
anal and pectoral fins are plain, with dark border.
The Michigan grayling is generally similar to the foregoing, but has
a somewhat larger dorsal fin and slightly different coloration. The
Arctic grayling has a higher dorsal fin, with 22 to 24 rays, a smaller
head (5i in length), and more brilliant colors; the back and sides are
purplish gray, the belly blackish-gray with irregular white blotches,
and the head brown; on the anterior part of the body are 5 or 6 dee[)-
blue spots, and on each side of lower jaw a blue mark; the dark gray
dorsal has i)ale blotches and cross rows of rich blue spots edged with
red; the ventrals show red and white stri])es.
The Michigan and Montana graylings rarely weigh 1^ pounds, and
average only h pound; the northern species is somewhat larger.
The Michigan grayling is naturally found only in certain streams in
Michigan, although the type specimen was said to have come from
Lake Ontario. It is one of the most attractive and gamy fresh-water
106
Fish Manual. (To face page 106.)
Plate 32.
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MANUAL OF FISH-CULTURE. 107
fislies, but is rapidly approaching extiuctioii, owing to excessive fisiiiug
and the polhition of streams.
The Montana grayUng exists only in streams emptying into the
Missouri Kiver above the Great Falls, principally in Deep or Smith
Eiver and its tributaries, and in the three forks of the Missouri, the
Jefl'erson, Madison, and (xallatin rivers, and their affluents. It prefers
clear streams of pure water with sandy and gravelly bottoms, though it
occasionally extends its range to those well strewn with bowlders and
broken rocks.
The Arctic grayHng ( Tlii/mallns si(/nifer) is found from the JNIackeuzie
River westward through Alaska and north to the Arctic Ocean.
The Michigan grayling spawns in April and the eggs are normally
laid in gravel beds in clear, cold streams, in water having a tempera-
ture of 5()o to 00° F. The incubation period is 14 to 20 days.
The spawning season of the 3Iontaiia grayling is in April and May,
dei)ending largely on the temi)erature of the water. In the north fork
of the Madison River the water is comparatively warm, and the gray-
ling spawns a month earlier there than in other waters of Montana.
In connection with the hatchery of the Commission at Bozeman, an
egg-collecting station has been established on Elk Creek, one of the
feeders of Red Rock Lake, where the fish are taken in a tra[) as they
ascend to the spawning-beds. They will proceed long distances to find
suitable spawning-grounds. At the approach of the season they go up
the Jefierson, through Beaver Head and Red Rock rivers, to Red Rock
Lake, 14 miles in length, aiul through the lake to the inlets at its head.
After spawning they return through the lake to the rivers below, none
stop|)ing in the lake, which is totally unsuitable for them. At spawning
time Elk Creek is fairly alive with grayling on the gravelly shallows,
where their large and beautiful dorsal fins are to be seen waving, clear
of the water, in the manner of shark tins on a flood tide. So eager are
they to ascend that they would be smothered in the trap were they
permitted to enter at all times, and the trap is therelore opened only
for a limited time during the day.
Although the cultivation of the Michigan grayling was undertaken
as early as 1874, it was never regularly or extensively conducted. The
artificial i)ropagatioii of the Montana grayling was begun at Bozeman
in 1898, and in 1899 5,300,000 eggs were taken and 4,507,000 fry were
hatched and liberated. The number of eggs varies from 2,000 to 4,000
to a fish, averaging 2,500 to 3,000. They are about 0.14 inch in diam-
eter, and run from 750 to 840 to a fluid ounce. The eggs in the ripe fish
lie loosely in the abdominal cavity, and the fish is quite easily stripped.
The eggs are fertilized by the dry process and fully 95 per cent are
fecundated. When first extruded they are perfectly free and separate,
and are of a rich yellow color owing to the presence of a large oil-drop
whicli makes them almost semi-buoyant; after a few days they become
almost colorless and as clear as crystal. If placed on ordinary flat
trays, crowding each other and exposed to a lateral current of water,
the eggs adhere in bunches, and fungus soon appears, entailing much
labor in i)icking and a great loss of eggs. The embryo becomes very
108 REPORT OF COMMISSIONER OF PISH AND FISHERIES.
active before the eye-spots appear, and the eggs are apt to float off
from the trays. For these reasons they should be eyed iu hatching-
jars, preferably, or in baskets in trouglis, such as are used for hatching-
salmon where the current of water or pressure is from below. After
the eye-spots appear the eggs are heavier and can be hatched like
trout eggs, on ordinary flat trays. The eye-spots are small gilt specks
with a minute black pupil, and appear in fiom 3 toi5 days. The period
of incubation is from 10 to 15 days at a temperature of 50° F. When
first hatched the fry have a very small yolk-sac, which is absorbed in
about a week, when they become free-swimming animals about half an
inch long and qnite slender and delicate, resembling the fry of whiteflsh
or shad.
Finely ground liver is the best artificial food for grayling fry; this
they take very well. Dry or floating food has been tried, but without
success. Baked liver, ground very fine, fish cake, yolk of hard-boiled
egg, corn meal, etc., were given a fair trial, but all were refused except
the i)owdered yolk of egg, which was eaten sparingly; beef chopped
fine and rubbed through a sieve was also refused. An examination
with the microscope shows that the fry have two sharp, retrorse teeth
in the ujjper jaw, similar to those iu the fry of the lake whiteflsh. This
would indicate that their natural food is minute animal organisms, and
experience at the station has confirmed this supposition. Such food is
not found in spring water, which, moreover, is usually too cold for the
delicate grayling fry. It has also been found that after feeding for a
week or ten days in the hatching-troughs containing spring water with
a temperature of 45° F, they began to die from the lack of warmer
water, sunshine, and their natural food.
As soon as the fry begin to swim, and before tlie yolk-sac is entirely
absorbed, they should be transferred to shallow, sunny nursery ponds,
with a deep current and supplied with creek water with a temperature of
60° to 65° F. At this period they have been kei)t alive in ajar of still
water, without change, for four days, showing that they could be success-
fully transported iu cans for planting, at this age. Unlike trout fry,
which seek the shade, grayling fry keep on the sunny side of the i)onds.
They begin foraging for natural food as soon as placed iu the ponds, and
are extremely active. If the water contains plenty of natural food, they
will do well, but at first they are fed at least six times a day.
The usual method of packing trotit and salmon eggs for transporta-
tion will not answer for grayling eggs, which will not bear crowding or
pressure. The egg trays must be o]uite shallow, the frames not over J
inch iu depth, with a cotton-flannel bottom tacked on tightly. The eggs
are placed in a single layer, covered with damp mosquito netting. The
temperature must not go above 45° F,, and should be kept lower, if
possible, by i:)acking ice with moss or shavings on all sides of the stack
of trays in the egg case. The ice hopper on top is of uniform area with
the trays, with perpendicular sides instead of the usual flaring sides, to
facilitate reicing during the journey. Packed in this way, and the tem-
perature kept about 40° F., to retard the development of the embryo,
grayling eggs may be carried any distance desired.
Fish Manual. (To face page 109.)
Plate 33.
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THE WHITEFISH.
DESCRIPTION, COMMON NAMES, ETC.
The common wliiteflsh {Corcgonus clupei/ormis) is eminently a lake
fish. It exists throughout tlie Great Lakes region, and is especially
abundant in lakes Erie, Huron, Michigan, and Superior. The eastern
limit of its range is Lake Champlain, and it is found in Lake Winnipeg,
and possibly farther west. It is landlocked in Otsego Lake, New York.
Efforts to introduce it into new waters in the States of the Pacific Coast
and Eocky Mountain region have not as yet been successful.
Its body is rather long and compressed, and the back, especially in
adults, is arched in front; the greatest depth is about one-fourth the
body length. The head is small and short, contained about 5 times in
the length of the body; the snout is blunt; the mouth is small and
nearly horizontal with the lower jaw included; the maxillary is short
and broad, reaching to a point under the pupil; the mandible extends
to a point under the posterior edge of eye. The eye is small, its diam-
ter being about one-fifth the length of the head. The rays in both the
dorsal and anal fins number 11. The number of rows of scales along
the side of the body varies from about 82 to 92, with about 11 above
the lateral line and 8 below. The gillrakers number about 28, of which
10 are on t\e upper arm of the gill-arch; the longest are contained
about twice in the length of eye. The general color of this fish is a
satiny white, with a faint olive-green shade on the back. The fins are
uniformly white, except the caudal, which normally has a dark edge.
This fish has a number of common names in different parts of its range.
It is the whitefish par excellence of the United States and Canada. As
found in Otsego Lake, New York, it is inai)propriate!y called "Otsego
bass." In alhision to its humped back it is called "highback white-
fish," "bowback whitefish," "buftaloback whitefish," and other similar
names, m Lake Superior.
While more is known of the habits of this species than of any other
member of the group, many i)hases in its life are still obscure, as it
remains in deep water most of the time. Besides the regular annual
movements of the schools to the spawning-grounds, there are other
well-marked migrations in some lakes. Whether these depend on food,
temperature, enemies, or other causes, is not known. Owing to its
small, weak mouth, it is seldom taken with a baited hook. It subsists
on minute animal foo<i, chiefly crustaceans, molhisks, and insect larvje.
The food of the fry and young fish is almost wholly small crustaceans.
109
110 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
COMMERCIAL AND FOOD VALUE, ETC.
The whitefisbes are by far the most important group of fresh-water
fishes of North America, probably of the workl. The common white-
fish is the best of the tribe, but some of the others nearly equal it in
merit, and all are more or less esteemed as food. Among the fishes of
the Great Lakes the common whiteflsh ranks next in value to the lake
herring, lake trout, and wall-eyed pike. In 1897 the catch in the United
States amounted to about 8,000,000 pounds, having a value of nearly
$300,000. If to this is added the yield of lake herring and other spe-
cies of whitefish, the aggregate is over 57,000,000 pounds, having a
value of nearly $800,000. The market value of the whitefishes taken
in 1898 in the British Provinces was reported as $877,000, a sura repre-
senting about 18,400,000 i)ounds.
The common whitefish reaches a larger size than any other species
of whitefish in the United States. Examples weighing over 20 pounds
have been taken, but the average weight is under 4 pounds.
Whitefish fishing is done chiefly with gill nets set at or near the bot-
tom in comi)aiatively deep water, although considerable quantities of
whitefish are also taken in pound nets, trap nets, and seines. A very
large part of the catch reaches the market in a fresh condition, although
formerly considerable quantities were salted. The leading centers of
the trade are Chicago, Detroit, Sandusky, Cleveland, Erie, and Buffalo,
\\ hence the fish are shipped frozen or in ice to all parts of the country.
SPAVi^NING^.
The spawning season of the whitefish begins the latter part of Octo-
ber and continues into December. At that season there is a general
movement of the fish to shoal parts of the lakes, similar to the migra-
tion of anadromous fishes from the ocean to the rivers; some of the
foreign whitefishes are typical anadromous species. After spawning,
the fish return at once to the deeper water.
The spawning habits of whitefish confined in i^ens have been observed.
The fish rise to the surface, occasionally in pairs, sometimes, but rarely,
in trios of one female and two males, the female emitting a quantity of
spawn at each rise. The males, always the smaller fish, persistently
follow the female and discharge milt at the same time the eggs are
emitted.
Whitefish reach maturity in the third or fourth year. A full-grown
specimen deposits from 10,000 to 75,000 eggs, depending on the fish's
size. A rule for determining the approximate spawning capacity is to
allow about 10,000 eggs for each i)ouiid of the fish's weight. The eggs
are an eighth of an inch in diameter, and 3G,000 make a fluid quart.
They swell somewhat after impregimtion.
DESTRUCTION OF WHITEFISH SPAWN IN NATURE.
In nature the eggs of the whitefish are subjected to the attacks of
many enemies for nearly five months. The mud-puppy [Nectvrus mac-
MANUAL OF FISH-CULTURE. Ill
vlafiifi), comiiioiily known as ''lizard" or "water-dog" by tlie people
along- the lakes, is especially destructive. During the month of Janu-
ary, 1897, many of these animals were pumped up with the water
supply of Putin Bay station. The stomachs of a considerable number
of them contained Avhitefish and cisco eggs, the contents of one stomach
being 288 whitefish eggs and -4 cisco eggs.
Another voracious destroyer of whitefish eggs is the common yellow
perch {Perca Jiavcscens). The deck of a boat has been seen covered
with the eggs of the whitefish and cisco pressed out of the stomachs of
perch taken from gill nets the last of ]S"ovember on the reefs, where they
had gone to feed on the eggs.
The various smaller Cyprinidce and some other fishes, crawfish, and
wild fowl make the eggs of fishes a considerable portion of their diet,
those which require the longest period in hatching, of course, suffering
most.
ARTIFICIAL PROPAGATION.
The artificial propagation of whitefish has long since passed the
experimental stage and has attained a high degree of perfection. The
work can be carried ou with great facility, and its value is especially
apparent when it is considered that under natural conditions only
a very small percentage of the eggs hatch, while through artificial
propagation from 75 to 95 per cent are productive. Practically all the
eggs taken for hatching purposes are obtained from fish caught by the
commercial fishermen, which would otherwise be lost.
The methods of culture hereafter referred to are those adopted at
the Putin Bay (Ohio) station, but these do not difier in any essential
particular from those in general use.
In the fiscal year 1897-98 the United States Fish Commission hatched
and planted 88,488,000 whitefish fry, and in 1898-99 152,755,000 fry
were hatched and liberated in suitable waters.
HOW THE EGGS ABE TAKEN AND TREATED.
The taking, impregnating, and handling of the whitefish eggs are
simple processes, but require great care at every stage. Eggs are
often injured by undue haste in stripping, and many are lost by allowing
them to fall too great a distance into the spawning-pan. Eggs are very
delicate Avheu first taken and before the absorption of water has made
the investing membrane tense, and if roughly treated will be seen to be
ruptured as viewed under the microscope. With care about four- fifths
of the eggs will hatch. While scarcit}^ of milt may lead to the non-
fertilization of the eggs, the manner in which the milt is brought in
contact with eggs is a more common cause of failure.
The eggs supplied by each spawn-taker should be examined daily,
and if it is found that a considerable number have ruptured yolks it may
be taken for granted that the spawn-taker has handled the fish and eggs
roughly, and if many are unimpregnated it is evident that he did not
use suflicient milt or that it was not properly applied to the eggs.
112 KEPORT OF COMMISSIONER OF FISH AND FISHERIES.
At Put-in Bay eggs are obtained from fish captured in pound nets
and gill nets, often at considerable distances from the station. The
spawn-taker, Miio is employed to take the ej;gs from the fish as they are
lifted from the nets into the boat, has with him two or three G-quart
pans, coated with asphaltum varnish to prevent rusting, in which he
takes the spawn ; a wooden keg or tin can holding from 10 to 15 gallons;
a 10-quart wooden pail, and a tin dipper. He is clothed in waterproof
garments, and his left hand is covered with a woolen mitten for con-
venience in handling the hsh.
After several ripe females and some rii)e males are collected, a female
is taken, and the body slime, which will interfere with impregnation if
it falls into tlie pan, is carefully removed. The spawn-taker then
grasps the fish firmly in his left hand, just forward of the tail, with the
back of the hand downward, the fingers outward, the thumb above and
pointing outward, the head of the fish being toward the spawn-taker's
body. The right hand is placed under the fish just back of the pectoral
fins, with the wrist pressing the head of the fish firmly against the body,
the thumb outward, fingers inward, thus grasping the upper abdomen
firmly. Tlie fish is now at an angle of nearly 45°, the body forming a
modified crescent, with the vent within 4 or 5 inches of the bottom of the
pan. This position of the fish's body brings pressure on the abdomen,
facilitates the flow of the eggs through gravity and the opening of the
vent, and prevents injury to them from falling too far.
Gentle pressure being now applied, the eggs flow in a steady, liquid
stream about a quarter of an inch in diameter, and a considerable
portion of them will be procured before the hand need be moved. As
soon as the stream slackens the hand is slowly moved toward the vent,
but only fast enough to keep the eggs coming in a continual stream.
When it finally stops the hand is replaced in its former position and
the process repeated until all the good eggs are procured. If, as is
frequently the case, when nearly all the ripe eggs are emitted a consid-
erable number of white ones appear, the work s'hould stop.
The dry process of impregnation is now universally considered to be
the better, and the pan in which the eggs are taken is only dampened
by dipping it into water before the stripping begins. After two or three
females have been manipulated the milt from one or two males is added
to the mass of eggs. This is done by grasping the fish between the
thumb and fingers 2 or 3 inches forward of the vent and moving them
toward the opening. The milt comes in a stream, an average fish pro-
ducing about a teaspoonful. If ripe males are scarce the fish is laid
aside, as he may be used again in a few minutes an'd considerable addi-
tional milt procured.
When the pan is one-half or two-thifds full of spawn and milt, the
spawn-taker gently stirs the eggs to incorporate them thoroughly with
the milt, using for this purpose the tail of a fish, from which the
slime has been carefully removed. The pan is then partly filled with
water and the mass again very gently stirred. After standing two or
Fish Manual. (To face page 1 1 2.)
Plate 34.
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MANUAL OF FISH-CULTURE. 113
three minutes, the water is poured off and fresh water added, and this
is repeated until the water comes away clear, when the eg^s are jmured
into the keg or can previously filled with water, and the work of taking
spawn is continued. Before adding another lot those previously put into
the keg are gently stirred. It is necessary to change the water on the
eggs at least once an hour, and oftenerif the weather is warm, and the
eggs should be gently stirred to the bottom of the keg every 30 minutes
until they are placed in running water in the hatchery.
When the spawn-taker has finished he turns over the eggs to a man
in charge of the field work, who cares for them until the collecting
steamer comes, when they are taken aboard and transported to the sta-
tion, some 2 to 5 hours having elapsed since they were taken. At the
station the eggs are kept in the kegs in which they were placed by the
spawn-taker and a stream of water of about 2 gallons per minute to
each keg is kept running on them until the next morning, and they are
stirred to the very bottom once an hour in the meantime. In this way
tlie eggs are given time to harden with less injury than if they were
immediately placed in the jars.
Formerly in shijjping eggs long distances they were kept in running
water in kegs, under the care of a watchman, but it has been found
much better to ship them in cases on trays. After having been in water
8 or 10 hours, whitefish ova may be safely placed two or three layers
deep on trays and shipped indefinite distances. If the weather is warm
(55° or 60° F.) the cases must be surrounded with ice, or sawdust and ice.
In placing the eggs on the trays a perforated dipper is used and a
little practice soon shows about how many to dip out for each tray, and
if just enough water is left Avith the eggs a slight tilting of the tray
will distribute them evenly over its surface. Then by setting the tray
with one corner on the floor and the diagonally opposite corner raised
3 or 4 inches, the surplus water will soon drain off. This may be facili-
tated by slipping a thin wooden wedge between the cloth and wood at
the lower corner of the tray.
In shii)ping a distance of 40 or 50 miles, the trays may be placed in
the cases with no other protection from change of temperature than
the wood of which they are constructed — an inch thickness of tray and
an inch of case with an inch of air-space between — which is found to
be safe in a cool car or room in a boat, but for longer distances about
20 trays are fastened together with thin strips of wood tacked to either
side and placed in a large case with from 4 to 6 inches of pine sawdust
well packed on every side.
After the eggs are placed on trays and drained, they are covered
with a thickness of mosquito netting, well washed and left damp, and
over this is packed enough damp moss to till the tray even with the
surface. If eggs are to go by express, unaccompanied by a messenger,
directions are fastened to the case stating that they must be kept cool
but not permitted to freeze. Whitefish eggs have been safely shipped
in this way from Nortliville, Michigan, to Australia. If tbe eggs are
r. M. — .-8
114 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
to be shii)ped a short distance — 25 to 50 miles — it is not necessary to
cover tliein with moss.
The trays used at the station are 10 inches square, outside, and are
made of white pine | by 1 inch, mortised together at the corners with
the widest side of the strip horizontal. On the bottom of these frames
heavy canton flannel is tacked, so that the nap will come next to the
eggs when in use. The cloth should be stretched very taut, otherwise
it will sag on being wet and dried. Tbe tacks are put 2J to 3 inches
apart, so that in a year or so it can be retacked between the ones first
driven to take up the slack. The trays are made square, as they then
go into the cases either way and time is saved in packing; square
cases are also more convenient in storing and in handling generally.
Such a tray will liold 50,000 eggs.
If the eggs have to be retained for several days in the field, they are
sometimes kept in floating-boxes adapted for this purpose. (See descrip-
tion of this box on p. 95.) But unless the conditions are very favor-
able it is far better to place the eggs on trays, sprinkling them lightly
once in two or three days.
When taken from the kegs and trays at the hatchery the eggs are
passed through a screen (with meshes sufficiently large to permit the
passage of a single egg) in order to remove scales and other foreign
substances that may be present. The screen is floated in a washtub
partly filled with water, the wire netting being well submerged.
For handling eggs and fry wooden kegs are by some preferred to
tin cans, as they do not subject the eggs and fry to sudden changes
of temperature, their contents are easily examined, and the water is
more readily poured off without danger of losing eggs. The kegs are
much lighter, only cost a third as much as cans, and last longer. For
shipping in wagons or by rail, however, tin cans with covers are indis-
pensable. Kegs should be made of white pine, painted outside but
not within, and hold about 15 gallons each, and should be provided with
iron drop handles.
PENNING WILD FISH.
The uncertainty of the seasons and the liability of failure to obtain
spawning fish owing to severe storms which occur in November, make
it desirable, wherever practicable, to capture fish in favorable weather
and place them in pens until ripe. After the fish are driven off' their
spawning-grounds by severe storms, they do not return m large numbers
during the spawning season, and the only way to insure a satisfactory
supply of eggs is by penning the fish.
Nets have been tried for penning, but they do not afford sufficient
facilities for sorting the fish of various degrees of ripeness and the fish
have to be handled too much, thus encouraging fungus growths on them
and causing many to abort their eggs. Penning is best done in crates
made of boards with openings sufficiently large to admit the free inter-
change of water. The pens are generally made about 16 feet long, 3 or
MANUAL OF FISH-CULTURE. 115
4 feet wide, and 4 to 8 or more feet deep. They should be placed end
to end in two rows, some 3 or 4 feet apart with a plank walk between,
for convenience in caring for them. The fish must be handled as little
and as gently as possible, otherwise the eggs will form into a hard mass
and never ripen. One cause of injury is the scoop net with which they
must be handled; the knots and the twine are so hard that they injure
the delicate scales of the wliiteiish, which struggles violently when
taken from the water. A net made by punching suitable sized holes
in a sheet of thin, soft, flexible rubber would be yielding and perhaps
cause the least injury.
HATCHING METHODS AND EQUIPMENT.
At Put-in Bay the water for hatching is obtained from Lake Erie
through a pipe that extends 75 to 100 feet into the lake. Pumps
elevate the water to the loft of the hatchery, where it is received into
supply-tanks, whence it is distributed by the usual methods of piping.
The circular supply-tanks, two in number, are about 11 feet in mean
diameter, 8 feet high, and have a capacity-of 5,000 gallons each. These
tanks are necessary to give an equal pressure in the pipes and to
provide a supply of water in the event of cessation of ])umpiiig. A
gauge in the boiler room shows the height of water in the tanks.
Whitetish eggs are hatched in the McDonald jar and the Chase jar;
the former is in more general use in the United States Fish Commission,
although both give satisfactory results. The eggs are put into the
hatching-jars by means of a dipper having a perforated bottom. The
proper number to a jar is 3f quarts, as determined by a gauge ; these will
swell to 4:1 quarts, which is about the proper quantity for the jars used.
The form of the embryo whitefish can be seen in the egg by the use
of a magnifying glass in from 10 to 15 days and the eye-specks and
color stars in from 15 to 20 days, the time depending much on the tem-
perature of the water. The fry being hatched, the food-sac is absorbed
in from 5 to 15 days, varying somewhat with the period of incubation.
If hatching is long retarded by low temperatures, the sac will be nearly
all absorbed when the fry hatches.
The microscope is a great aid in whitefish culture, enabling the
operator to determine the exact percentage of dead eggs and to a great
extent the cause of their loss, thus allowing him to remedy some if not
all the evils. For examining eggs in their early stages the microscope
is placed horizontally, the eggs being held in a cell filled with water.
This may be easily made by fastening two ordinary glass slides to a
strip of wood an eighth of an inch thick, with a portion cut away to
form a receptacle for the eggs. The wood is thoroughly saturated with
asphaltum varnish, and after drying the sides should receive a thin
coat, the slides being laid on and placed under pressure to dry. When
dry an additional coat to the outer joints of contact will guard against
possible leaks.
116 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
If the egg be examined G or 8 lioiirs after it is fertilized, the germinal
disk will be found to have contracted to a saucer-shaped cap extending
over about a fifth of the surface of the yolk. It is smooth and even,
gradually thinning to a sharp outer rim, with a thickness in the center
of the cap of about a fifth of its diameter. At this stage — segmentation
not having commenced — the impregnated eggs can not be told from the
unimpregnated ones. At 18 hours segmentation will be well advanced
and the disk will have contracted into six or eight rounded nodules of
uneven size, with well defined valleys between, there being no longer
a sharp rim to the disk. At 24 hours — the best time to determine
the percentage of live eggs — the disk presents a somewhat similar
appearance, except that it will be divided into 25 or more segments,
easily seen under the glass; the disk of the unimpregnated egg of
the same age forms an almost exact hemisphere, is perfectly smooth
in appearance, and is therefore easily distinguished from the live egg.
Segmentation now goes on rapidly, and at 72 honrs the cells look under
a 1-inch objective — a suitable power to use in this work — about the
size of a mustard seed, the disk having in the meantime assumed an
hemispherical shajje.
During the entire period of incubation, but more especially during
the early stages of growth, the eggs should be worked as gently as
possible; that is, only sutticient water should be used to keep them in
slow motion and to prevent "banking." At the commencement they
require about 6 quarts of water per minute to the jar, but later they will
run with a quart less per minute. The eggs require constant watching
for the first week or more, and although not considered an adhesive egg,
agglutination takes place occasionally when the water becomes roily.
Unless the "banks" so formed are separated by gently stirring them
with a long feather (the long wing feathers of a turkey are suitable),
the eggs forming the pack soon die and form a mass in the jar.
In a few days, varying with the temperature of the water, the unim-
pregnated and other dead eggs begin to "fungus" — that is, a growth
makes its appearance; on them and they rise to the top of the egg mass —
when they must be removed by the use of a siphon, and if live eggs are
among those drawn olf, they must be set up in what are called " hospital
jars," where the live and dead ones are more readily separated.
The dead eggs are drawn off' every day, otherwise they are lijible to
become loaded with silt from the water and sink, mixing with the live
eggs and making it difficult to separate them.
For the removal of dead eggs from the jars a longdistance siphon is
used at Put-in Bay station, which saves much labor. It is constructed
thus: To the short end of the ordinary siphon, which consists of a thin
quarter-inch brass tube about a foot long bent into the form of a goose
neck, is attached a piece of common rubber tubing 3 or 4 feet long with
a finch interior diameter. This is connected with a rubber tube of the
same size and long enough to reach the whole row of jars or all in the
Plate 35.
MANUAL OF FISH-CULTURE. 117
lionse if desired. The couuectiou is made by a thin brass nipple with
the same interior diaineter as the piece of rubber tube to be joined by
slipping it into the longer piece and lashing it on the outside with twine,
leaving about three-quarters of an inch outside to slip into the shorter
piece after the siphon is started. The otlier end of the long tube is
connected with a like piece of brass tubing, bent to a quarter circle to
prevent tlie rubber tubing from kinking, to and through the center of
a wooden float some 12 inches in diameter and 1 or 2 inches thick.
This is placed in a tub or large pail; the short siphon is started and
connected as above described, and the long siphon is in working order.
The water runs over the rim of the tub into the sluice, over which it is
placed, and the eggs settle to the bottom. A whole hatchery can be
operated without moving the tub, although it is better to raise it 5 or 6
feet from the floor for the upper rows of the jars, as the suction
otherwise becomes a little too strong and liable to injure the good eggs
when passing too rapidly through the tube.
For convenience and for economy of space and water, the hatching
jars are arranged in t'ors, constituting what is known as a "battery."
The structure of a battery, with its complicated system of supply
and waste troughs and with the jars and their attachments, is rather
difficult to describe clearly, but may be understood by reference to
plate 35.
Each battery is divided into two sections, which have four rows of
jars on each side, setting on shelves 3 feet apart. The water is admitted
through an iron pipe to the uppermost cross-tank; from there it runs
into the uppermost supply-trough, which, like all tlie others, is 13 inches
wide and 9 inches deep, insiile measurements. The iron pipe is provided
with a ball-cock, regulating automatically the supply of water. The
supply-troughs are from 22 to 34 feet long, the upper ones being the
shortest and the lower the longest. The first supply-trough has a row
of brass cocks on either side taking the water 1 inch from the bottom.
A half-inch rubber tube, 0 inches long and forming when adjusted a
quarter circle, is slipped over the outer end of the cock and the upper
end of the iron tube, which is inserted in the jar. The water flows from
this upper supply trough, which may be called Ko. 1, in section l^o. 1,
through the cock, rubber tube, iron tube, and jar, from which it is dis-
charged into what may be called waste-trough No. 1, which is directly
below supply trough No. 1. This discharges its water into a cross-tank,
the second from the top, which carries the water across to supply -trough
No. 2, M'hich is in section No. 2. This supplies the second of the eight
rows of jars, through whicli all the water jjasses, and after passing
through the j ars, as before described, it empties into waste-trough No. 2, in
section No. 2, which carries it to cross-tank No. 3, which in turn carries
it across and delivers it to supi)ly-trough No. 3, which is in section No.
1. Thus the water goes back and forth from one section to the other,
dropping a step at each passage, until it finally enters the fry- collecting
tank on the floor, which is 3.i feet wide, 9 feet long, and 2 feet deep.
118 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
The cross-tanks are in steps, like a flight of stairs, which accounts
for the unequal lengths of the supply-troughs. Each has an overflow
in the center, over which a small amount of water is kept running, so
that the attendant can see at a glance that all of the troughs are full.
Screens are interposed at such places in the cross-tanks that the frj'
discharged into them through the waste-troughs cau not enter the oppo-
site supply-troughs, but will float with the overflow successively into
the lower cross-tanks down to the fry-collecting tanks.
The fry-collecting tanks, one for each battery, are connected with the
main collecting tanks by means of 2inch gas-pipe, fltted with valves,
passing under the floor of the hatchery. The main tanks, eight in
number, are 3 feet wide, 16 feet long, and 2 feet deep; in these the fry
are retained until dipped out for shipment or planting.
The only marked difference between the method of operating the jars
at Put-in Bay and other stations is the use of a |-iuch iron gas-pipe,
instead of a glass tube, for supplying the jars with water, and the addi-
tion of a tin cone, 6 inches long and 1 inch in diameter at the lower
end, which is soldered to the end of the iron pipe and reaches within
one-eighth inch of the bottom of the jar. The tube is held in place by
an iron bracket, fastened to the supi)ly-trough and held by a thumb-
screw. The cone has the eflect of spreading the water and giving an
easier and more thorough motion to the eggs than can be obtamed with
a straight tube.
At Put-in Bay the water passes through eight rows of jars, and the
fact that the eggs in the lower rows of jars are just as good as those
in the upper rows is j)roof of the practicability of the plan.
The jars require 6 quarts of water per minute to each jar on the top
row, this amount again supplying the successive tiers of jars on the
shelves below. If more jars are placed on the lower shelves than on
the toj> one, a greater quantity of water must necessarily be added,
equal to G quarts of water to each jar.
The temperature of the water must, of course, with the large quan-
tities used, be what nature makes it, but if much above 50° F. good
results can not be expected with whitetish eggs. When the work
begins, early in November, the temperature of the water in Lake Erie
is from 40° to 50° F., wiiile late m the month it is generally about 35°
to 38°. As soon as the lake freezes over, or ice in any considerable
quantity forms, the temperature of the water as it passes through the
jars remains very uniform at 32^°. When the ice goes out, which is
generally about the middle of March, it rises slowly, and when the fry
begin to hatch, the latter part of the month, It is generally up to about
33° or 34°.
The jars, tubes, troughs, etc., should be kept scrupulously clean.
The usual coating for the inside of troughs and tanks is asphaltum
varnish, but a mixture of coal tar and turi)entine has proved an excel-
lent substitute. For the first coat on new wood equal parts of each
are employed; for the second and third coats one third turpentine and
Fish Manual. (To face page 1 18.)
Plate 36.
1. Unfertilized whitefish egg 24 houis old.
2. Fertilized whitefish egg 6 hours old, geminal discs form-
ing, no segmen-tation having taken place.
3. Whitefish egg, 12 hours, showing first cleavage.
Water 38°.
4. Whitefish egg, 18th h ■" Water 38°, showing second
segnnentatiun, f.jur cells formed.
5. Whitefish egg, 24 hours. Water 38°. 6. Whitefish egg, 48 hours. Water 38°.
DEVELOPMENT OF THE WHITEFISH EMBRYO.
Fish Manual. (To face page 1 18.)
Plate 37.
7. Fertilized whitefish egg 72 hours old, showing segmentation 0. Whitefish egg, seventh day, embryo beginning to show,
well advanced.
9. Whitefish egg 43 days old, showing embryo.
10. Whitefish egg 90 days old, showing embryo.
11. Whitefish egg, yolk-sac ruptured by rough handling, 24
hours old.
12. Whitrfi-,h I 'i^r with triple discs
DEVELOPMENT OF THE WHITEFISH EMBRYO
Fish Manual ( To face page 1 1 3.)
Plate 38.
1 3. Whitefish egg, showing twin discs, i days old.
14. Whitefish egg, showing twin discs, 6 days old.
15. Whitefish egg, showing twin discs, 7 days old.
16. Whitefish egg, showing twin discs 8 days old.
17. Whitefish egg, showing twin discs, 13 days old. 18. Whitefish egg. showing twin discs, 15 days old.
DEVELOPMENT OF THE WHITEFlzH ET.'T.RVO
Fish Manual (To face page 1 18.)
Plate 39.
1 9. Double-headed whitefish fry just hatched.
20. Double-headed whitefish fry.
21. Curved spine, a common deformity of whitefish fry. 22. Whitefish fry just hatched, three-eyen, curved spine.
23. A common deformity of whitefish fry. 24 Four eyed whitefish Uy.
DEVELOPMENT OF THE WHITEFISH EMBRYO.
MANUAL OF FISH-CULTURE. 119
two thirds coal tar. The tar should be as warm as the touch will bear,
and the turpentine, whicli should be i)ure, should be added slowly while
the mass is being vigorously stirred. The mixture dries quickly and
forms a hard, durable surface, which is entirely waterproof and much
more lasting than asphaltum ; it is also much cheaper, an important item
in a large station. While applying it the tin pail in which it is mixed
is kept in another and larger one partly filled with moderately hot
water. For pitching the cracks and joints the best asphaltum pitch is
used, softened with parailin to the consistency of chewing-gum — that
is, just so that it will not break in cold water. This pitch holds fli-mly
to the wood and keeps its place in warm Aveather. Other i)itches which
have "been tried will run in warm weather and get hard with use,
breaking when cold.
THE (JARE AND PLANTING OP THE FRY.
When the fry hatch they immediately leave the jar and follow the
course of the running water, some going through the succeeding jars,
provided there are no screens interposed to prevent this, others through
the overHows from the cross-tanks, until all reach the fry-collecting
tank at the bottom, whence they are carried to the main collecting
tanks. It has been urged by some that it is injurious for the fry to
pass down through the lower jars with the complement of eggs, but iu
practice this has not been the case.
An air-jet on the inside of the screens will prevent clogging by the
accumulation of eggshells and impurities suspended in the water. This
uuiy be easily arranged by providing an air puiu}) and connecting with
it a pii)e carried along the side of each tank on the inside of the screen
and thence at right angles parallel to the screen and about an inch
distant. This cross-pipe should be perforated on one side with holes
3^; inch in diameter and 3 inches apart, the holes opening toward the
screen and upward at an angle of about 45°. When the air is turned
on, an apparently solid mass of bubbles will arise along the whole sur-
face of the screen. W^ith this arrangement the screens will run hours
or even days without any attention, whereas without the air-jet one or
more men are employed keeping the screens clean, and many fry are
unavoidably killed by being forced against the screens and by the work
of the men in keeping them free. The thorough aeration of the water
thus indirectly accomplished is very beneficial when large numbers of
fry are passing over, and double the number can be safely handled in
troughs thus eciuiijped.
At Put-in Bay the fry are i)lanted as soon as hatched. They are
dipi)ed from the fry tanks into kegs, in which they are transported to
the natural spawning-grounds on the reefs; each keg containing 00,000
to 100,000 fry, according to the distance to be traveled. If they are to
be taken any considerable distance, fresh water is kept running on
them. If the facilities are such that the fry can be held in tanks until
they attain a length of au inch before being planted, they would be
120 REPORT OF COMMISSIONER OF FISH AND FISHERIES."
better able to take care of themselves than if deposited at an earlier
stage. In tlie spring of 1896, about 1,000 wliitetisli fry were held in one
of the station troughs until late in April, with no other food than the
entomostraca and other minute life which came into the troughs with
the water j)umped from the lake. They grew considerably and were
remarkably active. Cannibalism was of frequent though not of general
occurrence; toward the close of the period through which the fry were
held, numbers could be seen which had seized others by the tails and
swallowed as much of the bodies as possible, which was, of course, but
little. In every case one of the larger had attacked one of the smaller,
the victim being dead and his destroyer swimming about actively with
the body of the dead fry trailing along his side. If these fry had been
regularly supplied with food, it is not probable that cannibalism would
have occurred.
REARING IN PONDS.
There have been few attempts to raise whitefish in ponds on a large
scale, but exi)eriment8 lead to the belief that under favorable condi-
tions whitetish can be raised in artificial ponds to some extent. Of
course an abundance of good cold water, suitable ground for the con-
struction of deep ponds, and convenience to railroad communication
would be essential to success.
A successful experiment in this direction was begun at Northville in
1882. The fish were treated as young trout are, being fed wholly on
liver. Three-year-old whitefish, artificially reared, yielded a large num-
ber of eggs, a fair percentage of which were fertilized. Fish weighmg
from 3 to 4i pounds, that had never been fed on anything but liver,
were plump and healthy. Similar successful experiments have beeu
made in Europe with one of the native whitetishes {Coref/onus lavaretus),
and noteworthy experiments in the rearing of whitefish in ponds have
been conducted by private enterprise at Warren, Indiana. It has been
found that in the raising of fry the temijerature of the water should
not go above 55° F., and that 65° is fatal, but fish three or four months
old will stand a much higher temperature.
Fish Manual. (To face page 1 2 1 .)
Plate 40.
THE SHAD.
DESCRIPTION OF THE SHAD.
The shad {Alosa sapidissima) is the largest, best-known, and most
vahiable member of the herring family in the United States. The body
is deep and compressed, the depth varying with the sex and spawning
condition, but averaging about one-third the body length. The head,
contained about 4^ times in the body length, is quite deep; the cheek
is deeper than long. The jaws are about equal, the lower jaw fitting
into a deep notch on the tip of the upper. Teeth are present in the
young, but are not found on the jaws in the adult. The eye is contained
51 to 6 times in the length of head. The gillrakers are long, slender,
and numerous, there being from 93 to 120 on the first arch. The fins
are small and weak, the dorsal containing 15 rays and the anal 21.
The lower edge of the body is strongly serrated, the plate-like scales
numbering 21 before the ventral fin and IG behind it. The scales in
the lateral line number GO. The body is dark-bluish or greenish above,
silvery on the sides, and white beneath. There is a dark spot behind
the gill-opening and sometimes a row of smaller spots along the side.
The vertical fins often have black or dusky edges. The peritoneum
is white. Supposed structural and color peculiarities in shad from
different regions or basins have not been verified.
From the otlier clupeoids with which the shad is frequently asso-
ciated in the rivers, it may be readily distinguished. In all of them the
cheek is longer than deep. The hickory shad or hickory jack {Pomolobus
mediocris) has a projecting lower jaw and a very straight i^rofile. The
river herrings or alewives are much smaller than the shad, have fewer
and shorter gillrakers, and a larger eye (3i in head). In the branch
herring (P. pseudoharengus) the peritoneum is pale, while in the glut
herring (P. (vstivalis) it is black.
The female shad is larger than the male, the average difference in
weight being more than a i)ound. The mature males taken in the
fisheries of the Atlantic coast weigh from li to G pounds, the average
being about 3 pounds; the females usually weigh from 3 to G pounds,
the average being 4f pounds. The general average for both sexes is
between 3^ and 4 pounds. In the early history of the fisheries, shad
weighing 11, 12, and even 14 pounds were reported, but 9-pound shad
are very rare on the Atlantic coast, and 10 pounds seems to be the
maximum. Some seasons an unusual number of large shad (7 to 9
l)ounds) appear in certain streams. On the Pacific coast shad average
a pouiul or more heavier than on the Atlantic, occasionally attaining a
weight of 14 pounds; many have been reported weighing 9 to 12 ])ounds.
121
122 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
DISTRIBUTION AND ABUNDANCE.
The shad is distributed along tlie entire east coast of the United
States, and nortliward and eastward to the Gulf of St. Lawrence. It
has gradually spread from the Sacramento Eiver, California, where it
was introduced by the California Fish Commission, and is now taken
from southern California (Los Angeles County) to southeast Alaska.
In the early history of the country its abundance excited unbounded
astonishment. Nearly every river on the Atlantic coast was invaded in
the spring by immense schools, which, in their upward <;<mrse, furnished
an ample supply of good food. Notwithstanding greatly iiutreased fish-
ing operations and the curtailment of the spawning-grounds, the sui)ply
in recent years has not only been generally maintained, but owing to
fish-cultural efforts has been largely augmented in certain streams,
notably in the Kennebec, Hudson, Delaware, Susquehanna, Choptank,
Potomac, Nanticoke, Eappahannock, York, James, Chowan, Koanoke,
Neuse, and St. Johns rivers, and in Chesapeake Bay, Albemarle Sound,
Croatan Sound, and Pamlico Sound, and the Sacramento and Columbia
rivers.
SHAD IN THE OCEAN.
The shad passes most of its existence at sea, and little is known of
its habits and movements when out of the rivers. The ocean areas to
which it resorts are unknown, and what its salt-water food consists
of has not been determined. In the Gulf of Maine it is known to
associate in large numbers with mackerel and herring during the
months of June, September, and October, being most numerous in June.
It has been taken at North Truro, Massachusetts, in the fall, when the
ocean temperature was from 43° to 49°. In the month of November,
one year after another, it has been found on the west side of Sakonnet
Eiver, Rhode Island. In May and June it has been captured with
mackerel a few miles northeast of Cape Cod Light. Some instances
of capture indicate that under certain conditions the adults may
remain in the fresh-water rivers a whole year. In November, 1890, 600
were taken in the Chesapeake Bay. It has been found in the Potomac
in considerable abundance in August and September, and even during
the last week in December. Its movements are largely controlled by
the water temperature. It is believed that it seeks to occu))y an area
having a temperature of 60° or 70°, and that its migrations are deter-
mined by the shifting of this area.
SHAD IN THE RIVERS.
The annual migration of the shad from the ocean to the rivers is
for the sole purpose of reproduction. It ascends to suitable spawning-
grounds, which are invariably in fresh water, occupying several weeks
in depositing and fertilizing its eggs in any given stream.
Its migrations from the sea are in quite a regular succession of
time with relation to latitude. It first appears in the St. Johns Kiver,
MANUAL OF FISTI-CULTURE. 123
Florida, about November 15, the season of greatest abuudauce being
February and March. In the Savannah Kiver, Georgia, and the Edisto,
South Carolina, the run begins early in January and ends the last of
March. In the North Carolina rivers these stages of the migration are
a little later. In the Potomac River advance individuals appear la(e
in February, but the fish is most numerous in April. In the Delaware
Kiver the maximum run is about the 1st of JVIay. It reaches the Hud-
son Kiver the last of March, and is found in the Connecticut toward
the end of April, is most abundant the last of May, and leaves the
stream late in July. In the Kennebec and Androscoggin rivers, Maine,
it is first taken m April and has left by the middle of July. In the St.
John Kiver, New Brunswick, it appears about the middle of May, and
in the Miramichi Kiver, New Brunswick, late in May.
The main body of shad ascends the rivers when the temperature of
the water is from 56° to 06°, the numbers diminishing when the tem-
perature is over 06°. Successive schools enter the Potomac from
Februarj^ to July, the males preceding the females. Of 61,000 shad
comprising the first of the run received at Washington, D. C, from
March 19 to 21, 1897, 90 per cent were males. Toward the close of the
season males are extremely scarce.
The movement of the shad up the rivers is not constant, but in
waves, causing a rise and fall in the catch. In some of the rivers the
fishermen claim that a fairly well-defined run occurs late in the season,
consisting of a somewliat different fish, known as "May shad."
The erection of impassable dams along the rivers and streams was
probably the first thing to curtail the natural spawning-grounds of
these fish and to seriously check their natural increase.
As shad enter the rivers only for the i)ttrpose of spawning, the
fisheries are necessarily prosecuted during the spawning season, and
often upon the favorite spawning-grounds. The increase of population
necessitates a larger supply of fish and requires the use of more
apparatus, and the number of shad that reach fresh water is therefore
greatly curtailed by assiduous fishing with all kinds of contrivances in
the estuaries and in the mouths and lower parts of rivers. Under these
conditions of a restricted spawning area and increased netting shad
would soon be exterminated without artificial propagation; or the fish-
ery, at least, would greatly diminish and become unprofitable. Such a
crisis was fast approaching in 1879, when the Fish Commission entered
upon systematic work in shad propagation.
From their birth until their return to the rivers shad are preyed
upon Incessantly by other fish, so that the larger portion of the young
do not survive their few months' sojourn in fresh water, and of those
which leave the rivers each season probably not one in one hundred
reaches maturity to deposit its eggs and contribute to the perpetuation
of its species. In the rivers striped bass, white perch, black bass, and
other predaceous fishes devour the young, and when they reach salt
water, sharks, horse-mackerel, kingfish, etc., undoubtedly destroy many
124 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
adults. It has been observed by North Carolina pori^oise fishermen
that as the shad swim close along the shore the porpoises follow aud
feed on them till they pass into fresh water. In the rivers the adult
shad is comparatively free from enemies.
To what extent the pollution of the waters has reduced the numbers
of shad is not known, but acids, sawdust, garbaiie, oils, gas tar, and
refuse from dye-works all tend to make the water of rivers unsuitable
for them.
FOOD.
After entering the rivers, the shad takes but little, if any, food
previous to spawning, but after casting its eggs it bites at flies or a'uy
small shining object, and has been known to take the artificial fly.
The mouth of the adult is practically toothless, and its throat contains
no functionally active teeth. The water which j)asses through the
branchial filter — the gillrakers — is deprived of the small animals which
are too large to pass through its meshes. It is a common remark with
fishermen and others that food is rarely found in the stomach of the
adult shad in fresh water, but examinations have shown that the shad
does, in some instances, eat small Crustacea, insects, etc. The only
substance commonly found in its stomach in fresh water has the
appearance of black mud. It is held by some that the shad swims
with its mouth ojien and may unintentionally swallow the small organ-
isms found in its stomach under such circumstances, but as far as
observation of fish in aquaria and experiences of net fishermen go, the
shad does not swim with its mouth open.
NATURAL SPAVP^NING.
Shad are liable to be ripe anywhere above brackish water, and under
favorable temperature conditions spawn wherever they happen to be,
but in some river basins they exhibit a well-defined choice of spawning-
places, i^referring localities below the mouths of creeks, Avhere the
warmer water of creeks mingles with the colder channel water. The
shad lays its eggs during the highest daily average temperature, a con-
dition realized about sunset, when the warmer shoal water commingles
with the colder channel water, establishing a balance. The principal
spawning occurs from 5 p. m. to 10 p. m. Observations on the Potomac
liiver show that of the eggs from- shad caught in a seine only 11 per
cent were taken between midnight and noon, the percentage in the
morning being 14 one year and 8 another.
The eggs in the ovaries remain in a compact mass until they ripen,
at first occupying but a small space, but gradually increasing until
they distend the whole abdomen, the average weight of the ovaries being
about 13 ounces. Close examination at the approach of the spawning
time will disclose large maturing eggs of rather uniform size and others
smaller and of variable size. Whether the latter are the forming eggs
for the next year, for two or three succeding years, or for the lifetime of
the fish has not been determined, nor is it known whether shad spawn
every year. The small and shrunken ovaries of a spent fish are still
Fish Manual. (To face page 124.)
Plate 41 .
A. Frt^slily extruded egg enlarged, showing its envelope much wriul^led and its surface covered with
small round vesit'les.
H. SliMd i-^'^^, showing vitellus and distended e},'K-nieinl)nine, natural size.
C. Shows the ;,'ra<lual accumulation of Kerniiiial matter at one ixile of ckk- "'c polar i)roininence ex-
ternally, and presence of plasmic i>rocesses extendiiiK down through the vitellus.
/>. Kndirvo shad in its natural position in its si)acioiis envelopini; membrane From a i)hotot;rai)h.
E. Diasrriunniatic representation of an endiryo to show eoi use of sejcmental ducts. sv/ and extension
outward of pectoral jilates pp. winch are intimately concerned in tlie (levelo|)ment of iiectoral tins.
F. Side view of a youiiK shad V-\ days old, viewed as a transi)arent object. a\i. rudiincntaiv air-
lilndder: /-. liver; CU. (jall-bladder.
Q. .\\\ endiryo in its envelope, on the third day of development, nearly ready to hatch.
Fish Manual. (To face page 124.)
Plate 42.
// aud /. Two views of an egg after the blastoderm has spread considerably and the embryonic area e is
j,"C-'il,'^-'!;;";;I,„Uched en.h,-yo. which developed in a te„>peratu>e of 4.-^" F.. producing distortions of tail
i^Xn'SSv^ope with its ..ontai-.e,! en.hryo, forty-four hotu's after in.pregnation, viewed as a trans-
itu.'e-^t^^^'elope with its contained embryo at the beginning of the third .lay of development. From
posterior ingiilars./' and j. h,i bulbus aorta?, re ventricle.
o: View of fore part of a young fish 17 days old, from ventral side.
Fish Manual. ^To face page 124.1
Plate 43.
r Youns fish imtiiprliatelv afr.-r hatcliiiiij. vi.-wp,l as an ..paqiR- .>b.;.-ct aiui somewhat oblK^ufly from one side.
t.. <lis„lav til.- n-latioiis n<i hraiichial aii.l h.v..maii(hlMilar arciies, and i.ositioii <.t pectora hii.
Q. Yom.K fish th.nl , lay alter hatrh.n.,'. vi.-w.-.l as a transparent ....jeot to show e.xtensiou of segmental duct
forward; clionlat/i. , , . , >■.,>. i,. , „i;,,i.t .-u...
B. Yountc fish h days after hatchina:, very much enlar;ied, and viewed as an ..pa.|iie object. ( )nl> a su-lit tem-
S Ym\nl' fwrM"\l;tt'"after\\aichinjr. viewed partly as an opaq.te an.l partly as a transparent object: ,>,, p.vlorus
aiid i'.diment;vrvaii--bla,l.ler above it; / intestine, filled with the remains of i.isested tood. The opercula are
already so far developed as paitly to conceal the frills.
MANUAL OF FISH-CULTURE. 125
found full of these eggs of different sizes. Shortly before spawning,
transparent eggs of large size, contrasting strongly with the opaque
golden hue of less mature ones, will be found scattered through the still
compact ovarian mass, and, becoming more and more numerous, the
ovaries disintegrate, the eggs fall apart, and extrusion begins, a liquid
stream of eggs and mncus flowing from the oviduct on the slightest
pressure of the abdomen.
Freshly de])osited shad eggs are of a pale amber or innk color, and
are transparent. They are about -i\ inch in diameter and somewhat
flattened and irregularly rounded in form. The egg membrane is much
wrinkled and lies in close contact with the contained vitellus. Imme-
diately after fertilization the egg becomes sj^herical through the absorp-
tion of water and a])parently gains very much in bulk, measuring about
Y of an inch in diameter; but this gain is only the distended egg mem-
brane, the vitellus or true germinal and nutritive portion not having
increased. The vitellus is heavier than water, and a-large space filled
with fluid now exists between it and the membrane, the vitellus rolling
about and changing its position as the j^osition of the egg membrane is
altered. No adhesive material is found on the outside of the membrane,
though when first extruded the eggs are covered with a somewhat sticky
ovarian mucus.
In a state of nature the shad deposits its eggs loosely in the rivers
without building a nest, the two sexes running along together from
the channel towards the shore, and the eggs and milt being ejected
simultaneously. On quiet evenings, at the height of the season,
spawning shad may be heard surging and plunging along the shores.
By fishermen this is termed "washing."
Shad are very liroliflc, but much less so than many other food-fishes.
The quantities of eggs taken by spawn-takers do not represent the
actual fecundity, for many are cast in advance of stripping. The
average number is not more than 30,000. Single fish have been known
to yield 60,000, 80,000, 100,000, and 115,000 eggs; and on the Delaware
liiver, in 1885, one yielded 15(),000. Many eggs fail to be fertilized,
and but a comi)aratively small percentage of those imjiregnated are
hatched. After being extruded, the eggs sink to the bottom, where
they remain until hatched, subject to the attacks of fish and other
water animals. Eels are very destructive to shad spawn and often
attack shad caught in gill nets, devouring the undeposited eggs and
sometimes mutilating half the catch of a gill net fisherman.
The development of fungus is one of the greatest dangers to shad
eggs in a natural state, and another potent agency for their destruction
is the mud brought down by heavy rains, burying and suttbcating
the eggs.
After spawning, shad are denominated "down-runners," "racers,"
and "spent fish." They are then very lean and hardly fit for food, but
they begin to feed and have become fatter by the time they reach salt
water in the summer or fall.
126 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
YOUNa SHAD.
In tLe Middle States the young fish remain in the rivers, feeding
and growing, until the cool weather of fall comes on. They then
begin to drop downstream, and by the last of November have passed
out into the ocean or bays, and are lost sight of until they come back
three or four years after, full-grown and ready to si)awn. They leave
the Potomac Kiver when the water falls to about 40°. By that time
they are about 3 inches long. For the last two or three years they
have been observed in great abundance about Bryan Point, feeding and
jumping out of the water about sunset. They keep witliin the open
streak of water between the shores and the water- grass which covers
the flats, in water 2 to 5 feet deep. After mild winters young shad have
been found in the Potomac Eiver in April, 30 miles above brackish
water and 160 miles from the ocean, associated with young alewives and
sturgeon. Some immature shad, apparently 2 years old, are caught
each year in seines operated in the fresh water of the Potomac Kiver,
and undersized shad are frequently caught in the New England rivers,
where the tidal waters are of little length.
COMMERCIAL VALUE.
The shad is one of the most palatable and popular of fishes. Its
flesh is rich, but not oily, and the roe is considered a delicacy. It is
the most valuable river fish of the Atlantic coast, and, next to the
Pacific salmon, the most important species inhabiting the fresh waters
of North America. In every Atlantic State from New Jersey to Florida,
inclusive, it is the most valuable fish, and in New York it is second only
to the bluefish. Among all the economic fishes of the United States
only the salmon and cod exceed it in value, and, considering all branches
of the fishing industry, only the whale fishery and the oyster fishery,
besides the foregoing, are financially more important than the shad.
In 1806 the shad catch of the Atlantic seaboard numbered 13,145,395
fish, weighing 50,847,967 pounds, and worth to the fishermen $1,656,580.
The value of the shad catch of the Pacific States in 1895 was $5,600, a
sum representing 366,000 pounds.
EARLY ATTEMPTS AT SHAD-CULTURE.
The systematic development and extension of shad-culture were
undertaken with the definife purpose of testing the value of artificial
propagation in maintaining an important fishery which was being
rapidly depleted. As early as 1848 shad eggs were artificially taken
and fertilized, and in 1867 more extensive experiments were made on
the Connecticut Kiver, and later on the Potomac, with encouraging
results. The attention of many States was thus attracted to the work,
and in 1872 it was taken up by the general government. Prior to the
experiments on the Connecticut, certain species of the salmon family
had been principally dealt with in fish-cultnre, and diflerent methods
from those in use were necessary for shad-hatching, owing to the less
specific gravity of shad ova and the much shorter period of tiine
required for the development of the fish from the egg.
MANUAL OF FISH-CULTURE. 127
The "Setli (Ireeu box,-' a modificatiou of tlie floating box used for
liatc'hing- trout and sabnon eggs, was flrst tried with great success, but
floating-boxes were subject to various accidents when used in tidal
waters, and in rapid succession devices of various kinds were brought
forward to supplant them. The most important were hatching-cones
and the pkinger-l)uckets, which, though imperfect, rendered hirger
operations possible. At this period the apparatus wa.s arranged on
flat-bottomed barges and towed from point to i)oint along the coast from
Albemarle Sound to the Susquehanna Elver, a slow and expensive
method. The Chase whitetish jar worked with considerable efficiency,
but required modifications, and finally the "universal'' hatching jar now
in use was a(lo])ted in 1882.
During the years of experimental work from 1872 to 1880, 97,471,700
shad fry were planted, beginning with SaOjCOO in 1872, while in 1880,
28,626,000 were distributed. Prior to 1880 deposits of a few hundred
thousand each were made in as many different streams as possible, but
the increased production of young fish made it possible to ship and
plant the fry by the carload, and by 1884 shad-culture was established
on a large scale, barge operations were abandoned, and the work
conducted on shore. The basins of the Chesapeake Bay and Delaware
River had meanwhile been selected by the United States Commission
as the natural seat of operations, though the State commissions from
Massachusetts to South Carolina were actively engaged on their own
account. At present the States, except ( 'onuecticut, New York, Penn-
sylvania, and ^Faryland, have practically abandoned shad-hatching,
leaving the work to the general government.
EGG-GROUNDS.
Every river on the Atlantic coast from Massachusetts southward has
been examined by the agents of some State commission or the United
States, or by both, in order to determine the natural spawning-grounds
of the shad. On nearly every stream hatcheries have been operated
at one time or another, but usually eggs were not obtained in sufficient
numbers to justify continued operations, except in the Chesapeake and
Delaware basins. However, it is ncrt unlikely that after further investi-
gation it will be found practicable to maintain hatcheries on rivers
which have long since been abandoned. It is certain that work on the
Albemarle Sound can be successfully conducted, and though operations
on the Hudson Kiver have not been on a large scale, better results may
be there obtained in the future.
In certain river stretches, apparently favorable, no ripe fish are found;
for exami)le, in the Roanoke Iliver for 15 miles above its mouth, where
10,000 to 15,000 shad are taken annually, mature eggs can not be found,
though the fish spawn just below there, as they do many miles above at
Weldon. In the Sutton lieach seine, the one in I^orth Carolina waters
which has afforded the most spawn, only about one spawning shad to
each 100 is caught, and the annual catcHi of this seine is 30,000 to 75,000
per annum. In view of such facts, it is not remarkable that difficulty
128 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
Las been experienced and time consiiuied in deciding on permanent loca-
tions for liatclieries.
The spawning period varies widely in different seasons; in some years
sbad are numerous and in spawning condition two or three weeks after
the time when they have ordinarily disappeared. They deposit eggs at
some iioint along the coast for six continuous months.
The following streams have been occupied by hatcheries, as some of
them are now, and it will be observed that the approximate spawning
periods, beginning early in the South, become gradually later toward
the North.
Waters.
Place.
Period.
"Ei^iftto Tiiver ............
Jacltsonboro. S. G
Mar. 5-26.
Apr. 1-30.
Apr. l.j to June 10.
Apr. 17 to June 15.
May 10 to June 20.
May 15 to Juno 30.
Do.
June 15 to July 5.
June 1 to Julj' 15.
1
A lUemarlft Sountl .. .........
Avoca, N.C
T*ot oTTiao, TMver ................
Below Washington, D.U
Below Havre de Grace, Md ...
Gloucester, N. J
Below Albany, IST. T
BirminLfham, Conn
Holyoke, Mass
Simduohann;! River .............
Delaware Hiver
Connecticut liiver.
The United States Fish Commission operates stations at Bryan
Point, 12 miles below Washington on the Potomac, and at Battery
Island at the mouth of the Susquehanna, while the steamer Fish Hawk,
fitted up as a floating hatchery, is engaged during the shad season on
the Delaware River. These two stations and the vessel can receive
respectively 10,000,000, 40,000,000, and 12,000,000 eggs. On more than
one occasion each has been taxed to its utmost capacity, but as the
average hatching period is 8 days, and four of the special cars of the
Commission are hatcheries in themselves and capable of taking 2,000,000
to 4,000,000 eggs aboard at a time, the hatcheries can be quickly relieved
in case of emergency.
In 1807, 205,000,000 eggs were taken, from which 134,545,000 fry were
hatched. In 1898, the total of shad fry hatched was 156,150,000, and
in 1899 it was 210,493,000.
In 1900, a permanent hatchery located on an arm of Albemarle Sound,
near Edenton, North Carolina, was operated for the first time. This sta-
tion is adjacent to one of the most important shad fishing- grounds in the
country, and is intended to replenish the waters of Albemarle, Croataii,
Eoanoke, and Pamlico sounds, and their tributaries — the Pasquotank,
Chowan, Eoauoke, Pamlico, Neuse, and various minor rivers. This
region annually yields upward of 8,500,000 pounds of shad, valued at
about $350,000, and contributes the principal part of the shad found in
the northern and eastern markets in winter and early spring.
Votomac liiver. — The Potomac River, immediately adjacent to Fort
Wasliiiigton (12 miles below Washington, D. C), is probably more pro-
(dnctive of ripe shad than any other area of the same size. Tliis was
Fish Manual, i To face page 128.)
Plate 44.
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MANUAL OF FISH-CULTURE.
129
discovered as early as 1880, and a station was soon developed there
with steauj pumps, tanks, and hatching vessels. The seine operated at
this point between 1887 and 1891 furnished 23 per cent of all eggs from
the river.
The following table, taken from the records of the station, shows the
value of the spawning-grounds;
Years.
Number of
eg!4s taken.
■.r Number of
^ «"■•■'*• ejigs taken.
1880
20, 749, 000
1891 32 980. 0(10
1881
43 200 000 189? 13 44 fi 000 1
1882
21, 800, 000
24, 274, 000
19, 000, 000
22, 576, 000
36 302 000
1893 9,423,000
1894 32,393,000
1895 66,065,000
1883
1884
1885
1886
1887
1888
1889
1890
1896 64, 788, 000
1897 39,707 000
59, 435, 00(1
81, 177, 000
58, 233, 000
35, 202, 000
1698 68, 724, 000
1899 49,283,000
1900 ^ 67,904,000
1
i
In 1889 immense collections of eggs were made on certain days —
8,308,000 on May C and 0,311,000 on May 7, and during seven days
there was an average of over 5,000,000 per day. This was before and
just after a freshet.
To increase the supply of eggs, seine fishing has been attempted by
the Commission on both the Susquehanna and Potomac, but the efforts
were only partially successful and were finally abandoned. The exten-
sion of egg-taking by seines can not be relied upon, especially as this
method of fishing has been declining for many years, owing to its
greater expense, and a corres])onding growth has taken place in the
gill-net fishery. It is often difficult to obtain the ripe eggs when the
shad are taken in a seine on account of the great numbers of alewives
taken at the same time.
The following comparative table shows the shad-egg production from
a Potomac Eiver seine, together with the i)roportion of males, females,
and spawning fish, and the number of eggs per fish:
Year.
Total
number of
eggs
obtained.
Total
ripe
fish.
i
1
Total Per cent
shad of
caught. , males.
Per cent
of
females.
Average
number
of eega
per fish
spawned.
Per cent
ripe.
' 1887
20, 956, 000
22, 657, 000
17,738.000
10, 262, 000
5, 270, 000
652
688
612
468
228
1
10,348 : 71.4
11,212 69.2
6,217 ; 52.3
4, 606 54. 3
3, 138 57. 1
28.6
30.8
47.7
45.7
42.9
32,100 6.3
32, 900 6. 1
28, 980 9. 8
21, 900 10. 1
23, 140 7- 2
1888
1889
1890
1891
F. M.
130 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
Had all other fisheries furnished an equal jiercentage of eggs, the
annual Potomac collections would have reached about 300,000,000.
But while the Fort Washington seine, with a catch of 10,000 shad, gave
20,000,000 eggs, and another, capturing 18,000, gave 17,000,000, a third
catching 60,000 shad, gave only 1,000,000.
Eggs taken by gill fishermen are usually superior to those from seines,
and tlie gillers attach enough value to the market for eggs to save
almost all within reach. At the commencement of the season many of
them secure spawning-pans, which they keep in their boats, taking and
fertilizing the eggs themselves, and when accidentally overlooked by
the regular spawn-takers they sometimes row several miles to bring-
in pans of eggs. In 1896 a giller who laid out his net with the special
object of securing spawning shad, caught 3,300 fish and sold over
6,000,000 eggs to the Commission. About 1,100 of his fish were roe
shad; of the total, about 6 per cent were ripe; of the 1,100 roe, about
20 per cent were ripe.
The average catch of shad by the gillers who supply eggs is 1,600 to
1,800 per season; but they do not all operate specially for the capture
of sx)awning fish, though this work is profitable and gillers are fast
turning attention to it. The Fort Washington gilling boats furnish on
an average about 1,000,000 eggs each a season, those at White House
400,000, Sandy Bar 350,000, Greenway 300,000, and Craney Island
150,000, the average being about 500,000 per boat.
Susquehanna Eiver. — The shoal water in the neighborhood of Battery
Station is an extensive and valuable spawning-ground. The station
is conveniently situated on an island and the possibilities in egg-
collecting appear to be almost unlimited. Hundreds of gill fishermen
are engaged and large seines are operated within easy distance. In
1886 the station was overrun with eggs; 170 universal hatching-jars
and 58 cones would not contain them, large numbers being held in
cylinders, buckets, and i^ans. In 1888 over 105,000,000 were taken,
and in 1880 7,600,000 were obtained in one night. Both egg-collecting
and hatching are carried on, and the establishment is complete in itself.
There is no transfer of the eggs except for occasional car shipments,
and the fry are carried to Havre de Grace in 10-gallon cans for railroad
transfer to the places of deposit.
Delaicarc Jxirer. — The steamer Fish Hatch has been employed in shad-
hatching on this river nearly every season since 1887, the egg- collecting
and other labor being performed by the crew. An interesting feature of
the work is the large yield of eggs per fish. Eggs from this river have
been saved regularly since 1887 from seines, but the available product
among the gill fishermen has never been fully ascertained.
The eggs collected by the Full HaicJc numbered 51,983,000 in 1899.
The methods pursued at the different shad hatcheries are very similar.
The following description applies particularly to the work on the Poto-
mac River at Bryan Point.
Fish Manual. ( To face page 1 30
Plate 45.
MANUAL OF FISH-CULTURE. 131
EGG-COLLECTING.
Collectiug eogs is the work of experienced watermen, who must be
prepared to endure all kinds of weather in open boats. The boats are
towed out to the fishing-grounds by steam-launches, where the sjiawn-
takers visit the nets of the market fishermen, obtaining from them the
spawning fish. After eggs have been obtained a ticket is dropped into
each panful, with the date and the name of the fisherman, for entry on
the books of the station. The price for eggs is always above the
market price of the shad, and payment is made at the end of tlie season
on the basis of 28,000 to the liquid (juart, the price being $10 to $20 per
1,000,000. On the Potomac 40 to 50 spawn-takers are employed at the
station, besides 12 or 15 men who are engaged as hatching attendants,
machinists, firemen, and cookf5.
The spawn-taker uses a 16-foot flat-bottomed bateau and is provided
with a lantern, six small and four large spawn pans, and a dipper
of suitable si/e. The pans are made of tin and are of two sizes,
11-iuch and 18-inch diameters, the latter with handles. The smaller are
for receiving eggs on delivery from the fish, and the larger for carrying
them. The i)ans are thoroughly washed each night after use and not
allowed to become rusty or indented. The dippers are round-bottomed,
hold nearly a quart, and have handles with open ends, with 5 inches of
the free end wrapped with seine twine. To obtain eggs from a seine,
double the above number of spawn vessels may be required.
Spawn-taking tubs of indurated wood fiber have been introduced in
Potomac Eiver operations and found superior to tin, being without
hoops or joints, non-corrosive, and non-conductors of heat. They have
wood covers which fit inside the rims, and the tops fit tightly by means
of a soft rubber joint: 4 inches of the central part of the cover is cut
away to admit air.
As the shad manipulated are sold and consumed in a fresh state,
fishermen waste no time in transferring them to market boats, which
are in waiting, and rapidity of execution is therefore required on the
part of the spawn-taker, who must be alert and exact in his methods.
In gill-net fishing there is usually ample time to assort the fish,
which are taken into the boat one at a time, excei)t when sudden
squalls or exceptional captures force the premature hauling in of the
net with the fish wound up in the meshes. Unskilled spawn-takers
are liable to the mistake of stripi)ing eggs without having the neces-
sary milt to impregnate them, for several spawners may be taken over
a period of ten or twenty minutes without the capture of a male fish.
In such cases (of great frequency late in the season) the female fish
must be placed conveniently, backs down, to prevent the eggs from
running out, and the males may have to be obtained from other boats.
When ripe shad are taken in seines, two or three large baskets should
be in readiness to receive them.
Sometimes the number of ripe fish will be sufficient to occupy all the
attention that can be devoted to them; at other times the run of fish
132 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
is greatly reduced by local conditions. Even when other conditions
are satisfactory, if neither hi<;h nor low water occurs about sunset but
few ripe fish are caught. The large seines laud toward the last of the
ebb tide, and gill net fishermen can do nothing except on the change of
the tide — on slack water. The fish spawn at a certain time of day,
and when taken at other hours are not in spawning condition. Thun-
derstorms sometimes occur for days in succession about sunset, the
very hour when most disastrous.
A scarcity of male fish toward the end of the season often cuts short
operations when eggs are plentiful. Unsuccessful attempts have
been made to capture the males at such times by using gill nets with
meshes smaller than those in the nets of market fishermen. Attempts
have been made to pen the adults, but without success, as the fish
become diseased and their eggs spoil within them. In gill nets the
adult is entangled in the mesh and can not escape by struggling, and
it therefore remains comparatively quiet.
The quality of shad eggs is generally impaired where the fish are
held for an hour or more in trap nets or seines. The eggs from fish
taken in large seines are usually of bad quality, but those from short
seines, which are landed quickly after the fish have been surrounded,
are usually good; and those from trap nets, in which the fish have been
held for some hours, are valueless. Eggs are rarely susceptible to fer-
tilization longer than 20 minutes after the fish are taken from the water,
though there are exceptions to this rule. On May 23, 1895, Potomac
shad were stripi^ed which had been out of the water about 1^ hours;
they were kept separate, and at the end of 48 hours produced 100,000
eggs, which yielded 98,000 fry.
The shad dies very quickly after capture and is immediately respon-
sive to electrical storms, the catch of seines and nets of all kinds falling
off promptly when a thunderstorm develoj^s. Even in seines already
laid out in the water, with lead line on the bottom, there is an appre-
ciable decrease in such event. On the Delaware Eiver, May 29, 1887,
nearly 50 per cent of the shad eggs on board the steamer Fish HawJc
I)erished during an electrical storm which continued from 0 p. m. to
midnight. There were 4,481,000 eggs with embryos well formed, and
without perceptible change in water temperature 1,918,000 were killed,
many turning white by 8 p. m.
Heavy freshets cause an abrupt suspension of fishing, but the effect
of a single freshet is usually temporary. The shad which have gone
above are backed down before the muddy water, but reappear ujion its
outward passage. An occurrence of this kind will effect a great
increase in egg receipts if the water temperature before muddy water
comes is suitable. The shad that were scattered above being thrown
back in a body, reascend in a body.
A season of clear water is undesirable both for fishermen and hatching
work, as the fish see the nets and avoid them, gill nets being put out
only on the night tide and half the fishing being thus lost. The water
MANUAL OF FISH-CCLTURE. 133
should be discolored enoiifjh to prevent the fish froiii soeinj;- the nets,
but not thick, say from 10 to L'O.* An occasional lieshet reduces the
temperature and prolongs the season; however, with an equal number
of fish in the rivers, clear water is probably more advantageous for
natural increase, as a large i)roi)ortion of naturally deposited eggs must
perish from sufibcation under the mud in seasons of freshet.
THE WEATHER AND SPAWN.
The development of eggs within the ovaries is hastened by heat and
retarded by cold. In a warm season fish ready to spawn are more
numerous early in the season than in a cold one, and the period for
obtaining them is apt to close earlier. The eggs, not only after they
are deposited and impregnated, but before they leave the body of the fish,
are affected by the temperature of the water, often being "blighted"
or "rotten ripe." This phenomenon was observed as far back as 1873.
It occurs on the water reaching 80° to 81°, or with a rapid rise. On
the other hand, a sudden fall in temperature has been observed to
arrest natural spawning, produce blighted eggs, and to destroy those
in the hatching-vessels. Continued low temperature is also disastrous
to fishing.
An abnormally inferior quality of the Potomac Eiver eggs was noticed
during the full period of operations in 1890. The bulk of the run of shad
made their appearance on a rapidly ascending temi)erature, and the
eggs were injured within the parent fish, more than half perishing
before conversion into fry. The rise in temperature was greater than
had been recorded in the eleven years preceding. The run of shad
increased proportionately, the catch at one seine increasing from 100
to 800 in 21 hours. A snowstorm on April 7 — morning air temperature
35° F. and mean air temperature 46° — was followed by heavy frost on
April 9, the morning air temperature on the last-named date being 34°.
The river water on April 10 was 4G°, rising to 48° on A])ril 12 and to
71° in the afternoon of April 21, thus gaining 25° in 10 days. After
April 21 the catch of shad fell off to such an extent that fishing was
no longer profitable.
The water of the Potomac early in March is usually of a temperature
of 36° to 40°, rising to 52° to 58° about the middle of April, when the
spawning period begins, and at the end of May, the close of the period,
it averages from <J5° to 70°.
STRIPPING AND FERTILIZING THE EGGS.
In stripping the eggs the shad is lifted with the right hand and
caught above the tail with the left. All slime and loose scales are
removed by going over the fish two or three times in (juick succession
with the right hand. The head is carried to the left side under the
*The coiHlitioM that permits the discernment of objects at a distance of 10 to 20
inches bencatu the water surface, the method of registration employed by the Wash-
ington (D. (J.) atiueduct olUce.
134 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
ami and there retained by the arm, the tail being bent slightly upward
with tlie left hand. When the fish is i^roperly adjusted its head is
nearly concealed. The fish is held firmly over a moist pan, and with
a moderate downward pressure of the right hand the eggs will flow
freely if mature. The strokes are continued until there are signs of
blood, which usually accompany the last eggs. The fingers should not
touch the gills of the fisli, as laceration of these organs causes a flow of
blood injurious to the eggs. Two fish may be strij)ped into each pan.
As soon as the spawn is all obtained, the shad is discarded, it being
impossible to preserve the life of such a delicate fish, even with the
utmost care. But though it has slight tenacity of life when taken from
the water, the shad is a very muscular fish, and if not firmly held it will
flounder and splash in the pan of eggs and i^robably throw a large
proportion out and damage some of those that remain.
The first half teaspoonful of eggs should be i)ressed out into the
palm of the left hand and inspected. Skilled operatives can usually
discern ripeness by general outward appearance. A slow and yet
almost positive test consists in running some of the eggs into water,
when, if dead, they will have the appearance of boiled rice. But bad
eggs are sometimes beyond the detection of the most skilled fish-
culturists. If the eggs are white, opaque, or of milky appearance, the
fish is put aside. Immature eggs are white, small, and adfiering in
clots; or they may be transparent and yet unyielding to pressure.
The former are valueless, while tlie latter can sometimes be utilized by
putting the fish aside to soften. Both rii^e and green eggs sometimes
occur in the same fish, but only expert operatives can hope to take the
one and leave the other. If eggs are mature, but little pressure is
necessary to start them, and if not, they are only injured by squeezing,
and will either not flow at all, or will come away with difficulty in clotted
masses and generally with a little blood. After the spawn is taken
away, the fish has a soft and flaccid appearance about the abdomen,
which after natural spawning becomes contracted and drawn up, taper-
ing slenderly toward the tail.
Eggs of the best grade may be impaired by intermixture of overripe
or green ones, lumps of milt, tissues of the si)erm sac, or fish scales. The
overripe and unfertilized ones can be discarded, and a tiny net, an inch
square, or a straw or twig, maybe used in removing foreign substances.
The spawn-taker should clean the eggs before delivering them at the
hatchery, and no subsequent care can compensate for his neglect.
Experienced men rarely bring in bad eggs, unless as a result of vari-
able and unfavorable weather conditions.
To obtain the milt the spawn-taker catches the fish by the back,
taking hold of the under side with the right hand. Without relaxing
pressure at any point the milt is forced out with the thumb and fore-
finger. Good milt is so thin that it flows in a steady stream, and from
some fish it can be ejected widely over the surface of the eggs, but in
MANUAL OF FISH-CULTURE. 135
fish wliicli have been dead some minutes the milt is kimpy and flows
only in drops. A teaspoonful will fertili/e 40,000 to 75,000. After the
milt has been applied, from half a pint to a pint of water from the river
is added and the pan given a slow rotary motion, continued till the milt
is thoroughly mixed, when a milky appearance is imparted to the water.
When the river water is turbid, clear water must be obtained before work
is commenced.
In gill-net boats eggs thus treated will expand without further imme-
diate attention, for there is sufficient motion from the boat to prevent
clotting; shad eggs do not <' cement" when the milt is applied to them,
as in the case with salmon and trout eggs ; but they adhere, and if left
perfectly quiet, as on shore, a large proportion will be lifeless. Those
comprising the lower strata may either lack sufficient expansive power
to absorb water under w^eight of the others, or in the suction of each
separate egg, in the natural tendency to absorb water, they may have
a cupping effect ujjon one another, thus preventing water contact.
Whatever the cause, they stick together in one mass, and only those
of the upper layers receive sufficient water; the others remain under-
sized and die. Large quantities of eggs must be separated, either by
agitating the water already in the pan or by the addition of more.
In one minute after thorough mixing the milt can be washed off with
safety, but usually several pans are to be looked after, when the milt
may be allowed to remain 5, 10, or even 15 minutes. After the last
pan of eggs has been fertilized, they are rinsed, beginning with those
first taken, by pouring in a quart of water, placing the edge of the
dipper so that the stream is directed between the eggs and the sides
of the pan, as the eggs may be injured if the water is poured directly
upon them. Then the pan is oscillated, the water being drained over
the edge slowly, and, the operation being repeated, the third quart of
water is left upon the eggs. The eggs must be well stirred with the
inflowing water.
There need be no fear of applying too much milt. The amount
obtained from one fish may be ample for the eggs from two, but it is
always better to employ two males. Eggs may look promising for two
or three hours, yet never expand to full size or produce fish. They lie
at the bottom, and underneath any good ones which may be in the
pan; they stick to the fingers, while the good ones will not, nor can
they be successfully removed from hatching-jars until after several
days' decomposition. By using two pans, good eggs may be separated
from bad by pouring, but the process is slow and there is usually no
time in the hatcheries for such operations.
Good eggs are very transparent and so soft and liglit that they are
not apparent to the touch when the fingers are moved among them.
When tlie temperature is about 70°, no change is observed for about
12 or 13 minutes after the milt is added, but about this time a careful
movement of the fingers in the pan discloses their presence, and in a
136 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
little more than 20 minutes from the time the milt is applied they feel
like shot against the fingers, and to an experienced eye are observed
to increase slightly in size; when a day old, they will not break if
dropped to the floor. In transferring to other vessels, the rim of the
smaller pan should be gently immersed beneath the water surface in the
larger one, and the pouring take place gradually. To prevent splashing,
in boats, a small pan should be put on the water surface of the larger
pan. Sudden jars must be avoided, all foreign substances excluded, and
the pans be free from grease and salt. After the application of milt
they expand to full size in 20 to GO minutes, depending partly on tem-
perature, and at this stage they may be doubled up in the larger pans, the
question of safety in moving them being determined by their hardness.
Paus used in cleauiu.n eggs.
When eggs are received at the station, in order to thoroughly remove
all impurities they are passed through netting, and for this i)urpose,
two 18-inch flared tin pans with handles, one pan fitting within the
other, are employed; 2 inches of tue bottom part of the inner pan are
evenly cut off and replaced with quarter-inch (bar) twine netting. The
lower pan is filled with water to a point just above the netting, and
then several quarts of eggs are gently j)oured in, when they drop through
the meshes, leaving the fish scales, etc., behind. Thus they are also
given a change of water, which should be clean and fresh and of about
the same temperature as that in the hatchery and river.
If the eggs have absorbed sufliicient water in the spawn-pan, they
swell and adhere to each other, forming a compact mass, and. are ready
to be transferred to the hatching-jars, but if they are not sufficiently
expanded or "water-hardened," they must remain in the pans, from 30
to GO minutes being required for their full expansion.
MANUAL OF FISH-CULTURE.
137
IIATCIIKIIIES AND EQUIPMENT.
The building for a sliad-luitcliery may be of" a teinporaiy eharacter, as
it is used only about two months each year, but ami)Ie light, space,
ventilation, and arrangements for moderate heating are necessary. The
steam boiler and i^umps should be in a separate structure.
In exceptional cases, as at Central Station, in Washington, river
water from city pipes can be utilized. If the water supply is taken
directly from the river the suction should be put below low-water mark,
and the end provided with a strainer and kept off the bottom to avoid
sediment. The water should be supplied from an open tank, not by a
force-pump, but if it is taken from municipal pipes a regulator may be
employed. A fall of IG feet it" desirable, or 8 pounds pressure per square
inch at the top of the hatching-jars. The amount required is 2 quarts
per minute to each jar.
Plan.
A
■:t\
— 1
1
r-i-
! ;
i i
1 ;
1
:; i
-,.. .
HJIKff rAiL
^
d
(§)
ii
Mi
i
i
f-— 1
Scale
=1=
Upper figure showing view from
above.
Lower left-hand figure : End view
.showing hatching-Jar in position.
Lower right-hanil figure: Cross-
section showing tiled rain-i)ipe and
trouglian center of table.
Section A-B
Shad-hatching tabic.
The jars are arranged on tables, as shown in the cut. From a large
iron pipe, branch piping of 1^ to 2 inches diameter is run over each
table, where ^-inch brass pet-cocks are inserted G inches apart. The
jars are connected with the supply-pipes by half inch rubber tubing.
Tight drains are required to carry away the waste water. Collector-
tanks for fry are rectangular and may be of glass or wood, the former
possibly preferred.
138 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
The overflow from the collectors is guarded by a wire-gauze or cheese-
cloth strainer. A safe and interchangeable device consists of a stout
wire frame, over which a cheese-cloth bag is drawn and tied. A
f-inch rubber hose is attached to the opening in the frame. The
strainer is put inside among the fry, and the outflow in an overflow cup.
The overflow cuj) is set at the proper height to control the water level
in the collector-tank. Long-handled nets of nr-inch mesh are required
to remove egg lumi^s or other matter from the jars.
THE AUTOMATIC HATCHING-JAR.
The United States Fish Commission, in the development of its
work, had presented to it the necessity of dealing with the eggs of the
whitefish and the shad ujion a
scale unprecedented in the his-
tory of fish-culture. Millions
were to be handled instead of
thousands, and the removal of
dead eggs by hand picking was
no longer to be considered.
After successive experiments
the McDonald automatic hatch-
ing-jar was devised, and it is
now generally employed.
The most meritorious feature
of this apparatus is that it
prevents the development of
the saprolegnious fungus, which
caused so great a mortality in
some other forms of hatching
contrivances in which all the ova
were not in continual movement.
The very gradual, gentle, and
continual rolling movement of
the ova upon each other in the
jar apparently i)re vents the
spores of the fungus from ad-
Automatic shad-hatching jar.
hering. The cleanliness of the apparatus is also advantageous, and as
the material of which it is made is glass, the progress of development
can be watched satisfactorily from the outside of the jar with a hand
glass or pocket lens of moderate power.
The jar is a cylindrical glass vessel, of about 7 quarts' capacity,
with hemispherical bottom, supported upon three glass legs. The top
is made with threads to receive a screw cap. It is closed by a metallic
disk perforated with two holes five eighths inch in diameter — one in
the center admits the glass tube that introduces the water into the
jar, the other, equally distant from the central hole and the edge of
MANUAL OP FISH-CULTURE.
139
the metiil plate, admits the ghiss tube whicli carries off the Avaste
water. The central tube is connected by half-inch rubber tubing with
the pet-cock, which regulates the supply of water. A groove in the
inner surface of the metallic plate carries a rubber collar, and when
the plate is in place the tightening of the metallic screw-cap seals the
opening hermetically. Both the inlet and outlet tubes pass through
stutiing-boxes provided with gum-washers and binding-screws. The
central or feed tube is provided with stutUng-boxes, one on the top of
the disk and one on tlie bottom, the better to hold it to a true center.
The outlet tube is provided with only one stufiing-box, and the binding-
ring is beveled.
In preparing the jar for work the side tube is fitted first. Tlie glass
tube should be wet, the gum-washer slipped on the tube about an inch
from the end and introduced into the opening. Holding the tube per-
pendicularly to the face of the plate, press fairly on the tube, and the
washer, rolling on itself, will fall into the seat provided for it. Screw
on the binding-
ring, and test by
seeing that the
tube slides freely
back and forth in
the stuffing-box;
if not, it should
be refitted with a
heavier or lighter
washer, as maybe
required. Glass
tubes can not be
l^rocured of abso-
lute uniformity in Egg Funnel,
size. Water is the only lubricant that should be used about the jar
fittings.
The jar, after being washed clean, is filled with fresh water. A
shallow tin funnel with a perforated rim is inserted, so that the water
will stand as high in the funnel-throat as possible, and the eggs are
poured in by dipperfuls, or when taken from transportation trays are
washed in by a jet of water. Care is used to have the eggs foil but a
short distance, and no fish scales or other foreign matter should enter
tlie jar with them, as the presence of anything but water and eggs ren-
ders a proper motion of the mass impossible, and usually results in the
loss of a large proportion of the eggs. Tlie requisite number of eggs,
80,000 to 100,000, being in the jar, it is put in position and closed,
care being taken that both the inlet and outlet tubes slide freely in
their stutting-boxes. If the tubes become gummed, let water trickie
down around the binding-screws. To close the jar, turn on the water,
place the feed tube in the jar, turning off the water immediately after
the feed-tube has passed beneath the surface of the water in the jar,
140 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
thus expelling all the air from the feed -tube; otherwise it would rise
iu bubbles, throwing a portion of the eggs out through the outlet-tube.
With a i)roper (juantity of semi-buoyant eggs in the jar and the
water turned on and regulated, the movement of the current estab-
lishes a regular boiling motion in the mass of eggs, which brings each
ai succession to the surface. This motion may be regulated without
altering the quantity of water. By loosening the upper bimling-screw
of the central stuffing-box, and ])ushing the feed-tube down until it
almost comes in contact with the bottom of the jar, the motion of the
eggs is increased. If the jar is working properly, the dead eggs when
brought to the surface remain on top, forming a distinct layer, and by
pushing down the outlet tube a suitable distance they are lifted up
by the escaping current and taken out.
When the water is turned on for the first time the jar should be
watched closely until a regular motion has been established. When
eggs have stood 15 or 20 minutes in the jar before the water is turned
on they do not readily yield to the boiling motion, but tend to rise in a
solid mass to the top of the jar. By quickly starting and stopping the
current the mass is readily disintegrated. The degree or intensity of
motion of the eggs varies not only with their age and condition, but also
with the condition of the water. If the water is muddy, the motion
should be rapid enough to prevent mud settling either on the eggs or in
the bottom of the jar. Ordinarily the best motion is that which readily
brings the dead eggs to the surface. After the hatching has progressed
far enough to dispose of a portion of the eggs there is less resistance to
the current, and it should be reduced by shutting off part of the supply
or by slightly lifting the central tube. If the motion is not reduced
from time to time as the hatching progresses, shells will be carried over
into the receiving-tank with the fish and, being very light, will be drawn
against the outlet screen, causing an overflow. The motion should be
so gentle at the time of the greatest hatching as barely to induce the fish
to swim out of the jar and leave their cast-off shells behind.
Very healthy eggs, exposed to bright direct sunshine, hatch so rapidly
that the combined effort of the swarming mass of young fish will
establish sufficient current to draw some shells over into the receiving-
tank. This may be modified by phicing a screen between the jar and
the light. The shells under normal conditions remain and form a
cloud-like layer above the mass of working eggs. As they accumulate
they should be removed by shoving down the outlet-tube until they are
drawn up with the escaping water. A good plan is to draw several
jars in succession into a large pan, whence any fish coming over with
the shells may be ladled into the receiving- tank.
A remnant of eggs may be long in hatching, and they should be
poured into a large, clean, bright pan and ex])oscd to bright sunlight,
when they will hatch in five or ten minutes.
If the connection of the jar nmst be broken, it is essential that the
rubber feed-tube does not drop down and siphon the eggs from the jar.
Fish Manual. (To face page 140.)
Plate 46.
MANUAL OF FISH-CULTURE. 141
In recoiniecting:. the air may be expelled with the metal top screwed
down in jiosition. To ettect this, draw both glass tubes up to the to^) of
the Jar and turn on a full head of water, when the air will be forced out
in bubbles above the eggs, the bubbles escaping through the outlet
tube. The central tube is now restored to its former position. The
automatic action permits entire sei)aration of bad from good eggs,
thongh some days may be re([uired to accomplish the full result. The
(lead become lighter from gases arising from decomposition. A net,
small enough to easily enter the mouth of the Jar and fixed to a handle
several inches longer than the Jar, is convenient for removing particles
of foreign matter.
Shad eggs are semi-buoyant, and those which will not rise commence
lumping on the third or fourth day. The usual period of hatching is
from G to 10 days, sometimes longer, according to temi)erature of water,
but with high temperature they will hatch in 3 days. Fry hatched in
less than 5 days are usually, though not always, weak. In general, the
period of incubation varies inversely with the prevailing temperature,
but continuous dark and cloudy days will retard and strong light will
accelerate development under precisely the same conditions of water
temperature, and other circumstances not well understood may also
have their influence.
Fry when hatched are about 0.37 inch long. They have been meas-
ured at intervals of from 5 to 15 days, from late in May to the middle
of October. Toward the middle of August the rate in growth dimin-
ishes. When 9 days old they are about 0.012 inch long. Fry 0.5 inch
long July 20th were 0.75 inch long 8 days later; on August 14th, 2 to
2.25 inches; September 20th, 3 to 4 inches; October 1st, 4 to 4^ inches;
November 4th, 5 to 7 inches. Some years they grow faster than others,
and in some streams more rapidly than in others. From the State fish-
ponds at Ealeigh, North Carolina, 33 were removed in November, 1884,
which measured 8 to 9 inches. Their usual size in the Potomac in the
fall is 3 to 4 inches.
3IEASURIN& THE EGGS AND FRY.
To estimate the number of eggs and of the young fry was for years <
rather a ditiicult matter to accomplish satisfactorily. The standard
made use of at the outset was undoubtedly much too high. The scale
most used at present is a light square, made of wood, the longer leg
being 15 inches and the shorter 7i inches long. The material is ^ inch
wide and ^ inch thick. The graduations are on the longer leg, and
read from the lower end upward. The first line is at a height corre-
sponding to the level attained in the Jar by a measured half-pint of
water, and the succeeding lines are determined by the introduction of
additional half-pints of water. When the scale is being constructed,
the central glass tube is stoi)ped at the lower end that it may displace
an amoun-t of water equal to the amount of eggs it will displace in
142 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
practice. Each line on the measuring stick registers 7,000 sliad eggs.
Tbe number of eggs in a liquid pint is established by actual count.
Tliose which are very young or have been lately on trays are not of
normal size and not qualified for measurement. The eggs are at rest
when measured.
The jar contents are determined by placing the short leg of the
measuring-stick over the top, with the otlier pointing downward and
touching the side of the jar. The number is indicated on the scale at
the point oi)posite the surface of the bulk of the eggs. Scarcely any
semi-buoyant eggs die, under proper conditions, after hatching out has
commenced, and a close apiiroximation to the number of fry may be
obtained from the last measurement, which is
made after the careful removal of all dead eggs
and the bursting forth of the first young.
FEEDING AND REARING.
The young shad swims vigorously, by rapid
and continuous vibration of the tail, from the
moment it leaves the egg. It is colorless, trans-
parent, and gelatinous. Several hundred in a
dipper are scarcely discernible. It has a rela-
tively large yolk-sac, but supports it with ease
during the first four or five days after hatching,
the small quantity remaining after this time not
being visible externally, although found in shad
fry 14 to IG days old. Minute conical teeth make
their appearance on the lower jaws and in the
pharynx about the second or third day after
hatching. The jaws at three months are armed
with teeth slightly curved.
Young shad feed on other minute organisms,
such as exceedingly small crustaceans. Food
has never been observed in the alimentary canal
until ten or twelve days after the young fish had
left the egg. . At about the middle of the second
Application of a raeasur- week considerable may be seen, but the intestine
iiigscaletoa jurofsiiad jg then not often very densely packed. At the
®SS^- age of three weeks an abundance of food is
found. They have been known at this early age to eat their own kind,
and later the young carp and salmon. When cold, raw winds drive
the crustaceans into deeper water, the yomig shad follow them, and
in aquaria they take Crustacea freely. In salt-water aquaria they may
be fed upon chopped oysters and canned herring-roe.
Experiments with young shad have been carried on for several years
at Central Station in salt-water aquaria. On one occasion about 250
were received in October, at which time they were about five months
old. They were put in brackish water, specific gravity 1.005, which
MANUAL OF FISH-CULTURE. 143
was added to from day to day for nearly a week, when it was brought
u}) to 1.018, or the same specific gravity as tlio water used in the marine
aquaria. At the time these were placed in the brackish water others
were put into fresh-water aquaria, but the latter died within three
day^. Those in salt water began in two or three days to take food,
consisting of chopped oysters, clams, and beef, the preference being
for oysters. At first they would take food only when it was sinking,
later they began taking it ott" plants where it had lodged, and finally
from the bottom. Nearly all remained healthy, plump, and active for
six months, some living until about midsummer.
For ten years past two or three million shad fry have been reared
annually at the Fish Ponds, Washington, D. C. A 0-acre pond is used,
the water supply being taken from the city water-works. The depth
varies from 2 to 3 feet, and throughout the whole extent there is a dense
growth of water-plants, among which crustacean food multiplies — new
supplies being brought in from the water-pipes. Fingerling shad are
so tender that the numbers annually liberated can not be ascertained;
they can not withstand the handling consequent upon counting them,
not even undergoing transfer in dippers of water, and their scales drop
oil' on being touched; consequently at high tide they are liberated into
the Potomac through a sluice-gate with an outlet pipe about 2 feet in
diameter. They require some days to make their escape. By conserva-
tive estimate 50 to GO per cent are held safely until about October.
Bearing has been experimentally tested at Wytheville and Neosho
with good results. At Neosho on the 3d of June, 1892, 700,000 fry were
received from Gloucester, N. J.; their growth was satisfactory. In
l)reparing for their release the hatchery branch was cleared of shoals,
drifts, and aquatic plants for three-quarters of a mile, and early in
November, when the branch was swollen with rain water, 200,000
G-months-old fish were allowed to pass through open gates; they were
some hours in escaping, in a continuous silvery mass. These were the
first fingerling shad planted in waters tributary to the Gulf of Mexico.
TRANSPORTATION.
Good, healthy fry will i)ass from the jar to the collector -tank as fast
as hatched, and unless too thick will not lie on the bottom of the tank,
although they sometimes crowd on the side nearest the strongest rays
of light. As many as 500,000 to 800,000 are collected in each tank.
In transporting, they must be kei)t in vessels witli smooth surfaces,
preferably tin-lined cans. Zinc vessels are destructive, and galvanized
cans are not recommended.
About 2,000 to 3,000 fry are put to a gallon of water, which must be
pure enough for ordinary drinking purposes and well aerated. The
water in the cans must be kept at 58° to 05°, though in rivers and
ponds the fry endure a temperature of 00° F.
As early as 1874, experiments were carried on to retard the develop-
ment of eggs, in order to provide a longer i)eriod between the delivery
144 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
of the eggs from the parent fisli aud the absorption of the yolk sac.
Eggs, when transported, were placed on trays and put under melting
ice, aiul later experiments have been conducted inside refrigerator
boxes.
Pathological changes or deformities are induced in the embryos when
subjected to too low a temperature or when held long enough on damp
flannel trays (ordinary air temperatures) to hatch.
It would appear that 55° to 53° is the lowest temperature in which
ova Avill safely undergo their normal development aud 9 days is the
longest period of incubation attainable at that temperature — time suffi-
cient, when added to the several days required lor the young to absorb
the yolk-sac, to ship them to lilurope, though efforts in this direction
have thus far failed. One drawback is the rapid development of fun-
gus, which grows over the eggs, i^euetrates the membranes, and kills
the ova.
The eggs are shipped in crates of 20 shallow trays, the frames of the
latter being of wood with bottoms of wire mesh about 8 to the linear
inch. Wood and wire are painted with asphaltum. Each tray is
covered with cheese-cloth, somewhat overlapping the edges, the cloths
being hemmed, to avoid ravelings. There are two frames of wood,
connected with leather straps; one the base and the other the cover for
the stack of trays. The trays, after being filled with eggs, are wrapped
in a long, cotton-goods apron and strapped together. There is an iron
handle on the top frame, and the lowermost tray is put down empty
with the wire surface upward. Then follow the trays containing eggs,
the uppermost one being put on empty with the wire surface up. The
top and bottom trays are merely to protect the others.
The greater part of the water above the eggs is poured off from the
jars and the remainder poured into tin pans along with the eggs.
The cloths, after soaking in water, are arranged one by one on the
trays and tucked closely into the four corners. The trays are stacked
up and eggs poured evenly over the surface of the top one with a
large dipper, and each tray, when filled, is put on the crate base. The
surplus water drains away to the manipulating table. Tray cloths
which are made of material too closely woven to let the water through
are unsuitable.
The eggs are bailed up in dippers with the water that they are in, and
usually spread two layers deep, but may be put on more thickly. When
eighteen trays are filled they are wrapped in the outer cloth, previously
soaked in water, and tightly buckled together. The crate covers aud
tray cloths are boiled in water each time after use.
Each tray — 14 by 19 inches area, with two layers of eggs — holds
about 20,000 eggs, the contents of a full crate representing from ,>00,000
to 400,000 eggs. While in transit the crates are sprinkled with river
water on the sides at least once an hour, and kept in the shade, away
from the cooling influence of the wind, to preserve even temperature.
MANUAL OF FISII-CULTURE. 145
TRANSPLANTING.
The propagation of shad is mainly carried on to maintain or increase
the supply in rivers where the species is native, but this fish has also
been planted in waters in which it was either unknown or found in
small (quantities. Large numbers of fry have been liberated in tribu-
taries of the Gulf of Mexico, but without marked results. Between
1873 and 1892 several million fry were experimentally placed in Great
Salt Lake, Utah Lake, and Bear Lake, Utah; and from 1884 to 1886,
3,000,000 fry were liberated in the Colorado River at the ISTeedles, in
Arizona, but these experiments were unsuccessful.
Remarkable success has, however, attended the stocking ot the
waters of the Pacific coast. In 1871, 12,000 shad fry from the Hudson
River were liberated in the Sacramento River by the California Fish
Commission, and in 1873 the United States Commission made a second
deposit of 35,000. Subsequent plants in the Sacramento, aggregating
009,000, were made by the United States Commission from 1870 to
1880. From these sn)all colonies, amounting to less than 1 per cent of
the number now annually planted in the Atlantic Slope rivers, the shad
have multiplied and distributed themselves along nearly 3,000 miles
of the coast from southern California to southeastern Alaska. They
reached Rogue River, Oregon, in 1882. In the Columbia a few were
taken as early as 1870 or 1877. About 1881 or 1882 they were on the
coast of Washington, reaching Puget Sound in 1882. They appeared
in the Fraser River, British Columbia, in 1891 ; in the Stikine River,
near Wrangell Island, Alaska, the same year, and ai-e now found along
the entire coast from Los Angeles County, Cal., to Chilkat, Alaska,
covering 22 degrees of latitude. Their distribution, from the standpoint
of commercial importance, is from Monterey Bay to Puget Sound.
On the northern part of the coast the first shad fry were introduced in
1885, the number being 00,000. Of these, 50,000 were put in the Willa-
mette River and 10,000 in the Snake River. The following year 850,000
were introduced into the Columbia River.
The shad is now one of the most abundant fishes of California. As
a result of the liberation of the first two consignments, adult shad were
caught in 1871, and by 1870 this fish had become numerous. In 1880
specimens of all sizes were taken in the Sacramento River and Monterey
Bay, and it was evident that the shad had begun to multiply, its increase
up to 1883 being marvelous. It is most numerous on the west coast in
San Francisco Bay and its tributaries, where, contrary to its habits in
Atlantic waters, it is found throughout the year. It is not common
above Sacramento, owing to the low water temperature. In the Col-
umbia it is regularly found as far as the Cascades, about 150 miles above
the mouth of the river.
F. M. 10
Fish Manual. (To face page 147 j
Plate 47.
MICROPTERUS SALMOIDES. I.nr'ji -iimiithnl lUark llaxg
MICROPTERUS DOLOMIEU, Siniill-iiinii^liiil llhirk liai:/,.
THE BLACK BASSES, CRAPPIES, AND ROCK BASS.
DESCRIPTION OF THE FISHES, COMMON NAMES, ETC.
The species treated of in this chapter are those members of the
Centrarchidae (or fresh-water simfishes) which have come under the
scope of tish-cnlture, namely, the large-mouth black bass {Microptervs
salmoide.s), the small-mouth black bass [MuroptcruH dolomieti), the rock
bass {AmhlopUtes rupestris), the crappie {Pomoxh annularis), and the
calico bass {Pomoxis Hparoides). Whatever is said of the rock bass will
apply equally well to other sunfishes, which might be here considered
but which have not been artificially reared.
The principal phj^sical characters of these fishes are indicated in the
following key, which serves to distinguish the two species of black bass
and the two species of crapiue from each other as well as from less
closely related species.
Large-mouth black bass : Body comparatively long, the depth about
one-third the length; back little elevated; head large, 3 to 3i in body;
eye 5 to 0 in head; mouth very large, the maxillary in adults extending
beyond eye, smaller in young. Ten rows of scales on the cheeks; body
scales large, about 68 in the lateral line, and 7 above and 16 below the
line. Dorsal fin low, deeply notched, larger than anal, with 10 spines and
12 or 13 soft rays; anal with 3 spines and 10 or 11 rays. Color above
dark-green, sides greenish-silvery, belly white; young with a blackish
band along sides from opercle to tail, the band breaking up and growing
paler with age ; caudal fin pale at base, white on edge and black between ;
older specimens almost uniformly dull greenish; three dark oblic^ue
stripes across opercle and cheek; dark blotch on opercle.
Small-mouth blade bass : Similar inform to large mouth bass. Mouth
smaller, the maxillary terminating in front of posterior edge of eye,
except in very old specimens. About 17 rows of small scales on the
cheeks; body scales small, 11-74-17. Dorsal fin less deeply notched
than in other species, with 10 S])ines and 13 to 15 rays; anal with 3
spines and 12 or 13 rays. General color dull golden-green, belly white;
young with dark spots along sides tending to form irregular vertical
bars, but never a lateral band; caudal fin yellowish at base, white at
tip, with dark intervening area; dorsal with bron/e spots and dusky
edge; three radiating bronze stripes extending backward from eye;
dusky spot on point of opercle.
Crappie : Body short, greatly compressed, back much elevated ; depth
147
148 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
2.V in length; eye large, one-fourtli lengtli of head; head long, 3 in
length; profile with double curve; month large, snout projecting.
Scales on cheeks in 4 or 5 rows; scales in lateral line 36 to 48. Dorsal
fin smaller than anal, with G spines and 15 rays, the spinous part the
shorter; anal with 0 spines and 18 rays; dorsal and anal fins very
high. Color silvery white or olive, with mottlings of dark green; the
markings mostly on upper part of body and tending to form narrow,
irregular vertical bars; dorsal and caudal fins with dark markings;
anal nearly plain. The figure of this species on the opposite page is
scarcely typical in the pattern of markings.
Calico bass : Similar in form to crappie, but the body shorter, back
more elevated, and profile of head straighter; dei)th, one-half length;
head one-third length; mouth smaller than in crappie; snout less pro-
jecting. Six rows of scales on cheeks, and 40 to 45 along lateral line.
Dorsal and anal fins higher than in crappie ; dorsal spines 7 or 8, rays 15 ;
anal spines G, rays 17 or 18. Color light silvery-green, with dark-green
irregular mottlings over entire body; dorsal, caudal, and anal fins with
dark-olive reticulations surrounding pale areas; whole body sometimes
with a delicate pink reflection (whence the name strawberry bass).
Rode hass : Body oblong, compressed, back moderately elevated;
depth 2 to 2^ in length ; head large, 23 iu length ; eye very large, 3^
in head. Scales 5-39-12, in G to 8 rows on cheeks. Dorsal fin much
larger than anal, with 11 spines and 10 rays; anal, with 6 spines and
10 rays. Opercle ending in two flat points; gillrakers less than 10.
Color olive-green, with brassy reflections; young irregularly barred
and blotched with black ; adult with a dark spot at base of each scale,
forming interrupted and inconspicuous stripes ; a black spot on opercle;
anal, caudal, and soft dorsal fins with dark mottlings.
The most reliable character for distinguishing the large-mouth from
the small-mouth bass is the number of rows of scales on the cheeks.
The colors of each species vary with age and the size of the mouth
varies with the size of the fish, but the scales are constant under all
conditions. With the crappies, the leading differential feature is the
number of dorsal spines.
By reason of their wide geographical range, the black basses have
received a multiplicity of popular names. The large mouth black bass
is known as Oswego bass, lake bass, green bass, yellow bass, moss
bass, bayou bass, trout, jumper, chub, and Welshman. In the North it
is generally called black bass; in Virginia and North Carolina it is
usually designated as the chub, and in Florida and the Southern States
it is often called trout. The small-mouth black bass has received the
common names of lake bass, brown bass, ninny bass, hog bass, black
perch (used iu the mountain sections of Virginia, Tennessee, and North
Carolina) trout perch, brown trout, jumper, niouaitain trout, together
with other names of purely local use.
Eock bass are variously known as red-eye, red-eye perch, and goggle-
eye, and are sometimes confounded with the warmouth {Ghccnohryttm
gulosus), which bears some of the same common names.
MANUAL OF FISII-CULTURE.
149
The calico bass lias also received the names of strawberry bass, grass
bass, bitter-bead, barfisb, lampligliter, gof?gle-eye, goggle-eye perch,
speckled perch, and speckled ti out. The crappie is known in its native
waters as crappie, new light, campbellite, sac-a-lait, bachelor, chinqua-
pin perch, croppie, and cropet. On account of the similarity of the
PoMoxis ANNULARIS. Crappie.
'<Sii^-
PoMOXis SPAUOiDES, CuUco Bass, Strau'berry Baas.
cali('o bass and crappie, anglers and flsh-culturists frequently confound
the two, the common and local names often being used interchangeably
throughout the regions to which both are native.
Possibly no common name of the black bass is more appropriate than"
"jumi)er" which is apiilicd in certain ]»arts of Kentucky. It is dillicult
to capture them with a .seine rigged in the ordinary manner, especially
150
REPORT OF COMMISSIONER OF FISH AND FISHERIES.
when they have the vitality and activity which is usual when living in
Mater of moderate tenipeiature, and in collecting brood stock it is well
to use a seine about three times the depth of the water, as the bagging
of a seine so rigged (;onfuses the fish and deters them from jumiuug.
While the black bass of the colder northern waters make a fight worthy
of the salmon, they may be taken from the waters of the south with
hardly a struggle.
Rock bass are exceedingly pugnacious, and sometimes seem to take
the hook rather on this account than from a desire for food. They are
well adapted for ])ond-culture, and under proper conditions will repay
the culturist in a large crop of young with the exi)enditure of very little
labor and time.
A.MBLOPLITES KUPESTKIS, 7iOc7; BaSS.
• The calico bass is a fairly game fighter, and its firm, white flesh has
a tine flavor when the fish is taken from cool, pure waters; but it is a
very delicate fish to propagate artificially. It seems to resent captivity,
and especially when taken from warm waters is exceedingly tender,
quick to yield to attacks of fungus, and liable to become blind and die.
Of large numbers collected and transplanted in new waters many have
died within a few days after being deposited.
The spawning and breeding habits of the calico bass and the cra])pio
are so nearly like those of the rock bass that special remarks on the
subject do not appear necessary.
GROWTH AND WEIGHT.
There is a wide difference in the i^te of growth, and there is no way
by which the age of a black bass can be determined from its size.
Some are comparatively large from the moment they are hatched, and
grow much more rapidly than the smaller members of the same school.
The average size of adults varies in diflterent localities, and may vaiy
from year to year in any parti(;nlar locality. The variations depend
upon initial vitality, upon the scarcity or abundance of food, and upon
MANUAL OF FISH-CULTURE. 151
the range and space given the fish. At the age of 5 or G months the
young bass measure from 4 to 8 inches, according to locality and sur-
roundings, though a few individuals are apt to run larger. lu 1892, at
Neosho station, a black bass, which was positively known to be under
18 months old, weighed on the scales 1 pound 9.^ ounces.
The large-mouth bass have been known to weigh 2'.i pounds, and a
6-pound or S-pound bass in the southern tributaries of the Mississipi)i
and in the inland lakes of Florida excites no surprise. The small-mouth
bass does not grow so large, 2^ pounds probably exceeding their aver-
age size, though they occasionally reach 5 or 6 pounds. The rock-bass
fry grow slowly, those G mouths old seldom averaging 2 inches in length.
The adult usually weighs from 4 to f ])oun(l, occasionally reaching 1
pound ; and examples have been recorded as high as 3 pounds.
The crappie and the strawberry bass will, as a rule, not exceed 1
pound in weight, though in Missouri the former has been taken as high
as 3 pounds. With similar environments, at G months old the j'oung
of both these species are about the size of black-bass fry of the same
age, possibly a little smaller. Each school will have a few individuals
much larger than the majority.
NATURAL HABITAT AND DISTRIBUTION,
The large-mouth and small-mouth black basses are widely distrib-
uted. The large- mouth is indigenous from the Great Lakes and the lied
Elver of the North to Florida, Texas, and Mexico, and west to the Dako-
tas, Nebraska, and Kansas. The small-mouth bass ranged formerly
from Lake Champlaiu to Manitoba, and southward on both sides of the
Alleghenies to South Carolina and Arkansas. The adaptability of these
fish to extremes of temperature and their great tenacity of life under
seemingly adverse conditions have made their distribution compara-
tively easy, and they have been successfully introduced into nearly all
the sections of the United States to which they were not native, and
into England, France, (Germany, and Finland. They have been planted
in California, Washington, Utah, and other Western States by the U. S.
Fish Commission. In three years they became so numerous in Utah
that 30,000 pounds were caught and marketed from one lake.
Two notable early instances of the successful transplanting of black
bass in a primitive way may be mentioned, the fish being transferred in
the tender of a locomotive — once in 1853, when the Potomac was stocked,
and again in 1875, when, under the direction of the Commissioner of
Fisheries of Virginia, adult blacii bass were removed from the Roanoke
River across tlie divide to the New River, a tributary of the Kanawha.
Up to 1875 the Kanawha contained no bass, and its edible fishes con-
sisted almost entirely of catfish, but for the past ten or a dozen years
thousands of bass have been taken from New River and its numerous
tributaries, draining ten counties of Virginia and running through
parts of North Carolina and West Virginia. New River was also suc-
cessfully stocked with rock bass by the A'irginia Fish Commission, the
fish being brought from Holston Hiver, a tributary of the Tennessee in
152 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
Wasliington Oouuty, Virginia, in Juue, 187G, and deposited in the
smaller tributaries of New River, in Montgomery County, Virginia,
whence tbey have colonized the entire New River basin.
Few fish thrive in water of such extremes of temperature as the large-
mouth black bass, and, to some extent, the small-mouth. The former
are found in water covered with ice and in that standing at 100° F. ; but
with both species sudden changes of temperature are apt to prove fatal.
The small inouth black bass seeks pure, rapid, fairly clear streams,
and lives at higher elevations and in clearer waters than the large-
mouth. In the northern part of its range it becomes torpid in winter,
but in the warmer waters of the South it is active throughout the year.
The large-mouth black bass also likes pure, clear water, but often
inhabits the hot and stagnant bayous and ponds of the South. It has
been seen in great numbers under conditions of high temperature and
muddy water which would ordinarily be fatal to all forms of aquatic
life except of a very low order. Many die in such cases, but numbers
live for months ana some possibly for years. Those from hot, stagnant
waters, however, have a soft, flabby flesh, and are apt to be infested
with i^arasites; they spoil quickly and are not palatable. They do not
voluntarily seek such unfavorable surroundings, their presence there
being attributable to accident. The bass thus found in the Mississippi
Valley have been left by spring freshets, and, failing to go out with the
slowly receding waters, they reproduce in great numbers in the ponds
and lakes temporarily formed in depressions of the hind. The neigh-
boring areas are usually either rich alluvial meadows or swampy forests,
from which the receding water drains an infinite quantity of natural
food for the sustenance of the fish retained in the temporary ponds.
The rock bass is indigenous to the Great Lakes region and Missis-
sippi Valley, and there is evidence to show that it is native to certain
streams on the east side of the Alleghauies. It has been successfully
introduced into many new waters. In its native waters it is found in
the winter months under ice, yet it stands a high summer temperature,
though not so great as the black bass. The highest temperature to
which it has been subjected at Neosho is 88°. In transportation this
si)ecies seems to suffer from change of temperature as quickly as the
black bass, with possibly this difference, that while the black bass
seems to be more quickly and fatally affected by a change from high to
low temperature, the opposite change more quickly and injuriously
affects the rock bass. Though sometimes found in muddy bayous and
in waters stained by decaying vegetation, the rock bass thrives better
in clear, i)ure waters well stocked with aquatic plants.
The natural habitat of the calico bass is the Great Lakes region, the
entire Mississippi Valley south to Louisiana, and the streams of the
Carolinas and Georgia east of the Alleghanies, while its close kin, the
crappie, is confined to the Mississippi Valley, though sometimes taken
in the Great Lakes region. The calico bass is said to need a higher
temperature and clearer water than the crappie, but this is not certain.
Fisli Minudi, i To face page 152.)
Plate 48.
MANUAL OP" FISH-CULTURE. 153
NATURAL FOOD, ETC.
The natural food of the black basses varies greatly and is influenced
by the spawning season, character and temperature of the water, and
the weather. The adults are voracious and pugnacious, and devour
other lish almost indiscriminately; their food comprises crawfish,
minnows, frogs, tadpoles, worms, and mussels, while the young fee<l on
insects and otlier minute forms of life found in water.
At times both thelarge -mouth and the small-mouth bass refuse the
most tempting bait, and at other times they bito greedily at almost
everything. Various kinds of animals of a suitable size, even rats and
snakes, and many varieties of vegetables, have been found in their
stomachs, and in a wild state under some conditions they devour almost
anything moving in or immediately over the surface of the water.
The black basses afltbrd perhaps the highest type among fishes of
parental care and watchfulness, guarding their young until after the
dispersal of the school of fry; but many of the young, so zealously
protected early in the season, subsequently furnish food for adult bass,
possibly their own progenitors. As witii trout, bass of the same school
of young vary in size, and the larger i)rey mercilessly on the weaker, often
attacking their own kind, even when other natural food is abundant.
COMMERCIAL IMPORTANCE.
The market value to the fishermen of the black bass taken in the
United States amounts to about $130,000 annually, a sum represent-
ing over 2,000,000 pounds of fish. A large part of the bass caught,
however, never reaches the market, being consumed by anglers and their
friends. The indirect value of bass fishing to rural districts, in the
expenditures of visiting sportsmen for boats, guides, teams, supplies,
and accommodations, is very great.
Ten years ago it was said that black bass did not exist in auflBciently
large numbers to ever become a staple ar.ticle of food, but they now
furnish important additions to the food supply of many thousands of
people. The annual sales in N^ew York City are estimated to be at
least 50,000 pounds, with an average value of 10 cents per pound.
The States in which the black- bass fishery is most important are
North Carolina and Ohio; in 1897, over 535,000 pounds, valued at
$23,600, were caught for market in North Carolina; in Ohio, nearly
300,000 pounds, worth over $22,000, were taken. Other States, in
which there is an annual yield of over 100,000 pounds, are Arkansas,
Florida, Minnesota, Missouri, and New York, and in about twenty
other States this fish is of some commercial importance. The fishermen
of Illinois ship nearly 50 tons of black bass to the markets annually.
The annual catch ofcrappie for market, according to recent statis-
tics, is about 850,000 pounds, having a first value of $39,000. The
leading States in this fishery are Arkansas, Illinois, Minnesota, Mis-
souri, and Tennessee, the three first named producing more than half the
yearly yield. The market value of the rock bass is not large. Crappies
are generally considered better food-fish than the rock bass and enter
154 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
much ufore largely into coimnerce. As with black bass, a very large
percentage of the catch of crappies, rock bass, and sunfishes does not
reach the markets.
LIMITATIONS OF BASS-OULTURE.
Unlike the shad and salmon, the artificial proi)agation of black bass,
by taking and impregnating the eggs, has not been, up to the present
time, practically successful. The eggs can otily be strii)ped with great
difficulty, and it has been necessary to kill the male to obtain the milt.
Another obstacle is the difficulty of obtaining eggs and milt at the
same time, even when the fish are taken from over the nests apparently
in the act of spawning. Interruption or handling seems to prevent the
discharge of eggs or milt. At Neosho unsuccessful efforts were made
daily lor several weeks to spawn a female black bass which was so near
the point of spawning that when held head downward the eggs could be
seen to roll forward toward the head, and when reversed to drop in the
opposite direction.
Since a ])racticable way to artificially impregnate the eggs of the
bass has not yet been developed, and the handling of eggs with indoor
apparatus is impossible, it is fortunate that the natural impregnation
of these fishes reaches a percentage closely approximating that which
fish culturists have been able to secure by artificial means from other
species, and also that the parental instinct is unusually developed.
The first conditions make pond-(!ulture necessary, and the second render
it ])ossible. The methods hereafter described are those in use at
Neosho station.
ARTIFICIAL PONDS.
The size of spawningiionds for rearing bass depends largely on the
amount of laud available, its topography, and the water supply.
Ponds not less than i acre in area, with the inlet at one end and the
outlet at the other in the line of the longest axis, generally produce
the best results, though smaller ponds have been successfully used.
At least one-fourtli of the pond should be not over 1 foot in depth,
and this portion should be planted with pond- weed [rotomoijeton) and
water- weed [Elodeaov Anacharis) to facilitate the production and growth
of the minute animals which furnish so large a part of the food for the
young bass. The rest of the pond should have a gradually sloping
bottom and a c()nse(|uent increase of depth to the kettle (or draw-off"),
where the water nuist be at least from 5 to <> feet deej) for the warm
Soutliern States, and 8 to 10 feet deep for the Northern States, to i)ro-
vide against the danger of freezing. In the middle third of the pond
water-lilies siiould be planted, ])! eferably those with large pads, such as
Nymphea ulba; these plants not only furnish the breeding fish a hiding-
idace from fish hawks, but serve as sunshades during the summer. It
is not advisable to i)lace large bowlders in the ])ond, as they are in the
way of seining or netting and furnish an acceptable resort for crawfish.
MANUAL OF FISH-CULTUKE. 155
Nursery jxinds should be constructed to artbrd younji; bass protection
from enemies and to produce the greatest (juantity of inse(;t life suited
to their sustenance, and this is better accoin])lished with a number of
small ponds than with one large one. A good working size is from 40
to 50 feet long by 12 to 15 feet wide, with a depth of from 30 to 36 inches
for the "kettle." Where the topography of the ground will permit, it
is best to have the nurseries immediately adjoining the spawning-pond,
with the water supply from the same source, so that there will be but
slight ditlerence between the temperature of the shallowest part of the
nursery-pond and the surface water of the other.
The young large-mouth bass is not a strong tish, and currents in the
spawning and nursery ponds should be avoided for some time after the
spawning period.
If the locality is infested with crawfish, it is advisable to i)ile or other-
wise protect the banks; and the entrance of snakes, frogs, and such
enemies may be prevented by surrounding the pond with finely woven
screens, or, better yet, boards let into the earth a few inches and pro-
jecting above the ground. The pond should be supi)lied with the aquatic
plants previously mentioned as desirable for the shallow parts of the
spawning-pond.
A spawning and nursery pond may be combined by constructing one
comparatively long pond, narrow near the middle, so that the general
shape will be like a dumb bell with a very short handle. Across the
narrow part is to be stretched a screen of one-fourth inch wire cloth,
which will confine the spawners to the deeper end of the pond, while
the fry, following their instinct of moving upstream, will find their way
through the screen into the upper shallower end. This form of pond is
advantageous where for any reason only a few ponds can be built.
In addition to the nursery ponds, tanks 6 feet wide and 10 to 12 feet
long and 5 feet deep, made of cement and brick, or wood, should be
provided for liolding the fish preparatory to shipment during the fall,
and are also very convenient for handling the fry when they are being
transferred from the spawning to tlie nursery ponds prior to being
assorted as to size. At Neosho, where the fry are removed from the
spawning-ponds at a very early stage, they are held in troughs similar to
those in general use for trout culture. A trough 14 feet long with 4 inches
depth of water at 57°, changing 2 gallons i)er minute, will support from
3,000 to 5,000 very young fry, and twice or three times as many rock bass
will live comfortably under like conditions. The same general care
and cleaning usually given to troughs containing trout fry is necessary
in cultivating bass. The trough should be swept down twice a day and
occasionally washed inside with a cloth, and the water supply, conduits,
and outlets frequentlj' examined and kept clear and clean.
The young bass is able to stand any temperature to which the sun
raises the water of the nursery; those hatched in water at 50° F. will
thrive two months later with the temperature at 80°. But bass grown
m a very high temperature are exceedingly tender, and can not be
156 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
handled and transported until the approach of fall and winter has
gradually reduced the temperature and thus hardened them; they are
also more liable to attacks of parasites, both external and internal.
While bass can live in water ranging from 83° to 98°, more moderate
limits are desirable. The GyclopH and some other of the natural forms
of food for young bass reproduce best at a tem])erature between G8° and
70°, and can not resist higher than 95°.
CARE OF PONDS.
It is desirable that the ponds should be "wintered" each year — that
is, entirely drawn oft" in the autumn, thus leaving the beds exposed to
the combined action of sun, winds, and frost. This tends to kill out
the larvai of the larger aquatic insects (dragon flies, beetles, etc.), and
to increase the following season's supply of small Crustacea, which fur-
nish an important element of food to the young bass. This purifying
process can be assisted by the free use of quicklime dropped into the
crawfish holes. There is no danger of the lime injuring the fish the
following year, and the limewater purifies the pond bed, besides killing
the crawfish and the like.
The accumulated decayed matter ought to be occasionally removed,
the frequency for this depending on the character of the water supply,
the amount of silt it brings into the pond, the character of the soil, and
on the thoroughness of the yearly removal of the surplus vegetation.
Scraping large ponds and hauling the accumulated muck involve con-
siderable labor and expense, possibly more than the yield of the pond
warrants, and in some cases it is advisable, once in four or five years,
to lay the i)ond bare for an entire year and cultivate it in peas or some
other deep-rooted vegetable.
While abundant pond vegetation is favorable to a large production
of fry, it is sometimes so luxuriant that it settles down in a blanket-like
mass and smothers many of the young fish. Under such circumstances
it should be removed some time in advance of lowering the ])ond level,
and during the process should be carefully picked ovi-r, as some of the
fry will be found among it. Wading into the i^ond leaves the bottom
tracked with deep footprints, which, as the water recedes, catch and
retain many of the young fishes, most of which die in a short time. To
avoid this a strong but lightly built flatboat is used, which can easily be
moved from pond to pond, as needed. At each end of the boat is a ring,
through which a stake is driven at the point in the ])ond to be worked.
The vegetation is raked from the water in small lots, and unloaded on
the banks with a pitchfork. It should be promptly removed from the
bank, as it will rot very fast and its presence is objectionable. At the
Texas station, where the vegetation is very luxuriant, it is hauled to
the banks with a long rake 8 feet wide, operated by two men, and is
then removed by means of long-handled forks. This method is simple
and very economical, two men accomplishing more than five or six by
the other method.
Fish Manual. (To face pa?e 1 56
Plate 49.
MANUAL OF FISH-CULTURE. 157
NESTS AND NEST-BUILDING.
Whenever the spawning period occurs, whether early or late, ample
warning is given by the preparation of the nests, which are built by the
mated lisli, sometimes working in company and sometimes separately.
In the Great Lakes region and the North and ]\liddle Atlantic States the
nests are ordinarily built of gravel, brushed into neat circular piles 18
to 3G inches in diameter, and are usually found in water Irom 18 to 3G
inches deep, though not infrequently in much deeper water and some-
times in water less than a foot in depth.
In the proper preparation of the newly-built spawning-pond clean
gravel, ranging in size from a buckshot to a hickory nut, is arranged in
small Hat heaps about 4 to 0 feet from the banks, as soon as the ice is
off in the spring, in advance of the spawning season, and, if well
located, it can be used through several seasons and more than once in
the same season. Gravel probably possesses no advantage of itself
over a hard-clay bed except that it presents more surface within a given
area for the eggs to attach themselves to.
The fish clean the gravel with the caudal fin and tail until it is as
bright as if every particle had been polished with a brush, often using
the liead and mouth to remove the larger stones from the nest. Some
bass build several nests in a season and are compelled to remove a
comparatively large quantity of rough and jagged material, yet very
few wounded or abraded bass are captured. At I^eosho the same bass
have been observed at nest-building for seven years without showing
a torn or worn caudal or anal fin. Trout, on the contrary, wear their
caudal fins and tails to the very bone, in their efforts, and often die in
consequence. In the Mississippi Valley, in Texas, and throughout
the Southern States, the black bass deposit their eggs on the clay or
mud, and rarely use gravel. At the Texas station, where gravel nests
were placed in the ponds they were seldom or never used.
The proximity of the nests to each other depends on the si/.e of the
pond and the number of fish. They are sometimes less than 5 feet
apart, and in a spawning pond of the Michigan Fish Commissior.,
having only 108 square feet of surface and containing 30 adult fish,
there Avere 8 nests. If the nests are near the banks, in water from 18
to 3G inches deep, the entire jjrocess of spawning and incubation is
easily observed. The larger fish are apt to select deeper water, but
they have been known to decline a clean lot of gravel, in water 3 feet
deep and 8 feet away from the embankment of the pond, to build a nest
on the naked clay bottom within reach of the bank, on which people
were passing almost every hour. Nesting bass should have seclusion,
although those reared in captivity probably fail to notice minor disturb-
ances at the time of spawning which would at other times alarm them.
Shade is important, for, although bass sometimes build nests where
there is no shade, in most instances they select places under over-
hanging grasses, lily-pads, stumi)s, and logs.
From the time the bass commence nest building the attendant keeps
158 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
the pond and its contents under constant surveillance and maintains a
close watch for tishhawks and herons. A record is kept, as nearly as
practicable, of the date when each lot of eggs is laid, so that it may
be known when to expect the young to hatch.
Artificial nests for bass have been used at one or two stations, as an
experiment, but have been abandoned except for rock bass at Wythe-
ville, Va. The nest is a wooden box about 20 inches square, with sides
2 inches high and slightly flaring outward. Cleats are nailed on the
side for convenience in handling. Coarse gravel is placed in the bottom
of the box and the remaining space is filled with fine gravel, flush with
the top of the box. The top layer is sufiticiently fine not to allow the
eggs to fall through the spaces and mix with the largo gravel under-
neath. The nest, thus completed, is placed in an excavation with the
upper edge even with the bottom of the i)ond. A stake is driven near
the nest and a board fastened to it, to afford seclusion and protection
from the sun and enemies.
BROOD-FISH.
Whenever procurable, domesticated fish are to be preferred to wild
fish for stocking the breeding-ponds, as they are less liable to injury
in handling and transjiortation. A disrupted scale, lacerated fin, or a
bruise on head or body frequently cau«es the death of wild bass, and
their native surroundings are such that it is difficult to collect any
considerable number of them. Moreover, adult fish captured from
their native waters frequently fail to spawn in the year or season in
which captured, on account of fright.
Bass not over 2 or 2i pounds are recommended if the work is carried
on in ponds which are to be frequently drawn off', but larger fish can
be used advantageously if they are to be but rarely transferred to other
ponds. Very large bass are more liable to injury when the ponds are
drawn and the fish transferred, as they are more difficult to handle
safely, and bruise and injure themselves in the tubs. Males and females
should be in equal proportion, as an excess of males may prove a dis-
turbing element at spawning time and later in the season may cause a
loss by preying on the fry. The sexes of the black bass are not as
easily distinguishable as of the trout. The number of adult fish for
breeding-ponds depends upon the food supply. For several years past
at Neosho an average of 30 breeding bass to the acre of water has been
allowed, but that number might be increased.
SPAWNING HABITS.
When the rests are prepared and the spawning time arrives, the
parent fish — especially the male — show considerable excitement and
swim back and forth over and around the nest. In the act of spawn-
ing they cross the nest, their bellies close together, the male a little
behind the female, and sinuiltaneously void the eggs and eject the
milt, the real act of spawning occupying a comparatively short time —
MANUAL OK FISH-CULTURE. 159
a minute or less. The eggs, when laid, are viscid, and as soon as voided
and impregnated atta(di themselves to the floor of the nest. Then
commences a parental watchfulness worthy of imitation on the part of
some higher aninuils, one fish hovering immediately over the nest and
maintaining a gentle motion of the fins for the purpose of keeping the
eggs free from sediment, and the other acting as an outer sentinel,
])atrolling 8 or 10 feet away. Both male and female show great courage
when guarding their eggs and young fry. A rock bass has been seen
to leap entirely out of the water to bite viciously at an attendant's hand
when moving aside the grasses sheltering the nest, and a black bass
when guarding its nest has been known to attack and kill a snake three
times its own length. The brightness of the nest makes the parent on
guard easily distinguishable by enenn"es, like the fislihawk and eagle,
but this danger may be materially lessened by planting the broader-leaf
water-lilies near the nests, to afford shelter when in danger.
Black bass begin to spawn in the northern part of the United States
about the middle of May, while farther south the season commences as
early as March, and in all localities it is later in deep than in shallow
waters. In the far South, in waters uniformly warm, the spawning
time may not depend entirely on the seasons. The period lasts about
two months. Many, if not all, discharge only a part of their eggs at
one spawning. The maturation of the entire ovaries is never fully
completed at one time, but the ripening is prolonged and the spawning
done at intervals. As far north as southern Missouri and Illinois,
black bass frecpiently spawn in the season following the spring when
they are hatched, but this is not always the case; and farther north
maturity comes later in life. Bass continue to yield eggs for a number
of years, and some have been held in the brood ponds at Neosho which
were adults when first taken to the station and continued productive
for as much as seven years.
Rock bass have been known to produce two separate broods within
one season as far m>rth as southern Missouri, and this is probably true
of some of the other basses. At Neosho they spawn when one year old.
EGGS AND FRY.
The eggs difller greatly in number and size, according to the age and
size of the fish, varying generally from 2,000 to 10,000 per fish and from
80,000 to 100,000 per quart; 17,000 eggs have been found in a large-
mouth black bass weighing 2i pounds, a little less than 7,0i 0 to the
pound of fish; but on another occasion a careful count of the mature
eggs showed only 2,074 to the pound of fish. Wide discrepancies in
the figures may sometimes result from different methods of counting, as
in rejecting or counting small eggs which are commencing their matur-
ation for the next production. The rock bass egg is fully three times as
large as that of the black bass, and the fry are correspondingly large.
The varying factor of initial vitality and the impossibility of equal-
izing the intensity of sunlight render it impossible to determine pre-
IGO REPORT OP COMMISSIONER OF FISH AND FISHERIES.
cisely the i)eriod of incubation of any eggs treated in pond culture.
With some kinds, under extreme temperatures and other less under-
stood factors, wide variations are found. Bass eggs require from 7 days
to 3 weeks for hatching, but usually from 8 to 10 days — depending
mostly on the temperature of the water. Eggs artificially impregnated,
in an experimental way, hatch in from 70 hours to 4 days at a tempera-
ture of 63^^ F., or somewhat over.
When the fry leave the eggs, they remain on the nest till the sac is
absorbed, this depending, as with other fishes, on the period of incu-
bation, modified by the temperature or condition of the atmosphere;
usually a fifth less time being required to absorb the sac than for hatching
the eggs. When the sac is absorbed, the fry rise and form a school
which hovers over the nest usually from 2 to 4 days, settling back at
night, except in extremely warm weather, when they may scatter in a
few hours. A sudden fall of temperature may cause the school to settle
back and remain a day or two longer on the nest. The tactics of the
parents change and they no longer stand guard over the nest, but circle
around the school, whipping back truants and driving oft" intruders.
When the school rises and hunger begins to be felt, the fry separate
and are driven for protection, by the i^arent fish, into shoal water or
into the thick grasses; there theyare deserted, and dispersing they seek
the minute Crustacea, larvine, and insects. The brood bass should then
be removed from the spawning-ponds to other ponds, or confined in
compartments in the same pond, so that they can not prey on the fry.
For the first three to five days black-bass fry do not average one-
fourth inch in length and are almost colorless, until the ])igment forms
along the back, making them appear quite dark when viewed irom
above, though it is difiicult to distinguish the color of an individual
fish when caught on a net of bolting-cloth.
Very young rock bass seem occasionally to attach themselves to the
sides and bottom of the nests and to submerged plants. This action
has not been noticed with black bass, possibly because their nests,
being in deeper water, are more difiicult of observation.
FOOD OF THE YOUNG.
Just how much food to give bass fry is as difficult to determine as
with any other young fish. They are very greedy, and, if acceptable
food is given them, ap[)ear to be hungry nearly all the time, and it is
more than probable that the troubles caused by overfeeding other fishes
would show themselves in the bass if they were overfed. Healthy fry
have been carried at Neosho for four months with a loss of only 2 i)er
cent. When first brought into nursery ponds or troughs they can not
be induced to take prepared food, as they are wild and must be tamed
or domesticated. They are fed almost every hour in the day, though but
little food is given at one time and that is well scattered through the
water. The attendant, without alarming them, should be about the
trough constantly, to accustom them to his presence, and, instead of
Plate 50.
culture
400
"500
MANUAL of' FISH-CULTURE. 161
beiuf? frightened and darting into dark corners at his api)r()ach, they
soon learn to come to meet him, not a few at a time, but all together.
For several days their food will have to consist of such minute ani-
mals as can be conveniently collected from the ponds with a dip-net of
cheese cloth. After four or five days they will accept prepared food,
as fish of some kind, ground to a fine i)aste. In general, bass fry under
l.i inches in length are too small to take artificial food, and it is very
doubtful whether it is good policy to transfer them to nursery ponds or
troughs prior to that stage.
The number of young bass to be put into a i^ond depends upon its
size and its capacity to produce food. If the nursery has been prepared
in advance with ac^uatic plants some Crustacea will be found there, and
the deficiency is supi)lied by the introduction of snails, Gammarus,
Corixa, etc. The use of beef liver as food is not advised. To a nur-
sery in fair condition from 3,000 to 5,000 young bass may be allotted.
The death of a part of these must be expected, and if even a fair per-
centage are to survive they must have much more food than the jiond
can probably grow. Should a large part of them survive the first few
weeks they can be distributed into other nurseries.
At Neosho finely ground crawfish have been used for food with good
results — not that crawfish have any value over other forms of aquatic
life, but they are abundant, cost nothing, and are acceptable to the fish.
Carp are cultivated for this purpose at the Fish Lakes in Washington,
several hundred thousand being used each season, the young carp
being liberated in spawning-ponds with the young bass a few days
after they are hatched. At the Forest Ponds of the Missouri Fish
Commission little branch chub are caught and placed in the pond
several weeks before the bass spawn. As the chub spawn and hatch
out before the bass, when the young bass are transferred to the nursery
they find a lot of young chub ready to be eaten. An objection is that
the old chub destroy the young bass, though this is easily obviated by
hatching the chub artificially and turning only the young chub into the
pond, or by removing the adult chub before the bass fry are introduced.
At San Marcos the bass fry are fed on young carp, buffalo, and mud
shad, in addition to the natural food, which is quite abundant early in
the season, but later they take chopped fish, salted fish roe, etc. No
effort is made to furnish the prepared food, though, until they reach IJ
inches in length, as they remain in the spawning- ponds until that time.
TRANSFER AND CARE OF FRY.
In transferring the fry to troughs or other ponds at Neosho two nets
of cheese-cloth are required. The main one is about 30 inches square,
supported by ribs from above; to the center of the ribs a handle is
attached, so that the net can be used 5 or 0 feet from the shore; the
net is made to sag to an open pocket in the center, which can be closed
and tied with a drawstring. The second net is easily made from au
F. M. 11
1G2 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
ordinary liinding-net by replacing the netting with cheese-clotli. This
will be useful in eatching the fry that escape from the larger net. The
transfer is made in tubs filled with water from the si)awning-poud in
order to preserve the same temperature as nearly as possible, letting
is done in the early morning, as the shallow waters of the pond become
cool during the night and the temperatures of the different waters are
more nearly equal. It requires patience and a degree of skill, which
comes with practice. The oj^erator stands on the bank and introduces
the net with a gentle and scarcely perceptible side movement under
the school and cautiously lifts it out, and when the net is clear of the
water, turns with a quick motion and brings it over the tub, so that the
part of the net holding water and fish can be readily submerged in
the tub. An assistant stands near the tub to catch the sides of the
net and help in the latter part of the operation. While the operator
holds the rod to which the frame of the net is attached, the assistant
slips his hands into the tub and unties the drawstring of the net
pocket, and the net is then gently lifted out of the tub. A bucket of
water from the pond and a dipper are kept at hand to wash into the
tub any of the fry that may stick to the cheese-cloth. The fry should
never be freed from the net with a feather or by shaking.
As soon as the collected fry are in the vessels they are carried to the
troughs or pools, when the temi^erature of the water in the bucket or cans
is compared with that flowing through the troughs. The experienced
fish-culturist can tell by the touch whether there is a material difference
in the temi^erature, and can take the stej)S toward ecjualizing it. Should
there be a difference of 3° or more, it must be corrected. If a vessel is
not crowded, an effective, but slow, method is to set or suspend the
vessel in the water flowing through the pool or trough. If the water in
the vessel is warm and the time short, in addition to setting the vessel
in the trough, a part of the water may be bailed from the vessel and
replaced with fresh colder water. This operation is called " tempering" ;
it requires care, good judgment, and patience.
It is well to have several large buckets made with "windows," that
is, a small screen of perforated metal in one side of the bucket, near
the top. This bucket is put in a trough under a small jet of water,
conducted by a rubber tube to the bottom of the bucket. The jet
discharging at the bottom of the bucket, and the surplus water escaping
through the ijerforated window, assist in equalizing the temperature,
and the fish are then carefully put into the troughs or pools.
A part of the fry do not find their way through the wire screens into
the cut-off", and all around the margin of the pond, even in the deep
water, straggling fry may be seen. Sometimes these scattered young-
sters are small, but generally they are the largest. After all the fry
have been captured from the cut-off" and the season's spawning is over,
the pond is drawn to collect and save those that have failed to come
into the cut-oft". This work is generally in June or July, when the
MANUAL OF FISH-CULTURE. 1G3
ponds arc (juite wiirm aud the temperature of the atmosphere is high,
and is carried out with extreme watchfulness and care, as tlie midsum-
mer drawing of a bass x>ond is the most delicate operation connected
with the propagation of this species in ponds. These fry need to be
"tempered" and sorted in the same way as advised for other fry.
At some stations of the Commission the fry are not transferied from
the spawning to the nursery ponds until they are IJ inches long. In
edecting the transfer a seine made of wash-netting or bobinet is used,
the length and depth of the net depending on the size of the jionds.
The fishing is usually done early in the morning, near the inlet where
the young fish collect. The fish are transferred from seines to tubs by
dip-nets, and thence to the tanks, where they are carefully assorted and
placed in the nursery ponds. Sometimes they are assorted in the tubs
and put at once in the ponds.
As the season advances it will be noticed that some of the fish grow
much more rapidly than others, and as this is generally the result of
cannibalism, the larger ones preying on the smaller, the fish must be
again sorted and those of different ages placed in separate ponds. The
successful raising of bass in ponds depends largely on frequent and
careful sorting.
Collecting for shipment occurs in the cool days of autumn, as experi-
ence has shown that the bass can be nmch better and more safely
transported in the spring and fall than in the summer. They can be
transported more chea[)ly in midwinter than any other time, but when
fisii are moved long distances in very cold weather (or at any other
time when much ice is used in the cans) many die from gill troubles.
After the ponds are free from vegetation and are ready for drawing ofl"^
the water level is reduced slowly. Every precaution is taken not to
frighten the fish, and with this in view no more attendants are allowed
about the bank than are absolutely necessary. Black bass when
frightened will burrow in the mud and live there an incredible length
of time, and if a fingerling burrow in the mud when the pond is being
drawn he may jjrove a dangerous occupant the following spring when
the young fry are introduced. The same precautions should be observed
in transferring lingerlings as with the very young fry.
During the various stages of its life the bass is subject to the attack
of enemies of many kinds. The fish-eating birds, like the kingfisher;
wading birds, like the heron, and amphibious animals, like the mink and
muskrat, must be guarded against. Snakes, frogs, turtles, and various
beetles are dangerous to the fry, and sometimes even to adult fish.
Fish Manual. (To face page 165.)
Plate 51,
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THE PIKE PERCH OR WALL-EYED PIKE.
BESORIPTION OF THE SPECIES.
The ]nko perch { Stizostalion vitreum) is the largest member of the
perch family inhabiting- American waters. The body is fusiform; its
depth being contained about 4J times in length. The head is long,
pointed, and a little more than one-fourth the body length. The large
mouth is provided with bands of villiform teeth, in addition to which
there are long, formidable canine teeth on the jaws and roof of mouth.
The eye is contained 4i to 5 times in head. Serrations exist on the
preopercular bone, and several spines on the jireopercle. The high
dorsal fins are well separated, and contain from 12 to 16 spines and 19
to 21 soft rays. The number of rows of scales in a lateral series is
from 110 to 132, with about 10 rows above and 25 rows below the lateral
line. The general body color varies from light yellowish to dark blue,
with indistinct lines and mottlings, the under parts being white or pink.
A large black spot involves the membrane of the last two or three
dorsal spines, the fin being otherwise nearly jdaiu; the second dorsal
and the caudal are mottled with yellow and olive; the pectoral is dusky
at its base, and the anal and ventrals are pinkish.
Three rather well-defined color varieties of the pike perch may be
recognized, dependent on age and environmental conditions. These are
the gray, yellow, and blue. The gray variety attains the largest size,
40 ])ounds being the maximum aiul 10 to 20 pounds being common. The
yellow form reaches a weight of 20 pounds, and is often taken weighing
5 to 10 pounds. It has the widest range and is the most numerous.
The blue pike occasionally may reach a weight of 5 i)ounds, but averages
under 1 pound. The gray and yellow varieties are usually found in the
larger streams, and in the Great Lakes seek water 10 to 40 feet deep,
while the blue variety seems to prefer water 30 to 75 feet deep.
The pike perch in that part of Lake Erie adjacent to the islands
of the western end are almost or entirely free from yellow, being a dark
gray, almost black, on the back, shading on the sides to lighter grays,
while the lower third and belly are silvery white; the body is less com-
pressed and tapers less toward the tail than the yellow variety. In
Sandusky Bay there is a uniformly yellow variety, of a fusiform shape.
Although Sandusky is connected with the lake by a deep channel over
a mile wide, it is reported that the yellow fish do not leave the bay and
the gray fish rarely enter except during the spring, when small numbers
resort to it to spawn.
From the sauger or sand i>ike [S. canadense), the wall-eyed pike is dis-
tinguished by its fewer pyloric coeca (3 instead of 5 to 7), fewer dorsal
165
1G() REPORT OF COMMISSIONER OF FISTT AND FISHERIES.
rays, larger size, presence of black blotch on second dorsal, absence of
similar blotch at base of pectorals, and some minor characters.
Various names are given to the pike perch in different parts of its
habitat, and two or more names in some localities. Wall-eyed pike
is the most widely used designation. Pike and pickerel are employed
in the Great Lakes. As both of tliese names are also borne by the
members of the genus Lvcius, much confusion has arisen. In the Sus-
quehanna and Delaware rivers and along the Ohio and its tributaries
the fish is very inappropriately known as salmon. Dory or dore is a
Canadian designation. Other names in use on the Great Lakes and
elsewhere are yellow pike, blue pike, glass-eye, white-eye, and Jack
salmon. In order to avoid confusion and to indicate the family rela-
tionship, the U. S. Fish Commission has recommended the name pike
perch, the fish being a perch of pike-like appearance and habits. This
name corresponds with the generic term Lucioperca, applied to a similar
European species. The sauger, however, is entitled to bear the same
name, although its usual designation is distinctive.
GEOGRAPHICAL DISTRIBUTION.
The pike perch prefers clear water, with rock, gravel, sand, or hard-
clay bottom. The center of its abundance is Lake Brie, but it is among
the most widely distributed of our fresh- water fishes, its range extend-
ing along the Atlantic seaboard from New Brunswick, New Hampshire,
Massachusetts, and Connecticut as far south as North Carolina; thence
to the northern jwrtions of Alabama, Georgia, Mississippi, and Arkan-
sas on the south, with Kansas, Nebraska, the Dakotas, and Assiniboia
its western limit and the Hudson Bay system its northern boundary.
Over the greater part of this vast area it is fairly abundant, and in all
of the waters of the Great Lakes region, the Mississippi basin, and the
southern portion, at least, of the Hudson Bay system it is commercially
important. In New Hampshire, Connecticut, New Jersey, and eastern
Pennsylvania it is not indigenous. Its adaptability to suitable new
waters is shown by its acclimatization in the Susquehanna and Dela-
ware in Pennsylvania, in many small lakes in Michigan, and in the
streams and lakes of Nebraska, where it has rapidly multiplied and is a
great favorite with anglers and epicures.
The range of the sauger is less extensive than that of the wall-eyed
pike. It embraces the Great Lakes region, west to the Ui^per Missouri,
and south to Arkansas and Tennessee.
ECONOMIC VALUE, FOOD AND GAME QUALITIES.
The pike perch is one of the most valuable fresh-water fishes. In
Lake Erie alone the annual catch is now upward of 6,000,000 pounds,
valued at $225,000, besides which over 3,000,000 pounds of saugers,
worth $75,000, are yearly taken in the same waters. Througiiout its
range it is caught nearly the year round, and, in spite of the zeal with
which it is pursued on account of its fine table qualities and the ease
MANUAL OF FISH-CULTURE. 107
with wliich it is captured, it is liokliug its own well owing to its hardi-
ness, its comparative freedom from disease, and the facility with which
it is produced by fish-cultural methods.
As a table article it ranks high. The smaller fish are delicious fried,
broiled, or boiled, while the larger ones, weighing from 5 to 15 pounds,
are excellent when baked. The flesh is firm and well flavored, even in
the warmest weather. Few fish stand shipment, holding, or freezing
better than pike perch. It is not so well adapted to salting as some
species, but this is not important, as the demand for it is so great that
the supply is always disposed of fresh or frozen. The abdominal cavity is
comparatively small and the head medium, so that little loss occurs in
dressing. The bones are somewhat numerous, but they are generally
large and easily separated. The gray and yellow varieties are consid-
ered superior to the blue for food, and are also better game fish.
The pike perch, although capricious, is readily caught with baited
hook, artificial fly, spoon, etc., and deserves high rank as a game fish.
About 100 tons are taken annually with hook and line through the ice
about the Bass Islands, Lake Erie; large quantities are also thus
caught near Buffalo, jST. Y., in Saginaw Bay, Mich., and elsewhere. In
ice fishing small minnows are generally used, the bait being taken near
the bottom.
FEEDING HABITS.
Although the pike perch is predaceous, observations would seem to
show that it devours fewer desirable species than any other jjredatory
fish. Its main food in Lake Erie the year round is a small cyprinoid,
usually called lake shiner, which abounds in these waters, with occa-
sionally crawfish in the winter and the larv;cof insects and the insects
themselves in the warmer months. A i)ike perch weighing lOi pounds
has been caught containing a bullhead which in its partly digested
condition weighed 9 ounces. The stomachs of hundreds have been
opened at all seasons of the year and under various conditions, and
the examinations have as yet failed to disclose one containing a white-
fish, black bass, or other valuable fish. Usually the stomach was empty
so far as the unassisted eye could discover, except for a thick, tough,
greenish-yellow slime.
The pike i)erch does not generally inhabit the de])ths of waters fre-
quented by the black bass, preferring the deeper portions of the shal-
low i)arts of the lake. Excepting the blue pike variety, it is not found
in deep water, which is the liome of the whitefish during all the year
except for a short period in the fall during its reproductive migrations.
And even the blue pike does not inhabit the deep waters where the
whitefish ami cisco spend most of their lives.
SPAWNING AND SPAWN-TAKING.
The pike perch is not a nest-builder, as are the basses and sunfishes.
The female discharges her spawn in shoal waters, the male following
and emitting milt in proximity to the eggs. The spawning time varies
168 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
greatly in different localities, extending from the last of March with
the yellow and gray varieties to the latter part of May. The blue pike
has not been hatched by fish-culturists, and comj^aratively little is
known of its spawning habits.
The work of collecting eggs for artificial propagation generally
begins about the 10th of April and extends to the 25th of that month.
The eggs are obtained from fish taken by commercial fishermen. Half
or more of these are hatched into vigorous fry and deposited in public
waters, and but for this work all the eggs thus saved would go to the
market in the abdomens of the fish and be entirely lost.
The pike j^erch develops a greater number of eggs in proportion to
its weight than the ^vhitefish, and but a small percentage of them are
fertilized under natural conditions. The eggs are 0.08 inch in diameter
and average about 150,000 to a fluid quart. About 00,000 eggs would
probably be a fair average per fish for Lake Erie, and as the sj^awning
fish will average about 2 pounds each, 45,000 eggs to the pound weight
of fish would approximate the true figures.
As the spawning time approaches spawn-takers are stationed at the
various j^oints on the lake where nets are to be fished. A spawn-taker
accompanies the fisherman on his trips to the nets and examines the
catch for ripe fish. His equipment is the same as that described in
the chapter on whitefish, except that he takes a quantity of swamp
muck for use in preventing adhesion of the eggs. After he has selected
and stripped a fish, it is returned to the fisherman. The eggs after
being fertilized are either shipped directly to the hatchery or through
some central collecting station.
The inner membranes of the egg are delicate and easily ruptured,
and the greatest care is necessary, from the taking of the spawn to the
hatching of the fry, and especially until they are cushioned by the
filling of the membranes with water.
The fish should be wiped so that slime will not drip into the spawn-
ing pan, as a very small portion will clog the micropile and prevent
impregnation. The female is grasped firmly in the left hand just for-
ward of the tail, with the back of the hand downward, the fingers
outward and the thumb above and pointing upward, the head of the
fish being held between the spawn-taker's right wrist and body, the
right hand grasping the fish from below, just back of the pectoral fins,
the fingers inward, the thumb outward. The anterior portion of the
abdomen is thus firmly grasped and the pressure brought to bear on
the eggs in the ovaries of the fish. A woolen mitten on the left hand
allows a firmer grasp on the slippery body than is possible with the
bare hand. The fish is now at an angle of 45°, the body forming a
modified crescent, with the vent within 2 or 3 inches of the bottom of
the pan. This position throws the pressure on the abdomen and
facilitates the opening of the vent and the flow of the eggs. Gentle
pressure is now maintained as long as the eggs come freely and in a
MANUAT. OF FISH-CULTURE. 169
fluid stream, jirobably over half of them being procured before the
baud is moved, but wheu the flow slackens, and not until then, the hand
should be moved slowly toward the vent without releasinj,^ the pressure
and only fast enough to keep the eggs flowing in a continuous stream.
When this stops the hand should be replaced and the process repeated
until all the good eggs are procured. If the eggs do not start readily
they should not be taken.
As soon as one female is stripped the milt is added, care being taken
all the time to allow no Avater in the pan until the lot is finished or
until the i)au is half or two-thirds full of eggs. If males are abundant
one is stripped for each female, and one for every two or three females
in any event. When the pan is about half full, ami before any water
is added, the eggs are very thoroughly and carefully stinted with the
outstretched, spread fingers, and enough water is added to incorporate
the egg mass and nicely cover the eggs, the whole being mixed again
with the fingers and allowed to stand for 2 minutes. Next the milt of
one or two more males and a little water are added, the mixture is
stirred as before, and again allowed to stand for 5 minutes.
Impregnation can not take place unless the milt and eggs come into
perfect contact, and as the niilt dies 2 minutes after water is added,
and as the eggs will not become impregnated after having been in
water G minutes, it can readily be seen that the eggs and milt must be
thoroughly and quickly mixed, both before and after the water is
added. A tablespoonful of muck solution is now stirred into the mass
and a pint of water added. The water is poured ofl" after standing and
this process is repeated every half hour, as described on pp. 174-175.
After the adhesion has subsided the eggs are placed in a keg nearly
filled with water and stirred every half hour, with a change of water
at least every hour from the time the eggs are taken until they are
delivered at the station. The stirring is thoroughly, but gently, done
with a dipper, care being taken that the dipper does not strike the
sides or bottom of the keg.
The eggs should never be exposed to the sun, and the water sur-
rounding newly taken eggs should preferably be kept between 40° and
50^ F. ; in fact, exjierience has shown that even 35° is not harmful.
Of course, all sudden changes of temperature should be avoided.
DEVELOPMENT AND CARE OP EGGS.
When the eggs arrive at the station they are held in 15-gallon cans
for about 24 hours, a gentle stream flowing into each can, this being
considered better than to place them at once in the hatching-jars, where
the motion is too violent for the green eggs. While thus hehl they are
stirred every hour. Kegs or cans may -be carried half full of eggs if
properly cared for.
For the handling of all eggs at Put-in Bay, except those to be shipped
by rail or wagon, 15 gallon ])ine kegs, painted outside, with iron hoops
and iron drop-handles, are preferred to tin cans. They are cheaper,
170 REPORT OF COMMISSIONER OF FI8H AND FISHERIES.
lighter, more durable aud coiiveuient. The eggs are iu full view when
beiug stirred and when water is poured oft' or added; the most impor-
taut point, however, is that the kegs retain the water at a more even
temperature, as they are less aft'ected by heat and cold than the cans.
All dishes aud implements with which the eggs come in contact should
be thoroughly scalded and cleaned at the beginning and close of each
egg-taking season.
For hatching pike-perch eggs at Put-in Bay the same jars are used
as for the whitefish eggs, and on pp. 115-119 will be found a description
of the hatchery and its equipment, the arrangement of the jars in a
" battery," the manner of operating them, etc. The pike-perch eggs
are lighter than many others, and, being hatched in comparatively
warm water, fungus quickly when dead. The water used in hatching
them should therefore be practically clear, for if it contains any con-
siderable portion of silt the fungused eggs will soon become so loaded
as to possess the same specific gravity as the living ones, and sink in
the egg mass, forming lumps which can be removed only by screening,
which is always more or less injurious. Even the live eggs will become
coated, interfering with the proper working of the jars. Where clear
water is used the fungused eggs remain buoyant, keep on top of the egg
mass, and are easily removed without loss or injury to the live ones.
Where water is only moderately turbid and a large number of eggs
are being handled, if the water temperature runs up to 55° or 00° the
eggs will fungus so rapidly that they can not be separated fast enough
to prevent the live eggs from becoming mixed with them. As it is
practically impossible to run "hospital jars" under such conditions,
many eggs must be lost, or the small percentage of live ones contained
in the mass of dead ones must be drawn off and distributed in the lake
and thus given a chance there to hatch. Both of these conditions are
to be deprecated and can be prevented by a filtering T)lant.
In order to insure perfect cleanliness, it is advisable to treat the
whole system of troughs and pipes through which the water runs, once
or twice a year, with a clear solution of chloride of lime, beginning
with the supply tanks, which should be thoroughly washed inside, and
following down until all have been reached, opening each faucet or
cock during the i)rocedure. In this way, at small expense, the system
is freed from infusoria and other forms, which at times are very
troublesome and more or less destructive to the eggs. This work
should be done in the fall, just before whitefish eggs are to be placed
in the jars, and again in the spring, as soon as the whitefish eggs and
fry are all disposed of and before the pike-perch eggs are received. If
these periods overlap, a battery at a time can be treated. After treat-
ment, the tanks are thoroughly washed aud the whole system is flushed
for an hour or more. Chloride of lime is much more effective for this
purpose than common lime. The preparation is made by dissolving 5
])ounds of chloride of lime in 10 gallons of water, and after it has settled
the clear solution is decanted off and added to many times its bulk.
Fish Manual. (To face page 1 70 i
Plate 52.
PHOTO-MICROGRAPHS SHOWING PHASES OF CANNIBALISM AMONG PIKE-PERCH FRY.
MANUAL OF FISH-CULTURE. 171
The fry of the pike-perch are ouly about as large round as ordinary
sewing thread and about -j-g- incli long; it therefore requires very fine
brass- wire-cloth screens to hold them in the tanks, and it is exceedingly
important that these screens be kept clear — preferably by the air jets
described in the chapter on whitetish (p. 119). This apparatus gives
perfect satisfaction and twice the number of whitefish or pike-perch
fry can be successfully carried in a given amount of water with the air
system than without its aid.
When the eggs are placed in the jars 24 hours after taking, allow-
ance is made for some additional swelling, and accordingly 3i quarts
of eggs are placed in each jar on setting them up. These will swell
to 4 or 4^ (juarts at the end of 3 days, and that number works best.
The eggs are worked with the least i)()ssible amount of water that will
keep them in motion throughout, and anything beyond this is harmful
and will result in ruptured yolks. The jars are inspected daily, and
one that is working too fast or is not working uniformly is carefully
adjusted.
The eggs are semibnoyant and very adhesive. A single large, spher-
ical oil-drop floats at the top of the yolk mass. The germinal disk is
on the side of the yolk. The first cleavage of the disk ordinarily takes
place in 5 to 6 hours in a water temj^erature of 45° to 50° F. Unequal
division of the disk is rare, although it sometimes occurs, while with
the whitefish and many other species inequality of cleavage is the
almost universal rule.
In a water temperature of 45° to 50° the form of the embryo may be
distinguished under a low-power glass in 4 days, and the eye-specks
can be seen by the unassisted eye in about 6 days. By this time the
pigment cells, or color stars, can also be seen with a microscope of mod-
erate power, as well as the pulsations of the heart and the coursiug of
the blood through the vessels — the red corpuscles being distinguishable.
At this stage any monstrosities, malformations, and other blemishes
may be easily discovered. They consist of embryos with double heads,
the most common form, more than the normal number of eyes, curved
spines, and various other deformities, some so slight as to be scarcely
discernible. All these erratic forms perish before hatching or soon
afterwards, and cause the loss of a large percentage of the eyed eggs,
which die before hatching; insuHiciont food supply in the yolk causes
the loss of the next greatest number, the two covering about GO per
cent of the whole loss of eyed eggs.
The eggs hatch in from 7 to 28 days, a mean temperature of about
57° producing the first result and about 40° the latter, neither extreme
furnishing the best of fry. At a temperature of about 48° the eggs
will hatch in 18 to 20 days and produce vigorous, healthy fry.
The absorption of the food- sac is governed by the period of incuba-
tion and in some measure by the water temperature, and a day or two
after its complete absorption cannibalism will begin. If 28 days have
been required the sac will be absorbed in from 5 to G days, while if a
172 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
shorter period — say of 14 days — has beeu required, it will likely take
10 days before the sac is fully absorbed and the fry begin to destroy
each other,
TRANSPORTATION OF EGGS.
The best method of shipping eggs a considerable distance before
hatching is a somewhat open question. The experiment of shipping
them on trays rather than in water in kegs or cans, as described above,
has been tried with varying success. If shipi^ed on trays they should
be accompanied by a watchful messenger, who will see that tliey are
not subjected to sudden jars while in transit. They should be spread
on the trays not over one-third of an inch deep, and should be sprinkled
lightly every day. The cases containing the eggs should be packed in
damp sawdust, so that all ])arts of them will be covered 0 or more
inches. Ice should be used if the air temperature is higher than iSo
or 50° F., as the nearer the eggs can be kept to 40° F. the better.
Eggs held from 2 to 5 days on trays at Toledo and then shii)ped 40
miles by steamer to Put-in Bay came out as well as the average of the
eggs received near home and held in running water 24 hours. A lot
shipped on trays from Put-in Bay to Cape Vincent, N. T., about 400
miles, came out badly, while those from the same lot carried in water
turned out well. This difterence is probably accounted for from the
fact that the eggs carried in water were not subjected to sudden jars,
while in the other case they doubtless were. It is quite possible that
failures in shipping pike-perch eggs on trays have been largely owing
to concussions received during transit, such as must result in carrying
them on railroad cars and wagons.
If the eggs are to be transported long distances, they should be
covered with cheese or mosquito cloth and the remaining space to the
top of the tray filled with damp sphagnum moss; but if only a distance
of 75 miles or less is to be traversed, this is unnecessary, care being
taken to keep the cases right side up.
Eggs that have been held on trays should be placed in running water,
in kegs or cans, a few hours before they are put in the jars, or an allow-
ance of about 12 per cent should be made for shrinkage of the eggs
while on the trays. Otherwise too many eggs will be put into the jars
to work well.
PLANTING THE FRY.
In order to prevent loss from the fry preying upon each other, when-
ever practicable they should be planted before the sac is fully absorbed,
but not for 3 or 4 days after hatching, since if they are so held they
gain strength, and if they are to be transported some distance, they
become better fitted for withstanding the hardships of a long journey.
But with large numbers, running into hundreds of millions, lack of space
makes it necessary to liberate them almost as fast as hatched. Dark-
ening the tanks prevents cannibalism, but owing to the absence of food
and possibly to the darkness the fry become weak and light-colored in
MANUAL OF FISH-CULTURE. 173
a day or two and will not stand transportation. They must, therefore,
be transported before the sac is fully absorbed or large numbers will be
lost by either cannibalism or starvation.
During the season of 1899 the water pumped from the lake for the
supply of the fry tanks at the Put-in Bay Station literally teemed with
Crustacea, such as Cyclops, Biaptomus, Dajyhnia, Alonopsis, etc., but at
first, after the food-sac was absorbed, the fry refused to partake of
these, their supposed natural food, and preyed on each other instead.
Three or four days later, however, a few hundred fry held for experi-
mental purposes devoured these Crustacea greedily and throve upon
them as long as the supply was kept up. When cannibalism was at its
height 50 fry were placed in a tin pan, with myriads of Crustacea. In 10
minutes there were 6 cases of cannibalism. In each case one of the fry
seized the tail of another and swallowed all it could. Close watching
failed to discover any of these fry attempting to seize one of the Crus-
tacea. It was also discovered that neither the fry of the whitefish nor
of the ])ike perch, when later they began to feed on the Crustacea, would
touch a Diaptomns, although the most showy of all the Entomostraca
present and resembling very strongly the Cyclops, with which it is
closely related. Wben a hungry fry would, as if by accident, seize a
Biaptomus it would at once reject it and go about showing unmistak-
able signs of discomfort. Contrary to the general belief, the fry do not
always die from the effects of eating other fry. The swallowed portion
may be digested and the head and attached tissues finally rejected.
It has been customary to employ the same method in planting pike-
perch fry as in planting whitefish fry ; that is, the fry are dipped from
the fry tanks of the hatching battery into cans or kegs and transported
on a steamer to the points selected, where the cans are carefully
lowered into the water and the young fish allowed to swim out.
Toward the close of the season of 1899 an experiment was made of
carrying fry to the planting-grounds in a tank on board the steamer.
The tank held 400 gallons, and was therefore equal in capacity to
forty 10-gallon cans, but it was found in practice that a half more
fry could be carried in this way with a given amount of water than
in cans, as there was a continual stream going in through hose con-
nected with a deck pump and out through screened siphons, whereas
with cans some must stand while the water in others is being changed.
Moreover, it is imiiossible to get a maximum number of fry in each can,
so that some cans are carried with fewer fry than they should contain,
while experience soon taught how many could be safely handled in the
tank.
The fry were drawn from the fry tanks in the house direct to the tank
on the steamer through a 1-inch rubber hose, acting as a siphon, the
suction end being held near the air supply, where fry collect in largest
numbers. This required 10 to 15 minutes, while by the old method of
dipping the fry into tubs and then distributing them into the kegs on
board it would take more than an hour. This saving of time is very
174 REPORT OF COMMISSIONER OF FISir AND FISHERIES.
important when fry are Latching rapidly. Another advantage is that
by jiassing the liose about close to the bottom of the tank nearly all
the shells are removed with the fry, thus keeping the tanks compara-
tively clean. Examinations showed that the fry were not injured by
passing through the hose, whicli is also au advantage over dipping
them out with scoops.
On arriving at the field of planting, the fry and water are discharged
through a sectiou of hose about 10 feet long, leading from the bottom
of the tank. The steamer is kept at a slow speed at the time and the
transfer of the fry to the water is accomi)lished as gently at least as
would be the case in emptying them from kegs. Considerable time, as
well as much hard work, is saved by this plan, and so far there appears
to be no objectionable features in it.
USE OF SWAMP MUCK TO PREVENT ADHESION OF EGGS.
Many experiments have been made from time to time to determine
the best means to i)revent adhesion in the pike-perch eggs. This may
be accomidished by constantly stirring the eggs from the time the
water is added until it fills the egg and adhesion ceases; but this
causes loss of time and a large percentage of yolks will inevitably be
ruptured. Another method is to allow the eggs to agglutinate into a
mass and stand thus until fully hardened, afterwards sei)arating them
by gently rubbing them between the hands, but this also sacrifices time.
The date of the first use of foreign, inert substances to prevent adhesion
is uncertain. Fine clay dust and clay in solution have been used with
success and experiments with starch have given good results. By a
series of experiments with eggs taken in the vicinity of the station
from the boats of the fishermen, and from the penned fish as well, it
was found that the proper use of swamp muck obviates the difficulty,
with a great saving of time, labor, and eggs.
In the spring of 1895 finely divided, washed, and screened swamp
muck was tried at Put-in Bay and has been used ever since, and
recently with complete success, owing to a change in the method of
application. The plan pursued up to 1899 was to add muck to the
water in the kegs into which the eggs were poured after impregnation
and to wash them quickly. The washing was done quickly in order to
prevent adhesion. This was effective, but it involved the use of too
much muck, which was removed from the water with some difficulty,
and which smothered the eggs if left in too long in any quantity, and,
furthermore, it was difficult to get exactly the right (luantity of the
mixture. Careful experiments were therefore made in using the muck
in the pan immediately after impregnation had taken place and satis-
factory results were obtained. The eggs are allowed to stand in the
milt for about 10 minutes with sufficient water to barely cover them,
being carefully stirred once or twice meanwhile. Then a tablespoonful
of the muck mixture, of the consistency of thick cream, is added.
Next the pan is nearly filled with water and stirred thoroughly, when
MANUAL OF FISH-CULTURE. 175
it is left half iiii liour, or while aiiotlier pun is beiug filled. Without
moving pan No. 1 more than is necessary the surplus water is poured
oft", the pan again iilled, stirred, and left as before, while pan No. 2 is
treated like the first. If the boat rocks so as to endanger tlie safety
of the eggs it is better to pour them carefully into the keg and let
them stand there, keeping only about an iiudi of water over them and
pouring the water oft" and adding fresh water at intervals of not more
than half an hour.
The important point in preventing adhesion is to leave the eggs
alone until the particles of muck, or the spermatozoa, in case the eggs
are held in the milt without the addition of muck, have settled, and
then pour oft" the com])aratively clear water, adding a fresh supply
and then gently agitating the eggs. It will be observed that most of
the muck particles will have settled in one minute, the water becoming
measurably clear. If the eggs are held in the milt, the water being
very milky from the mixture, the water will become comparatively clear
in 3 or 4 minutes. This is because the spermatozoa are slightly heavier
than the water and settle to the bottom. In either case it is important
to retain the particles in the remaining water and eggs until adhesion
has ceased, in order to keep the eggs separated from each other, for
although the particles of muck or the spermatozoa, as the case may be,
are adherent, sticking to the surface of the egg, they are easily washed
oft", thus permitting the eggs to come into contact and become listened
together. Aside from the washing oft", the area of the egg membrane
becomes constantly greater, removing the particles farther and farther
from each other until finally the surfaces meet and adhesion takes place.
This will not occur if the muck particles or the milt are left in the egg
mass until adhesion has ceased or until the egg has become practically
filled with water — that is, has finished swelling.
The first great loss of eggs is owing to lack of impregnation, and the
second, shown by their turning white, is owing to the rupture of the
sac. While the eggs are soft and not cushioned by the absorption of
water, the greatest care possible will not prevent the rupture of a con-
siderable percentage of the sacs where the old method is pursued of
constant working to prevent adhesion. By holding the eggs in the
milt — which is better than the old way and requires less labor, but is not
to be compared with the muck process — or by using muck, with reason-
able care in all other directions, the loss is very slight, as has been
shown by careful experiments and counts.
Muck has proved far superior to starch or any other substance which
has been tried at the Put-in Bay Station, starch being prone to settle
into a hard mass among the eggs, requiring considerable work to again
dissolve it, with more or less injury to the eggs.
The preparation of the muck solution is very simple, but should be
carefully conducted, as follows:
At a suitable place in a swamp a depression is dug, which quickly
fills with water. Muck is now suspended in this water by thorough
176 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
beatiug and stirring until most of the muck particles are freely divided.
Care is taken not to get the mixture too thick, as the sand will not
settle out nor can the mixture be screened freely. This is poured
through a screen placed across a washtub until the tub is full, when
the debris is knocked off the top of the screen and another tub is filled.
The i^artially clear water is poured off of tub No. 1, it is again filled
with muck, and this is continued until there are a few quarts of muck
of the consistency of cream in the bottom of the tubs. The tubs are
next filled with water, which is agitated thoroughly, and then allowed
to stand a few seconds to give the jjarticles of sand time to settle.
The contents of the tubs are then emptied into kegs or cans, when the
water may be poured off in an hour or more. This leaves quite a thick
mixture of even consistency, as shown under the microscope. It should
be free from sand, which would collect in patches in the bottom of the
jars and interfere with the working of the eggs.
It is very necessary that the muck be now thoroughly cooked or
scalded, otherwise infusoria will develop on the eggs, causing much
inconvenience and some loss. Finally the muck is drained off, dried in
any desired form, and held ready for use. It should be prepared before
the egg-collecting season begins. The screen is about 20 inches by 30
inches and is made by tacking to a wooden frame a fine wire cloth of
40 meshes to an inch. The finest mesh that will let small particles of
muck through is best. The cloth is bagged down somewhat, with the
tack heads up, in order to present a smoother surface for the quick
cleaning of the screen.
PENNING FISH.
The plan of holding in pens adult fish taken prior to the spawning sea-
son has been tried with pike perch as well as with whitefish. This is
done to insure a sufficient and definite number of spawners, the collec-
tion of which during the spawning season is sometimes interfered with by
stormy weather or other causes. Contrary to what would be naturally
expected, the pike perch is much more difficult to handle in this way
than the whitefish, i)robably owing to the higher temperature of the
water at the time the work is carried on. Fewer can be transported in
the tanks on board of steamers and fewer can be held in the pens.
Where injuries have occurred fungus is apt to set in much earlier than
with the whitefish, and on this account excessive care is necessary in
handling pike perch, as well as to prevent injury to eggs in the ovaries.
While the male whitefish can be held and used over for two or three
days, the pike perch can be used but once, and when held for several
days, especially late in the season, the milt comes from the fish thick-
ened as if taken from a dead fish, and is far from being at its best.
However, this is true to a great extent with the fish taken fresh from
the nets late in the season. Females which do not "ripen" within two
or three days are likely not to furnish eggs at all, and if held even two or
three days late in the season are likely to yield eggs which will not hatch.
MANUAL OF FISH-CULTURE. 177
Pike perch are obtained in the same manner as the whitertsh, from
the pound nets of the tishermen. They are sometimes taken directly
into the tanks on board the steamer from the i)ound when it is raised,
bnt more often are dii)ped into supplemental nets by an employee of the
Commission, who accompanies the fishermen when thei)()und is lifted, and
are held until they can be picked up at leisure by the steamer. This
permits the gatheriug offish from many nets, while if they were taken
directly from the pound only one liftinjif boat can be followed at a tin)e
and (u)mparatively few fish collected. The snpj)lemenral nets are
placed at each pound net where fish are expected. They are 3 feet in
diameter and 7 feet in depth, and are held oi)en at top and bottom by
rings of half-inch iron, the bottoms being' provided with ])uckering-
striugs to close them. The top ring is fastened to the outhaul stake
and rim line of the pound, the lower one hanging free and acting as a
weight to hold the end in place, and also serving to keep the net open
so that the fish will have plenty of room and not be scaled by chafing
against the meshes. When thus located, the supplemental net is in a
convenient position for receiving the fish when the pound is lifted.
Kowboats transfer the fish in tubs to the steamer, where they are placed
in tanks and transported to the pens, where they are counted and
assorted according to their ripeness.
The pens or live-boxes used in the pike-perch work are the same as
those used for whitefish. Stationary live boxes, supported by piling,
have been used, but as the water at Put-in Bay becomes too warm for
this, the boxes are now made so that they can be towed, like a raft, into
open waters where the current is more vigorous and the temperature
more uniform. Another advantage gained by this method is that an
equal depth of water is maintained in the live boxes, the rise and fall
in this section varying from 4 to a feet in a single day, according to
the direction and velocity of the wind and the atmospheric pressure.
The boxes are 1<) feet long, 8 feet wide, and 8 feet deep, divided into
two ecpuil compartments 8 feet scjuare, provided with false bottoms
controlled by standards running in guides at the ends. The standards
are pierced by inch holes at intervals of (> inches, so that the false
bottoms may be held at any desired place.
The pens, in groups of five, are fastened end on between booms, and
the whole thus forms a raft. The booms are made of 4 by 8 hemlock
joists, 2 feet apart on the outside, trussed at frequent intervals by
diagonal cross braces and ties, on top of which are placed two tiers of
1-foot wide hemlock i)lanks, thus making the booms when completed
5-5 feet long, li feet wide, and 1 foot deep, and quite strong and rigid,
capable of withstanding seas of considerable violence. At eacli end
and between all the crates are placed 2-fo()t plank walks, giving ample
room for working on all sides, which is a great convenience in handling
fish and procuring eggs, especially iu stormy weather. The pens are
now made of boards .J inches wide, nailed 1^ inches ai)art, which gives
sufficient s[)ace for free circulation of water. The lumber is dressed
F. M. 12
178 REPORT OF COMMISSIONER OP FISH AND FISHERIES.
on all sides and all inside corners are ronnded, as tlie fish injure
their noses on square corners in their attempts to escape. All parts ot
the pens are interchangeable and easily taken down for storage, being
held in place by 4-inch log bolts. The pens are fastened to the booms
by log bolts 0 inches long.
Much depends on the work of transporting either whitetish or pike
perch from the nets to the pens, not only in moving the fish with the
least possible injury, but in the saving of time, so that greater numbers
may be penned and the risk of holding the fish in the supplemental
nets may be minimized. Tow cars have been used, but they retard the
speed of the steamer fully one-half, and tanks on the decks of the
steamers have therefore been adopted. It is better to have several
smaller tanks than one large one, as the fish can be dii)ped more readily
from the small tanks and the water is not so violently agitated during
rough weather. A convenient size is about G feet long, 4 feet wide, and
3 feet deep. The tank has two lids, submerged about an inch, arranged
to open crosswise of the center and held by lugs below and by pins
above. The lids are made of 3-inch boards nailed firmly upon cleats on
the upper side, with about :i-inch space intervening. This prevents
slopping in any weather when fish should be handled. The tank is
smooth and it has no obstructions inside. A 2-iuch hole at the bottom
at one end is provided for drawing off water, and one of the same size
within 3 inches of the top for an overflow, when fresh water is being
added. Fresh water must be furnished, varying as to the number of
fish. This can be supplied with a "donkey-pump," the hose being
carried from one tank to another as required. With three tanks of the
dimensions given above, six or seven hundred pike perch of average
size can be transported.
For coating these tanks inside, as well as all tanks and troughs about
the hatchery, coal tar with about one-third its bulk of good spirits of
turpentine, free from benzine, is applied as hot as it can be made.
This forms a smooth, hard, strong, impervious coat which lasts well,
and is cheaper than asphaltum varnish.
The use of a proper dip net in handling the fish is of great impor-
tance. The splitting of fins and removing of scales is to be avoided as
far as possible where any species of fish is to be penned. The scales
of the pike ])erch are not so easily abraded as those of the whitefish,
but it suffers even more as the result of injuries, owing to the higher
temperature of the water at the tiuie it is penned. The ideal net would
be made of cofferdam rubber of suitable thickness, perforated at fre-
quent intervals so as to permit the free discharge of the water — that is,
a rubber net — but where many are necessarily in use and subject to
rough handling, especially in freezing weather, their expense would be
considerable. The hoop of the net used at the Put in Bay station is of
'|inch spring steel wire, that being the stiffest and strongest material
obtainable of its weight. It is bent in the form of a parallelogram 22
inches long and 20 inches wide, with rounded corners. This is fastened
MANUAL OF FISH-CULTURE. 179
into an ash handle about (5 feet long. The bag is of cider-press cloth
(which is made of large, soft twisted thread, loosely woven), with each
alternate thread over a considerable space in the center of the net
pulled out. The bag is fastened to the hoop with small copper wire, as
twine is soon cut off in working around the nets and pens. The bag
of the net is 8 or 10 inches, for if much more is given it will let the lish
form a pocket against the wire and prevent an easy discharge.
Netting with a 1-inch mesh and large thread has proved to be a fail-
ure, the tails of many fish being split by it. It is believed that netting
with a very small mesh and the largest thread that can be woven will
do the work well, the greatest objection being the knots, which injure
tender species.
A frame made like a stretcher, with gunny cloth ta(;ked on in such a
manner as to bag about 2 feet, is convenient for holding flsli preparatory
to spawn-taking. It should be about 0 feet long and 3 feet wide, making
the bag 3 by 4 feet, with handles 1 foot long at each end.
A gate made of light stuff as long as the pens are wide (8 feet)
and L> feet deep, covered by ordinary netting drawn taut and fastened by
small staples, is useful in sorting the fish in the pens. The false bottom
is lifted and fastened in place with the pins. There will now be about
a foot of water over the floor and 1 foot of tlie top of the pen will be
out of water, lieginning at one side the gate is gently moved along until
the fish are all confined in a sufficiently restricted space. They are
sorted, the ripe fish placed in the "stretcher," preparatory to stripping
them, the medium in a tub to be taken to the proper pen, and the hard,
which it is assumed will be in the majority, are put back over the gate
into the same ])en they were taken from.
The pens are numbered and a careful memorandum kept of the fish,
the number of males and females received from and turned back to the
fishermen each day, the number stripped, and the number in each pen.
All unnecessary noise near the pens must be avoided, especially jars
or discharge of firearms, and no one should go near them except in
the ijerformance of duty. The quieter fish are kept and the less and the
more gently they are handled the greater the chances of procuring a
large number of good eggs, while the opposite course will cause many
"plugged" females and failure generally. In transferring the fish from
one net or receptacle to another it is preferable to handle only one at a
time, except when they are small.
Fish, particularly females, taken from a depth of from 30 to 35 feet,
often come to the surface of the water in the pens and can not descend,
owing to the expansion of air in the swimming bladder. The pressure
maybe relieved without injury by inserting a small-sized aspirating
needle, at an angle of about 45°, through the flesh of the fish into the
bladder, about halfway between the middle of the spinous dorsal and
the lateral line. The air can be heard escaping and when the sound
ceases the needle may be removed.
Fish Manual. (To face page 181 )
Plate 53.
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MISCELLANEOUS FRESH-WATER FISHES.
Besides the fresh-water and auadromous fishes considered in the fore-
going chapters, a number of others have been artificially cultivated,
including some species introduced from Europe. The special methods
of propagation already referred to are in general applicable to all fishes
of similar character, and need not be described again in detail.
MINOR TROUTS.
The different methods of hatching the eggs of the various members
of the salmon family are practically interchangeable, so that in con-
sidering the following species it is not necessary to dwell again on
fish-cultural processes.
Several varieties of tlie black-spotted trout {SaJmo mykiss) are artifi-
cially propagated. This fish is somewhat similar to the European sea
trout or salmon trout {Salmo trutta) and in parts of its range has the
same half-migratory habits. It is widely distributed, very abundant,
and subject to great variation in color and structure. It is found from
Alaska to Mexico in the streams of the Coast Range, Sierra Nevada, and
Rocky Mountains, and in some lakes in the same regions. It attains a
weight of over 30 pounds, although the average is, of course, much less.
Among the varieties whose eggs have been artificially hatched are
the Lake Tahoe trout or Truckee trout {Salmo myl"iss hen.shaivi), which is
extensively propagated by the California Fish Commission at hatcheries
on Lake Tahoe; the Colorado River tront {Salmo mykiss pleuriticus),
and the yellow-fin trout {Salmo mykiss macdonaldi), both of which are
cultivated by the U. S. Fish Commission at its station at Leadville,
Colorado. All of these species are handsome game and food fishes.
In the vicinity of Leadville the spawning season extends from May 1
to July 15. The eggs are hatched in the same troughs and under the
same conditions as those of the brook and rainbow trouts. In water
ranging from 42° to 00° and averaging about 52° F., the eye-spots
appear in 20 days and hatching ensues in 30 to 45 days.
The Scotch lake trout, or Loch Leven tvoxit {Salmo trutta levenensis),
and the European brown trout or brook trout, or Von Behr trout {Salmo
fario), were introduced by the Fish Commission a number of years ago,
and have been widely distributed in the United States. They are now
propagated in many States from eggs taken from brood fish retained
in ponds. At Northville the spawning season of these fish is the same
181
182 REPORT OF (X)MMISSIONKR OF FISH AND FISHERIES.
as tliat of the brook tiout. Tbeir <'jj;g\s are somewhat larger than those
of llie latter tish, but tliey are handled in the same way, the i)rogress
of incubation is similar, and the fry are fed on the same materials.
Small numbers of the European sea trout or salmon trout {Sahno
trutta) have also been propagated at Craig Brook and other stations,
and have been reared to full maturity in ponds. The Swiss lake trout
of Lake Geneva (Salmo lemaiiiifi) has been sparingly propagated in the
United States and has been introdu(;ed into some of the Adirondack
lakes and other suitable waters.
The European charr or saibling {Salvelinus alpinus) has been propa-
gated on a small scale from eggs taken from pond fish, which in turn
were hatched from eggs sent from Switzerland. This species is similar
to the brook trout and other native charrs, and its eggs are subjected
to the same methods.
The representative of the saibling found in certain New England
lakes, known as the Sunapee trout or golden trout {Salvelinus alpinus
aureolus), has also received some attention from fish-culturists.
Argyrosomcs aktedi, Lake Herring, Cisco.
THE LAKE HERRING AND OTHER WHITEFISHES.
While the common whiteflsh is the only member of the tribe that has
received much attention from fish-culturists, it is probable that several
other species of whiteflsh will in time be extensively propagated. The
lake herring [Argyrosomus artedi) has already been artificially hatched
to a limited extent at Put-in Bay station, and the long-jaw or bloater
(Argyrosomus 2)rognathus), the bluefin or blackfln (^1. nigripinnis), the
tullibee {A. tiillibee), and others will doubtless become the subjects of
fish-cultural work in certain lakes. The eggs of all these fish can be
hatched by the same methods as are used with the common whiteflsh,
but the spawning seasons differ.
The lake herring is readily distinguished from the common whiteflsh
by its smaller size, projecting lower jaw, long and numerous gillrakers.
MANTTAL OF FISH-CULTURE. 183
absence of arch on back, etc. It is the most abundant of the white-
fishes, being- especially numerous in lakes Erie, Michigan, and Huron,
and larger quantities are taken each year than of all other species
combined. The average length is lli to 14 inches and the average
weight is under a pound, although a maximum weight of 3 or 4 pounds
is attained. The tish is generally known as " herring " but has numer-
ous other names, among which are cisco, blueback herring, greenback
herring, grayback herring, and Michigan herring.
The spawning season of the lake herring begins somewhat later and
terminates sooner than that of the whitefish. The eggs are procured
and hatched in the same manner as are those of C. clupeiformis, and
recjuire about the same time for incubation, namely, 4 to 5 months,
depending on the temperature of the water. The eggs are smaller than
those of the common whitetish, 70,000 making a fluid quart.
These two species are readily hybridized artificially. The milt of
either species will impregnate the eggs of the other as effectively as if
there were no cross fertilization. Large specimens of apparently hybrid
fish of this character have been obtained in Lake Erie. The use of
milt of the lake herring for impregnating whitefish eggs is resorted to
only when the eggs would otherwise be lost.
The round whitefish or menominee {Corecjonus quadrilateralis) is
propagated by the New York Fish Commission. It is very widely
distributed, ranging from New Brunswick to Alaska, and is abundant
in some of the Adirondack lakes, where its eggs are taker, and hatched
in comparatively large numbers. It rarely exceeds a pound in weight,
but its food qualities are good, and it is taken for market in considerable
quantities in lakes Huron and Michigan.
In the New York lakes, where the fish is known as the frostfish, the
spawning season is from the middle of November to the early part of
January, although the period in any one lake is less prolonged. The
eggs are buoyant, nonadhesive, and ^ inch in diameter; the average ])er
tish is 3,.")00, but 12,000 have been taken from a If-pound fish. In the
very cold water of these lakes the incubation is protracted, being 150
days with the water at 33<^ F. The sac is absorbed in 10 to 20 days.
THE MUSKELLUNGE.
The muskellunge {Lucius masquinongy) is the larget^t representative
of the pike family. Its maximum weight is about 80 pounds and its
average weight 2."i or 30 ])onnds. Its range includes the Great Lakes,
Upper Mississippi Valley, Ohio Valley, and lakes in Wisconsin, Minne-
sota, New York, Ontario, and elsewhere. It is much sought by anglers
and is of some value as a food fish. Being provided with a very large
month, armed with strong, formidable teeth, its food consists chiefiy of
living fish, which it cai)tures by making sudden darts from its place of
concealment among the water plants at the bottom of a lake or stream.
This fish is artificially propagated by the New York Fish Commission
at Chautauqua Lake. Upward of 3,000,000 fry are sometimes hatched
184 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
in a year. The eggs are taken from fish caught in the lake, and are
luitched in submerged boxes, provided with double wire-mesh tops and
bottoms. Tlie eggs are simihir to whitefish eggs, being semibuoyant
and nonadhesive. A 30i-pound fish has been known to have ovaries
weighing 5 pounds, and a 35-pound fish has yielded 205,000 ripe eggs.
Spawning takes place in May, in shallow, grassy places. The eggs
are about ^ of an inch in diameter and number 74,000 to the quart.
About 1)7 per cent of the eggs impregnated are hatched. With the
water temperature at 55° F., hatching ensues in 15 days, the yolk-sac
being absorbed in the same time. The fry are very helpless when first
hatched.
Owing to the extremely voracious habits of the muskellunge, great
caution should be exercised in distributing the fry, which should, as
a general i)ractice, be placed only in those waters in which the fish
already exists.
THE YELLOW PERCH.
The yellow perch {Perca flavescens)^ known also as ring perch, striped
perch, and raccoon perch, is one of the most strikingly marked and best
known fresh- water fishes of the Atlantic and North-central States. It
is commonly regarded as the type of the spiny-rayed fishes and in some
systems of classification is given the first place among fishes.
The general body color is golden yellow, the back being greenish and
the belly pale; six or eight broad verti: al blackish bars extend from the
back nearly to the median line of abdomen; the lower fins are largely
bright red or orange, most highly colored in the breeding male; the dor-
sal fins are dull greenish. The body is elongated, back arched, mouth
large and provided with bands of teeth on jaws, vomer, and palate.
It is Ibund from Nova Scotia to North Carolina in coastwise waters,
throughout the Great Lakes, and in the Upper Mississippi Valley, and
in most parts of its range is very abundant. Through the eftbrts of
the Commission it has been very successfully introduced into lakes
in California, Washington, and other Western States, and is now met
with regularly in the markets of some of the cities of that region.
The usual length of the yellow perch is less than 10 inches, and its
average weight is under a pouiul. It is a food fish of fair (luality, and is
taken for market in very large (juantities annually in the Middle States
and Great Lakes, fyke nets, gill nets, seines, traps, and lines being used.
The value of the output is over $300,000 yearly, more than a third of
which sura represents the fishery in the Great Lakes. It bites readily
at the baited hook and is caught in large quantities by anglers.
Artificial propagation, in the full sense of the term, has not been
attempted with the yellow perch. The eggs have neither been artifi
cially taken nor artificially im])regnated, but the brood fish have been
impounded and their naturally fertilized eggs hatched. The extent to
which this modified cultivation of yellow perch may be carried on in
the coast rivers, in the Great Lakes, and elsewhere is almost limitless.
MANUAL OF FISH-CULTURE.
185
The fish is so {ibniuhuit, however, juul the suijply so well iiuiintiiined
that fish-cultural work in its behalf is not now generally required.
This fish spawns in late winter and early spring in the fresh waters
of the coast rivers and in the Great Lakes. In the Potomac liiver
spawning- takes place in February, March, and Apiil. The water tem-
|)erature at which spawning- begins is about 44° F., while 49° seems to
mark the maximum limit. This narrow range of temperature which
bounds the spawning act is somewhat noteworthy.
Ovary of a yellow perch with nearly ripe eggs, the lurked
extremity being the anterior part of the roe.
The eggs of the yellow perch are among the most remarkable that have
been artificially hatched. The spawn is in one piece, a much elongated
ribbon-like structure, of a semitransparent light-grayish color. One
end of the large egg mass, corresponding to the anterior part of the roe,
is larger than the other, and is bluntly forked. The string is very long,
Part of a receutly-laid mass of yellow perch eggs.
but may be much compressed lengthwise by virtue of its arrangement
in regular transverse folds like the sides of a bellows or accordeon.
When deposited the eggs are iu a loose globular form, and after being
fertilized and becoming "water-hard" their mass rapidly becomes many
times larger than the fish which laid them. The length of the strings
is from 2 to more than 7 feet, dei)ending on the size of the fish. One
186 REPORT OP COMMISSIONER OF FISH AND FISHERIES.
fish in ail a([uaiium at Wasliiugton deposited a striiij;' of eggs 88 inches
long, 4 inches wide at one end and 2 at the other, whose weight after
fertilization was 41 ounces avoirdupois, while the weight of the fish
before the escape of the eggs was only 24 ounces.
A cavity extends the whole length of the egg mass, its walls being
formed by the delicate membrane in which the eggs are imbedded. The
cavity is almost closed, small apertures occurring irregularly, which
have the appearance of being accidental, but may be natural, m order
to permit the circulation of water on the inside of the mass.
The egg-string is quite light and resilient or si)ringy, the least agita-
tion of the water causing a quivering motion of the whole mass.
The diameter of the egg is 1-3- inch. The quantity can not be easily
measured, but the number is approximately 28,000 to a quart.
The best method of securing the spawn is to place mature fish of
both sexes in suitable tanks with running water. The females selected
should be those whose external appearance indicates that the eggs
are still undeposited. Spawning takes place at night, and the eggs are
naturally fertilized. Under proper conditions, it is the exception to
find unfertilized eggs. In the morning the eggs are transferred to the
hatching apparatus.
The eggs of this fish have been hatched at diflerent stations of the
Commission. One season, at Central Station, Washington, D. C, 130
ripening females and about an equal number of males taken from the
Potomac were placed in aquarium tanks supplied with water from the
city water- works. Spawning began March 10 and continued till April 3,
and 98 strings, containing nearly 1,000,000 eggs, were deposited.
The eggs are hatched in the automatic shad jar, provided with a cap
of fine-meshed wire netting; the usual inflow tube is retained, but the
siphon tube is withdrawn, the water escaping over the top of the jar.
The amount of water circulation is not great enough to force the mass
of eggs to the upper part of the jar or to give much motion to them.
They are lighter than shad or whitefish eggs, and when i)ut in rapid
motion to dislodge adhering sediment they would clog the outlet tube
if the ordinary method of manipulating this jar were employed.
The eggs from several fish may be placed in one jar. They perhaps
need as little care as any eggs handled by fish-culturists. When one
string of eggs or one lobe of a string dies it may be removed with a
small net, or the entire contents of the jar may be turned into a pan.
The period of hatching varies from two to four weeks, according to
the temperature. As the fry hatch, they pass over into tanks provided
with screened overflows, where they are held till planted. The fry are
very hardy, and may be readily retained in aquaria for several weeks.
The percentage of eggs hatched is large. From one lot of 955,000,
754,000 fry, or 79 per cent, were produced.
MANUAL OF FISH-CULTURE. 187
THE STRIPED BASS AND THE WHITE PERCH.
The striped bass, or rocktish {Roccus lineatus), ranges from ^ew
Brunswick to western Florida. It is especially abundant from New
York to North Carolina, and is taken m large (jnantities for market, by
means of seines, gill nets, pound nets, and lines, on the coast and in
the bays, sonnds, and rivers. It is one of the best food-fishes of
American waters. The annual valne of the catch is about $300,000.
Through the efforts of the Commission, this flsh has been introduced
into the waters of California, where it has become very abundant; it
occurs along almost the entire coast of that State, but is most numerous
in iSan Francisco Bay and tributaries. It supports a special fishery,
and the estimated catch in 1897 was about 1,000,000 pounds. It meets
with ready sale, and is one of the most popular fishes of the west coast.
The striped bass attains a weight of over 100 ])ouiids; examples
weighing 50 to 75 pounds are not uncommon ; but the usual size of those
taken for market is 3 to 20 ])ounds. Its form, size, and markings make
it readily distinguishable from other fishes. The color of the body
is light silvery-green above, white below, with seven or eight blackish
stripes along the sides.
The striped bass passes most of its time in salt water, but in spring
ascends the rivers to spawn. Important spawning-grounds are the
tributaries of Albemarle Sound, Chesapeake Bay, Delaware Bay, and
New York Bay. The eggs are sometimes deposited quite near the ocean,
in brackish or salt water. The number that may be deposited by a
single fish is immense; a fish weighing only lli i)ounds, caught at the
mouth of the Susquehanna Kiver, in May, 1897, yielded 1,280,000 good
eggs.
The commercial imi^ortance of the striped bass and its comparative
scarcity in some waters in which it formerly abounded make its culti-
vation very desirable, and its eggs have been artificially impregnated
and hatched on several o(;casions; but difficulty has been experienced
in finding a locality where ripe eggs can be regularly taken in large
quantities. The eggs are free, transparent, and semi-buoyant, about
I of an inch in diameter, and have a very large oil-globule. In quiet
water they gradually sink to the bottom of a vessel and remain there,
but a very slight agitation of the water causes them to rise and remain
in suspension for some time. The nuuiber in a quart is about 24,000.
The automatic batching-jar is adapted to hatching the eggs of this
fish. At a mean temperature of 58° F., the hatching period is about
74 hours. A large oil-globule in the anterior part of the yolk-sac causes
the younger fry to assume a perpendicular position, with the head toward
the surface of the water.
The white perch [Morone americana) belongs to the same family as
the striped bass, and closely resembles it in range and habits; but it
is much smaller and less valuable commercially, although one of the
188 REPORT OP COMMISSIONER OP" FISH AND FISHERIES,
choicest of pan fishes. Its eggs are deposited about the same time and
in the same places as those of striped bass and are susceptible of the
same methods of hatching. Kipe fish are frequently taken in shad
seines. The average yield of eggs per fish is about 40,000. The period
of incubation is like that of the striped bass.
THE ALEWIVES OR RIVER HERRINGS.
The alewives or river herrings have the appearance of being small-
sized shad, but on close inspection will be seen to have characters which
entitle tliem to generic distinction. From the shad {Alosa) they differ
chiefly in having the cheeks longer than deep, fewer and shorter gill-
rakers, and no notch at the tip of the upper jaw. They also closely
resemble the common sea herring {Clupea), but may be distinguished
from it by the absence of teeth on the vomer, by a less elongate body,
and by much stronger scutes or ])lates along the ventral edge of the
body. The two species of alewives so closely resemble each other that
they are often confounded by fishermen.
The branch herring {Pomolohns pseudoharengus), also known as the
branch alewife, gaspereau, wall-eyed herring, etc., has a rather deep
and compressed body (the depth being contained 3.^ times in length),
a large eye, and a pale or gray membrane (peritoneum) lining the
abdominal cavity. The glut herring {Pomolohns (cstivalis), also called
blueback, sawbelly, kyack, summer herring, etc., has a more elongate
body, smaller eye, lower fins, and a dark or black peritoneum.
The alewives are the most abundant food-fishes of the east coast
rivers and rank next to the shad in commercial value among the
anadromous fishes of the Eastern States. Both species range along
the entire Atlantic coast of the United States, but the glut herring is
more numerous southward and the branch herring is more important
in New England. The average weight of each species is one-third to
two-fifths of a pound. The maximum is only half a pound. The age
at maturity is three or four years.
There is an alewife fishery in every coast State from Maine to Florida,
but two-thirds of the catch is taken in Maryland, Virginia, and North
Carolina, Chesapeake Bay and Albemarle Sound being the chief cen-
ters of abundance. The total output in 1896 was 62,060,622 pounds,
having a value of -$459,598. These fish usually go in large schools or
bodies, which are often of immense size. Many hundred thousand
have frequently been taken at a single seine haul, and they have at
times been so abundant in North Carolina and elsewhere as to crowd
out shad and other fish and cause a suspension of shad fishing.
Besides furnishing food for man, in a fresh, pickled, and smoked con-
dition, alewives are consumed in large quantities by other food-fishes,
especially in salt water, and are extensively utilized as bait in the
important line fisheries of New England.
The annual migration of the alewives from the ocean to the fresh-
MANUAL OF FISH-CULTURE. 189
water rivers is wholly for the purpose of spawning. The time of their
arrival in a given place is quite constant from year to year. The
branch alewife preciedes the summer alewife by three or four weeks,
and also arrives several weeks before the shad. The run of the glut
herring occurs during the middle of the shad season. The branch
herring ascends the small streams to spawn, often entering branches
only 10 feet wide and not more than G inches deej). After spawning,
very little is known of the habits of the fish or of the departure from
the rivers; nor has their winter abode been ascertained.
The eggs resemble those of the sea herring rather than of the shad,
being glutinous and adhering to brush, stones, piling, and other
objects under water. The netting, ropes, and stakes of traps in which
the fish are caught are often covered with the fertilized eggs; the ale-
wives thus have a great advantage over the shad, and to this fact
must largely be attributed the continuance of the supply in the face of
very extensive fishing not counteracted by artificial proi)agation. The
eggs are about -g^,- inch in diameter.
There has been no eftbrt to regularly hatch the eggs of ale wives
artificially. The undiminished abundance of these fish in the regions
of the most extensive fisheries has made their artificial propagation
unnecessary. In the ISTew England States, where the alewife is an
important fish in many of the smaller towns, the supply has been
maintained by constructing fishways which permit the fish to reach
their spawning-grounds. In this way comparatively small streams have
annually yielded very large quantities of fish, and many streams, in
which the alewife run had been entirely inhibited by obstructions, have
been reopened and very successfully restocked.
As early as 1871 the eggs of the alewife were artificially fertilized
and hatched, and those of the branch herring were similarly treated in
1877. Their cultivation presents no S})ecial difficulties, and can be
prosecuted on a large scale whenev^er it becomes necessary. The milt
is first taken in a pan, and then, while one person keeps the pan in
motion, another expresses the eggs; this prevents the eggs from mat-
ting together and facilitates the contact of all with the milt. Eggs
adhering to the side of the pan may be removed with a stream of water.
The automatic shad jar is the proper apparatus in which to hatch the
eggs, which are treated precisely like those of the shad. Sufficient
water is supplied to keep them moving freely and to overcome adhesion.
The alewives are much more prolific than either the shad or the sea
herring. On one occasion, in the Potomac Kiver, Oil female branch
herring yielded 60,206,000 eggs, an average of 102,800 per fish. Prob-
ably 100,000 may be taken as a fair average. The eggs hatch quite
quickly under normal conditions. The period of incubation, in water
having a mean temperature of 00° F., is 6 days. The fry are very
minute. They are planted at the same time and in the same manner
as shad fry. Those in the rivers and lakes attain a length of 2 to 3
inches by the time they move toward salt water in the fall.
190 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
THE SMELT.
This fish ( Osmerus mordcu) is ])ropiigate(l by the New York Fish Com-
mission at its station at Cold Spring Harbor, Long Island. As a food-
fish, it is held in liigh esteem, the flesh being delicate and of excellent
flavor. Its range is from Maine to Virginia, on the United States coast.
It is of economic importance in all the States between New York and
Maine, but is taken for market in largest (juantities in Maine. The
average length of those sold is 0 to 9 inches, and their weight from 2 to
4 ounces. The fish enters the fresh- water rivers in fall and winter for
the purpose of spawning and feeding and is then caught with lines and
nets. The annual catch is about 1,700,000 pounds, valued at $125,000.
The smelt spawns in spring, in either fresh or brackish water of
rivers or brooks. The eggs, which are adhesive, are attached to stones,
weeds, sticks, or other objects.
The results of smelt propagation on Long Island have been quite
marked; not only has there been a large increase in the catch, but the
fish have appeared in streams where they were previously unknown.
The return of mature fish apparently artificially hatched has permitted
the taking of many more eggs than was at first possible. In a stream
previously destitute of smelts, in which fry were planted in 1885, nearly
32,000,000 eggs were collected in 1894.
The eggs are 0.05 inch in diameter and number 406,000 to the fluid
quart. Smelt weighing only 2 ounces yield from 46,000 to 50,000 eggs.
Some fish only 3 or 4 inches long are full of spawn.
The fish-cultural work with this species is similar to that with the
yellow perch and flatfish. The spawning fish, of both sexes, are placed
in troughs, which are covered to exclude light. The eggs are naturally
laid and fertilized, and become attached to each other and to the
troughs. They are scooped up with a flat shovel, placed on wire trays
in water, and are forced through the meshes of the trays to separate
them, the o])eration being repeated if they are not sufficiently separated
at first. They are then transferred to automatic shad jars, blanketed
to exclude light, which is very injurious to them. If during hatching
the eggs form into bunches, they are removed from the jars and again
passed through the meshes of the wire trays.
THE GOLDEN IDE.
This fish, known as the golden ide or orfe (Idus idus), has been
introduced into the United States from Europe by this Commission.
Although a food-fish of fair quality, it is seldom eaten in this country,
but is chiefly used for ornamental purposes. Its usual length is about
a foot and its weight 1 pound. It is a very showy fish, being of a uni-
form reddish-golden or silvery color. The small, weak mouth restricts
the character of the natural food to vegetable and diminutive animal
substances.
The fish is reared in ponds, like carp, tench, and other similar species.
The ponds should be 3 or 4 feet deep, with either spring or running
MANUAL OF FISH-CULTURE. 191
water, and must have a very abundant growth of myriophyllum or
other water jdants. In the latitude of Washington, D. C, spawning
takes place in April. The fish makes no nest, but de])Osits its egga on
water-plants, gravel, stones, and other substances. The eggs being
adhesive, like those of most cyprinoid fishes, become attached as soon
as ejected, and so remain until hatched. The eggs are about ,^r i»ch in
diameter. They are extremely tender, and it is important that at the
time of spawning the water be of an even temperature.
Under favorable conditions the eggs develop rai)idly, and at a mean
tem])erature of 5G^ F. hatch in 5 or G days. In suitable ponds, with
plenty of shade ami a healthy growth of plants, the natural food that
the fry will secure renders artificial feeding unnecessary for a month or
more. After the fifth or sixth week the young may be given small
quantities of cooked corn-meal mixed with flour. They take finely
divided fish flesh, bivalves, and crayfish, but the main dependence
should be on the corn meal flour mixture.
At the end of six months the young have attained a length of 3 inches,
and in a year are 6 inches long. Maturity is attained at an age of 3
years.
THE STURGEONS.
There are six species of sturgeon in the waters of the United States.
The common and the short-nose sturgeons {Acipenser stnrio and A.
brevirostris) are found only on the Atlantic Coast, ascendnig rivers to
spawn. The white sturgeon and green sturgeon {A. transmontanns and
A. medirostrh) inhabit only the waters of the Pacific Coast. The lake
sturgeon or rock sturgeon [A. nihicundus) exists in the Great Lakes, the
Upper Mississippi Valley, and other northern interior waters. The
shovel-nose sturgeon or white sturgeon {Scaphirhynchus phityrhynchus)
is found in the Mississippi and other streams of the Southern and
Western States.
While all of the sturgeons are edible and caught for market, the
most valuable species are the common sturgeon and the lake sturgeon,
which alone have been artificially propagated.
The catching of sturgeon for market is a business of comparatively
recent origin. A few years ago enormous numbers were annually killed
and thrown away by salmon, shad, and whitefish fishermen, to whom they
were of no value. The special apparatus employed in taking sturgeon
consists of gill nets and set lines, but many are caught in pound nets,
seines, etc., set i)rimarily for other fish, Tlie principal fisheries are in
the Great Lakes, Delaware River, and Sacramento Kiver. The present
yearly value of the yield is about $3()(),()()0. Very important secondary
products are derived from the sturgeon, namely, caviar, isinglass, and oil.
The sturgeon fishery is declining, and affords a remarkable illustra-
tion of the comparative facility with which the supply of river and lake
fishes may be exhausted by indiscriminate fishing. In some localities
the change in the sturgeon fishery within a single decade has been from
a condition of great abundance, with little appreciation of the value of
192 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
the fish, to active prosecution of the fishery without regard to season,
age, or spawning state, resulting in practical extermination and the
8usi>ension of fishing operations. Considering the entire country, it is
estimated that during the past decade the decrease in the sturgeon
catcli has been 60 to 80 per cent. Much of the decline in some places
is attributable to the destruction of the young, which linger near the
mouths of rivers and, becoming entrapped in nets and pounds, have been
killed on account of the annoyance caused the fishermen.
The common sturgeon of the Atlantic Coast attains a weight of over
500 pounds, but the average in recent years is not more than 150 pounds.
The lake sturgeon reaches a weight of about 200 pounds; the average
at the present time is 60 pounds. The known maximum weight of the
Pacific white sturgeon is 848 pounds, and those weighing 500 pounds
or more were not rare in the Columbia River some years ago, when the
average weight was fully 150 pounds; but at present, as well as in the
Sacramento River, the average is much less.
The spawning time of the sturgeon is spring and summer. When
fully mature, the ova constitute from 20 to 30 per cent of the total
weight of the female. When ripe, the eggs are free from the ovarian
walls and lie loose in the abdominal cavity. The number of eggs pro-
duced by the common Atlantic sturgeon is from 1,000,000 to 2,500,000.
The spawning of the anadromous species takes place in either the fresh
or brackish waters of the streams. The lake sturgeon prefers rocky
ledges near the sliores of lakes. When deposited naturally the eggs
soon become glutinous and adhere to sticks, weeds, brush, and other
objects. The diameter of the egg is ^ inch.
The cultnre of the sturgeon has not been systematically carried on in
the United States or Canada, although the time seems opportune for
rendering aid to nature in order to keep up the supply. Experimental
work indicates that there are no insurmountable obstacles in the way
of extensive artificial propagation, although the work presents some
unusual difticulties.
One of the drawbacks met with in the Atlantic rivers is that of
obtaining ripe male and female fish simultaneously. The important
fact has been determined, however, that both eggs and milt may be
cut from live or recently killed fish and fertilization be thus successfully
ac(*omi)lished. In order to secure the milt, pieces of testes may be
obtained and the milt squeezed therefrom through a coarse cloth.
A large proportion of the females taken at the fishing centers are
not ready to spawn when caught, and their retention in the crude pens
used by the fishermen, together with the rough handling they receive,
appears to render their eggs incapable of fertilization. The successful
penning of the fish pending the ripening of the eggs and milt would
greatly add to the success of this work, as the spawning season in a
given place usually extends over a number of weeks.
The glutinous nature of the sturgeon's egg has been a drawback in
the propagation experiments heretofore conducted. The eggs become
MANUAL OF FISH CULTURE. 193
viscid in about 20 minutes after fertilization and stick together in
masses of various sizes. This interferes with their aeration, lowers the
vitality, and leads to the attack of fungus. The practice heretofore
adopted foi" overcoming this condition has been either to spread the eggs
in very thin layers on the hatching trays prior to the development of
the adhesive quality, so that after becoming fixed they would be proi)erly
aerated, or to stir them continuously for several hours in order to over-
come their adhesiveness. The high degree of success attending the
hatching of the glutinous eggs of the flatfish and the wall-eyed pike
indicates that the difficulty encountered with the similar sturgeon egg
may be readily overcome. By gently stirring recently fertilized eggs
with a mixture of dry cornstarch and water or fine swamp muck and
water, the tendency of tbe eggs to stick together and to other objects
is avoided through the partial coating of the individual eggs with
particles of starch or dirt. Other substances that will remain suspended
and not be dissolved in water can doubtless be employed to advantage.
Swamp muck is probably the best, because cheapest and most easily
obtained; 2 quarts of it may be mixed with 10 gallons of water, which
will be sufficient to render non-glutinous about 3 gallons of eggs; the
same proportion of water, eggs, and cornstarch is recommended. After
being transferred to the hatching station, the eggs may be placed under
running water and the superfluous foreign particles washed away before
being placed in the hatching apparatus.
The apparatus used in hatching sturgeon eggs has been chiefly boxes
placed in the open water of the river. The glutinosity being overcome,
there seems no reason why hatching may not be conducted in the auto-
matic shad jar or in other modern appliances.
In the experimental hatching operations many eggs have been lost
through attacks of fungus, induced by the character of the apparatus
employed. The use of floating boxes in open water has led to the loss
of eggs by storms, rough water, and sudden changes of temperature.
The incubation period is about 7 days in water having a temperature
of 62° to 60° F. The outline of the fish appears in 48 hours.
The question as to whether eggs of the common sturgeon can best
be hatched in fresh or brackish water is not yet determined, but the
indications are that brackish water is preferable. One reason is that
the eggs are less liable to attacks of fungus in such water.
An attempt to rear artificially hatched sturgeon at Northville was
unsuccessful, owing to the failure of the young to eat. The mouth of
the sturgeon fry is very small, and the food is largely of a microscopic
character, consisting of unicellular algjc, infusoria, insect larva3, etc.
In Euroi)e, where the sturgeon fisheries are vastly more important than
in America, the results of experiments in sturgeon-culture have scarcely
been as satisfactory as in this country. No method of separating gluti-
nous eggs except by stirring seems to have been devised, and the same
difliculty has been found in obtaining fish with ripe spawn and milt.
The retention of fish in inclosures has not generally been successful.
F. M. 13
Fish Manual. (^To face page 1 95.)
Plate 54.
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THE COD.
DESCRIPTION OF THE FISH.
The body of the cod is moderately long, compressed and tapering
behind; the greatest depth is about one-fourth its length. The large
head is narrowed anteriorly and is contained 3^ to 4i times in the
body length. The mouth is large; the lower jaw is included within
the upper when the mouth is closed; the maxillary extends to about
middle of eye. The diameter of the eye is about half the length of the
snout and one-fifth that of the head. There is a conspicuous barbel on
the chin The number of dorsal tins is 3 and of anal fins 2; the
dorsal rays are usually about 14, 21, and 19 in the respective fins, and
the anal rays are 20 and 18. The ventral fins are well developed, with
about 7 rays. The cycloid scales, with which tbe body is covered, are
very small. The air-bladder is large and thick. The color varies
greatly, depending on food, kind of bottom on which found, and other
conditions. Fish taken offshore in deep water are usually olivaceous
on the back and whitish b(Mie;itb ; the so-called rock cod, found in shoaler
water among rocks and kelp, vary in color from green to deep red. The
back and sides are covered with small, round, reddish-brown spots.
The lateral line is conspicuous, of a whitish color. The fins are dark.
From other species of the family, taken in the same waters, the cod
is readily distinguished. From the haddock it differs in having a pale,
instead of a black, lateral line; in its spots (absent in the haddock),
and in its larger maxillary bone, which reaches past the eye, while in
the haddock this bone does not extend to the eye. The features dis-
tinguishing the pollock from the cod are the smaller size, the projecting
lower jaw, the uniform coloration above, the sharp snout, the smaller
barbel, etc. Tiie hakes have only 1 anal and 2 dorsal fins, a filamentous
prolongation of the first dorsal ray, and a ventral tin consisting of two
or three very long filamentous rays.
The status of the cod of the North Pacitic Ocean is somewhat uncer
tain. It has generally been considered identical with the Atlantic
species, but its smaller air-bladder and other features may entitle it to
recognition as a distinct species.
RANGE, MOVEMENTS, FOOD, ETC.
Cod are widely distributed in the North Atlantic Ocean. To the
north they range far beyond the Arctic Cir(;le, and to the south as far
as Cape Uatteras, although they are not common south of New Jersey.
195
196 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
The cod of the North Pacific Oceau is found from Bering Sea south to
Oregon and Japan.
The movements of cod are not well understood. They go in schools,
but in much less dense bodies than do mackerel, herring, and men-
haden, and wlien moving from one ground to another they are in more
compact schools than when on the feeding-grounds The movements
on and off shore and from bank to bank are due to several causes,
among which are the ett'ects of water temperature, the presence or
absence of food, and the spawning instinct. In the winter months
there is a well-marked movement of large bodies of codfish to the
shores of the New England and Middle States, and important fisheries
are there carried on in regions from which cod are absent at other
times. This movement seems to be chiefly for the purpose of finding
shallow grounds for spawning. That the cod sometimes makes very
long journeys is shown by their capture on the New England coast
with pecnlia-r hooks in their bodies which have been identified as
similar to the hooks employed by the French cod fishermen on the
Grand Banks.
Although sometimes found in shallow water, cod are essentially deep-
water fish, preferring water from 20 to 70 fathoms deep and being
found even at a depth of 300 fathoms. Those caught for market are
usually taken at depths of 20 to 40 fathoms.
The cod takes its food on the bottom, at the surface, or at intermediate
points. It is an omnivorous and extremely voracious feeder, consuming
all marine animals of suitable size. Favorite articles are bivalve
mollusks, crabs, lobsters, starfish, and fish. Among the fish consumed
in large quantities are capelin, lant, herring, alewives, menhaden,
mackerel, and haddock, although many others are also eaten. The
abundance and movements of such fish have an imi)ortant relation to
the presence and abundance of cod in a given region.
WEIGHT AND GROWTH OF COD.
The largest cod recorded from New England waters weighed 211^
pounds and was over 6 feet long; it was taken on a trawl off the
northern Massachusetts coast in May, 1895. The capture of a number
weighing from 100 to 175 pounds could be cited, but those exceeding 100
pounds in weight are by no means common, and even 75-pound cod are
not numerous. The average weight of the large-size cod caught in the
shore waters of New England is about 35 pounds; on Georges Bank,
25 pounds; on the Grand Banks and other eastern grounds, 20 pounds;
the average weight of the small-size fish caught on all these grounds is
about 12 pounds.
Observations in Massachusetts of the rate of growth of the cod show
that those 1^ to 3 inches long are about G months old; those 9 to 13
inches long, and weighing 7 or 8 ounces, are 1^ years old ; those 18 inches
long, and weighing 2 to 2;^ pounds, are 2i years old ; and those about 22
inches long, and having a weight of 4 to 5 pounds, are 3| years old.
MANUAL OP FISH-CULTURE. 197
SPAWNING.
The principal spawning time of the cod on the New England coast
is winter, but the season begins as early as November and continues
until April. Spawning fish are occasionally caught from October until
May. The si)awning period for an individual fish is greatly prolonged,
and probably covers six or eight weeks, only a small percentage of the
eggs maturing at one time. The male and female cod may attain
sexual maturity when weighing only 3i or 4 pounds. The ages of
normal fish having these weights are supposed to be three to four
years.
When impelled by the spawning instinct, the cod seek the shoal
waters of the coast or banks in schools consisting of both sexes. The
female is less active than the male at this period, and probably rests
quietly on the bottom while discharging the eggs. There is no evidence
to show that the sexes are paired or in close proximity during the act
of spawning. On the contrary, it seems likely that fertilization is
generally accomi)lished by accidental contact of the sexual products
as they are swept about by the elements, having risen to or near the
surface as soon as extruded.
The cod is one of the most prolific fishes. The ovaries of a 21-pound
fish hnve been computed to contain 2,700,000 eggs, and a 75-pound cod
has been estimated to have 9,100,000 eggs, these figures being deduced
by careful weighing or measuring of a known number of eggs. The
egg is from -^ to -fV inch in diameter, the smallest fishes having the
smallest eggs; the average size may be taken as iV inch. The approxi-
mate number in a fluid quart is 337,000.
The destruction of cod eggs in nature is necessarily large. The
l^rincipal loss is probably through failure of impregnation, the eggs
losing their ability to become fertilized and the milt its vitality very
soon after being thrown from the fish. Incalculable numbers are thrown
on the shore by the waves and there die. Cod eggs are also destroyed
by numerous animals, including fish, birds, and invertebrates.
COMMERCIAL IMPORTANCE AND FOOD VALUE.
The cod is one of the most valuable of all food-fishes, and in the
United States ranks as the most prominent commercial fish. In the
matter of persons engaged, vessels employed, capital invested, and
value of catch, the taking of cod in the United States is more extensive
than any other fishery for fish proper.* The number of vessels which
fish wholly for cod or take cod in noteworthy quantities, together with
other "ground fish," is not less than 600, of over 25,000 net tons burden,
carrying about 7,000 men, and with a value of $3,000,000, besides which
there are very large fisheries carried on from boats and small vessels
of less than 5 tons burden. The approximate annual value of the cod
* The oyster fishery is the most important branch of the fishing industry of the
United ^States.
198 REPORT OF COMMISSIONER OF PISH AND FISHERIES.
catch ill 1898 was about $2,000,000, a sum representing the first value
of the fish. The weight of tlie fish as landed from the vessels (fresh,
split, and salted) was about 90,000,000 pounds.
The cod fishery is prosecnxted in all the coastal States from Maine
to New Jersey, being most important in Massachusetts and Maine.
Gloucester and Boston are the principal fishing centers. On the
Pacific coast there is an important fishery in Alaska, carried on by San
Francisco vessels.
Cod are taken with hand and trawl lines, baited with fish, squid, etc.,
and fished from small boats or the vessel's deck. The principal grounds
in the Atlantic are the famous "banks" — Grand, Georges, Western,
Quereau, etc. ; on the Pacific coast the Shumagin Islands are the chief
grounds. Small quantities are taken in traps at places on the l^ew
England shore.
ARTIFICIAL PROPAGATION.
The cod is propagated artificially on a more extensive scale than
any other marine fish. Artificial hatching was first undertaken at
Gloucester, Massachusetts, in the winter of 1878-79, and has since been
regularly prosecuted on an increasingly large scale at both Gloucester
and Woods Hole. Up to and including the season of 1896-97, the
number of cod fry liberated by the Commission on the east coast was
449,764,000. The output of fry in the last-named year was 98,000,000.
The unmistakable economic results which have attended these efforts
warrant all the time and money devoted to them and justify the greatest
possible expansion of the work.
COLLECTING EGGS ON THE FISHING-GROUNDS.
The following methods are pursued in collecting cod eggs for the
United States Fish Commission station at Gloucester.
As cod are abundant in Ipswich Bay during the winter, vessels from
Gloucester, varying in size from 10 to 70 tons, engage in fishing there,
starting from Kittery Point. Maine, or Portsmouth, Kew Hampshire,
where they market their catch, secure bait, and obtain supplies. At
the beginning of the cod season (which usually opens from the middle
to the last of November) arrangements for the board of the men, dory
and building hire, trausporta4;ion of eggs, etc., are made with persons
at Kittery Point and permission to place spawn-takers aboard the
fishing vessels is obtained, with the understanding that they will be
allowed to take eggs from the fish secured, that they be given the
freedom of the vessel in order to properly care for the eggs, and that
no charges be made against the Commission except that 25 cents be
paid for each meal furnished the spawn-takers. After these arrange-
ments are made the men are directed to board such of the flee* as are
at the time meeting with the best fishing, but as the fish are not of
uniform abundance in the bay it is necessary to keep a vigilant watch
on each vessel's catch as it is landed, daily, to know where to place
the spawn- takers to the best advantage.
Fish Manual. (To face page t98.)
Plate 55.
MANUAL OF FISH-CULTURE. 199
xV spawn-taker's outfit consists of a water bucket or pail, a dipper, a
siphon, a tliermometer, and a tin si)awn-kettle about 2 feet long, 1 foot
wide, and 8 to 0 inches deep; the kettle has a cover and handle.
When new spawn-takers are employed they are instructed in the
work and sent out in vessels with the experienced men to familiarize
themselves with the methods. The spawn-takers ordinarily leave their
boarding-places at 1 o'clock in the morning (though the time varies
somewhat, according to the weather) and join the boats anchored in the
harbor of Kittery or at Portsmouth. During moderate weather the men
frequently go aboard before midnight, as the vessels must sail when
the tide is favorable, to avoid getting becalmed or meeting a head tide,
either of which might prevent them from reaching the fishing-grounds
in good season.
After joining tlie vessels, the spawn-takers usually assist the fisher-
men in getting under way, managing the ship, etc., and on reaching the
idace where the nets or trawls are set — usually 0 to 10 miles distant —
the spawn-takers help the crews in hoisting out and dropping the dories
on the gear as each buoy is reached, the men remaining on the vessel's
deck with the captain while the fishermen are hauling or under-running
their gear, and until they return to the vessel with the fish.
As soon as the dories begin to arrive with fish, the work of the spawn-
taker begins. As the fish are pitched aboard, the spawn-taker stands
ready to examine each one and select those that may contain ripe eggs
or milt. As the dories are usually picked up in the same order in which
they are dropped, there is opportunity to strip the fish without nuich
hurry, but sometimes several are picked up in a short space of time,
and if a large quantity of fish is landed the catch remains on deck
until the spawn-taker can overhaul it. In bad weather, however, when
the fish would be in danger of being washed away, they are put in bins
on deck and can be pitched from one bin to another by the spawn-
taker as the condition of each is determined. Usually one of the crew
assists in this work and often renders valuable assistance. Great care
is taken not to get any green or dead eggs with the good ones and to
keep the eggs as free from foreign matter as possible; but in rough
weather, when the vessel is pitching or rolling heavily, vigilance in
these respects is necessarily somewhat relaxed.
The spawn-taker seizes the fish by the tail, places the head under the
left arm, if it is not too large, leaving the right arm free for stripping
the fish, which is done in the usual way. Only live fish or fish recently
dead are used.
The eggs are first taken in a common i)ail, the inside of which has
been moistened with water. Then a sufficient quantity of milt to
fertilize the eggs is added and thoroughly mixed with them and allowed
to remain fiom 10 to 20 minutes, or longer, after which water is added
and the eggs are carefully cleaned by siphoning oft" the old water
and i)utting in fresh water until all the slime and milt are drawn from
the pail. The good eggs, which rise to the surface of the water, are
200 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
then transferred to the spawn-kettle containing clean water and the
poor or dead eggs are thrown away.
All the eggs obtained on a given vessel are kept in the kettle until
the receiving-house on shore is reached, the water on the eggs being
changed at intervals during the passage in; and to keep the tempera-
ture uniform, the eggs -are shifted from one part of the vessel to
another, according to conditions. Sometimes, when the sea is very
choppy or rough, the pail can not safely be used, as the eggs will spill
out, and they are then stripped directly in the spawn-kettle and cleaned
as well as possible.
It was formerly the practice to take cod eggs in a small quantity of
water, but during the season of 189G-97 it was determined to test the
relative efficacy of the so-called wet and dry methods of fertilization.
Some of the spawn-takers were instructed to employ the dry method
and others the wet method. The experiments show that when eggs
were taken by the dry method a much larger percentage was fertilized
than when taken in water. Eggs from fish caught on trawl lines inva-
riably yield a larger percentage of fry than those from fish caught in
nets, although fine eggs are frequently obtained from net fish. The
explanation seems to be that fish caught in nets soon become entangled
and are either drowned, or nearly so, shortly after being meshed; they
struggle a great deal more than fish on trawls and the greater part of
them are dead when taken into the boats, many of them being scaled,
which indicates severe exertion in trying to escape. Trawl fish, on the
other hand, are almost always alive and active when taken from the
water, and very few fish without scales are found unless the gear has
been out a long time or has been set during a heavy storm, when, of
course, many of the fish will be dead.
Better results are obtained from eggs taken when the weather is
fairly cold than when it is warm, as when the temperature is high it is
difficult for spawn-takers to keep the water containing the eggs at a
safe temperature, and before the egg house on shore is reached there is
almost always a heavy loss. When the weather is too cold for eggs to
be kept on the vessel's deck the spawn-takers put them below the deck,
where the temperature will be suitable.
Many difficulties and much exposure are encountered by the men
who collect cod eggs on the fishing vessels, and during severely cold
and windy weather, when the deck is covered with ice and the fish
freeze stiff" in the dories before they reach the vessel, it is practically
impossible to get good eggs. During boisterous weather, when the
fleet succeeds in hauling the gear only once or twice a week, the greater
part of the catch is generally dead when taken. A spawn-taker often
secures a good lot of eggs and can find no ripe milt fish, but in this
event he will, if the weather permits, visit the nearest vessel in quest
of milt. Sometimes there is a school of milt fish in the bay and very
few female fish, and a vessel may catch several thousand pounds of cod
day after day without finding ripe spawn in any of them, while another
Fish Manual. ^To face page 200.)
Plate 56.
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MANUAL OF FISH-CULTURE. 201
vessel, lisbiug: only a short distance away and not catching many fish,
will .uet a comparatively large number of spawners.
The spawn-takers are instructed not to take eggs from fish that have
died on trawls or in nets, although tine lots of eggs are often taken from
fish tliat die in the dories before they reach the vessel, showing that the
eggs do not die immediately after the fish expire. The vitality of the
eggs after the death of the fish varies in difterent cases and depends on
the conditions of the eggs and the fish at the time the fish are <;aught,
the state of the weather, etc. An experienced spawn-taker can almost
always distinguish readily between good and poor eggs, although it is
not always possible to determine whether or not a given lot of eggs will
live. As the weather and the nature of the school of fish in the bay
regulate the collection of eggs, the results of a season's work can not be
estimated in advance. It has been observed that roe fish are found in
largest numbers previous to an easterly storm and when the wind is
from the south or west. During heavy westerly winds cod appear to
approach quite close to the beach, and when the wind blows from the
eastward and the sea begins to rise, they leave for deeper water.
When fishermen are hauling their nets and trawls, they frequently
notice spawn being emitted from fish when they are landed in the
dories. Such fish are laid away on their backs in the stern of the boat
and when the vessel is reached are carefully passed to the spawn-taker,
many eggs that would otherwise be lost being thus saved.
When the price of fish is low at Portsmouth or the wind is unfavor-
able for making that harbor, some of the fleet go to Kockport to sell
their fish, and should spawn-takers be on such vessels they immediately
take their eggs to Gloucester when the vessels arrive in Kockport.
Usually the fishing vessels return to Kittery Point between 1 o'clock
and 10 o'clock p. m. Immediately on landing, the spawn-takers carry
their collections to the egg house on shore, where the spawn is carefully
examined, cleaned, packed, and shipped to Gloucester by first train.
In shipping eggs large fruit jars are used. About 350,000 eggs are put
in each jar, the jar is filled with water, the top is securely fastened,
and the jar is placed horizontally in a large iron kettle made especially
for the purpose and holding five jars. The jars are wrapped in burlap
before they are put in the kettles, to prevent them from breaking, and,
when necessary, snow or ice is put in each end of the kettles to keep
the temperature uniform during transit, but it is not allowed to come
in direct contact with the jars,
A messenger usually accompanies the eggs and gives them constant
attention until they are delivered at the station. The snow or ice is
removed from the kettles, if the temperature falls too low, and replaced,
if necessary, the messenger making frequent use of a thermometer.
In preparing eggs for shipment without messenger, they are first
cleaned carefully by drawing off all dead eggs or dirt, then put in large
fruit jars in the same manner as when they are shipped to Gloucester,
and the jars are packed horizontally in large wooden cases holding nine
202 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
jars each. lio(;kweed or moss, together with ice or snow, is used in
packing theui, the former being phiced around the jars and the latter
put in the bottom, sides, and top of the case to keep the eggs cool.
Successful shipments are often made by express.
Some difficulty has been experienced in keeping large lots of eggs
over night at Kittery Point, as the facilities are insufficient for chang-
ing water or for spreading the eggs out to overcome the injurious effects
of prolonged crowding; but when it is necessary to so retain them, they
are put in McDonald jars in which the water is changed as often as the
supply will permit. As the water in the harbor is partly fresh and
unfit for this purpose, it is necessary for spawn-takers to bring in a
supply from the open bay in large transportation cans.
CAPTURING AND PENNING BROOD COD.
Practically all of the cod fry hatched at Woods Hole prior to 1896
represented eggs taken from penned fish. Some of the cod collected
for breeders are caught by the crew of the Fish Commission schooner
Grampus and some are purchased from commercial fishermen. Two
or more smacks usually engage in fishing for the station during the
collecting season, which is from about October 1 to N^ovember 30. The
grounds resorted to are east of Nantucket and around Block Island.
The fish are taken with hand lines fished from the deck while the vessel
is drifting, in water from 10 to 40 fathoms deep. Those taken in the
shoaler water are preferable to those coming from deep water, as the
change to the shallow cars in which they are held at the station is less
pronounced. Great care is exercised in catching the fish, for when
hastily hauled up from deep water they are very liable to be " poke-
blown," that is, they have their stomachs turned inside out through the
mouth. When drawn in with moderate speed, they become adapted to
the gradually diminishing pressure and do not suffer injury. It is also
important in unhooking the fish not to injure its mouth any more than
is absolutely necessary, as the wound caused by the hook frequently
spreads and forms a large sore and eventually kills the fish. All the
vessels which collect cod for the station are provided with wells in which
the fish are placed and held while in transit.
When a vessel arrives at the station with cod, the fish are immedi-
ately transferred with dip nets from the well to live-cars 16 feet long,
6 feet wide, and 5 feet deep, which are constructed of wood and divided
into two compartments by a crosswise partition. As the fish obtained
from smacks are paid for by the jjound, it is customary to weigh about
10 per cent of each load and estimate the total weight by the average
of those weighed. While being weighed, the cod are also counted,
about 500 being put in each car. The cars are moored in the middle
of a pool or basin protected on all sides by a wharf, which breaks the
force of the sea in stormy weather and affords a sheltered place for
handling the fish and taking the eggs.
Cod take little or no food when s))awning. The impounded brood
fish are often tempted with fresh flsli ;ind with fresh and salted clams,
MANUAL OF FISH-CULTURE. 203
but they can rarely be induced to eat. A certain percentage of the
penned fish die and are removed at once from the cars. The develop-
ment of the sexual organs is noted when the dead fish are taken out.
Fish about ready to spawn are placed in a separate car and carefully
watched. They are examined two or three times a week and any ripe
eggs are taken.
In taking and fertilizing the eggs of brood cod the same general
methods are followed as are adopted on the Ashing vessels in Ipswich
Bay. The spawn-taker grasps the rii)e fish near the tail with his left
hand and holds the fish's head either between his body and left arm or
between his thighs, using his right hand to strip the fish. The eggs
are usually taken in a backet. Both the dry and wet methods of fertil-
ization are used at Woods Hole. Usually about 80 per cent of the eggs
taken are fertilized. Unlike many other fishes artificially propagated,
the cod does not yield all of its eggs at one time. After expressing all
the eggs possible from a given fish, it is returned to the live-car, and in
a few days will have matured more eggs, which are then taken. When
the ovaries have discharged all their eggs, the fish is released.
In recent years from 1,600 to 0,000 cod have been penned annually
in the protected basin at Woods Hole. Only from one-ninth to one-
third of these, according to the season, yield good eggs.
CHARACTERISTICS OF COD EGGS.
Cod eggs are nearly transparent, and float at the surface of the water
when first taken. They vary in color from a pale green to a deep red,
those having the green color being the best. Good results are seldom
obtained from the red eggs, and those of a deej) red color almost invari-
ably die in three or four days after being received. Unless the density
of the water is low, the eggs normally float during the entire hatching
period. However, it frequently happens that, owing probably to the
accumulation of sediment, the eggs gradually sink during the last third
of the incubation period, and finally mass together on the bottom of the
hatching-box; here they would quickly smother but for the current.
Floating eggs are not necessarily good ones, for unfertilized and
injured eggs usually float 18 to 36 hours before going to the bottom.
Unfertilized eggs may be readily detected, as they have no disc which
marks fertilization and have a milky appearance. Th«e dead eggs
quickly sink, and are easily distinguished from the sound eg^s by a
white spot in the center.
Eggs received at the hatchery are transferred from th« vessels in
which they came to Chester jars partly tilled with water, and in 10
or 15 minutes they rise to the surface in a dense mass. The eggs are
put in each jar to the depth of an inch, a quantity representing approx-
imately 379,000 eggs. If the hatchery is full, about a fifth more eggs
may be put in a box, the maximum number that may be safely carried
being 450,000. The first measurements are carefully made, as they form
the basis for subsequent estimates. As soon as the eggs ai-e measured
they are transferred to the hatcliing-boxes with dippers.
204 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
THE APrAKATUS USED IN HATOHINCI COD,
The apparatus and methods employed iu cod culture are the out-
growth of long" experience and study and have as their special features
the closest possible simulation of natural conditions. The apparatus
now in general use is the so-called McDonald or automatic tidal box.
The boxes are constructed in series of 1-5 or less, the number depend-
PLAN.
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a, siphon.
c, partitions fonning upper pockets.
d, partition forming space al upper end of
compartment.
<?, partition forming space at lower end of
compartment.
/, glass gate.
r/, slot between adjoining compartments.
ing on the size of the hatching-room, the arrangement of the hatching-
tables, or other conditions. The Gloucester hatchery has 8 tables of
9 boxes each, and Woods Hole 14 tables of 12 each. At Gloucester
25,000,000 eggs can be hatched at one time, and at Woods Hole
65,000,000. For a wooden framework to accommodate 9 boxes such
as are used at Glouicester the outside dimensions are: Length, 10
Fish Manual. (To face page 204 )
Plate 57.
MANUAL OF FISH-CULTURE. 205
feet; width, 3 feet 8 inches; depth, 11 inches. The table or trough is
constructed of 2 inch lumber and raised to a convenient height by
short, stout legs. The table is divided into 9 water tight compart-
ments by means of crosswise partitions of IJ-inch plank.
At Woods Hole the dimensions of the troughs containing 12 boxes
are as follows: Length over all, 13 feet; width, 2 feet 7 inches; depth,
12 inches. The plank is lA inches thick. The bottom of the trough is
2^ feet above the floor. The compartments are separated by l^-inch
partitions and are 22 inches long, 12 inches wide, and lOf or 11
inches deep.
Two inches from each end of each compartment there is a 1-inch
wood partition. The partition d at the supply or upper end of the
compartment extends with its middle portion to the bottom of the
trough, while the two sides extend only to within li inches of the bot-
tom. The partition e, at the discharge or lower end of the compart-
ment, extends its full length to within li inches of the bottom of the
trough. Between the two partitions d and e in each compartment there
is snugly fitted a movable box in which the eggs are jdaced. This
box, which is constructed of i-inch plank, is 0 to 9i inches deep in the
center, but only 8 inches deep at the corners, the bottom sloping
upward toward the sides and ends of the box and being covered with
linen scrim. A wooden strip at the bottom, J inch thick and conform-
ing to the shape of the bottom of the box, extends the length of the box.
The box rests on cleats in the corners of the compartments which keep
the center of the box li inches above the bottom of the trough.
The space at the supply end of each compartment is divided into
three pockets by 1-inch wood partitions. The middle pocket connects
with the main compartment by means of a small hole (t^ to ^ inch)
through the center of the partition and end of the box immediately
above the lengthwise strip, and the two lateral pockets connect by a
space at the bottom with the main compartment.
At Woods Hole the water used in hatching is pumped from the
liarbor to two tanks of about 18,000 gallons joint capacity. The water
is led to the hatching-room through a 4-inch wooden pipe and is sup-
plied to the hatching apparatus through a 2J-inch hard-rubber pipe
which branches from the main pipe and runs directly over each row of
tables. At Gloucester the main supply-pipe is of hard rubber, 3 inches
in diameter; this leads from a tank of 15,000 gallons ca^pacity, the
bottom of which is about 6 feet above the level of the troughs. A small
soft-rubber tube, provided with a rubber pet-cock, carries the water to
the middle pocket at the back of each box. As the pocket is always
full of water when the boxes are in operation, a considerable amount
of water goes through the small hole with nuich force, creating a strong
current in the box and keeping the eggs in constant rotary motion.
This current is one of the principal features of the apparatus.
Much more water enters the middle pocket than can pass through
the smaW hole into the box, and the surplus flows over the sides and
206 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
enters the main compartment from below, coming up through the scrim-
covered bottom into the movable box.
The partition forming the pocket at the lower or front end of the box
only extends to within 1^ inches of the bottom, leaving a space
through which the water runs from the compartment. In the bottom
of the pocket there is an opening in which the vertical waste-pipe fits.
This pipe is brass, i inch in diameter and 10 or 11 inches long; the top
of the pipe is 7 inches above the bottom of the table. The waste-pipes
from the difierent boxes discharge into a trough which carries the water
from the building.
A particularly important part, and the one which gives the name
*'tidal box" to the apparatus, is used in conjunction with the waste-
pipe. This is a brass siphon-cap, which fits over the upper end of the
waste pipe. The cap is a tube, closed at the top, 9 inches long and IJ
inches in diameter. It is kept at any desired height on the waste-pipe
by wire springs in the cap or by other means.
By virtue of the siphon attachment the water in each box rises to
the height of the top of the waste-pipe and begins to run over. This
partly exliausts the air in the cap, more water rushes in, and the pipe
becomes filled with water; then the siphon begins to act and takes off
the water to a level of the bottom of the siphon-cap. Usually the cap
is pushed about half down the waste-tube, although the height of the
water in the box after the disciharge ot the siphon is regulated by the
manner in which the eggs are working. About 7 minutes are required
for the water to be drawn down and the box to again fill, and approxi-
mately two-fifths of the water is taken off at each discharge. By this
arrangement the water in the boxes is constantly rising and falling
automatically; the movements of the waves are thus simulated, the
eggs are kept in constant circulation, and fresh water is continually
entering the boxes.
The Chester box was generally used in cod-culture up to a com-
paratively recent date, and is still occasionally employed in marine
fish-cultural operations. The general object of its construction is the
production of an automatic rise and fall of water, as in the McDonald
box, although it differs from the latter in some essential particulars.
It consists of a box of variable dimensions in which jars are placed for
the reception of the eggs. A convenient size of box is 7.^ feet long, 2
feet wide, and 2^ feet deep. From 4 to 8 large glass jars are arranged
on wooden supports 7 or 8 inches above the bottom of the trough.
Smaller boxes, to accommodate only 2 or 4 jars, are also used. The jars
are about 9 inches in diameter and are of two heights — 9 inches and 17
or 18 inches; they have straight sides and a flat bottom with a central
half inch hole.
The jar is placed in the box in an inverted position, with its bottom
above the level of the top of the trough. The sea water supplying the
trough enters the compartment at one end of the trough and escapes
Fish Manual. ^To face page 206 j
Plate 58.
CHESTER BOXES.
MANUAL OF FISH -CULTURE 207
by means of ii siphon in the other coni[)artment, running through a hole
several inches below the top of tlie trough. The trough fills with water
up to a level with the hole, when the siphon begins to act and takes oflf
the water more rapidly than it enters, to a level with the inner end of
the siphon, the fall being 4 to 5 inches. Air then enters the siphon,
and it ceases to act until the water has again risen to the height of the
discharge hole. The water thus rises iuui falls in thejars automatically,
the interval between the successive discharges being regulated by the
length of the inner arm of the siphon, the size of the tube, and amount
of water supplied.
After the eggs are introduced into thejars a piece of cheese-cloth or
linen scrim is placed o\er the top, and fiistened by means of rubber
bands. The jar is then inverted and i)laced on the wooden supports
provided for the purpose, and the plug in the bottom removed to allow
the escape of the air and the rise and fall of water. The number of
eggs per jar is about 190,000 or 200,000.
DEVELOPMENT OF THE EGG.
The development of the cod egg is greatly influenced by the water
temperature, which fluctuates from day to day and makes it diflicult to
state exactly when the eggs will hatch. With a high temperature the
advancement of the egg through the ditt'erent stages proceeds rapidly
and can readily be ai»preciated with the unaided eye, while with a low
temperature the development is slow and may be greatly prolonged
by very cold water. With a mean temperature of 47° cod eggs begin
to hatch in 11 days, although 2 or 3 additional days are usually nec-
essary for all the eggs of a given lot to hatch. At 43° the time is 14
or 15 days, and at 38° it is 20 to 23 days. The best results are obtained
when the temperature ranges from 41° to 47°. The hatching proceeds
satisfactorily with the water at 38°, but with a lower temperature
t^e incubation period is vso long that the fry are very weak. On the
natural spawning-grounds the water seldom gets below 38°, while at
the stations after January 1 the water used for hatching rarely gets
as warm as 37°, and often is as low as 31°; from the middle of January
to the latter part of February it remains at about 32°. Since it is
impossible to do even fair work when the water gets below 35°, it has
been the practice to warm the water by passing it through a coil of pipe
contained in a tank of warm water or by introducing steam directly
into the water pipe whenever the hatchery water gets below 37°.
The water being at 47°, during the first 4 days the egg passes
through the different stages of segmentation; at the end of that time
the germinal area begins to assume the general form of a fish; and by
the ninth day the fish is quite well formed, and may be readily seen
with the naked eye. By the tenth day the embryo shows signs of life,
and under the microscope the heart may be seen to beat.
208 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
Following is a table showing the approximate time reqnired for cod
eggs to hatch, with the water at the stated mean temperatures :
Mean water tem-
perature.
No. of
(lays.
1
50
40
35
31
28
25
31° F
32° F
33° F
34° F
35° F
36° F
Mean water tem-
perature.
37° F
38° F
39° F
40° F
41° F
42° F
No. of
days.
23
21
19
17
16
15
Mean water tem-
perature.
43° F
44° F
45° F
46° F
47° F
No. of
days.
14
13
12
11
10 or 11
Moderately clear water is essential to the healthy development of
the fry. If much sediment is present it collects on the eggs and acts
very injuriously, often killing them. Sometimes eggs become so coated
with sediment that the fry appear to be unable to burst the shell;
some lots of eggs thus aifected have been known to retain fry fully two
weeks beyond the normal period of incubation.
With eggs carefully taken and fertilized, and clear water of a
temperature from 41° to 47° F., it is possible to hatch from 70 to 85
per cent of the eggs, but when the temperature gets below 38° the
percentage of fry hatched is only from 25 to 50, and the average for the
season is thus greatly reduced. The number of fry hatched is deter-
mined by deducting the losses shown on the hatching-cards from the
number of eggs originally in the box. One liquid ounce is estimated
to contain 10,524 eggs.
CLEANING THE EGGS.
Owing to the accumulation of sediment and other foreign matters in
the hatching-boxes, it is necessary to clean the eggs daily, running the
sound eggs from one box to another through a slot, the dead eggs
being left behind. The slots in the j^artitions dividing the hatching
compartments correspond with similar slots in the boxes ; they are 3
to 3^ inches long and 1^ inches deep, and are jilaced 3 inches from the
front of the compartments. To begin the cleaning of a given row of
boxes, a glass slip is fitted into the slot between the second and third
boxes, the first box being left empty for the purpose of receiving the
cleaned eggs from the second box. A wooden plug is then put in the
current hole at the back of the second box, and the sijihon cap is
removed from the waste-pipe; this allows the box to fill with water,
and the eggs, undisturbed by the current, rise to the surface. The
water is allowed to enter the first box and to graduall}' fill it to the
level of the waste pipe, and is then turned off. A plug is next put in
the waste-pipe of the box containing the eggs; the water rises till it
reaches the slot, and then runs over into the first box, carrying the good
eggs with it, while the dead eggs remain in the box. The regular water
circulation is then established in the first box.
The inner box from which the good eggs have been removed is taken
out and the remaining eggs are washed into one end and poured into
MANUAL OF FISH-CULTURE. 209
a glass graduate. The dead eggs quickly sink and the quantity, in
ounces, is noted on a card attached to each box. If there are any good
eggs in the glass they are saved; the si)oi]ed eggs are thrown into the
waste-trough. IJoth the inner box and the trough in which it rests are
thoroughly washed and sponged after each change.
When the inner box is replaced it is made ready for the eggs to be
transferred from the third box, and the same method is pursued until
all the boxes have been cleaned. Eggs recently taken, being on the
surfiice, run over very quickly, 5 or 10 minutes usually sufticing for
the transfer of a box of 400,000 eggs; but when eggs become heavier,
as a result of development, the cleaning takes much longer, as it is then
necessary to run them into the lower part of the box (as in removing
dead eggs) and to dip them out, care being taken to keep the lower
end of the box in the water while manipulating them. As the loss of
eggs has ceased by the time they reach this stage, everything in the
box may be dipped over, and with care no damage is done the eggs.
THE FRY.
When the fry first hat(;h they are much curved in shape and show
but little vigor. If the water is comparatively warm they rapidly
straighten out and become stronger. At this stage they float at the sur-
face, except when forced about by the current. As they get older they
frequent the upper water less and if kept in the boxes till the mouth
begins to functionate most of them remain on or near the bottom.
As soon as the first fry in a given box make their appearance the
eggs are all runrover for the last time. As the fry are comparatively
delicate they are handled as little as possible and with great care.
The fry are planted as soon as practicable. If all the eggs of a given
lot have not hai;ched it is better to plant them with the fry rather than
hold the latter until incubation is complete, for the boxes soon become
foul from the accumulation of eggshells and the eggs will haitcii in a
very short time, especially as the water on the spawning-grounds is
usually 3 or 4 degrees warmer than the water in the hatchery.
When the fry are to be removed from the boxes, preparatory to plant-
ing, a plug is put in the current hole at the back of the box, ajid in a
short time most of them will come to the surface. They are then dipped
oint and put in transportation cans. About 200,000 fry may be safely
carried in a 10-gallon can. Deposits are usually made on the natural
spawning-grounds,
F. M 14
Fish Manual. (To face page 211.)
Plate 59.
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THE MACKEREL.
DESCRIPTION, SIZE, ETC.
The genus Scomber, of which the mackerel {Scomber scombrus) is
the leading representative, is distinguished from related genera of
scombroid fishes of the Atlantic coast [Auxin, the frigate mackerels;
Gijmnosarda, the little tunnies; Thunnii.s, the great tunnies; Sarda, the
bonitos, and Scomberomorus^ the Spanish mackerels and kingfish) by
the small size of the species, by the absence of a median keel on each
side of the caudal peduncle, by a short spinous dorsal fin having 0 to
12 spines, by the pattern of coloration, and by a number of other
characters.
The body of the mackerel is fusiform and but little compressed later-
ally. The standard length is 3J times the depth. The caudal peduncle
is slender, with a small keel on either side. One-third of the total
length without tail consists of the head. The eye is rather small, its
diameter being only one-fifth the length of the head. The mouth is
large and armed with a row of small slender teeth in each jaw. There
are two dorsal fins, the anterior containing 11 spines and the posterior
V2. rays, following which are 5 finlets; the formula of the anal fin is 1
spine, 11 rays, and 5 finlets. The scales are very small, numbering
several hundred along the lateral line. The color is dark blue above
and white below. About 35 dark wa-vy vertical streaks mark the back.
The cmnmon mackerel closely resembles the other species of the same
genais found on both the Atlantic and Pacific coasts, namely, the bull's-
eye, chub, or thimble-eye mackerel [8. colias), but is separated from it
by the absence of the air-bladder, more dorsal spines, smaller eye, and
somewhat diftereut markings.
The length of the full-grown mackerel is 17 or 18 inches, but fish a
little over 20 inches long, and weighing upward of 3:^ or 4 pounds, are
occasionally taken. The average length of the market catch is about
12 inches. Such a fish weighs from three-fourths of a pound to a pound.
Small mackerel are known among the fishermen by several names,
such as " spikes," " blinkers," and " tinkers." Spikes are the smallest
ca^ight b}^ the commercial fishermen ; they are 6 or 0 inches long and
are o to 7 moiiths old. Tinkers are under 9 inches in length and are
supposed to be about two years old. Blinkers are intermediate in size
and age. Maturity is probably attained in the fourth year.
DISTRIBUTION, MOVEMENTS, ABUNDANCE, AND SPAWNING.
This species inhabits the North Atlantic Ocean. On the American
coast its range is from Cape Hatteras to the Straits of Belle Isle. On
the European coast the fish is found from northern Norway, in latitude
211
212 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
71°, to the Mediterranean and Adriatic. It is not recorded from the
West Indies, Bermudas, Gulf of Mexico, South America, or Africa.
On the east coast of North America mackerel first appear in the
spring off Cape Hatteras and subsequently reach the shores of the
Middle and Xew England States and the British possessions, migrating
in from the sea from a southerly or southeasterly direction. Certain
bodies of lish seek the New England shore, while others first strike the
shore of Nova Scotia and follow it into the Gulf of St. Lawrence.
They leave the coast in the same way in fall and early winter.
The mackerel is a wandering fish. Its movements when in the coast
waters are undoubtedly regulated by external causes not yet clearly
understood, but food, temperature of water, and reproduction are potent
factors.
The mackerel is one of the most abundant fishes found on the Atlan-
tic coast. It goes in schools, often of immense extent. The testimony
of reliable fishermen relative to the size of schools observed often
seems incredible; thus one school seen in the South Channel in 1848
was half a mile wide and at least 20 miles long. Another school noticed
off Block Island in 1877 was estimated to contain 1,000,000 barrels. The
schools swim at the surface or at varying depths beneath the surface,
and present a comparatively broad front.
From the earliest times, there have been periods of scarcity of mack-
erel alternating with seasons of abundance. As early as 1G70 the
Colony of Massachusetts enacted laws for the preservation of mackerel.
Since 1885 there has been the most noteworthy and prolonged scarcity
of the fish of which there is any record. The New England catch in
1885 was 330,000 barrels, and in the 8 years ending in 1885 averaged
309,000 barrels; in 188G it fell to 80,000 barrels, and in the succeeding
10 years aggregated only 481,000 barrels; was several times below
25,000 barrels, and never exceeded 89,000 barrels. The yield in 1898
was 5,709,000 pounds, fresh, valued at $307,000, and 15,500 barrels,
salted, worth $179,000.
The spawning season on the east coast of North America includes
the months of May, June, and July, June probably being the principal
month. The spawning-grounds are in rather deep water and extend
along the entire coast from Long Island to the Gulf of St. Lawrence.
Most of the bays and sounds of the New England coast are important
spawning-grounds, as is also the Gulf of St. Lawrence. Prior to
spawning and for several weeks thereafter the mackerel are lean and
poor and never make No. 1 fish when salted.
FOOD AND ENEMIES.
The mackerel feeds on a large variety of small animals, and is in
turn eaten by a number of fishes, birds, cetaceans, etc. The relations
existing between the presence of favorite food and of enemies on one
hand and of mackerel on the other are fully appreciated by the com-
mercial fishermen, who are often guided in their search for fish by the
appearance of mackerel food in abundance or of their well-known
MANUAL OF FISH-CULTURE. 213
euemies. The presence of food is frequently shown by flocks of birds,
especially phalaropes, which are called " mackerel geese."
The principal food objects of the mackerel are small crustaceans;
copepods predominate, but shrimps of various kinds, young crabs, etc.,
are also important. One of the surface-swimming copepods, known
as "red feed," "cayenne," etc., is a very favorite food; when mackerel
have been feeding freely on it, they spoil very quickly after being
caught, owing to their sides rotting or " burning." Fish constitute a
rather important part of the mackerel's diet; herring, anchovy, sand
launce, silversides, menhaden, and many other small fishes are eaten.
Among fishes, sharks are, perhaps, the most destructive enemies;
mackerel sharks and dogfish are known to prey on the mackerel,
driving and scattering the schools. Other fish enemies are bluefish
and cod. Porpoises and whales are often seen feeding on the mackerel
schools. Large sfpiids do great damage to small mackerel. Among
birds, the gannet is especially destructive.
THE MACKEREL FISHERY.
The mackerel is one of the best and most valuable food-fishes of the
Atlantic Ocean. It is the object of important fisheries in Norway,
Ireland, and Great Britain, and is extensively taken in the United
States and the British provinces of Korth America. The fishery is
prosecuted with vessels using purse seines, gill nets, and lines, much
the largest part of the catch being taken in seines. In the boat fishery,
lines and nets are employed. Stationary appliances, such as pound nets,
traj) nets, and weirs, also secure considerable quantities of mackerel.
In the United States the vessel fishery is carried on chiefly from
Gloucester, Mass. The vessels sail south in early spring, and fall in
with the fish when they first appear off the coast of the Southern and
Middle States, the catch being landed fresh in New York and Philadel-
phia. The fleet next seeks the fish on the southern shore of Nova
Scotia and follows the school north to the Gulf of St. Lawrence.
During the summer some of the vessels enter the gulf, but most of
them cruise on the New England shore, where most of the fall fishing
is also done. Some ot the finest fishing vessels of the United States
are engaged in this fishery. In recent years the fleet has numbered
only laO to 225 sail, but formerly nearly 1,000 vessels were at times
employed in this branch.
The shore and boat fishing is carried on from New Jersey to Maine.
The fish thus caught are as a rule sold in a fresh condition.
The fishery is much less productive than formerly, and during the
past ten years has not as a rule been profitable, although each year a
few vessels make good catches and yield very satisfactory returns,
owing to the high i^rice of fish. The local fishing does not supply the
home demand, and large (luantities of fresh and salt mackerel are
annually imported from Norway, Ireland, and the British i)rovinces.
214 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
ARTIFICIAL PROPAGATION.
The artificial propagation of mackerel was more extensively ])rose-
cuted iu 1896 tliau in any previous year. The long-continued scarcity
of mackerel on the Atlantic coast of the United States seemed to
warrant some efforts on the part of the Government to increase the
supply by artificial means. The limitations of mackerel culture dei)end
on the erratic movements of the fish in a given season or on a given
part of the coast and the difficulty of securing healthy eggs in large
quantities from fish taken by the commercial fishermen. During the
summer of 1896, 24,000,000 mackerel eggs were collected. The work
was largely experimental and only a small percentage of fry was hatched,
but the outlook is good for a great expansion of mackerel i^roiiagation.
The egg of the mackerel is one of the smallest dealt with by the fisli-
culturist, being only .,\- inch in diameter. Being provided with a large
oil-globule, it floats at the surface, like the eggs of many other marine
fishes. Within 48 hours after fertilization it generally begins to sink,
remains in suspension a short while, and then falls to the bottom,
where it remains until hatching ensues.
Owing to the inability to retain mackerel in ponds or live-cars pend-
ing the ripening of the eggs, as is done with the cod, it is necessary to
depend for the egg supply on the nets of the fishermen. The eggs
collected at Woods Hole are secured from fish captured in pound nets
near Chatham and at other jioints on the southern Massachusetts coast;
at Gloucester traps in the vicinity furnish the eggs. As the nets are
usually hauled only once or twice a day, the fish have often been caught
for many hours, and the tender eggs have undergone considerable loss
of vitality; the quality of the eggs seems to have a direct relation to
the length of time the fish have been in the nets.
One of the most favorable grounds for collecting mackerel spawn is
Casco Bay, on the coast of Maine. Mackerel are taken chiefly in drag
nets set about 4 o'clock p. m., and hauled from 9 o'clock p. m. to day-
light. Eggs from fish caught in the first hauls of the nets are of much
better quality than those taken in the last lifts.
In collecting eggs from pound nets the spawn-takers accompany the
fishermen when they visit their nets and overhaul the mackerel as they
are taken into the boats. The collection of eggs from the drag-net
fishermen requires the spawn-takers to remain on the fishing-grounds
from early in the afternoon until the next morning.
There is nothing peculiar in the methods of stripping the fish, mixing
the eggs and milt, and transferring the eggs from the field to the hatch-
ery. Although both the wet and the dry methods of fertilization have
been practiced, the latter apparently gives better results. The average
number of eggs taken from a fish is probably about 40,000. Three
mackerel, stripped at Woods Hole iu 1893, yielded 434,500 ripe eggs, an
average of 144,833 eggs. As many as 546,000 eggs have been taken
from a 1^-pound fish, and the largest fish probably yield fully 1,000,000
MANUAL OF FISH-CULTURE. 215
eggs. The largest number of eggs taken from one fisli in Casco Bay
in 1897 was 20(),0()().
From tlie field the fertilized eggs are conveyed to the station in Jars,
as described in the chapter on cod propagation. For short shipments
they may be transported in buckets or cans.
Mackerel eggs may be artificially incubated in a variety of ways. In
1S9G three forms of apparatus were employed for comparative purposes.
These were (1) the McDonald hatching- jar, with the water sui^plied
through the long central tube and discharged through a cheese-cloth
top; (2) the Chester jar, and (3) the automatic tidal-box; the latter
gave the best results.
Owing to the very small size of the eggs, from 200,000 to 225,000
may be placed in a Chester jar and 450,000 or more in a tidal box 20
by 11 inches. The eggs are manipulated in about the same way that
cod eggs are, but, owing to the short period of incubation, require very
little handling.
For reasons not yet definitely determined, but apparently connected
with the condition of the eggs rather than the methods of hatching,
mackerel ova are liable to exceedingly large mortality during incuba-
tion. While as many as 75 per cent of certain small lots of eggs have
produced fry, less than 1 per cent of most of the eggs hatch.
The period of incubation at a mean water-temperature of 58° is about
5 dajs. In 48 hours after impregnation the embryo is discernible, and
in 08 hours its development is far advanced. The critical period seems
to be the end of the third day, when a large part of the eggs die.
The fry are planted within 24 hours of hatching. They are taken
to the natural spawning-grounds in regular transportation cans and
liberated below the surface of the water.
Fish Manual. (To face page 21 7.-)
Plate 60.
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THE FLATFISH, OR WINTER FLOUNDER.
The body of the flatfish {PscndopJeuronectes aniericanus) is reguhirly
elliptical. The eyes aud color are on the right side. The upper side
of the head is covered with imbricated ctenoid scales similar to those of
the body; the blind side of the head is nearly naked. The teeth are
close-set, incisor-like, and ibrni a continuous cutting edge; the right side
of each jaw is toothless. The length of the head is contained 4 times
in the length of the body and the depth 2^ times in the body length.
The dorsal fin contains G5 rays and the anal fin 48 rays. The lateral
line, which is nearly straight, has 83 scales. The color above is dark
rusty-brown, either plain or mottled with darker; the young are olive-
brown, spotted with reddish; the under parts are white.
This species has a comparatively small mouth, and feeds chiefly on
small shells, crabs, and other bottom animals. It is found on sandy,
nuiddy, or rocky bottoms, and seems to prefer sheltered coves and
bays. Its coastwise and bathic movements ai'e limited. It is one of
the most abundant flounders of the Atlantic coast, being especially
numerous in southern ISTew England and J^ew York. It ranges as far
north as Labrador and as far south as the Carolinas, but is not present
in noteworthy quantities south of New Jersey. It does not attain a
large size, the usual length being only 12 to 15 inches and the weight
about li i^ounds. Very rarelj^ examples are taken over 20 inches long,
weighing as much as 5 pounds.
The winter flounder is exceedingly prolific, over a million eggs being
laid by a large fish. Along the coast of the southern New England and
Middle Atlantic States the spawning season is from February to April.
By August the young fish, having attained a l*ength of 1 or 2 inches,
are found in shallow water along sandy shores. The species is obtained
l)rincii)ally during the winter and si)ring months, and large quantities
are sent to the markets, where it sells readily at good prices. The
flesh is white, firm, and of excellent flavor. Next to the halibut and
the summer flounder, or plaice {Paralichthys dentatus), this is the most
important flatfish of the Atlantic coast.
The winter flounder has been more extensively proi)agated than any
other species of ricuronectida', owing to the facility with which its eggs
are obtained at Woods Hole, where its propagation tills in the time
between the taking of cod eggs on one hand and of lobster eggs on the
other, slightly overlapping the ending of the former and the beginning
of the latter. The work covers that part of the year when the most
217
218 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
inclement and cliangeable weatber occurs, and is necessarily somewhat
limited in extent by uncontrollable physical and other conditions.
During the fiscal year 1895-90, the collections of flatfish eggs num-
bered 11,008,000, which yielded 8,472,000 fry; in the year 189G-97
84,591,000 eggs were taken, from which 04,095,000 fry were hatched.
The flatfish from Avhich eggs are obtained are very plentiful during
February in the Woods Hole region, being found on sandy or hard clay
bottom, and taken in fyke nets set in water from 0 to 14 feet deep. As
many as GO to 70 fish are sometimes taken at one lift of a fyke net, but
as a rule not more than two or three of this number are gravid fish.
These nets are usually some distance from the station, and the fish are
carried to the hatchery in transportation cans, six or eight being put
in one can. In some cases this trip is made by water in a sail or row
boat, while at other times it is made overland by team. The fish are
often carried 10 or 12 miles without change of water and without
apparent injury. A few are caught while the water temperature is
as low as 33° F., but they are more numerous after the tem])erature
reaches 34° or 35° F. On arriving at the station the fish are put into
wooden tanks supplied with constantly changing water, and here they
are held until ripe. It is customary to put both males and females in
the same box or tank. The fish are examined daily and the eggs are
taken from all which are found to have ripened, the stripped or spent
fish being released.
The eggs of the flatfish are quite small, there being 30 in a linear
inch. Unlike the eggs of the cod, haddock, mackerel, and other marine
fishes, they do not float, but sink to the bottom of the vessel in which
they are held. They are not so heavy as those of the lobster, and a
slight current causes them to rise and carries them to a point w^here there
is still water, when they again go to the bottom. When first deposited,
the eggs are very adhesive and stick together-in one mass or in clusiers
of different sizes. This adhesiveness is overcome, in a measure, by
thoroughly washing them, and, as this force gradually weakens as the
eggs become older, usually nearly all the eggs are separate when they
begin to hatch. The use of dry powdered starch is very effective for this
purpose; this mixes readily with the saltwater and admirably over-
comes the glutinosity of the eggs. Its action is purely mechanical.
In stripping, it is customary to fill a Chester jar with water and i)lace
inside the jar a bag made of cheese-cloth, into which the eggs are
allowed to fall. The fish is grasped by the head with the left hand, the
mouth being in the palm of the hand, and the edge on Avhich the vent
is located turned from the spawn-taker. The right grasps the fish near
the tail, and as it is moved with gentle pressure toward the vent, at the
same time that the left thumb is moving crosswise and exerting similar
pressure, the eggs are extruded. The milt is then expressed in the
same way; the eggs are stirred slightly with the hand to thoroughly
mix them with the milt, and after allowing a short time for the action
MANUAL OF FISH-CULTURE. 219
of the milt they are cleaned and the snpertiuons milt washed off by
introducing a gentle stream of water into the bag and rolling the eggs
from side to side.
It frequently happens that fish held in tanks to mature deposit their
eggs during the night. In such cases the eggs are found on the bottom
of the tank the next morning. They are usually in clusters and when
examined with the microscope it will be found that practically every
egg is fertilized.
After the eggs have been taken and fertilized the number is calcu-
lated by measuring in a glass graduate and computing 48,720 eggs
to the liquid ounce. The average number of eggs is about 500,000 to
a fish. On March 6, 1897,30 ounces, or J, 402,000 eggs, were taken
from a fish 20 inches long and 11 inches wide, its weight being 3^
pounds after the eggs were taken.
Flatfish eggs may be hatched in several kinds of apparatus, but the
Chester jar is most used, in combination with the McDonald tidal box
employed in incubating cod eggs. From 400,000 to 500,000 eggs are
usually placed in each jar. The top of the jar is covered with cheese-
cloth held in place by rubber bands. The jar is then inverted and
placed in a tidal box. The usual complement of each box is 2 jars. A
wooden frame of 1-inch strips is placed lengthwise on the bottom of
the box for the jars to rest on, so as to raise them and allow the free
circulation of the water. A hole in the bottom of the jar allows the
air to pass in and out as the water inside rises and falls. The inner
compartment, with a bottom of cheese-cloth, used in cod-hatching is
omitted.
As in using the jars the eggs are generally on the bottom all the
time, the experiment has been tried of employing the McDonald box
with the automatic current in order to keep the eggs in circulation. It
having been found that the current commonly used for cod eggs caused
the eggs to pile up in the end nearest the outlet, a stream was intro-
duced into each end of the box and the water was allowed to escape in
all directions through a perforated nozzle; the water was kept about 3
inches deep in the bottom of the box by using a quantity sufficient to
prevent the breaking of the siphon. By this means a constant current
is formed, the eggs develop nicely, and the fry hatch, but the current
necessary to keep the eggs in circulation is strong enough to kill the
fry by forcing them against the sides of the box. This experiment is
therefore not considered a success.
The period of incubation when the mean water temperature is 37° or
38° F. is 17 or 18 days.
The fry of the flatfish, although much smaller than those of the cod,
are much more lively, and are straightened out when first hatched.
Unlike the young cod, they do not float on the surface, but are scat-
tered through the water from toj) to bottom, many being seen among
the eggs on the bottom of the jars. UnUke the adults, the flatfish fry
220 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
swim with the body upright, as young fish of other families do, and
when first hatched the eyes are ou opposite sides of the head. At the
age of about three mouths, liowever, one of the eyes will have moved
to the other side of the head, to conform with the change of the
body in swimming from an upright to a flat position. The position
constantly assumed by the very young fry is peculiar, the long axis of
the body being vertical, with the head upward. This is owing to a
large oil-globule in the anterior part of the yolk-sac.
The fry are quite hardy and stand transportation very well. They
have been kept three weeks without change of water in a bottle hang-
ing in a box of running water to maintain an even temperature in the
bottle. In planting the fry, which is done in one or two days after
hatching, they are put into the transportation cans commonly used for
such purposes and taken in a boat to localities in which the brood fish
are found. The cans are put overboard and sunk until the mouth is
submerged, when the contents are gently turned out. For a trip of not
more than two or three hours' duration, with water temperature about
38° F., from 400,000 to 500,000 fry may be safely carried in a 10-gallon
can.
THE SAND-DAB AND FOUR-SPOTTED FLOUNDER.
Besides the flatfish or winter flounder, two other flounders have been
artificially hatched, on a small scale, at Woods Hole; these are the
sand-dab [Bothus mactdatus) and the four-spotted ^o\\nAe>v {Paralichthys
ohlongus). The eggs of both fish are buoyant, and deposited in May.
Those of the former are oV inch in diameter, and of the latter -jV inch.
The period of incubation, at a temperature varying from 51° to 54° F.,
is about 8 days.
Fish Manual. (To face page 221.
Plate 61.
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MISCELLANEOUS MARINE FISHES.
In addition to the salt-water fishes previously considered, a number of
others have been artificially propagated by the U. S. Fish Commission.
With some of these the fish-cultural work has been rather extensive;
with others, hardly more than experimental. Among those to which
most attention has been given are tautog, Spanish mackerel, pollock,
and haddock. Others that have come in for a share of either practical
or experimental work are sea herring, scup, sea bass, squeteague,
cunner, sheepshead, and several flounders.
The same methods of culture mentioned hereafter in connection with
tautog are applicable in general to scup, sea bass, squeteague, and other
species having floating eggs.
THE TAUTOG.
The tautog ( Tautoga onitis) is a strongly marked species. It belongs
to a family {Lahridw, or the wrasses) characterized in part by one
dorsal fin, thoracic ventral fins, double nostrils, thick lips, and strong
teeth in the jaws. The tautog has an elongated body and a large head
with a convex profile. The rather small mouth is armed with strong
conical teeth in two series. The eye is small and placed high on the
side of the head. The body is covered with small scales, in about 60
transverse rows and 40 longitudinal series. The head is destitute of
scales, with the exception of a small patch behind the eye. The dorsal
fin is long and low, with IG strong spines and 10 soft rays. The anal fin
contains 3 spines and 8 rays. The body length is 3^ or 3^ times that of
head and 2§ or 3 times the depth. The gillrakers are short, feeble, and
number only 9. The color of adults is almost uniformly blackish or
greenish; the young are marked by dark irregular crossbars on a pale
brownish background; chin, white; iris, bright green.
The tautog is of considerable importance in certain parts of its range.
It is found from Maine to South Carolina, but is most abundant in
Massachusetts, Khode Island, and New York. It is one of the best-
known shore fishes of the east coast, and goes by a variety of names,
among which are blackfish, chub, oyster-fish, and moll, besides the
most generally used name of tautog.
The tautog inhabits principally rocky bottom, where it hides in crev-
ices, often with its body in an apparently very unnatural position. It
is quite susceptible to changes in temperature, and during winter enters
into a state of hibernation in the more northern parts of its range.
Its coastwise movements are very limited. Its sharp strong teeth
enable it to consume mollusks and crustaceans, which are its chief
food; it also eats sand-dollars, worms, and other animals.
221
222 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
The tautog is taken for market in considerable numbers by means of
lines and trajis. It bites quite readily and is a favorite with anglers.
Its average weight as caught for sale is not more than 2 or 3 pounds,
but tautog weighing from 6 to 15 pounds are not rare. The maximum
weight is about 22.] pounds; such a specimen from New York, 3Gi inches
long, is preserved in the U. S. National Museum. Tbe annual commer-
cial catch of tautog is about 1,000,000 pounds, valued at $25,000. Most
of the yield is from Massachusetts, Rhode Island, and New Jersey.
The spawning season on the southern New England coast extends
from April to August, although June appears to be the principal month.
The young are very abundant along the shores in the fall.
The artificial propagation of tautog was experimentally undertaken
at Woods Hole in 1880. In 189G, 31,431 ,000 eggs were taken in June;
from these 17,575,000 fry were hatched and planted in neighboring
waters.
Tautog from which eggs for hatching are taken are obtained from
nets or from line fishermen near the station and transferred to live-cars.
When first brought in they seldom yield any eggs, but in 2 to 6 hours
they may be stripi)ed of a part of their eggs. The eggs taken after fish
are held more than G hours are usually of no value, and those obtained
ftom fish retained one night are invariably worthless.
The tautog is very i^rolific. In 189G a 9f-pound fish yielded 1,142,000
eggs, and it was estimated that the ovaries contained fully as many
more eggs that were not yet mature. The average number of eggs per
fish is from 150,000 to 200,000.
The eggs of the tautog are about i}^ inch in diameter. They are
buoyant, like those of the mackerel, and are susceptible of the same
method of hatching. When placed in the automatic tidal box, they
hatch in about 5 days, with the water temperature at G9° F., and in 2
or 3 days with the temperature at 71°.
The newly hatched fry are transparent and exceedingly small, the
length being only -^.j inch. They are quite hardy and stand transpor-
tation well. They are planted shortly after hatching.
THE SPANISH MACKEREL.
The Spanish mackerel {Scomheromorus maculatus) is the best-known
fish of the genus and the only one that has received the attention of
fish-culturists. From the other species of Scomheromoms found on the
eastern United States coast {S. re(jaUs, the kingfish, and 8. cavaila,
the cero) this fish is, in part, distinguished by its smaller size and by
the insertion of the soft dorsal fin in advance of the anal. The body
is long, the head small and pointed, the mouth large and armed with
prominent teeth. The anterior dorsal fin has 17 spines, the soft dorsal
has 18 rays. The anal fin has 2 spines and 17 rays. Behind both the
dorsal and anal fins are 9 small finlets. The lateral line is wavy and
has about 175 pores. The general color is silvery, dark-bluish above
and whitish below. The sides have nnnierous rounded yellowish spots.
MANUAL OF FISH-CULTURE. 223
This fisli is widely distributed, being found on both coasts of North
America. On the west coast it does not enter United States waters,
but on the Atlantic seaboard it ranges from Texas to Massachusetts.
It is especially abundant in the Gulf of Mexico, among the Florida keys,
in Chesapeake Bay, and on the coast of the Middle Altantic States.
Its maximum weight is about i) pounds. Many weighing only 1 or
li pounds are caught for market, and the average is less than 3 pounds.
The Spanish mackerel is one of the choicest food-fishes of American
waters; in popular estimation it is scarcely surpassed by any marine
species except the pompano. It is caught throughout its range on the
east coast with gill nets, seines, pound nets, and lines. The principal
fishing is on the west coast of Florida, on the Louisiana coast, in the
lower part of Chesapeake Bay, and on the coasts of New Jersey and New
York. The approximate annual value of the catch at present is $112,000,
wiiich represents 1,700,000 pounds. In 1880 the output was 1,887,000
pounds, having a value of $132,000. The yield in the Middle States is
much less than formerly, while in the (lulf States it has increased.
The iish spawns throughout its entire range on the United States
coast. The spawning season is (juite prolonged, extending from April
in the Carolinas to September in New York, and in a given locality
continues from six to ten weeks. All of the eggs in the ovaries of a
given fish do not mature at one time; eggs in all stages of development
may be found, suggesting a comi)aratively long spawning season for
individual Iish as well as for the species as a whole. The eggs, when
laid, float at the surface, where they are driven about by wind and tide.
Doubtless a large percentage of the eggs do not hatch, through failure
of fertilization and by being stranded. The eggs are very small, their
diameter being only -^^ to -gVof an inch.
The artificial impregnation and hatching of Spanish mackerel eggs
were first accomplished in 1880, since wbich time the propagation of
the fish has been taken up on a number of occasions, although the
work in any one season has been comparatively limited.
The serious diminution in the supply of this species in certain sec-
tions seems to call for its artificial cultivation whenever it can be taken
up without detriment to the propagation of other more or equally
important fish.
In the work of artificially propagating this fish recourse has been
had to the nets of commercial fishermen for the supply of spawn and
milt. Chesapeake Bay has been the seat of the principal operations,
which have been conducted by tlie steamer Fish ITaick. The catch of
Spanish mackerel in this bay in pound nets and other appliances is
very large, and the facilities for fish-cultural work of this character
are doubtless superior to those of any other section, with the possible
exception of the west coast of Florida.
The necessity for depending on the fishermen for the supply of eggs
is somewhat detrimental to the best results and prevents extensive
work, although the owners of fishing apparatus heartily cooperate.
224 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
Owing to the fact that the fish appear to spawn mostly at night,
when the pound nets are lifted in the morning the ripe eggs liave in
many cases been extruded before the spawn-taker could secure them.
The injuries which the fish sustain while in the pound nets and during
the hauling of the nets appear to seriously affect the eggs and cause
the non-hatching of a comparatively large percentage. Undoubtedly
better results may be obtained if a number of nets are fished exclu-
sively for this purpose, insuring the careful removal of fish at the best
times for taking and fertilizing the eggs.
The eggs are very delicate and susceptible to meteorological influ-
ences. Their development is markedly affected by water temperature
and atmospheric conditions; electrical disturbances, as with other fish
eggs, are injurious, but to what extent and in what way are not known.
The largest number of ripe eggs thus far taken from a single si)ecimen
is 60,000, but the average is only 20,000.
The Chester jar, such as is used in hatching flatfish eggs, has been
found the best apparatus for Spanish mackerel eggs. If the jars are
kept clean and not overcrowded, a constant current of water does not
seem to be essential; of a lot of 60,000 eggs in a jar of quiet water, 90
per cent hatched. The cod tidal-box is also adapted to this work.
In ordinary bay water having a density of 1.014 to 1.019, the eggs
are buoyant and remain at the surface until hatching ensues; but in
water of low specific gravity they sink and give unsatisfactory results.
The period of incubation is very short. Under normal conditions eggs
hatch in 20 to 30 hours, averaging 25 hours, at a temperature of 77°
or 78°. The fry are planted soon after hatching.
HADDOCK, POLLOCK, AND OTHER GADID^E.
The methods of culture employed with the cod are applicable to other
members of the cod family having buoyant eggs. The United States
Fish Commission have frequently taken and hatched eggs of the pollock
{Follachius virens) and the haddock {Melanogrammus a'glijinus). Both
are important food-fishes, but much less valuable than the cod, and the
collection of eggs has generally been only sui^plemental to cod work.
The pollock is found from New Jersey nortiiward. It goes in large
schools, which are often found at the surface, thus differing from the
cod and haddock. The average weight is 9 or 10 pounds, and the
maximum about 30 pounds. Fishing is chiefly done from small vessels
and boats, and is most important in Massachusetts. The value of the
annual catch is about $65,000. The pollock is an excellent food-fish
in both a fresh and a salted condition.
The eggs of the pollock have at times been gathered in large num-
bers in the vicinity of Gloucester; during some seasons about 40,000,000
eggs have been taken. The eggs measure about ttV inch in diameter.
The pollock spawning season includes the months of October, Novem-
ber, and December, The fish from which eggs are obtained are taken
MANUAL OF FISH-CULTURE. 225
with uets and lines by commercial fishermen; the average number of
egg's to a fish is from 200,000 to 250,000. The period of incubation is
somewhat shorter than that of the cod, being 1) days at 43° and G days
at 49°. About 5 days are required for the absorption of the yolk-sac.
The haddock ranges from Delaware northward, and is, as a rule, very
abundant on the "banks'' lying off the New England shore. In its
habits it is similar to the cod, frequenting the same grounds and being-
caught at the same time. Its average weight is about 4 pounds and
the maximum under 20 pounds. The fishery is very extensive in Mas-
sachusetts, most of the catch being landed fresh in Boston. The
annual yield is about 50,000,000 pounds, worth $850,000.
The artificial propagation of haddock has been conducted chiefly at
Gloucester, where as many as 30,000,000 eggs have been collected in a
single season. The eggs are about r- inch in diameter, and are quite
delicate and tender. The spawning time extends from January to
June. The average production of eggs per fish is about 100,000.
The eggs are slightly glutinous and have a tendency to form into
small lumps during hatching. At a mean temperature of 37° they
hatch in 15 days, and at 41° in 13 days. The yolk-sac is absorbed in
10 days at a temperature of 41°.
The tomcod or frostfish {Microgadus tomcod) has been extensively
propagated by the New York Fish Commission. It is a small but
excellent food-fish, found along the Atlantic coast from New York to
the Bay of Fundy. It is most abundant in early winter, when it
approaches the shores and ascends streams for the purpose of spawn-
ing. It rarely exceeds 10 or 12 inches in length.
THE GUNNER.
The eggs of the cunner or chogset {Ctenolahriis adspersus) are of the
same size and character as those of its near relation, the tautog, and
are deposited during the same season. In water having a mean tem-
perature of 5G° F. they have been hatched in 5 days, in the tidal cod-jar.
On account of the small size, great abundance, and comparatively
little commercial value, the propagation of the cunner has not been
regularly undertaken.
THE SCUP.
The scup {Stenotomus chrysops) is a rather important small food-fish
found along the Atlantic coast from Cape Ann to South Carolina; it is
most abundant in southern New England. It spawns in June. The
eggs are ^V inch in diameter and hatch in 4 days at a mean tem-
perature of 62° F.
THE SEA BASS.
The eggs of the sea bass {Gentropristes striatus) are of the same size
as scup eggs, are deposited in June, and hatch in 5 days with the
water temperature 59° or 00°. The sea bass is an important food-fish,
F. M. 15
226 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
found from Massacliusetts to Florida; it is taken in large quantities
from New Jersey northward with lines and traps. It attains a weight
of 5 pounds, but the average weight is only 1 or 1^ pounds.
THE SQUETEAGUES.
The squeteague or weakflsh ( Gynoscion regnlis) is a prominent food-
tish of the Atlantic and Gulf coasts, the northern limit of its range
being in the vicinity of Cape Cod. It goes in immense schools and is
taken in large quantities for market, in IJ^orth Carolina, Chesapeake
Bay, Delaware Bay, on the !N'ew Jersey and New York coasts, and in
southern New England. It varies greatly in size; the average weight
is under 5 poiinds, but it has been known to attain a weight of 30
pounds. In the vicinity of Woods Hole this fish spawns in June. Its
eggs are /„ inch in diameter, and at an average temperature of 00° F.
hatch in 2 days.
The spotted squeteague or "sea trout" (Cynoscion nchulosum) has
also been propagated on a small scale. It is a valuable food-fish from
Chesapeake Bay southward, being taken in largest quantities in Vir-
ginia, North Carolina, Florida, and the Gulf States. Its average weight
is 2 pounds and its maximum 10 pounds. It spawns in bays and sounds
in sjiring and summer, the time varying with the latitude. The eggs
are buoyant, ;jV inch in diameter, and hatch in about 40 hours at a
temperature of 77° F. This species has been artificially hatched on
the southwest coast of Florida by the steamer Fish Hawk.
THE SHEEPSHEAD.
The sheepshead [Arcliosargus prohatocephalus) is generally regarded
as one of the best food fishes of American waters. Its deep body, of a
grayish color, marked by 8 transverse black bands, and its peculiarly
shaped head, with mouth armed with prominent incisor teeth, make it
readily recognized. It ranges from Cajie Cod to Texas, but is most
abundant from Chesapeake Bay southward. It attains a weight of
over 20 pounds, but the average weight on the Atlantic coast is not
over 7 or 8 pounds, and in the Gulf of Mexico scarcely exceeds 3 pounds.
In southern waters the fish is a permanent resident, but in the northern
part of its range it is found only during spring, summer, and autumn.
The spawning season is from March to June, according to the locality.
The artificial hatching of the sheepshead has been undertaken on
several occasions, but is not regularly prosecuted. The most extensive
work was conducted by the Fish Haivlc in March and April, 1889, when
23,400,000 eggs were taken in the vicinity of San Carlos Bay, on the
southwest coast of Florida. These yielded 16,500,000 healthy fry, most
of which were planted in local waters.
In capturing spawning fish on the Florida coast it was found that
the best time to use the seine was Just before sundown, as the flood tide
was about to " make." Tlie fish were then easily taken in large numbers.
Seine hauls in the morning consisted only of male fish. Spawning
MANUAL OF FISH-CULTURE. 227
sheepshead swim iu schools, and seem to prefer sandy beacbes, along
which they resort at a depth of (J or 8 feet.
The shcepshead egg is very small, transparent, and of less specific
gravity than sea wpter. The diameter is ;j\, of an inch, and the number
in a Ihiid ounce is about 50,000, or 1,000,000 in a quart.
The eggs are satisfactorily incubated in the tidal cod-jar, about
300,000 eggs being placed iu each jar. The development is very rapid,
and in the warm water of the Gulf (7G° or 77° F.) the eggs hatch in 40
hours. The newly hatched fry are very small, but active and strong,
and withstand considerable rough handling. They are planted when
72 to 80 hours old.
It is i)robably not practicable to carry on extensive sheepshead
hatching north of Florida, although small quantities of eggs could
doubtless be taken in IS^orth Carolina and Virginia.
THE SEA HERRING.
The sea herring [Chipea harenfjns) may be distinguished from other
clupeoid tishes found in United States waters by the following char-
acters: Body elongate and laterally compressed, the depth contained
4i times in length; mouth at end of snout; lower jaw i^rojecting,
extending to beneath the middle of eye; roof of moutii with an ovate
patch of small teeth; gillrakers long and slender, about 40 below
the angle in adults, fewer in young; dorsal fin with 18 rays, inserted
slightly behind middle of body; ventral fins beginning beneath middle
of dorsal; anal fin with 17 rays; median line of belly with 28 weak
spines or scutes in front of ventral fins and 13 behind tins; scales thin,
easily detached, posterior edges rounded, 57 in lateral series; color
bluish or bluish-green above, light-silvery below.
The sea herring exists iu great abundance on both shores of the
Atlantic Ocean north of the latitude of about 37° north. On the coast
of iSJ^orth America it is not regularly abundant south of Cape Cod, but
it is occasionally found as far south as Chesapeake Bay. In number of
individuals this species is probably exceeded by no other fish. On the
Pacific Coast a similar and almost equally abundant species {Clu;pea
pallasii) is found from Alaska to Mexico.
There are no well-defined movements of the herring on the west
shore of the Atlantic, if those induced by the spawning instinct are
excepted. There was formerly a distinct shoreward migration, during
the winter months, in the Bay of Fundy, but this run has not occurred
for a number of years. In many places the herring, especially the
smaller individuals, appear to be resident in the shore waters. The
maximum length of this fish is about 17 inches, and the usjual length of
spawning fish on the United States coast is from 11 to 14 inches.
The herring subsists on minute invertebrates, chief among which are
copepods, larval worms, and larval mollusks. In turn it is consumed
iu enormous quantities by cod, haddock, sharks, and many other fishes.
228 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
With respect to the time of spawning, the herring may be divided
into two groups, one spawning in tlie spring, in April, May, and June,
and the other between July and December, The spring spawning
occurs entirely east of Eastport, Maine, and the fall spawning princi-
pally, butnot entirely, west of that place. Probably the greatest spawn-
ing grounds south of the Gulf of St. Lawrence are at Grand Manan.
where the eggs are deposited principally iu July, August, and Septem-
ber. Thence the season becomes progressively later westward, on the
coast of Maine occurring between September 1 and October 15; on the
eastern coast of Massachusetts, between October 1 and November 1,
and south of Cape Cod from October 15 to December 1.
The female of average size deposits between 20,000 and 47,000 eggs
at a spawning, usually not far from 30,000. The eggs are deposited
upon the bottom, and, being covered Math a glutinous material Mhich
soon hardens in contact with the water, they become firmly attached
to extraneous materials, to which they often adhere in masses as large
as a walnut. The egg measures about ,4 inch in diameter, and is
usually polyhedral from mutual pressure exerted by the eggs in masses.
The commercial value of the sea herring is almost incalculable. It
is undoubtedly the most important of food-fishes, althougli in the United
States it is surpassed in economic value by many marine and fresh-
water species. Some time ago the annual yield of the world was esti-
mated at 3,000,000,000 fish, weighing 1,500,000,000 pounds, the principal
part of which was taken in Norway. In the New England States the
annual catch is about 70,000,000 pounds, with a first value of $600,000.
The herring has been artificially propagated both in this country and
in Europe, but owing to its great abundance the work has been only
experimental. In the United States there has as yet been no perma-
nent diminution of the supply that renders the cultivation of the species
necessary, notwithstanding an extremely large fishery and the sacrificf
of enormous quantities of very small fish. The first successful attempt
to propagate this fish was in 1878, in Germany, when elaborate experi-
ments Avere made. In the same year the artificial hatching of the
species was accomplished by the U. S. Fish Commission. The eggs,
owing to their cohesion into masses, showed a tendency to molding,
but this difficulty could doubtless be obviated by the use of starch, as
with other cohesive eggs.
Development takes place in water ranging in temperature between
33° and 55° F., the time of incubation varying from about forty days at
the former temperature to eleven or twelve days at the latter. Sudden
and extreme variation between the tem])erature limits mentioned had
little or no effect except to retard or accelerate the hatching in accord-
ance with the rule j ust mentioned. When water of a temperature lower
than 33° F, was used many of the embryos were deformed. The degree
of salinity of the water does not appear to exert much influence upon
the hatching of the eggs.
Fish Manual. (To face page 229.)
Plate 62.
HOMARUS AMERICANUS, Atiiffi' an Lobster.
THE AMERICAN LOBSTER.
DESCRIPTION.
The lobster {Tlomartis amcricanus) belougs to that group of the Crus-
tacea called the 1 )ecapoda, because all of its members are x)rovided with
teu feet, more or less adapted for Avalking. To the Decapoda also belong
the crabs and the shrimps, prawns, and crayfish. The crabs are less
related to the lobster than the other forms mentioned, and may be
readily distinguished from them by the relatively great breadth of the
body and the small size of the abdomen or tail, which is doubled under
the thorax to form the '• apron," The lobsters, crayfish, shrimps, etc.,
are elongate forms with the tail or abdomen very large and extended
more or less in the same horizontal plane with the anterior part of the
body. The lobster and the crayfishes are somewhat closely related, but
differ, among other characters, in the number and structure of the gills
and in the relative size of the flat plate or scale which is attached at
the base of the antenna^, or long feelers. The Pacific Coast crayfishes
have 18 gills, those east of the Kocky Mountains have 17, while the
lobster has 20. The appendage of the antenna is large in the cray-
fishes, but very small in the lobster. Moreover, the crayfishes rarely
exceed 5 or 6 inches in length, while the adult lobster is much larger,
as seen in the markets, seldom measuring less than 9 or 10 inches.
The spiny lobster, the "lobster" of the Pacific Coast, is readily distin-
guishe<l from tJie crayfish and the common lobster by the total absence
of great claws, by the greater length and stoutness of the antennte, and
by the presence of large, broad-based, spinous processes on the back.
The body of the lobster is divided into two distinct regions, the
cephalothorax and abdomen. The former consists of the head and
thorax fused into one united whole. That portion which would consti-
tute the head, were it separate, bears the eyes, the two pairs of feelers,
and the mouth, with the several pairs of modified limbs which surround
that organ and assist in tearing up the food and passing it into the
mouth. The thoracic portion of the cephalothorax is furnished with five
pairs of stout limbs, the first pair bearing the great claws, which are
rarely of the same size on the two sides, and the last four pairs being used
in walking. From the fact that this portion of the body bears five pairs
of api)endages, it is assumed that it represents five fnsed segments.
The abdomen is narrower than the cephalothorax and is com])osed
of six separate segments movable on one another. In the female the
229
230 RKPORT OF COMMISSIONER OF FISH AND FISHERIES.
first five pairs of abdominal appendages, known as swiuimerets, are all
similar and consist of a sliort basal piece and two terminal pieces side
by side. The appendages of the sixth segment consist of the same
arrangement of parts, bnt the pieces are broad and paddle-hke, and,
with the terminal i)late attached to the last segment, constitnte a
powerful caudal paddle or tail. In the male the abdomen is narrower
than in the female, and the first two pairs of swimmerets differ much
from those which follow.
The color of the lobster is subject to great variation, but most fre-
quently is dark bluish-green above, mottled with dark-green blotches;
there is usually more or less red or vermilion on the appendages,
especially on the tubercles, tips, and under side of the great claws
and on the antennae; the walking legs are light blue with reddish tips
and tufts of hair. Occasionally s])ecimens are found which are almost
entirely red, and more frequently they are blue or bluish in general tone.
DISTRIBUTION AND ABUNDANCE.
The lobster is found from Labrador to Delaware, its range covering
about 1,300 miles of coast line. Stragglers have been taken on the
coasts of Virginia and North Carolina. While the bathic range is prac-
tically limited by the 100-fathom line, it is occasionally found long
distances from land on the fishing-banks off' the New England coast.
The lobster is most abundant in the northern part of its habitat.
On the United States coast it is most numerous in Maine. In the
provinces of Nova Scotia, New Brunswick, and Quebec, and also in
New^foundland it is extremely abundant.
MOVEMENTS.
The movements of the lobster are chiefly on and off" shore. Such
coastwise movements as characterize the mackerel, bluefish, and men-
haden are never undertaken by the lobster. This fact makes possible
the rapid depletion of fishing-grounds, and even tlie i)ractical exter-
mination of tlie lobster in given areas; it also affords basis for the
belief in the efficacy of artificial means for maintaining and increasing
the supply.
There are well-marked movements of the lobster induced by various
influences, among wiiich are the abundance or scarcity of food, the
water temperature, and the spawning instinct. On the United States
coast there is in the spring months a shoreward movement of large
bodies of lobsters; ^on the approach of winter the lobsters move out
into deep water.
FOOD.
The principal food of the lobster is fish, either dead or alive. Such
bottom species as the sculpin, flounder, and sea-robin can doubtless be
readily caught by the lobster, and they also consume a large number
of invertebrates, among them being crabs and other crustaceans, clams,
conchs, and other mollusks, starfish, sea-urchins, etc. Lobster eggs
MANUAL OF FISH-CULTURE. 231
Lave been found in a lobster's stomach, and algic sometimes serve as
food. Fish is the bait most extensively employed iu the lobster fishery.
REPRODUCTION.
The reproductive function of the lobster is not generally understood,
and until a comparatively recent date a number of important questions
in relation thereto were undecided. From the standpoints of the com-
mercial fishermen, fish-culturist, and legislator, it is necessary that the
]>rincipal phases of this subject be clearly api)reciated, in order that
the supply may be maintained.
The principal spawning- season for lobsters on the United States coast
is summer, especially July and August, when probably three-fourths of
the lobsters deposit their eggs. The remaining eg"g-i)roducing lobsters
lay during the fall and winter. A given lobster does not spawn oftener
than every second year, as has been shown by recent studies conducted
by the Commission.
The eggs are fertilized outside the body of the female. The sper-
matic fluid is deposited in a recei)tacle at the base of the third pair of
walking legs, and retains its vitality for a long time. When the eggs
are being extruded, the female lobster lies on her back and folds the
tail so as to form a kind of chamber to retain the eggs. After their
discharge from the body, the eggs become coated with a cement substance
secreted by glands in the swimmerets; this substance hardens after
being in contact with the water and firmly unites the eggs to the hair-
like filaments on the swimmerets. The exact method by which the
fertilizing principle is conveyed to the eggs from the ])ouch iu which it
is contained is not known.
The incubative period is much prolonged. After the eggs are
extruded and become attached externally, they are carried 10 or 11
months before hatching ensues; during this time they are carefully
protected, and are perfectly aerated by the active motion of the swim-
merets. On the United States coast most of the lobsters emerge from
the egg in June, although some of the hatching is completed in May
and some in July or even later. A few eggs are now known to hatch
in winter. All of the embryos do not come from the eggs at the same
time, the hatching occupying a week or more. The young receive no
attention from the adults, but lead an indei)endent existence immedi-
ntely after escaping from the egg.
The lobster egg is about i\ inch iu diameter. When newly laid it is
usually of a dark-green color, but is sometimes light-grayish or yellow-
ish-green.
The known maximum number of eggs produced at one time by a
lobster is 97,44:0; the average from lobsters taken for market is 10,000
to 12,000. The number depends largely on the size of the lobster,
apparently in conformity to the following rule: The numbers of eggs
laid by given lobsters vary in a geometric scale, while the lengths of
the lobsters vary in an arithmetic scale.
232 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
The followiug table illustrates, with approximate accuracy, the egg-
producing capacities of lobsters of the lengths indicated under normal
conditions:
Lengtli of lobster.
Number of
egfxs laid.
.'), 000
10,000
20, 000
40, 000
80, 000
lu inches
12 inches
14 inches
MOLTING AND GROWTH.
The act of shedding the shell, or molting, is important and critical.
It is only after shedding that growth takes place; during the early
stages of the lobster's existence this function is often exercised in a
comparatively short time, while later it occurs only at long intervals.
Molting in the lobster consists in throwing off the entire external skele-
ton, together with the lining of the digestive tract.
The first molt takes place about the time the young emerges from
the egg, when it is about a third of an inch long, and many lobsters
do not survive this. During this first stage the larval lobster swims
at or near the surface. A second molt ensues in from 1 to 5 days, and
the lobster enters on its second stage, its average length being about
two-fifths of an inch and its habits similar to the first stage. In 2 to
5 days another molt takes place, and the length of the larva increases
to about half an inch. This is followed in 2 to 8 days by another molt,
and the lobster enters on the fourth stage, when its length becomes
slightly greater. From 10 to 20 days later the fifth molt ushers in the
fifth stage, after which the surface-swimming habit is discarded and the
larva goes to the bottom and begins to assume the characteristics of the
adult. This stage lasts 11 to 18 days, and in it the young lobster has
attained a length of about three-fifths of an inch. From this time on the
molts are at longer and longer intervals until the fully mature condition
is reached, when shedding takes place only once in one or two years.
The food of lobsters during the larval stages consists chietly of small
crustaceans. A very pugnacious instinct then characterizes them, and
active cannibalism prevents their artificial rearing for lack of abundant
natural food.
Larval lobsters are very susceptible to the influence of the sun (helio-
tropic) while in the first three stages, being attracted by bright rays
to the surface of the ocean or to the side of a vessel. This peculiarity
is lost during the fourth stage.
During the first year the young lobster, which since the fourth stage
has become more and more like the adult in form and habits with each
molt, attains a length of about 2 or 3 inches. At the end of the second
MANUAL OF FISH-CULTURE. 233
year the length is 5 to 7 inches. By the end of 4i or 5 years a length
of about 10 inches is reached. The rate of growth, however, depends
greatly on the environment, the abundance of food being a very impor-
tant factor.
The adult lobster usually molts in summer, and in the case of the
female, shortly after the hatching of the eggs. As several months are
ro(iuired for the new shell to acquire the hardness of the old ; as newly-
laid eggs are rarely found on a soft-shell lobster; as molting does not
ensue while the eggs are on the swimmerets; and, furthermore, as
dissection has shown that the ovaries of a lobster whose eggs have
recently hatched are in an immature condition and will not yield eggs
until the succeeding year, it follows that the mature lobster deposits
eggs not oftener than once in two years, with an alternating molt.
SIZE AND WEIGHT.
The average size of lobsters caught for market is now much less than
it "was in the earlier days of the fishery, and their average weight is
probably not over 2 pounds. A lobster 9 inches long weighs, on an
average, 1^ pounds; a lOi-inch lobster. If pounds; a 12-inch lobster, 3
pounds; and a 15-inch lobster, 1 to 5 jiounds; while a lobster 20 inches
long weighs 20 pounds or more. Lobsters weighing as much as 15 or
20 pounds are uncommon, and those weighing over 20 pounds are very
rare. Up to a recent date, the largest lobster of authenticated weight
wat about 25 pounds. In 1897, however, 3 lobsters, each Aveighing over
30 pounds, were taken oft" Sandy Hook, N. J., the weight of the largest
being 3.") pounds.
The male lobster weighs more than the female of the same length,
the difference in 11 -inch lobsters, for instance, being about a quarter
of a pound.
The size at which the lobster attains sexual maturity is a very
important question. In the I^ew England and Middle States and the
Canadian Provinces the laws relating to the minimum size of market-
able lobsters are quite various and illustrate the absence of detinite
information on this subject. In Maine, Massachusetts, New Hamp-
shire, and New York the minimum limit of size of lobsters that maybe
sold is now lO.J inches; in Khode Island it is 10 inches, and in Con-
necticut it is 9 inches. In the British Provinces the limit is much
lower than in ]Maine.
Investigations conducted by the Fisli Commission on the New England
coast show that the female lobster attains maturity when from 8 to 12
inclies long. Comparatively few lobsters under 9 inches in length
lay eggs. Of over 1,000 egg-bearing lobsters collected at Woods Hole
during a period of years, less than 2 j)er cent were under 9 inches long.
On the other hand, by the time they have reached the length of lOi
inclies most lobsters will have produced eggs, and this should be the
minimum size permitted in the markets.
234 REPORT OF COMMISSIONER OF P'TSH AND FISHERIES.
COMMERCIAL VALUE.
The lobster is tbe most important crustacesin of the United States.
It is the object of a special fishery, carried on with pots or traps, in all
the coastal States from Delaware northward, and also in Nova Scotia,
New Brunswick, Prince Edward Island, (Quebec, and Newfoundland.
In Maine, where the fishery is more important than in any other State,
the lobster is the principal fishery product. Over 4,500 persons are
engaged in this fishery in the United States; the capital invested is
about $875,000, and the catch in 1896 amounted to 15,121,000 pounds,
valued at $1,319,000. In 1880 the yield was larger (20,!240,000 pounds),
but the market value was much less, being only $188,000.
Between 1889 and 1899 the New England lobster catch decreased over
15,000,000 pounds, or 50 per cent, while the value increased more than
$400,000, or 50 per cent. For a number of years this fishery presented
the anomaly of a diminishing supply and an augmented catch, owing
to the more active prosecution of the business; but the decline in the
yield has for some time been unchecked, notwithstanding the employ-
ment of more apparatus and the prolongation of the fishing season.
With a singular disregard for their own welfare, many fishermen have
continually violated the State laws for the protection of small, imma-
ture lobsters and females bearing eggs. Only the rigid enforcement of
restrictive measures by the States and the extensive artificial proi^aga-
tion of the lobster can ward off the destruction which threatens this
valuable fishery.
INCEPTION AND PROGRESS OF LOBSTER-CULTURE.
If egg-bearing lobsters were not liable to destruction by man, arti-
ficial propagation would hardly be necessary. Notwithstanding the
enactment of stringent laws prohibiting the sale of '■'• berried " lobsters,
the frequent sacrifice of such lobsters, with their eggs, and of iiiauy
immature lobsters, has seriously reduced the lobster output and rendered
active and stringent measures imperative. By the present methods
millions of lobster eggs are annually taken and hatched that would be
lost, and the females producing them, amounting to several thousands,
are liberated.
Prior to 1885 experiments had been conducted at various points look-
ing to the artificial j^ropagation of the lobster. The only i^ractical
attempts of this nature previous to those made by the Fish Commission
were by means of " parking," that is, holding in large naturally inclosed
basins lobsters that had been injured, soft-shelled ones, and those below
marketable size. Occasionally female lobsters with spawn were placed
in the same inclosnres. One of these parks was established in Massa-
chusetts in 1872, but was afterward abandoned ; another was established
on the coast of Maine about 1875. It was soon demonstrated, liowever,
that the results from inclosures of this cliaracter, so far as the rearing
of the lobsters from the young were concerned, would not be suilflcient
to materially affect the general su)))rlv.
Fish Manual. (To face page 2 34 1
Plate 63.
LABORATORY, HATCHERY, AQUARIUM, AND MUSEUM, U, S, FISH COMMISSION WOODS HOLE, MASS.
RESIDENCE, U. S. FISH COMMISSION, WOODS HOLE MASS.
MANUAL OF FISH-CULTURE. 235
The completion of the new marine laboratory and hatchery at Woods
Hole in 1885, with its complete system of salt-water circulation, per-
mitted the commencement of experiments in artificial hatching on a
large scale, which had not been practicable theretofore, although small
(juantities of lobster eggs, as well as tTiosc of other crustaceans, had
been successfully hatched. In 1880 the experiments had progressed so
successfully that several million eggs were collected and hatched at
Woods Hole, the fry being deposited in Vineyard Sound and adjacent
waters. From 1887 to 1890, inclusive, the number of eggs collected
wiis 17,821,000.
From the eggs collected up to 1881) the average production of fry was
about 51 per cent. During these years experiments were conducted as
to the best method of hatching the eggs. The various forms of appa-
ratus used were the Chester jar, the McDonald tidal box, and the
McDonald automatic hatching-jar. In 188!) the results secured in the
latter form of apparatus were so much better than with the others that
it was adopted, and in 1890, from the 4,353,000 eggs collected, over 81
per cent yielded fiy. Work was continued at Woods Hole on about
the same scale until 1894, when the collections aggregated 97,000,000
eggs. In the same year lobster propagation was undertaken at Glouces-
ter and a collection of 10,000,000 eggs was made there.
During the fiscal year 189 ! the number of eggs taken by the Fish
Commission was 105,188,000, the resulting fry liberated numbering
97,579,000, or about 93 per cent; and in 1897 the collections amounted
to 133,502,000 eggs, of which 115,000,000, or 90 per cent, were hatched.
COLLECTION OF EGG-BEARING LOBSTERS.
Although the new eggs appear on the lobsters during the months of
July and August, no special effort is made to secure egg bearing
lobsters until the following spring. The collections usually commence
in April and continue until the middle of July. At Woods Hole it
has been the recent practice to receive at the station and jjlace in the
hatching-jars during the fall and winter any lobsters having external
eggs that may be captured by local fishermen. The collecting-grounds
extend from New London, Connecticut, to the eastern end of Maine.
For Woods Hole station eggs are secured from fishermen oi)erating
between New London, Connecticut, and Plymouth, Massachusetts.
The most important grounds in Connecticut are in the vicinity of Xew
London and Xoank; in ^lassachusetts. New ]>edford. South Dartmouth,
Plymouth, Woods Hole, and numerous localities in Buzzards Bay and
Vineyard Sound. Eggs for the Gloucester station are secured from the
fishermen operating between Boston and Rockland, which territory
comprises the most important lobster fishery in the United States. The
schooner (irdmpuH is used in making the collections between Portland
and liockland, the lobsters being delivered at Gloucester early in the
season and later on to the steamer Fish JIawk, which is stationed at a
suitable point in Casco Bay.
236 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
As the laws of Massachusetts, New Hampshire, and Maine prohibit
the holding of the "berried" lobsters by the fishermen, arrangements
are made with the State authorities by which certain officials of the Fish
Commission are appointed deputy wardens and authorized to hold egg-
bearing lobsters for fish cultural purposes in live-boxes. Karly in the
spring all of the lobster fishermen in the territory referred to above are
visited by agents of the Commission, who arrange with them to hold
all of their egg lobsters in live-cars until called for, at a price agreed on.
Collections are made from Woods Hole and Gloucester by steam
launches and sailing vessels. The steam launches visit the near points
three to four times a week to obtain egg-bearing lobsters. The vessels
collect at more distant points in Connecticut and Maine. Local agents
at Boston and Plymouth, Massachusetts, and Kittery Point, Maine,
also collect egg-bearing lobsters, which are held in live-boxes until the
agent has a sufficient number to make a trip. On the arrival of the
vessel or launch at the station the lobsters are transferred to tanks
supplied with running water and held until the spawn-taker is ready to
strij) the eggs.
TAKING AND MEASURING THE EGGS.
The receptacle into which the spawn-taker strips the eggs from a
lobster is either a glass jar (9 inches in diameter) or a water-bucket,
which, after thorough cleaning^ is partly filled with water.
The operator, with his left hand, grasps the lobster from above and
turns it on its back, lowering it into the spawning vessel head down-
ward. By pressing it firmly against the sides of the jar it is prevented
from using the anterior part of its body or its mandibles. The hand is
then slipped farther back toward the tail and the segmented i)ortion of
the body is held firmly to prevent its closing. The lobster is then ready
for stripping. x\ rather dull, short-bladed knife is used to separate
the eggs from the swimmerets, to which they are attached by hair- like
fibers; stripping begins at the last pair of swimmerets and gradually
proceeds toward the body. As the eggs are scraped off" they fall into
the water in the jar. Some which adhere to the claws of the lobster
are washed off' by means of a small stream of water. The lobster is
then put back into a tank, w4iere it remains until liberated.
Lobsters received by the local agents at Boston and Kittery Point
are held until a suitable quantity is on hand and are then stripped, the
eggs being taken to the station in transportation cans and the adults
released. Early in the spring the eggs stand transportation well, but
late in the season, as incubation becomes more advanced, they are very
delicate and are quickly affected by rough handling or sudden changes
iu temperature.
Before being transferred to the hatching-vessels the eggs are accu-
rately measured, generally with a glass graduate, into which they are
poured, the water being drawn off. The basis of measure is an ounce,
which contains about G,090 eggs.
MANUAL OF FISH-CULTURE. 237
HATCHING APPARATUS AND OPERATIONS.
Experiments conducted during a series of years having demonstrated
that the automatic hatching-jar was the best form of ai)paratus for
hatching lobster eggs, it has been adopted at the stations of the Com-
mission since 1889. A full description of this jar is given in the article
on shad-culture, pp. 150-152. The manipulation and operation of the jar
is practically the same as with shad eggs, except that frequently, where
the water supply is inadequate, three jars are connected by means of
rubber tubing and the water used over and over. This is accomplished
by connecting the overflow from the first jar with the supply to the
second and so on, but can only be done during the early stages before
the fry commence to hatch. When flrst placed in the jar the eggs are
matted together by the fine hair-like fibers, but after a few days they
separate and work very much like shad eggs.
From 400,000 to 500,000 eggs (equivalent to about 2 to 2i quarts) are
usually placed in each jar, although at times when the hatchery is
crowded a few more may be successfully cared for.
The fry pass voluntarily from these jars to cylindrical glass jars, 9
inches in diameter and either 9 or 18 inches high, placed in the center
of the table and covered with cheese-cloth at the top to prevent their
escape.
The period of incubation depends entirely upon the age of the egg
when collected. For example, eggs taken in October do not hatch until
the following May, whereas eggs collected in June frequently hatch
in 24 hours after being placed in the jars. During one season eggs
collected from December 12 to January 25, numbering 1,717,000, at a
temperature of 45°, commenced hatching May 25 at a temperature of
54°. To determine how soon the new-laid eggs can be taken from the
parent and hatched artificially, collections were begun early in July
and continued until fall, for several seasons, the eggs being placed in
hatching-jars at the Woods Hole Station ; all those collected prior to
October 15 died. In November, 1895, 15,000,000 were placed in jars
and carried through the winter under very unfavorable conditions, but
hatched with a loss of only 50 per cent. The density of the water at
Woods Hole varies from 1.023 to 1.025, its average temperature being
from 49° to 04° during the months of April, May, and June.
THE LOBSTER FRY.
Owing to the cannibalistic habits of young lobsters when closely
crowded, it has been the policy of the Commission to liberate the fry
as soon after hatching as possible. They are taken out in ordinary
10-gallon transportation cans, about 200,000 being placed in a can for
short shipments and 125,000 for long shipments, and liberated in the
vicinity of the grounds from which the adult lobsters were taken.
When this is impracticable, they are liberated in Vineyard Sound and
Buzzards Bay with an outgoing tide, so as to insure their wide distri-
238 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
bution. The question of the transportation of lobster fry any great
distance is still an unsettled one, as in but few instances has it been
attempted to ship them by rail, and then the trips were comparatively
short — namely, from Woods Hole to Cold Spring Harbor, New York;
from Woods Hole to Provincetown and Plymouth, and from Gloucester
to Kittery Point. The shipments from Woods Hole have all been very
successful, and there seems little doubt that the young lobster will
stand transportation for 24 hours with excellent results.
Fish Manual. (To face page 239.'
Plate 64.
VIEWS OF CAR NO. 3.
THE TRANSPORTATION OF FISH AND FISH EGGS.
During the earlier years of the Commission young lisli were carried
by messengers in baggage cars on regular passenger trains, but as tlie
work increased it was found that tbis method was inadequate and that
other arrangements must be made to transport the large numbers of
tish which were being hatched. Accordingly, in 187U and 18S(), experi-
ments were successfully made in moving shad fry in si)ecially equipped
baggage cars, and it was found that large numbers of fish could be
economically moved with little loss. A car was therefore constructed
specially adapted for the distribution of live fishes, the requirements
of such a car being a compartment for carrying the fish in which an
even temperature could be maintained, i)roper circulation of water and
air in the vessels containing the fish, and sleeping and living accom-
modations for the messengers atteiuling them.
A baggage car, the body of which was 51 feet long, 9 feet 10 inches
wide, 13 feet 8 inches high, was purchased. At one end of the car was
a room containing a stove, sink, and berth for the use of the cook,
besides a boiler, pump, etc. ; and at the other were two sections of
berths, like those in a Pullman car, which would accommodate two men
on each side. Each comi)artment was about 7 feet long. In its center
was a refrigerator compartment 30 feet 3 inches long by the full width
of the car, and extending up to the clear story. The ice was carried in
two racks, holding 1 ton each, which were located in the corners of the
refrigerator, diagonally opposite each other. Cylinder cans, placed on
galvanized iron tanks 9 feet 4 inches long, 28 inches wide, and 8 inches
high, were i)rovided in which to carry the fish. The tanks were placed
on opposite sides of the car, with a passageway between them.
An apparatus for circulating water was arranged in the following
manner: In the top of the car, extending the full length of the clear
story, was a long, semicircular iron tank 12 inches in diameter, which
was filled through the top of the cai*. From this the water was brought
into a 0 in(;h pipe extending all around the top of the refrigerator
com])artment. The pipe contained a sufficient number of pet cocks to
snjjply the number of cans carried, the water being conveyed to the
cans through rubber tubing. From the cans it passed into the tanks
through the same-sized tubing, whence it was drained into 2-inch pipes
underneath the car, and from these pipes was pumped up to the tank
in the clear story.
AVhile this circulating api)aratus worked well, its arrangement neces-
sitated the carrying of a large amount of water in the top of the car,
239
240 REPORT OF COMMISSIONER OF FISH A:ND FISHERIES.
thus causing it to roll from side to side iu such a uianner as to make it
unsafe. It was also fouud that while the refrigerator compartment
carried the fish safely, the health of the messengers was injuriously
afl'ected owing to the sudden changes of temperature experienced in
going to and from the compartment. Accordingly, another car was
built in which these defects were remedied, and the original car was
altered to conform to the improved plan.
The Commission now has five transportation cars in use. Vv^hile they
differ somewhat in construction and arrangement, four of them are
essentially alike; the fifth is simply a baggage car with living quarters
and circulating apparatus. The car known as No. 3 is regarded as the
best type. Its dimensions are: Length of body, GO feet; total length
from end to end of phitforms, G7 feet 10 inches; width, 9;^ feet; height
from top of rail to top of roof, 13g feet.
The frame of the car is so braced as to permit of two large doors in
the center, extending from floor to roof, which simplify loading and
unloading. Underneath, between the trucks, is a reservoir tank hold-
ing GOO gallons of water. The car is fully equipped with all modern
improvements in the way of brakes, couplers, signal whistles, etc., and
has Pullman trucks and 33-incli Allen paper wheels.
The interior is finished iu ash, and due arraugements are made for the
comfort and convenience of the crew. In one end is an office, an ice-box
of 1^ tons capacity, and a pressure tank holding 500 gallons of water; at
the other are the boiler-room and kitchen. The tanks and cans used
in transi)orting fish are carried iu two comi)artments running along the
sides of the car between the office and boiler-room. They are 30 feet
long, 3 feet wide, and 25 inches deep. In the middle of the car, over the
compartments, are four berths and several lockers for the use of the crew.
The office is fitted with two berths, lockers, writing desk, and typewriter.
In the boiler-room are a 5-horsepower boiler for furnishing the necessary
power, a circulating water pump, and an air and feed pump.
For the transportation of fry ordinary 10-gallon irou cans, tinned, are
used, 24 inches high, 12 inches in diameter on the outside, with sloi)ing
shoulders and cover, and two handles on the sides for convenience in
moving. The water is introduced by means of a rubber hose connected
with the pressure tank, or sim])ly with- a dipper or bucket.
For the transportation of large fish the cars are equipped with 22
tanks holding 52 gallons each. They are 27 inches square by 24 inches
high, and are made of No. 18 galvanized iron, with a splashboard 3
inches from the top, which extends into the tank 2^ inches, thus pre-
venting the water from splashing out when the car is in motion. They
are also provided with a three-eighths inch overflow, which connects
with the suppl}^ tank under the car and can be drained by means of a
3-inch flat valve placed in the bottom.
The supply of water is carried iu the iron pressure-tank located in the
body of the car next to the office. The water is circulated by means
MANUAL OF FISH-CULTURE. 241
of;i steam-puiiip tliroujili galvaiii/ed-iroii jjiping, which runs from the
puiup to the pressure- tank, thence along the sides of the refrigerator to
the transportation-tanks, whence it flows by gravity to a tank below the
floor. From here it is pumped into the supply tank for redistribution.
To provide sufficient air circulation, the air is driven by a pump to a
3()-gall()n reservoir in the top of the car over the boiler-room, from wliicli
it is taken to the transi)ortation tanks or cans through two lines of iron
piping running along the sides and top of the car. One pet-cock is
placed in the pipe for each tank to be supplied with air, which comes to
it through a hole 3V i^^^^i i'' diameter. From the pet-cock the air is car-
ried into the tank with rubber hose and released in the water through
liberators made of American linden, placed in hard rubber holders.
The car has a hatching outfit, consisting of eight lead-lined boxes
about 6 inches high, which may be placed on top of the refrigerator
compartments and made to fit in place of the lids, which can be removed.
Each box holds six McDonald Jars. An aquarium, specially made for
the work, is placed in the center of each box, with three jars on each
side of it. The Jars and aquarium are securely wedged in the box, so
that they can not move. The supply of water for the Jars comes from
the supply pipes in the refrigerator compartments, the pipe coming up
through the top of the refrigerator near the center, then branching out
on each side with pet-cocks in it, to which is attached the rubber tubing
to supply the jars. The overflow is through a pipe leading out of the
bottom of the boxes into the tank under the car.
Fry are carried in cans, and yearlings and adults in the transporta-
tion-tanks, (rreat care is taken not to make a sudden change in the
temperature. If the air and water circulations are not used it is neces-
sary to aerate the water with a dipper, that is, to take a dipperful of
water from the can and, holding it up about 2 feet, pour it back, thus
taking air with the water to the bottom of the can.
Whitefisli fry are carried in water at a temperature from 33"^ to 45° F.
If necessary to reduce the temperature, ice can be placed in the water
with the fry. If the air and water circulations are used, about 40,000
fry may be carried in each can. Without the circulation 20,000 are
carried, and to aerate them it is necessary to draw off in a ])ail, through
a screened siphon, about one-half the water in the can. This is then
thoroughly aerated in the pail with a dipper and returned to the can,
with a small amount of fresh water added. When a car arrives at its
destination, the cans are taken to a tugboat or steamer and carried to
the grounds where the whitefisli are to be planted. On board the boat
they are given fresh water as fast as is required to keep them alive.
Shad fry are carried in water at a temperature of from 55^ to 05°,
depending on the temperature of the water in which they were hatched.
Each can contains 20,000 to 30,000. These fry can not be carried suc-
cessfully with the circulating system of water or air, and aeration by
the use of the dipper is therefore necessary. When the water is to be
I'\ M. IG
242 REPORT OF COMMISSIONER OF FlsH AND FISHERIES.
cbau^ed, it is diawii ott' tbrougli a sii)lion into a pail, the bead of tbe
sipboii being in a wire cage, covered with cbeese-clotb, to prevent tbe
fry from escaping. After tbe water iu the pail bas been tborougbly
aerated and ice added to secure tbe desired temperature, it is i)oured
back tbrougb a large funnel wbicb reacbes nearly to tbe bottom of tbe
can. To prevent tbe force of tbe water from injuring tbe delicate fry,
tbe lower part of tbe funnel for about (5 incbes is made of perforated
tin. During long trips tbe sediment collecting on tbe bottom of tbe
cans is removed by drawing it off tbrougb a sipbon into a pail. Sbould
any fry come out, tbey are returned to tbe can by dip])ing tbem out
after tbe sediment bas settled to tbe bottom of tbe pail. If a trii) lasts
five or six days, tbe cans are cleaned every otber day by transferring
tbe fry witb a dipper from one can to tbe otber and cleaning tbe empty
can before tbe fry are returned to it. Sbad fry are more tender tban any
otber young fisb moved on tbe cars, and tbe greatest care is necessary
in bandling tbem.
Trout and salmon fry are carried in water at a temperature of 36° to
46°, tbough rainbow trout are sometimes transported in water 10° or
15° warmer. If it is necessary to reduce tbe temperature, ice is placed
in tbe cans witb tbe fisb. Each can contains 5,000 trout fry, or 2,000
to 3,000 salmon fry, wben tbe air and water circulations are used;
witbout air circulation, 3,000 or 4,000 trout or 1,200 to 1,500 salmon
fry are allowed to eacli can — according to tbe length of the trip and
age of tbe fry. Tbese fisb are moved as soon as tbe sacs are absorbed,
or when they first begin to swim uj) from the bottom. If shipped before
this i)eriod of life, tbey are apt to collect on the center of tbe can in the
bottou) and smotber. If tbe fry will keep away from the mouth of the
can, the water is aerated by dipping it directly from the can and letting
it fall back; but if tbe fish do not go down when tbe dipper is intro-
duced, the water is siphoned into a pail, aerated, and tben poured back.
Small yearling trout are sometimes carried in cans, but usually in the
galvanized-iron tanks — 100 to 200 in each can if tbe air circulation is
used, tbe water being kept cool by introducing ice. As salmon and
lake trout are more delicate tban tbe others, tbe number placed in each
can is reduced. But few adult trout can be shipped in each tank, only
from 20 to 50 if of large size. They are given all tbe air and water cir-
culation ])ossible and carried at a low temperature; when in distress
they come to the surface of tbe water, and if the water is then vigor-
ously aerated tbey will return to tbe bottom of tbe tank. Incessant
watchfulness is necessary in transporting these fisb.
When black-bass fry are distributed they should be shipped in water
from 40° to 00° F., according to the temperature of the water from
which tbey are taken ; but it is ijreferable to hold these fisb in tbe ponds
or feeding-troughs until tbey are from 3 to 0 mouths old, when tbey
will have attained a length of from li to 3 or 4 inches, fish hatched at
the same time often varying considerably in length. In transiwrting
MANUAL OP FISII-CULTURE. 243
these older fish a temiicrature of from 40° to 00° is leciuired, jiccordiug
to circumstances. Youiij^' black bass arc very voracious, aud begin to
eat each other as soon as they are confined, in cans or tanks for trans-
portation. The number of bass carried in each tank is api)roximately
as follows: Fifty <S to 12 inches long; one hundred and twenty 5 to 8
inches long; two hundred and fifty 2 to 5 inches long.
Crappie are carried in the same manner as black bass, although it is
more difficult to handle them. Kock bass are commonly carried in
cans, about TiOO to 700 in each if the fish are about an inch long. The
temperature of the water is from 40° to 00°.
Cod fry are moved in cans with water of a temperature of 33° to 38°.
The trips arc usually short. The water is aerated by drawing it from
the can through a screen siphon into a pail and returning it after it has
been thoroughly aerated.
Large lobsters, on long trips, are packed in seaweed in wooden trays
about () inches high and of a size convenient for handling. Strips of
wood attached to the bottoms of trays have open spaces between them
to allow air circulation. About 2 inches of seaweed are si)read on the
bottom of the tray and the lobsters placed on it with their claws toward
the outer ends, so that they can not injure each other, and the trays are
then filled with seaweed. They are packed in the refrigerator compart-
ments, and the temperature of the air is kept, if possible, at from 40° to
48° F. A supply of salt water, filtered through cotton, is taken along,
and the lobsters are sprinkled with it three or four times a day, and
are also daily overhauled and repacked. If the desired temperature
is maintained, 50 to 60 per cent can be carried 5 or 6 days. Lobster fry
are moved in the same manner as cod fry.
In transporting adult salt-water fishes, as many as possible are placed
in the tanks without overcrowding. The water is kept fresh by air
circulation only. Ice is packed around the galvanized-iron tanks to
keep them cool, and if necessary to reduce the temperature a can filled
with ice is placed in the water. Marine fishes have been transported
successfully for 0 days or more.
A large number of fish are distributed yearly by messengers, acting
independently of the cars. Each messenger is supplied with a number
of 10-gallon cans, a dipper, a ogallon iron pail, a large tin funnel with a
perforated bottom, a thermometer, and a piece of finch rubber hose,
about 4 feet long, for use as a siphon, besides a supply of ice. When it
is necessary to renew the water, the messenger sees that it is clean,
fresh, and free from deleterious substances. Especial attention must
be given to this in passing through limestone regions, and fresh water
must be tested before the supply on hand is thrown away. The fry are
cared for and aerated in the same manner as has been already described
for transi)orting them in cans.
SPAWNING SEASONS OF FISHES PROPAGATED, CHARACTER
OF FISH EGGS, PERIOD OF INCUBATION, ETC.
Ill the following table there are presented, in a form convenient for
reference, some of the more important facts connected with eggs of the
fishes artificially cultivated in the United States. It should bo under-
stood that there is considerable variation in many of the items, depend-
ing on climatic conditions, size and age of fish, etc.; the information for
such can therefore be only approximately correct. For certain of the
less important fishes, it is possible, from the data available, to supply
only a part of the information indicated by the column headings. The
spawning season given is generally that of wild fish in the regions where
fish-cultural work is prosecuted; this varies much with latitude and
local conditions.
Fish eggs, as regards their physical characters, naturally fall into
four classes, as follows :
(1) Buoyant or floating, as the eggs of the cod, mackerel, and most
I^elagic fishes, which come to the surface when first deposited and
remain there during at least the early stages of incubation.
(2) Semi-buoyant, as the eggs of the shad and whitefish, whose spe-
cific gravity is but slightly greater than that of water.
(3) Heavy, non-adhesive, as the eggs of salmon and trout.
(4) Heavy, adhesive or glutinous, as the eggs of the flatfish, sea her-
ring, yellow perch, and most pond fishes.
The differences in the tyjies of hatching apparatus depend primarily
on the foregoing characters of the eggs.
At the hatching stations the size of eggs is determined by i)lacing a
number of moist eggs, shortly after taking, on a flat surface, side by
side, and noting how many are required to cover a linear inch. Owing
to capillary attraction between adjoining eggs leading to compression
or flattening of the contiguous sides, this method is liable to slight
error, the extent of which is in inverse j)roportion to the size of the
eggs.
By means of the microscope, accurate measurements of small eggs may
be made. The size of eggs of a given species often varies considerably,
sometimes amounting to 25 per cent.
245
246 RErORT OF COMMISSIONER OF FISH AND FISHERIES.
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MANUAL OF FISH-CULTURE.
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NOTES ON THE EDIBLE FROGS OF THE UNITED STATES
AND THEIR ARTIFICIAL PROPAGATION.
BY
F. M. CHAMBERLAIN,
Assistant, U. S. Fish Commission.
249
NOTES ON THE EDIBLE FROGS OF THE UNITED STATES AND
THEIR ARTIFICIAL PROPAGATION.
The frogs are familiar representatives of the great class of cold-
blooded vertebrates knowu as the Batrachia. The batrachiaus are
intermediate anatomically and physiologically between the fishes and
-the reptiles (snakes, tnrtles, terrapins, alligators, etc.); they are chiefly
characterized by the metamorphosis which the young undergo before
assuming the functions and habits of the adults. The young are mostly
aquatic and breathe by means of gills, which absorb oxygen from the
water. Later the gills disappear and are replaced by lungs.
The frogs are included in the order Salientia (the leapers), distin-
guished by having a short, depressed body and four limbs, the hind
pair being much enlarged and adapted to leaping and swimming; the
tail, present in the young, disappears with age. In the related orders
( frodcia, containing the salamanders and newts; Proteida,ihe mud-
puppies or water-dogs, and Tracliystomata, the sirens or mud-eels) the
tail persists in adult life and the hind limbs are small, but the metamor-
phoses and habits otherwise more or less closely resemble the Salientia.
Associated with the frogs {Ranida;), in the order Salientia, are the
families {Bufonidw and Bylidcc) to which the toads and tree frogs
belong. The toads are very closely related to the frogs, but differ in being
more terrestrial in their habits and, among otlier structural features, in
the absence of teeth and the possession of an expansible thorax; their
uncouth form and the pungent secretions which have brought them
immunity from the attacks of other animals have added to the preju-
dice against their relatives, the frogs. The tree frogs are characterized
by arboreal habits and corresponding changes in structure. More than
250 species of true frogs {Ranidcv) are known. They are most numer-
ous in Africa and the East Indies. .
The edible frogs of the United States belong to the genus h'ana
(Latin, a frog). Of these, Professor Cope in his Batrachia of North
America (1881)) lists 13 species and 6 subsi^ecies or varieties, to which
there have since been some additions.
FOOD VALUE OF FROGS.
The value of frogs as food is now thoroughly recognized. The meat
is white, delicate, and very wholesome and i)alatable. Although eaten
at all times, it is in best condition in fall and winter; in spring it is of
251
252 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
relatively inferior quality. Only tlie hind legs a^e commonly utilized,
the meat on the other parts of the body being edible, but in very small
quantity. In some localities, however, the entire body, after the removal
of the viscera, is fried with eggs and bread crumbs. The legs are pre-
pared for the table by broiling, frying, or stewing.
A prejudice formerly existed against frogs as an article of food, per-
haps based on their uncanny appearance and heightened through tlieir
appropriation by witches and empirics for spells in love affairs and the
cure of various diseases. For a long time the French people alone
availed themselves of this delicacy, though it was known to the liomans.
From France the use of this food j)assed into Germany, England, and
other i^arts of Europe, and later into the United States, where frogs
are now more generally consumed than in any other country, and
where, during the proper seasons, they may be found in the markets
of any of the larger cities.*
FROG-HUNTING.
The business of taking frogs for market has greatly increased in
recent years. It is now carried on in all sections of the United States,
and is of economic importance in about fifteen States, while in nearly
all the remaining States and Territories frogs are taken for local or
home consumption, of which it is impossible to get a statistical account.
The States supplying the largest quantities for the markets are Cali-
fornia, Missouri, ~New York, Arkansas, Maryland, Virginia, Ohio, and
Indiana. More frogs are taken in iSTew York than in any other State,
but on account of their comparatively small size their vahie is less than
in Missouri and California. The Canadian Province of Ontario also
yields a rather large supply of market frogs. As ascertained by
inquiries of the United States Fish Commission, the annual catch in
the United States is but little less than 1,000,000, with a gross value to
the hunters of about $50,000. The yearly cost of frogs and frog legs
to the consumers is not less than $150,000.
The localities in which especially important frog hunting is done are
the marshes of the western end of Lake Erie, and Lewis and Grand
reservoirs, in Ohio; the marshes of the Sacramento and San Joaquin
rivers, California; the valley of the Kankakee Kiver, Indiana; Oneida
Lake, Seneca Kiver, and other waters of northern New York, and the
St. Francis Eiver and the sunken lands of the Mississippi liiver, in
Arkansas and Missouri.
In taking frogs for market, lines baited with red cloth, worms, or
insects are extensively used; guns, small-bore rifles, and spears are
also employed, and cross-bows are adopted for this purpose in Canada.
They are often hunted at night, a lantern furnishing light for the
* While it is popularly supposed that the cousumptiou of frogs in Franco is much
larger than elst^where, this is uot the case, and, on the authority of the Revue des
Sciences Naturelles Appliciuees (1S8S»), it may be stated that the annual consumption
of frogs in the United States is teu times that in France.
MANUAL OF FISH-CULTURE. '253
liuuter's aim, and at the same time blinding or dazing tlie frogs. After
entering on their hibernation, many arc dug out of the mud, hirge
numbers often being found together at this time.
In the basin of the St. Francis Eiver, in Missouri and Arkansas, where
the business is im])ortant, frogs are captured by means of spears, with
liues at the end of long rods, and with firearms. In the early part of
the season, when the frogs retire to the mud during the cool nights, and
oi:ly appear on warm, bright days, they are taken on hooks baited with
red cloth and by guns and rifles. Later the bulk of the catch is made
at night by means of spears with one to three barbed prongs. Two men
usually hunt together in a boat, one rowing, the other standing in the bow
with spear and a large reflector made especially for the purpose. The
s< ason in this region is principally from March to June. Only the hind
legs are preserved ; a pair of these weighs about half a pound.
The prices received for frogs varies greatly, and depends on the con-
dition of the market, the size of the frogs, and the locality. Dressed
legs yield the hunters from 12i to 50 cents a pound, and live frogs
from 5 cents to |4 a dozen. In the Kankakee Valley, Indiana, for
example, the prices received by the hunters are 75 cents a dozen for
large frogs, 10 cents a dozen for medium-sized frogs, and 5 cents a,
dozen for small frogs, while in Sau Francisco the market price is $3 to
$4 a dozen.
The unrestricted hunting of frogs threatens their practical extinction
in all places where their abundance and shipping facilities or proximity
to market render the business profitable. Already a marked decrease
in the supi)ly is manifest in Lake Erie, in northern New York, and
other places, and in order to meet the increasing demand hundreds of
people are exi)erimenting or preparing to engage in frog-culture.
The need of definite information as to the methods of procedure has
been generally felt and frequent inquiries concerning frog culture are
received by the United States Fish Commission. While the practica-
bility ot artificial propagation has not been demonstrated, it is evident
that the number of salable frogs from a given area may be largely
increased by artificial means. To undertake intelligent work in this
line a knowledge of the natural history of the frog is essential.
HABITS AND DEVELOPMENT OF FROGS.
All frogs undergo a tadi)ole stage, though in some species this is so
rapid as to lead the casual observer to think it omitted.
Upon the disappearance ot frosts at the close of winter the hibernating
Itogs return to active life, and as the waters become warmer in the spring
sun their notes are heard in suitable localities all over the country.
In some species the song is distinctly a chant d'amour; in others it is
continued long after the breeding season is over. During the breeding
season the social instinct i)revails,and s])ecies of usually solitarj^ habits
congregate in large numbers, thus becoming ready prey for the hunter.
254 REPORT or' COMMISSIONER OP FISH AND FISHERIES.
The eggs are extruded by tli(> female and are fertilized by the male
as they pass out, very few failing to be impregnated. The process of
oviposition or laying continues through several days, and during this
period several hundred eggs may be deposited. The size of the ova
varies with the species, but averages about 1.75 millimeters (.07 inch)
ill diameter. In i)assing down the oviduct the i'gg receives a thin
coating of albuminous material ; this rajiidly swells when the egg enters
the water and forms the well known uelatinous mass in which the froir
eggs are always found imbedded. The toad's eggs are laid in long
strings and are readily distinguishable. The salamander's eggs are also
idaced in the water, but the gelatinous mass is somewhat firmer and
the eggs are slightly larger than the frog's, and they are usually
de])0sited somewhat earlier.
The eggs begin development, under favorable circumstances, as soon
as fertilized, the rapidity depending mainly on the temperature of the
water; incubation is much retarded by cold, and some seasons many
eggs are killed by late frosts. At first the upper part of the eggs is
black and the lower white, but the rapid growth of the black embryo
makes the entire egg dark. The egg, which is at first spherical, soon
becomes ovoid. In iroin 4 to 30 days the tadpole is able to wriggle
out of its gelatinous envelope and shortly attaches itself to some plant
or other support by means of a sort of adhesive organ in front of the
mouth. At first the mouth and anus are closed, and food can only be
obtained by absorption, the first food consisting of the gelatinous egg-
envelope. In a short time the moutli and anus become fancti(mal, the
alimentaiy canal lengthens, and macerated animal and vegetable matter
becomes the food. The prevalent idea that the tadpole is exclusively
vegetarian, based on its anatomical structure, horny jaws, and long
intestine, is incorrect. Eecent observations have shown that animal
matter is i)referred to vegetable; all food must be in a state of macera-
tion, especial fondness for dead animals being shown.
Kespiration is at first carried on by means of external gills. They
are soon replaced by internal structures covered by opercula.
Kapidity of development depends upon the abundance of food and
the temperature of water. The most favorable conditions are a shallow
pool, readily warmed by the sun and well stocked with organic matter,
that is, an old pond. In this stage the frogs may reach a length of
several inches, the bullfrog tadpole being largest. The various species
closely resemble each other, but can be distinguished after some expe-
rience by certain points of mouth structure, size, and coloration.
In a period varying from two months to two years the first indication
of the adult form appears in the protrusion of the two hind legs. The
forelegs or arms, owing to their being concealed by the gill membranes,
are much later in coming out.
As the legs become functional the tail is absorbed and furnishes
material for growth, so that little food is taken. In the case of the
second-year tadpole the capture of insects is begun before the tail is
MANUAL OF FISH-CULTURE.
25n
lost. As the gills are replaced by lungs during this period, it is essen-
tial that the tadpoles have access to land or resting-[)laces, and it is a
time of peculiar ditlieulty in the creature's existence. When the tail
is almost fully resorbed, the purely acpiatic life is forsaken for the
amphibious and the food is changed from dead to living matter, which
must demonstrate its living condition by motion. The peculiarly formed
tongue — loose behind, so that it maybe thrown out to quite a distance —
is covered with a viscid secretion so that the frog readily captures
any insects or small animals that api)roach it closely. Tadpoles are
commonly satistied to wait patiently for their food, and even the adults
do not often search actively for food. Sexual maturity is reached in
about three or four years, being latest for those varieties that pass the
first winter iu the tadpole stage. It is generally believed that frogs
live for 12, 15, or even 20 years.
During the tad[)ole stage they furnish tempting morsels for fish, rep-
tiles, some mammals, and other frogs, and especially for wading birds,
like herons and cranes. Their defenseless condition and the shallow-
ness of their natural habitats at this period make them ready prey.
Spring Frog or Leopard Frog (liana rirtscens).
and it is in the prevention of this wholesale destruction that man may
profitably intervene. In the adult frog stage the relentless pursuit by
birds and reptiles is continued until of the hundreds of eggs deposited
few become reproducing individuals. Only slight revenge for all this
slaughter can be taken. They may occasionally capture disabled fish
or small fish of sluggish habits found in the mud or on the bottom, and
instances are recorded of their eating snakes, toads, and young birds,
but insects and lower forms are their staple diet.
DESCRIPTIONS OF MARKETABLE FROGS OP THE UNITED STATES.
Tlie species of frogs commonly eaten are the bullfrog {Bona cafes-
hiana), the green frog {liana clamata), the si)ring frog {Rana vircscens),
and the western bullfrogs {Rana pretiona and Rana aurora).
The following references to their geographical distribution and brief
descriptions of their color and form have mainly been extracted from
l*rofessor Cope's work on The I>atrachia of North America (Bulletin
No. 34, U. S. National Museum, 1889).
256 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
Tlie most widely distributed species is the common frog, spring frog,
shad frog, or leopard frog {liana virescens). It is found from the
Atlantic Coast to the Sierra Nevada Mountains, and from Lake Atha-
basca, in Canada, to Guatemala, Central America, but is most abundant
in the Eastern States. It reaches a length of about 3J inches, exclusive
of legs. The toes are well webbed, but the web does not reach the
tips of the fourth toe, as in the common bullfrog. The head is moderate
in size, the snout being rather pointed; the tympanum (ear) is distinct
and nearly as large as the eye. The hind limb being carried forward
along the body, the tibio-tarsal articulation reaches nearly the tip of
the snout. The color is usually bright green, marked by irregular black,
dark-brown, or olive blotches edged with whitish or yellowish. These
spots form two irregular rows on the back and one or two more or less
Green Frog or Spring Frog (Itana clamata).
indefinite rows on the sides. The blotching is continued as spots or bars
on the posterior extremities. These spots are frequently smaller and
more numerous than shown in the specimen figured. The glandular
fold which runs from the orbit to the posterior i^art of the body is
yellow. The under surface is whitish or light yellow and unspotted.
The leopard frog jjasses the tadpole stage the first season, and is more
gregarious than the bullfrog or green frog. These considerations are
of importance from a culturist's standpoint.
The green frog or spring frog {Rana clamata) is found throughout the
Eastern and Central States and neighboring parts of Canada. The
body and limbs are stout and massive, the legs are short, and the head
is more rounded than in R. rirescena. The tympanum is very large,
though this differs in the sexes, as a rule being larger than the eye in
MANUAL OF FISII-CULTURE.
257
males aiul siuallcr in icinales. A fold of skin runs from the eye back-
ward, with a short branch from the tympanum to the shoulder. The
femur and tibia are equal in length, the web of toes not reaching end
of fourth toe.
The color above is dark olive posteriorly, passing into brilliant green
anteriorly. It is sometimes greenish-brown above and on sides, with
small round brown spots. The buttocks are usually mottled with brown
and yellowish white, but are almost uniformly black in some specimens.
Below, this species is white or greenish white, sometimes more or less
mottled and blotched. The throat is citron yellow.
This frog is especially aquatic in habits, not hunting on land; it fre-
quents all kinds of fi-esh waters. It is more solitary in its habits than
M. virescens, living singly, in pairs, or in small companies. It is active
on land and in water, but not noisy. A nasal "chung" is occasionally
uttered. When disturbed it often emits a shrill cry as it leaps into
liana catethiniia. I'pi)er fig-
ure fomali'. lower fi^urn male.
Raiia clamata. Upper figure fe-
male, lower fijiure male.
Figaros illustrating relative size of the t.vmpuuum iu the two sexes.
the water. It is preeminently an inhabitant of swamps and marshes,
especially those connected with rivers or large creeks. "It is the first
species heard in spring, and although its voice is not loud, the noise
produced by thousands of them is deafening when heard (ilose at hand,
and is transmitted through the atmosphere ior many miles. It may be
imitated by the syllables chock, cliocl-, chockJ''
The pickerel frog, marsh frog, or tiger frog {Bana palustris) closely
resembles the leopard frog, but may be readily distinguished from it by
the bright yellow on the thighs and legs. It is solitary in its habits
and is often found in the grass, although preferring cold spring streams.
In the Allegiiany Mountains it is the most abundant frog. It is a very
active species, taking longer leaps than any of the others here menticmed.
The note is a prolonged, low, grating <Toak. Owing to its disagreeable
odor it is but rarely eaten.
F.M 17
258 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
The bullfrof? {Rana catesbiana) is the largest of i^ortli American
frogs, reaching a body length of over 8 inches. It has much the same
geographical range as the spring frog. The body is very bulky and
clumsy, the legs are thick, and the head is broader than in R. clamata.
A fold of skin extends from the eyes over the tympanum, around the
insertion of forearm, and disappears on the breast. There are no folds
on the sides of back, as in B. clamata and B. rirescens. The skin is
slightly rough above. The tympanum is larger than eye, with the same
sexual differences as in B. clamata. The tibia is slightly shorter than
the femur. The hind toes are fully webbed. The complete webbing of
the fourth toe, with the absence of dorsal folds of skin, furnishes means
of distinguishing this from the spring frog.
Common Bullfrog {Rana catesbiana). Male.
The color above is olivaceous, brown, or ferruginous, with darker
blotches half the diameter of the eye, more or less uniformly distributed.
The color is sometimes yellowish green without blotches or other mark-
ings. The hind legs are barred above and the buttocks blotched with
nearly black markings. The lower parts are white, with obscure
mottlings of brown, the throat sometimes being briglit yellow. In the
young the blotches above are reduced to distinct black dots, and the
under parts are yellowish anteriorly. The habits are much the same as
those of B. clamata. Both species pass the first winter in the tadpole
stage and are said under unfavorable circumstances to pass even the
second winter so. This fact, with the solitary habits of the adult, is of
importance to the culturist.
The Western frogs are not well known. The range of B ana, pretiosa
is from Montana west to Puget Sound, thence south to southern Cali-
fornia. It is the common frog of the Northwestern States. The body
is stout and depressed like B. catesbiana. The head is obtuse, rounded,
subtruncate, and broader than long. The eyes are small and the
MANUAL OF FISH-CULTURE.
259
tympauum, which is sometimes indistinct in some small specimens, is
smaller than the eye. Skin thick. The femur is shorter than the tibia
and not quite half length of body. Tlie toes are fully webbed. A
depressed ridge extends from eye to flank. The color is dull yellowish-
Western Frog (Banapretiosa).
brown (dead leaf) above, darker on sides, with circular brown blotches
between the ridges. The outer surface of the limbs is blotched trans-
versely. The body spots are often less numerous and smaller than in
the specimen figured. The under parts are yellowish white, with obscure
brown marbling, posteriorly salmon color.
Western Bullfrog (Rana aurora).
Rana anrora is found in the western coast region of the United States.
The body is depressed and elongated; limbs slender, well developed;
head broad, acute, rounded anteriorly; eye moderate; tympanum
smaller than eye, but not so small as in preceding species. A fold of
2G0 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
skin runs from eye to liind leg. The femur is shorter than the tibia,
which is rather more than half the length of body. The toes are not
quite fully webbed, the last joints of all the toes and last two of the
fourth toe being- free. The color above is greenish-yellow, with golden
reflections, spotted with black. The sides of abdomen and hind legs
are reddish-orange. The under parts are dull yellowish-green, spotted.
While the species of frogs described are those commonly used for
food, there seems no valid reason why any of the Ranidw may not be
eaten. The small size of some, with possibly a disagreeable odor, has
prevented their use up to this time.
SUGGESTIONS FOR FROG-CULTURE.
From the foregoing discussion of the development of the frog it will
be seen that its culture must be of necessity a matter requiring time,
patience, and an appreciation of the animal's habits and needs. So
far as can be learned, attempts thus far made in the cultivation of
frogs from the egg stage have been arrested at the period when the
larva assumes the adult form. From this time the food must be living,
and it generally consists almost entirely of insects. The difficulty,
approaching impossibility, of furnishing these in sufficient quantity
has been the great drawback. The placing about the pond of meat
and decaying matter to attract flies has been suggested, but the con-
tamination of the water by the i^oisonous matters of decomposition has
counteracted all benefits produced. The frogs, failing in the supply of
more natural food, have been compelled to devour one another.
To rear the tadpole is comparatively easy. Anyone may obtain a
supply of eggs by visiting the stagnant pools in early spring with a
dipper and bucket, but this method is said to be less advantageous
than the stocking of suitable waters with a sufficient number of pairs
of mature frogs. The young can be protected by building a close fence
around the edge of the pond to exclude such enemies as raccoons and
reptiles, while a screen must be provided so that wading birds, whose
long legs furnish them special facilities, can not stand in the water and
devour the helpless tadpoles. Any device to be effective must be so
arranged that there is no room for birds or other animals to stand on
shore or in shallow water, either on or under the screen, and at the
same time it must aHow the young to come to land, for if there is no
opportunity for the tadpoles to breathe the air at rest and exercise the
legs, the ])eriod of metamorphosis will be indefinitely delayed. They
have been kept in atpiaria for years in the tadpole stage.
Food daring this period is readily provided. If a shallow old pond
is chosen, already well stocked with organic matter, it will supply, un
aided, food for a large number of frogs. This may be readily increased
by supi)lying animal refuse, liver and such material, care being taken,
of course, not to leave a surplus to putrefy and infect the water. The
more abundant the food and the warmer the water the more rapid is the
MANUAL OF FISIl-CULTURE. 261
growth, hence the desirability of selecting a shallow pond. The young
should be separated from the adult frogs during this time, as they are
eagerly eaten ; and it is needless to say that the pond must be free
from lish, turtles, snakes, and crayfish.
The critical period occurs at the time of metamorphosis. The crea-
ture is now abandoning its aquatic habits and lias not yet a perfect
apparatus for terrestrial life. Any slight disarrangement of the natural
environment is liable to destroy the equilibrium. The rapid resori)ti(m
of the tail furnishes matter for growth, so that food is not so much a
necessity, but as soon as the terrestrial habit is fully assumed live food
is absolutely requisite, and should be furnished in liberal quantities.
There seems to be no reason why this might not be accomplished by
transfer of the tadpoles to waters where natural food abounds. It is
useless to attempt to supply this food artificially by any method at
present known, neither has any device to increase the natural abundance
of insects been i)racticable as yet. The pond should have a growth
of rushes and other plants; wild rice {Zizania aquatica) has been recom-
mended, but it might attract birds that would prefer young frogs and
tadpoles to their vegetable fare. Shade is ne(!essary. Such a iioiid
will furnish natural food for a large stock of frogs, and give opportunity
for successful breeding.
One of the most successful " frog farms " is in Ontario, in the Trent
Eiver basin. It has been in operation about twenty years and annually
yields a comparatively large product of frogs. The waters were stocked
by means of mature mated frogs. No attempt is made to confine the
frogs until near the time for shipment to market. They are then taken
alive at night, with the aid of a torchlight, and confined in small pens
that can be drained when the frogs are desired for market. No food is
given, as this is naturally present in sufficient amount for successful
growth. The species is the eastern bullfrog {Rana cateshiana); it
begins to breed at the age of three years and reaches a marketable size
in four years. During the years 1895 and 189(5 this "farm" yielded
5,000 pounds of dressed frog legs and 7,000 living frogs for scientific
purposes and for stocking other waters.
While at present it would perhaps be advisable to limit practical
attempts at frog-culture to stocking natural waters with paired breeders,
experiments in artificial methods should not be abandoned. There
seems no reason why methods similar to those at present pursued in
fish-culture may not eventually be successful in the case of frogs.
OYSTERS AND METHODS OF OYSTER-CULTURE.
BT
H. F. MOORE,
Assistant, U. S. Fish Commission.
263
CONTENTS.
Page.
In t loductioii 265
Distributioii :
Atlantic coast 265
Pacific coast 266
Description :
Eastern oyster, Osirea virginica 266
Pacific coast "native," Ostrralurida. 267
Reproduction and dcvplojnnent:
Sexual tliaracteiistics 267
Ril)ening of the generative organs. . . 268
Spawning 268
Embryonic development 270
Fixation, set, or spatting 274
Growth 274
Anatomy 276
Physical and biological conditions on oy«-
ter-beds :
Tempera tiare of water 280
Temperature; planted beds in San
Francisco Bay 281
Density of water; determination of
density and temperature 281
Silt, mud, and suspended matter 283
Tides and currents 284
Depth of water 285
Weather conditions — storms, gales,
and ice 285
Food 286
Enemies 288
264
Page.
Description of natural bed 292
Destruction of natural beds — causes and
remedies 295
Increase of supply by artificial means 296
Planting with seed :
Preliminary considerations 298
Pre])aring bottom 299
Seed 301
Sowing the seed 302
Working the beds 303
Planting with cultch or stool:
Preliminary considerations 304
Preparing bottom 305
(Jultch, collectors, stool 305
Coating <-ultch 309
General considerations on spat-col-
lecting 310
Working the beds 312
Protection from enemies 313
Increase on planted beds 320
Growing oysters in ponds 320
Breeding oysters in ponds 322
Artificial projjagation 330
Artificial feeding 335
Fattening, pliuuping, floating 336
Greening 337
Transportation and length of life when
removed from the wati^r 338
Notes on clam culture 339
OYSTERS AND METHODS OF OYSTEE-GULTURE.
Ry H. F. Moore,
Assistant, United States Fish Commission.
INTRODUCTION.
This paper is designed to briefly set forth the principal facts relating
to the subject of oyster-culture in the United States. It embraces the
practices of proved commercial value as well as a summary of the
methods aud results of investigations which ai^pear to give some prom-
ise of utility in certain places and under special conditions, or which
indicate the lines along whi(;h profitable experiment may be carried on.
It is intended primarily as a guide to those persons who are exhibiting
an interest in the subject and who contemplate embarking in tbe
industry, yet hesitate on account of unfamiliarity with the methods
employed. To aid such persons to a more thorough understanding of
tbe problem involved, certain matters are considered which do not
strictly appertain to the practical side of the subject, but which may
assist in explaining observed phenomena or in indicating the lim-
itations and possibilities of experiment. Such are the chapters on
development and anatomy.
Attention is directed chiefly to the eastern oyster, Avhich is the species
of principal, one might almost say only, interest in this country, aud,
practically, the great problem of oyster-culture applies to it alone.
For comparative purposes, however, and to round out the information
presented, it has seemed advisable to incorporate some facts regarding
the native oysters of the Pacific Coast.
DISTRIBUTION.
ATLANTIC COAST.
Upon the eastern coast of [N^orth America there is but one species of
oyster, Ostrea virginica, which occurs along the northern side of the
Gulf of Mexico, on the Atlantic coast from- Florida to Cape Cod, and on
the southern and western shores of the Gulf of St. Lawrence. In
Massachusetts Bay and on the coast of Xew Hanipshire and Maine it
does not now occur, though it was found in abundauce locally at the
time of the settlement of the country, aud the former existence of beds
of great extent is indicated by the vast quantities of the valves in the
ancient Indian sliellhoaps. Oyster fisheries are located in every coast-
wise State from Texas to .Massachusetts aud in the Maritime Pro\iuces,
265
26G REPORT OF COMMISSIONER OF FISH AND FISHERIES.
the most ini])ortant being in Chesapeake Bay, mainly upon the natural
beds, and in Long Island Sound, principally upon planted grounds.
The C'anadiau oyster-beds are much depleted, and an effort is uow
being made to restore them to a productive condition.
PACIFIC COAST.
Upon the western coast of North America there are five, and perhaps
six, recognized species of oysters, but only two of them are of i)resent
importance.
The eastern oyster was planted in San Francisco Bay about 1872 and
has there formed the basis of a somewhat important industry ever
since. The supply has been maintained by the annual i^lanting of seed
oysters from the east, and while the species appears to be propagating
itself to a limited extent, no reliance has been placed upon this fact
for the maintenance of the beds. The United States Fish Commission
has recently planted oysters in Willapa Bay, Washington ; Yaquiua
Bay, Oregon, and Humboldt Bay, California, but it is still too early to
say with what success.
The native oyster [Ostrea lurida) of California, Oregon, and Washing-
ton is found at various places on the coasts of the States mentioned,
but attains its greatest size and ])erfection in Willapa Bay. It is much
inferior to the eastern oyster in size, but its flavor is esteemed by many.
In the Gulf of California is found a large species, Ostrea iridescens,
which resembles the eastern species and is an object of some trade in
the adjoining portions of Mexico. Attempts have been made to intro-
duce this form in the markets of San Francisco, but the mortality en
route has been large and the venture unprofitable.
Two smaller oysters, Ostrea palumea and Ostrea palumea glomerata,
are also found in the Gulf of California.
DESCRIPTION.
EASTERN OYSTER, OSTREA VIRGINIOA.
The shell of this species is generally elongate, but varies much with
age and the conditions under which it grows. In the younger stages it
is often nearly round, with ear-like. i)rojections on each side of the
hinge and stout radiating ridges near the margin, thus bearing some
resemblance to the European oyster. In shells which are actively
growing there is a broad fringe of yellow cuticle around the edge of the
valves, which, however, soon becomes thickened by a deposit of lime.
The shell is subject to great variation in thickness, but it is rarely
so thin as in the Pacific coast oyster. The exterior is marked by
laminations and more or less concentric lines of growth; it is often
covered by a yellowish cuticle, but is sometimes white and flinty in
appearance. The inside of the shell is generally white, somewhat
tinged with purple near the margins, and with a more or less pearly
luster. The muscular impression is generally nearer to the posterior
OYSTERS AND METHODS OF OYSTER-CULTURE. 267
margin than to the hinge; it is a well-detined soar, kidney-shaped in
specimens of ordinary size, but becoming more elongate in very hirge
individuals; in young specimens if, is pale, but it afterwards becomes
purple or almost black. The left or lower valve is deeply concave
within, the upper valve being flat or, usually, slightly concave. The
animal portions are large, nearly tilling the shell, and the mantle border
is comparatively narrow. (Plate v.)
PACIFIC COAST "NATIVE," OSTREA LURIDA.
The shell of this species is thin and irregular, varying in shape from
almost round to elongate elliptical; the surface is sometimes laminated,
but is never ribbed; the color is variable, being sometimes purple,
sometimes dirty green or gray; the inside of the shell is greenish,
sometimes tinged with purjile. The muscular impression or scar is
purple, but paler than in the eastern oyster, and its greatest length is
usually longitudinal rather than transverse; it is situated about mid-
way between the hinge and the lips or nibs of the shell, and its ventral
margin is usually prolonged toward the liinge. There is rarely a well-
defined pit or excavation beneath the hinge, the inner face of the shell
sloping off gently from the ligament. The lower valve is deeper than
the upper one, but is rarely so strongly concave as in the eastern
species. (Plate vi.)
REPRODUCTION AND DEVELOPMENT.
SEXUAL CHARACTERISTICS.
In the European oyster the individuals are hermaphrodites — that is,
each is both male and female; in the common eastern oj'ster the sexes
are separate, each individual being either male or female, but not both.
Although the sexes differ remarkably in physiology and minute
anatomy, it is not possible to distinguish male from female by any
known external characters. It is only by an examination of the genital
glands, which in the male produce the spermatozoa or milt and in the
female the ova, eggs, or spawn, or by examining the genital products
themselves, that the one sex may be distinguished from the other.
The differences between the ovaries of the female and the testes of
the male are explained in the section treating of the anatomy. When
the animals are ripe, the distinction of the sexes is most conveniently
made by an examination of the genital products. A drop of genital
fluid is extracted from the oyster in the manner described under the
head of artificial fertilization (p. 332) and let fall into a glass of clear
sea water. If the individual be a ripe female, the drop will break up
into a uniformly distributed cloud, which, if examined against a black
background, will be seen to consist of separate minute white granules
or eggs. If the eggs be unripe, they will remain aggregated in little
compound masses. If the specimen examined be a male, the drop of
milt will form an irregular, stringy cloud, showing a tendency to drift in
2G8 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
streaks if the water be agitated, and with no particles distingnishable
by the naked eye.
Anotlier test is to spread out a droi) of the genital fluid, mixed with
a drop of water, in a thin film upon a piece of glass, such as a micro-
scope slide. If the specimen be a female, an examination with a strong
hand lens will reveal many minute pear-shaped or oval bodies or eggs,
each with a clear spot, the nucleus or so-called germinal vesicle. If the
specimen be a nuile, the lilin can not be resolved into distinguishable
particles Avhen viewed with the lens, but consists of a milk white mass,
having a quivering api)earance owing to the effect of the combined
movements of the indistinguishable spermatozoa.
The histological characters which distinguish the testes and ovary
are considered under the head of anatomy.
According to Professor Schiedt, an hermaphroditic oyster occurs on
OUT northwest coast, the specimens examined coming from the State of
Washington, the exact locality not being mentioned. Sexually, there-
fore, this species resembles the common oyster of Europe.
RIPENING OF THE GENERATIVE ORGANS.
In spring, when the water begins to warm, certain changes begin to
manifest themselves in the generative organs, preparatory to the act
of spawning. In the female some of the minute eggs in the ovaries
increase in size and become loosened in the follicles or little pockets of
tissue in which they have undergone their early development. All of
the eggs which are to be discharged in any one year do not ripen at the
same time, so that the si^awning of each individual extends over a
greater or less period. An examination of the ovary at any time will
always show great numbers of minute immature eggs, most of these
being ova which will ripen and be discharged during some subsequent
year. Other changes, which it is not necessary to mention here, take
place in the eggs and tissues, but the ultimate result is that the ovary
becomes enlarged by the growth of the ripening eggs and the latter
pass into the oviducts, which stand out as milky-white and much-
branched vessels on each side of the body.
The spermatozoa develop in somewhat the same manner, but the
generative cells, instead of developing into eggs, undergo rapid divi-
sion, each into a number of minute active bodies, which pass into the
sperm ducts and gorge them with a white fluid, the milt, in general
naked-eye appearance, closely resembling the ovarian fluid.
SPAWNING.
The act of spawning consists in the discharge of the ripe genital
products into the surrounding water, where fertilization is left to chance.
The genital duots, one on each side, open into the chambers above
the gills, and the ova in the one sex and the spermatozoa in the other,
gradually oozing out of the openings, are caught up by the currents
of water passing through the gill-canals and expelled from the body,
OYSTERS AND METHODS OF OYSTER-CULTURE. 269
together with the various Avaste products resulting Iroin digestion and
respiration.
The season at which oysters spawn differs with the latitude of the
bed and with local conditions. As a general rule, it may be said that
they ripen earlier in the south than in the north, and that in the same
region the genital products mature earlier in shallow tlian in deep water.
These facts appear to be dependent primarily u])ou the temperature,
other things being equal, southern waters warming before the northern,
and the sliaHows before the depths.
It is stated that the raccoon oyster of South Carolina spawns from
the middle of March to the middle of August, liipe individuals are
found in shallow- water creeks during January and February, and it
is probable that intermittent spawning may take place at any time
during the year when favorable conditions i)revail. In Chesapeake Bay
oysters are found spawning from April to October, but apparently a
few scattered individuals spawn at other times, though most of the spawn
appears to be cast during the latter part of July or early in August.
In Long Island Sound spawning takes i)lace, according to the locality,
during May, June, July, and August. Sometimes many oysters are
found with well-developed ova during April, but this api)ears to be
unusual, and Dr. Dean remarks that when it occurs "it will almost
invariably be found that the spring has been warm and dry."
Not only the time of spawning, but the quantity of spawii, appears
to be affected by the weather conditions. Sudden changes produce
very marked results, and a transfer of the oyster from one place to
another during the spawning season is almost certain to interfere with
reproduction or even absolutely arrest it.
The age at which the oyster becomes capable of reproducing its kind
varies with the locality, but it appears that in regions of rapid growth
the generative organs ripen during the first year. The number of eggs
discharged by the female is naturally dependent upon its size. Accord-
ing to Dr. Brooks, the Maryland oyster of average size produces
1(),0U(),000 eggs each year, while a very large individual may produce
60,000,000. The spermatozoa, being extremely minute, are present in
the milt in inconceivable numbers.
Notwithstanding the great fecundity of the individual oyster the
reproductive jiower of the beds is not so vast as is generally supposed.
If the oysters are scattered, or the number spawning at a given time is
small, most of the genital matter will be wasted, as the contact of the
male and female cells is entirely dependent upon chance, and the fewer
such cells there are in a given body of water the smaller the probability
of their meeting and fusing in the manner constituting the act of fer-
tilization. Neither the eggs nor the spermatozoa live long after tliey
are discharged from the parent, and if fertilization is to take place at
all the two elements nmst be brought into contact promptly; and it will
be seen, therefore, that nature must supply a vast number of germ cells
to insure the survival of but a few.
270 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
EMBRYONIC DEVELOPMENT.
The following popular account of the early stages in the development
of the oyster is slightly modified from the description by Dr. W. K.
Brooks :
The ovarian eggs are simply tlie cells of an organ of the body, the ovary, and they
difl'er from the ordinary cells only in being much larger and more distinct from each
other, and they have the power, when detached from the body, of growing and
dividing np into cells, which shall shape themselves into a new organism like that
from whose body the egg came. Most of the steps in this wonderful process may be
watched under the microscope, and owing to the ease with which the eggs of the
oyster may be obtained this is a very good egg to study.
Abo)it 15 minutes after the eggs are fertilized they will be found to be covered with
male cells, as shown in plate vii, hg. 1.* In about an hour the egg will be found to
have changed its shape and appearance. It is now nearly spherical, as shown in plate
A'li, fig. 2, and the germinative vesicle is no longer visible. The male cells may or may
not still be visible upon the outer surface. In a short time a little transparent point
makes its appearance on the surface of the egg and increases in size and soon forms
a little projecting transparent knol) — the 2)olar globule — which is shown in plate vii,
fig. 3, and in succeeding figures.
Recent investigations tend to show that while these changes are taking place one of
the male cells penetrates the protoplasm of the egg and unites with the germinative
vesicle, which does not disappear but divides into two parts, one of which is pushed
out of the egg and becomes the polar globule, while the other remains behind and
becomes the nucleus of the developing egg, but changes its appearance so that it is
no longer conspicuous. The egg now becomes pear-shaped, with the polar globule
at the broad end of the pear, and this end soon divides into two parts, so that the
egg (plate vii, fig. 4) is now made of one large mass and two slightly smaller ones,
with the polar globule between them.
The later history of the egg shows that at this early stage the egg is not perfectly
homogeneous, but that the protoplasm which is to give rise to certain organs of the
body has sejiarated from that which is to give rise to others.
The upper portion of the egg soon divides up into smaller and smaller spherules,
until at the stage shown in plate vii, figs. 5, 6, and 7, we have a layer of small cells
wrapped around the greater part of the surface of a single large spherule, and the
series of figures shows that the latter is the spherule which is below in plate vii, fig. 4.
This spherule now divides up into a layer of cells, and at the same time the egg, or
rather the embryo, becomes flattened from above downward and assumes the shape
of a flat oval disk. Plate vii, figs. 10 and 9, are views of the upper and lower surface of
the embryo at about this time. In a sectional view, plate vii, fig. 11, it is seen to be
made of two layers of cells, an upper layer of small transparent cells, e c, which arc
to form the outer wall of the body and which have been formed by the division of
the spherules which occupj the upper end of the egg in plate vii, fig. 6, and a lower
layer of much larger, more opaque cells, ;/, which are to become the walls of the
stomach, and which have been formed by the division of the large spherule, a, of
plate VII, fig. 6.
This layer is seen in the section to be pushed in a little toward the upper layer,
so that the lower surface of the disk-shaped embryo is not flat, but very slightly
concave. This concavity is destined to grow deeper until its edges almost meet, and
it is the rudimentary digestive cavity. A very short time after this stage has been
reached, and usually within from two to four hours after the eggs were fertilizedi
the embryo undergoes a great change of shape and assumes the form which is shown
in three different views in plate vii, figs. 12, 13, 14, and 15.
* References to figures in (juoted portions of this ])ai)<^r do not correspond with the
originals, being altered to accord with their sequence in the present article.
OYSTERS AND METHODS OF OYSTER-CULTURE. 271
A circular tuft of long hairs or cilia has now made its appearance at what is thus
marked as the anterior end of the body, and as soon as these hairs are formed they
begin to swing backward and forward in snch a way as to constitute a swinuning
organ, which rows the little aniuial up from the bottom to the surface of the water,
where it swims around very actively by the aid of its cilia. This stage of develop-
ment, plate VII, tig. 12, which is of short duration, is of great importance in raising the
young oysters, for it is the time when tliey can best be siphoned otf into a separate
vessel and freed from the danger of being killed by the decay of any eggs which
may fail to develop. On one surface of the body at this stage, the dorsal surface,
there is a well-marked groove, and when a specimen is found in a proper position for
examination the opening into the digestive tract is found at the bottom of this groove.
Plate VII, fig. 13, is a sectional view of such an embryo. It is seen to consist of a cen-
tral cavity, the digestive cavity, which opens externally on the dorsal surface of the
body by a small orifice, the jtrimitive mouth, and which is surrounded at all points,
except at tlie mouth, by a wall which is distinct from the outer wall of the body.
Around the primitive mouth these two layers are continuous with each other.
The way in which this cavity, with its wall and external opening, has been formed
will be understood bj^ a comparison of i)late vii, tig. 13, with plate vii, fig. 8. The
layer which is below in plate vii, fig. 8, has been pushed upward in such a way as to
convert it into a long tube, and at the same time the outer layer has grown downward
and inward around it, and has thus constricted the opening. The layer of cells which
is below in plate vii, fig. 8, thus becomes converted into the walls of the digestive
tract, and the space which is outside iind below the embryo, in plate vii, fig. 8, becomes
converted into an inclosed digestive cavity, which opens externally by the primitive
mouth.
This stage of development, in which the embryo consists of two layers, an inner
layer surrounding a cavity which ojiens externally by a mouth-like opening, and an
outer layer which is continuous with the inner around the margins of the opening,
is of very frequent occurrence, and it has been found, with modifications, in the most
widely separated groups of animals, such as the starfish, the oyster, and the frog;
and some representatives of all the larger groups of animals, excejit the protozoa,
appear to pass during their development through a form which may be regarded as
a more or less considerable modification of that presented by our embryo oyster.
This stage of development is known as the f/antrula stage.
The edges of the primitive mouth of the oyster continue to approach each other
and finally meet and unite, thus closing up the opening, as shown in plate vii, fig. 16,
and leaving the digestive tract without any communication with the outside of the
body, and entirely surrounded by the outer layer. The embryo shown in plate vii,
figs. 12 and 16, are represented with the dorsal surface below, in order to facilitate
comparison with the adult, but in plate vii, (ig. 17, and most of the following figures,
the dorsal surface is uppermost, for more ready comparison with the adult.
In other lamellibranchs, and doubtless also in the oyster, the shell
begins as a deposit in an invagination or pocket on the dorsal side of
the body. In its manner of formation this shell-gland resembles the
primitive mouth for which it lias been more than once mistaken by
investigators. In some forms the shell is at first single, but in the
oyster they are said to be separated from each other from the beginning,
and appear independently. Dr. P>rooks says further:
Soon after they make their appearance, the embryos cease to crowd to the surface
of the water and sink to various de])tlis, although they continue to swim actively in
all directions, and may still bo found occasionally close to the surface. The regi(m
of the body which carries the cilia now becomes sharply defined, as a circular pro-
jecting i)ad, the relnm, and this is present and is the organ of locomotion at a much
later stage of development. It is shown at the right side of the figure in plate vii,
272 REPORT OF COMMISSIONER OF FISH AND FISHERIES. "
fig. 17, aud ill plate vii, i\g. 18, it is seen in surface view, drawn in between the shells,
and with its cilia folded down and at rest, as they are seen when the little oyster
lies upon the bottom.
The two shells urow riqjidly, and soon become quite regular in outline, as shown in
plate VII, fig. 17, and plate viii, fig. 1, but for some time they are much smaller tliau the
body, which projects from between their edges around their whole circumference,
except that along a short area, the area of the hinge upon the dorsal surface, where
the two valves are in contact.
The two shells continue to grow at their edges, and soon become large enough to
cover iiji and project a little beyond the surface of the body, as shown in plate viii,
fig. 1, and at the same time muscular fibers make their ajipearauce aud arc so arranged
that they can draw the edge of the body and the velum in between the edges of the
shells in tlu^ manner shown in i)late ^'ii. fig. 18. In this way that surface of the body
which lines tiie shell becomes converted into the two lobes of the mautle, and
between them a mantle cavity is formed, into which the velum can be drawn when
the animal is at rest. While these changes have been going on over the outer sur-
face of the body other important internal modifications have taken place. We left
the digestive tract at the stage shown in plate vii, fig. 16, without any communica-
tion with the exterior.
Soon the outer wall of the body becomes pushed inward to form tbe true mouth,
at a point (plate vii, fig. 17) which is upon the ventral surface and almost directly
opposite the point where the primitive mouth was situated at an earlier stage. The
digestive cavity now becomes greatly enlarged and cilia make their appearance
upon its walls, the mouth becomes connected with the chamber which is thus formed
and which becomes the stomach, aud minute particles of food are drawn in by the
cilia and can now be seen inside the stomach, where the vibration of the cilia keep
them in constant motion. Up to this time the animal has developed without growing,
aud at the stage shown in ])late vii, fig. 16, it is scarcely larger than the unfertilized
egg, but it now begins to increase in size. The stages shown in plate viii, fig. 1, and
plate vii, fig. 18, agree pretty closely with the figures which the European embry-
ologists give of the oyster embryo at the time when it escapes irom the mantle
chamber of its parent. The American oyster reaches this stage in from twenty-four
hours to six days after the egg is fertilized, the rate of development being deter-
mined mainly by the temperature of the water.
Soon after the mautle has become connected with the stomach this becomes united
to the body wall at another i)oint a little behind the mautle, and a second opening,
the anii.s, is formed. The tract, which couuects the aiinti with tlie stomach, lengthens
and forms the intestine, and soon after the sides of the stomach become folded off
to form the two halves of the liver, as shown in plate viii, fig. 1. Various muscular
fibers now make their appearance within the body, and the animal assumes the form
shown in plate vixi, fig. 1, aud jilate \ii, fig. 18. *
What follows this stage may be best told in the words of Professor
Huxley, who speaks of the European oyster, in which the metamor-
phosis from the free-swimming fry to the fixed spat and finally the
adult oyster is essentially the same as in our species.
The young animal which is hatched out of the egg of the oystiir is extremely
unlike the adult, and it will be worth while to consider its character more closely
than we have hitherto done.
Under-a tolerably high magnifying power the body is observed to be inclosed in a
transparent but ratlKU- thiclc shell (plate viii, fig. 2, L), composed, as in the parent,
of two valves united by a straight hinge, h. But these valves are symmetrical and
similar in size and shape, so that the shell resembles that of a cockle more than it
does that of an adult oyster. In the adult the shell is composed of two substances
'Report Maryland Fish Commission, Annapolis, 1880, pp. 19-25, in part.
OYSTERS AND METHODS OP OYSTER-CULTUKE. 273
of different character, the onter brownish, with a friable prismatic structure, the
inner dense and nacreous. In the larva there is no such distinction, and the whole
shell consists of a glassy substance devoid of any definite structure.
The hinge line answers, as in the adult, to the dorsal side of the body. On the
opposite or ventral side the wide mouth m and the minute vent v are seen at no
great distance from one anothei-. Projecting from the front part of the aperture of
the shell there is a sort of outgrowth of the integument of what we may call the back
of the neck into a large oval thick-rimmed disk termed the velum, vl, the middle of
which x>resents a more or less marked prominence. The rim of the disk is lined with
long vibratilc cilia, and it is the lashing of these cilia which propels the animal, and,
in the absence of gills, jtrobably subserves resi>irati()n. The funnel-shaped mouth
Las no palps; it leads into a wide gullet, and this into a capacious stomach. A
sac-like process of the- stomacli on either side (the left one, /, only is shown in fig. 2)
represents the "liver." The narrow intestine is already partially coiled on itself, and
this is the only departure from perfect bilateral symmetry in the whole body of the
animal. The alimentary canal is lined throughout with ciliated cells, and the vibra-
tion of these cilia is the means by which the minute bodies which serve the larva for
food are drawn into the digestive cavity.
There are two pairs of delicate longitudinal muscles, rs ri, which are comjietent to
draw back the ciliated velum into the cavity of tlie shell, when the animal at once
sinks. The complete closure of the valves is effected, as in the adult, by an adductor
muscle, am, the fibers of which pass from one valve to the other. But it is a very
curious circumstance that this adductor muscle is not the same as that which exists
in the adult. It lies, in fact, in the forepart of the body and on the dorsal side of
the alimentary canal. The great muscle of the adult, fig. 3, M, on the other hand,
lies on the ventral side of the alimentary canal and in the hinder part of the body.
And as the nuiscles, respectively, lie on opposite sides of the alimentary canal, that
of the adult can not be that of the larva, which has merely shifted its position; for
in order to get from one side of the alimentary canal to the other it must needs cut
through that organ ; but as in the adult no adductor muscle is discoverable in the
position occupied by that of the larva or anywhere on the dorsal side of the aliment-
ary canal, while on the other hand there is no trace of any adductor on the ventral
side in the larva, it follows that the dorsal or anterior adductor of the larva must
vanish in the course of development, and that a new ventral or ])osterior adductor
must be developed to play the same part and replace the original muscle functionally,
though not morphologically.
if H # # * * *
When the free larva of the oyster settles down into the fixed state, the left lobe of
the mantle stretches beyond its valve, and, applying itself to the surface of the stone
or shell to which the valve is to adhere, secretes shelly matter, which serves to cement
the valve to its support. As the animal grows the mantle deposits new layers of
shell over its whole surface, so that the larval shell valves become separated from
the mantle by the new layers (plate viii, fig. 3, S), which crop out beyond their
margins and acquire the characteristic prismatic and nacreous structure. The sum-
mits of the outer faces of the umbones thus correspond with the places of the larval
valves, which soon cease to be discernible. After a time the body becomes convex
on the left side and flat on the right ; the successively added new layers of shell mold
themselves upon it, and the animal acquires the asymmetry characteristic of the
adult.*
The liorny convex shell of the fry (plate viii, fig. 3, L) may be seen, for
a considerable time after attachment, at the umbo or beak of the develoj)-
iug shell of the spat (plate viii, fig. 3, S). The under or attached valve of
the latter at first conforms closely to the surface to which it has become
* Huxley, Thomas H. Oysters and the Oyster Question. The English Illustrated
Magazine, London, Oct. 1883 and Nov. 1883, vol. 1, pp. 47-55, and pp. 112-121.
F. M. 18
274 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
attaclied, being usually flat, but afterwards, as a rule, becomiug deep
and strongly concave, tlirough an upgrowiug along the edges.
FIXATION, SET, OR SPATTING.
At the time of fixation the fry will, under proper conditions, attach
itself by its left valve to any hard or firm body with which it may come
in contact.
The first essential is that the surface should be clean and that it
should remain so a sufficient length of time to enable the young oyster
to firmly establish itself. So long as this condition obtains, the nature
of the material seems to matter but little. In most bodies of water the
spat fixes itself at all levels from the surface to the bottom, but in cer-
tain 2)arts of the coast its place of attachment is confined to the zone
between high and low water, the mid-tide mark being the place of max-
imum fixation. It has been suggested that this was due to the density
of the water preventing the sinking of the fry. There are a number
of objections to this theory, but no better one has been ofiered, and it
may receive provisional acceptance.
GROWTH.
At the time of its attachment the oyster fry measures about one-
eightieth or one-ninetieth of an inch in diameter. The valves of the
shell are strongly convex and symmetrical, and are composed of a
horny material quite different from the finished shell of the adult.
The mantle, a thin flap of tissue which envelops the body of the
oyster on each side, projects freely from between the lips of the valves
and is the organ which secretes the shell. Upon its outer surface suc-
cessive layers of horny material are laid down, these becomiug impreg-
nated with calcareous matter arranged in a prismatic manner, and thus
forming the stony shell which characterizes the adult.
The mantle increases pari passu with the growth of the soft parts in
general, and as it is always capable of protrusion a little beyond the lips
of the valves, it follows that each successive layer of shell is slightly
larger than that Avhich preceded it, and the shell increases in length
and breadth as well as in thickness. From the nature of its growth,
therefore, the youngest or newest part of the shell is on the inner face
and at the edges, the latter always being sharp and thin in a growing
oyster. The shell of the young oyster is always thin and delicate, and
is generally more rounded than in the adult. The lower valve at first
adheres closely to the body to which it is attached, but later its edge
grows free and the valve, as a whole, becomes deeper and more capa-
cious than its fellow. The small larval or fry shell remains visible at
the beak of the spat shell for a considerable time, but becomes eroded
away before the oyster reaches the adult condition.
The soft parts of the oyster assume their adult form in general soon
after attachment, although the genital glands do not become fuDctioual
until a much later period.
OYSTERS AND METHODS OF OYSTER-CULTURE. 275
The rate of growth (plates x, xi, xii, xiii) varies with locality and
conditions. It is more rapid when food is abundant and at seasons
when the oyster is feeding most vigorously, these conditions being filled
most thoroughly in summer and fall, when the warm water increases
the vital activities of both oyster and food.
In South Carolina oysters not more than six or seven months old were
found to have reached a length of 24 inches, and in the warm sounds
of North Carolina they reach a length of li inches in from two to three
months. In the coves and creeks of Chesapeake Bay they attain about
the same size by the end of the first season's active growth, and by the
time they are two years old they measure from 2i to 3f inches long and
from 2 to 3 inches wide. On the south side of Long Island the growth
of the planted oysters is much more rapid than in Connecticut, it being
stated that "two-year plants" set out in spring are ready for use in the
following fall, while upon the Connecticut shore it would require two or
three years to make the same growth. On the south side of Long Island
oysters If inches long in May have increased to 3 inches by November
of the same year.
The amount of lime in the water is a factor in determining the
character of the shell, and oysters growing in waters deficient in that
respect have thinner shells than those which are well supplied, and are
therefore more susceptible to the attacks of the drill.
The shape of the oyster to a certain extent determines its value in
the market. Single oysters of regular shape Mith deep shells and
j)lump bodies will bring a better price than those which are irregular
and clustered. The shape depends largely upon the degree of crowding
to which the oyster has been subject. When numerous spat become
attached to a single piece of cultch, such as an oyster shell, there is
often insufficient room for the development of all. Many will be crowded
out and suftbcated, while the survivors will be distorted through the
necessity of conforming to the irregular spaces between the valves of
their fellows. Sometimes the pressure exerted between the rapidly
growing shells is sufficient to break up the more fragile forms of cultch,
and the separated oysters then usually improve somewhat iu shai)e.
The crowding of oysters reaches its clinuxx uiion the "raccoon"
oyster beds. Kaccoou oysters are usually found in localities where the
bottom is soft and the only firm jdace which offers itself for the attach-
ment of the spat is upon the shells of its ancestors. Temperature and
other conditions are favorable, growth is rapid, the young oysters are
crowded into the most irregular shapes, the shells are long, thin, and
sharp-edged, and eventually the mass of young is so dense that it
crowds out and smothers the preceding generations which produced it
and offered means for its attachment. Oysters crowded in this excessive
manner are poor-fiavored as well as ill-shaped, but both defects are
corrected if they be broken apart, as may be readily done, and i)lanted
elsewhere.
276 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
ANATOMY.
The following popular description of the anatomy of the oyster is
extracted from the writings of Professors Brooks and Ryder:
The general structure of an oyster may be loughly represented by a long, narrow
memorandum book, with the back at one of the narrow ends instead of one of the
long ones. The covers of such a book represent the two shells of the oyster, and the
back represents the hinge, or the area where the two valves of the shell are fastened
together by the hinge ligament. (Plate i, lig. 1 Z.) This ligament is an elastic, dark-
brown structure, which is placed in such a relation to the valves of the shell that it
tends to throw their free ends a little apart. In order to understand its manner of
working, open the memorandum book and place between its leaves, close to the back,
a small jnece of rubber to represent the ligament. If the free ends of the cover are
pulled together the rubber will be compressed and will throw the covers apart as
soon as they are loosened. The ligament of the oyster shell tends, by its elasticity,
to keep the shell open at all times, and while the oyster is lying undisturbed upon
the bottom, or when its muscle is cut, or when the animal is dying or dead, the
edges of the shell are separated a little. '
The shell is lined by a thin membrane, the mantle (plate i, fig. 1, mt), which folds
down on each side, and may be compared to the leaf next the cover on each side of
the book. The next two leaves of each side roughly represent the four gills, g, the
so-called "beard" of the oyster, which hang down like leaves into the sjiace inside
the two lobes of the mantle. The remaining leaves may be compared to the body or
visceral mass of the oyster.
Although the oyster lies upon the bottom, with one shell above and one below, the
shells are not upon the top and bottom of the body, but upon the right and left
sides. The two shells are symmetrical in the young oyster (plate viii, fig. 2), but after
it becomes attached the lower or attached side grows faster than the other and
becomes deep and spoon-shaped, while the free valve remains nearly flat. In nearly
every case the lower or deep valve is the left. As the hinge marks the anterior
end of the body, an oyster which is held on edge, with the hinge away from the
observer and the flat valve on the right side, will be placed with its dorsal surface
uppermost, its A'entral surface below, its anterior end away from the observer, and
its posterior end toward him, and its right and left sides on his right and left hands,
respectively.
In order to examine the soft parts, the oyster should be opened by gently working
a thin, flat knife blade under the posterior end of the right valve of the shell, and
pushing the blade forward until it strikes and cuts the strong adductor muscle, M,
which passes from one shell to another and pulls them together. As soon as this
muscle is cut the valves separate a little, and the right valve may be raised up and
broken off from the left, thus exposing the right side of the body. The surface of
the body is covered by the mantle, a thin membrane which is attached to the body
over a great part of its surface, but hangs free like a curtain around nearly the whole
circumference. By raising its edge, or gently tearing the whole right half away
from the body, the gills, g, will be exposed. These are four parallel plates which
occupy the ventral half of the mantle cavity and extend from the posterior nearly
to the anterior end of the body. Their ventral edges are free, but their dorsal edges
are united to each other, to the mantle, and to the body. The space above, or dorsal
to the posterior ends of the gills, is occupied by the oval, firm adductor muscle, M,
the so-called "heart." For some time I was at a loss to know how the muscle
came to be calhul the "heart," but a friend told me that he had always supposed
that this was the heart, since the oyster dies when it is injured. The supposed
"death" is simply the opening of the shell, when the animal loses the power to
keep it shut. Between this muscle and the hinge the space above the gills is occupied
Fish Manual. (To face page 276.)
Plate
Fig. 1. Oyster witli rislit shell and mantle removed, a and a, (iriRin of arteries from the ventricle:
ajt. auricle <)f heart: hr. vessel carrviiiK lilood from the Kills to the auricle of the heart; /)/. outline
of orttan of Hojanus, the so-calleil kidney: /<//. pores fioui which the water issues nito the i)ranchial
canals after passing thioutrh the ^ilis: el. I'loaca: d. /H/.and s<i. coiniective and two ^auKlia of the
nervous system: ;/. tri'ls: f/c. cavit\- lielweentlie two mantle' folds: h. hiuKe: /. li^rameiit: .1/, ad-
ductor muscle: );(. mouth: int. mantle, the arrows show the (lire<-tion of currents i)roduced hy the
cilia: i>. palps: //. outer end of ritrht jiedal muscle: .s-, external opening of .se.xual and renal organs
of ritrlit side: v. aims: iv. ventricle of heart.
Fig. •»*. J)ia;;ram to show sexual organs of the oyster, d, duct of sexual glaud. Other letters as above.
OYSTERS AND METHODS OF OYSTER-CULTURE. 277
by the body, or visceral mass, which is made up maiuly of tho light-colored repro-
ductive organs aud the dark-colored digestive organs, packed together in one
contiuuons mass.
If the oyster has been opened very carefully, a transparent, crescent-shaped space
will be seen between the muscle and the visceral mass. This space is the pericar-
dium, and if the delicate membrane which forms its sides be carefully cut away, the
heart, re and an, may be found without any difficulty lyiug in this cavity and pulsat-
ing slowly. If the ojster has been opened roughly, or if it has bcsen out of water for
some time, the rate of beating may be as low as one a minute, or even less, so the heart
must be watched attentively for some time in order to see one of the contractions.
In front of the gills, that is, between them and the hinge, there are four fleshy
flaps — the lips, p, two on each side of the body. They are mucli like thi; gills in
appearance, aud they are connected with each other l)y two ridges, which run across
the middle of the body close to the anterior end, and between these folds is the large
oval mouth, w, which is thus seen to be situated, not at the open end of the shell,
but as far away from it as possible. As the oyster is immovably fixed u])ou the
bottom, and has no arms or other structures for seizing food and carrying it to the
mouth, the question how it obtains its food at once suggests itself. If a fragment of
one of the gills is examined with a microscope it will he found to be covered with very
small hairs, or cilia, arranged in rows, plate viii, fig. 3, c. Each of these cilia is
constantly swinging back and forth with a motion something like that of an oar in
rowing The motion is quick and strong in one direction aud slower in the other.
As all the cilia of a row swing together they act like a line of oars, only they are
fastened to the gill, and as this is immovable they do not move forward through the
water, but ]trodiice a current of water in the opposite direction. This action is not
directed by the animal, for it can be observed for hours in a fragment cut out of
the gill, and if such a fragment Ije supplied with fresh sea water the motion will
continue until it begins to decay. While the oyster lies undisturbed on the bottom,
with its muscle relaxed and its shell open, the sea water is drawn on to the gills by
the action of the cilia, for although each cilium is too small to l>e seen without a
microsco])e, they cover the gills in such great numbers that their united action pro-
duces quite a vigorous stream of water, which is drawn through the shell and is then
forced through very small openings on the surfaces of the gills into the water tubes
inside the gills, and through these tubes into the cavity above them, and so out of
the shell again. As the stream of water passes through the gills the blood is aerated
by contact with it.
The food of the oyster consists entirely of minute animal and vegetable organisms
and small particles of organized matter. Ordinary sea water contains an abundance
of this sort of food, which is drawn into the gills with the water, but as the water
strains through the pores into the water tubes the food particles are caught on the
surface of the gills l)y a layer of adhesive slime, which covers all the soft parts ol
the body. As soon as they are eutangled the cilia strike against them in such a way
as to roll or slide them along the gills toward the mouth. When they reach the
anterior ends of the gills they are pushed off and fall between the lips, and these
again are covered with cilia, which carry the particles forward until they slide
into the mouth, Avhich is always wide open and ciliated, so as to draw the food
through the (esophagus into the stomach. Whenever the shell is open these cilia
are in action, and as long as the oyster is breathing a current of food is sliding into
its mouth.
The cilia and particles of food are too small to be seen without a microscope, but
if finely powdered carmine be sprinkled over the gills of a fresh oyster, which has
been carefully ojjened aud placed in a shallow dish of sea water, careful observation
will show that as soon as the colored i»artick's touch the gills they begin to slide
along with a motion which is quite uniform, but not much faster than that of the
minute-hand of a watch. This slow, steady, gliding motion, without any visible
278 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
cause, is a very striking sight, aud with a little care the particles may be followed
up to and into the mouth.
In order to trace the course of the digestive organs, the visceral mass may be split
with a sharp knife or razor. If the split is pretty near the middle of the body each
half will show sections of the short, folded fcsophagus, running upward from tlie
mouth, and the irregular stomach, cut 1, s, with thick, semi-transparent walls, sur-
rounded by the compact, dark-greenish liver, 1 1. Back of the liver and stomach the
convoluted intestine, i, will be seen, cut irregularly at several points by the section.
There are no accessory organs of reproduction, and the position, form, and general
appearance of the reproductive organ, plate i, fig. 2, is the same in both sexes. As the
reproductive organ has an opening on each side of the body, it is usually spoken of
as double, but in the adult oyster it forms one continuous mass, with no trace of a
division into halves, and extends entirely across the body and (against) the bends
and folds of the digestive tract.*
Cut 1.
The stomach is pretty definitely marked off from the other portions of the digest-
ive tract. It may be said to be that portion, of the latter which is surrounded by the
liver. The portion of the intestine immediately following the short, widened region
which we regarded ns the stomach is the most spacious portion of the gut, and in it
is lodged a very singular organ, which has been called the "crystalline style." This
is an opalescent rod of a glass-like transparency and gelatinous consistence, which
measures according to the size of the oyster from half an inch up to one and a half
inches in length. Its anterior end is the largest, and in a large specimen measures
nearly an eighth of an inch in diameter, but at its posterior end is scarcely half as
thick; both ends are bluntly rounded. I fell into an error in supposing that this
style was lodged in a special pouch or sac, as described in my rejiort to the Maryland
commissioner in 1880. The "crystalline style" really lies in thi; first portion of the
intestine and extends from the pyloric end of the stomach to the first bend of the
* Brooks, W. K. Studies from the Biological Laboratory of Johns Hopkins Univer-
sity, No. IV, 1888, pp. 5-lU in part.
OYSTERS AND METHODS OF OYSTER-CULTURE. 279
intestine, where there is a marked constriction of the alimentary canal. It appears,
therefore, to be a sort of loose valve in the cavity of the gut; its function may bo to
prevent coarse particles of food from passing or it may in some way assist digestion.
In specimens hardened in acid or alcohol this rod is destroyed, or at least disappears,
so that I have been unable to liud it. The greater portion of its substance is appar-
ently made n^i of water.
The peculiar donble indnplication of the wall of the intestine is described in
another place. The fecal matters are extruded in the form of a demi-cyliuder, with
one side excavated in a groove-like manner. This shape of the fecal matters is due
to the presence of the double fold. The feces themselves are composed of extremely
fine particles of quartz or sand grains, the tests of diatoms, organic matters, humus,
cellulose, fragments of the chitinous coverings of some of the minute worms and
articulates, etc., which have been swallowed and digested by the animal. The anus, v,
is situated on the dorsal side of the great adductor muscle where the intestine ends.
The organs of sensation of the oyster, though not very highly developed, are of
sufficient importance to merit attention. The auditory sense, although I have never
been able to dissect out the auditory vesicles, I am satisfied exists, because one can
not noisily approach an oyster bank where the oysters are feeding without their
hearing so that instantly every shell is closed. The tentacles of the mantle are often
extended until their tips reach beyond the edges of the valves. If the animal in
this condition is exposed to a strong light the shadow of the hand passing over it is
a sufficient stimulus to cause it to retract the mantle and tentacles and to close its
parted valves. The mantle incloses, like a curtain, the internal organs of the crea-
ture on either side, and lies next the shell, and, as already stated, secretes and
deposits the layers of calcic carbonate composing the latter. The free edges of the
mantle, which are purplish, are garnished with small, highly sensitive tentacles of
the same color. These tentacles are ciliated and serve as organs of touch, and also
appear to be to some extent sensitive to light.
The nervous system of the oyster is very simple, and, as elsewhere stated, is to
some extent degenerate in character. It is composed of a pair of ganglia or knots of
nervous matter, plate i, tig. 1, sg, which lie just over the gullet, and from these a pair
of nervous cords, d, pass backward, one on each side, to join the hinder pair which lie
just beneath the adductor muscle, j) g. The mantle receives nerve branches from the
hindmost ganglia or knots of nervous matter; these, as their centers, control the
contraction and elongation of the radiating bundle of muscular fibers, as well as
those which lie lengthwise along the margin ; the former contract and withdraw the
edges of the mantle from the margin of the shell, while the latter in contracting
tend to crimp or fold its edges. The tentacles are mainly innervated by fibers
emanating from the hindmost ganglia, while the internal organs are innervated from
the head or cephalic ganglia. The hind ganglia also preside over the contractions
of the great adductor muscle. The nerve threads which radiate outward from it to
the tentacles dispatch the warnings when intruders are at hand that it must contract
and close the shells.*
Ryder, John A. ; Fishery Industries of the United States, pp. 714-715.
280 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
PHYSICAL AND BIOLOGICAL CONDITIONS ON OYSTER-BEDS.
TEMPERATURE OF WATER.
The oyster lives in waters of widely varying temperature, both as to
the average for the year and the extremes met with at different
seasons. Perhaps the greatest divergence between the extremes is
iu Chesapeake Bay, where the range is from the freezing-point of
brackish water, something below 32°, to 90° F. In New Jersey and in
Chesapeake Bay the shallow-water oysters, which are exjjosed or
nearly exposed at low water, are frequently frozen, an event which is
not necessarily fatal if they are gradually thawed. Young oysters
in shallow water are sometimes "winterkilled," or their vitality is
seriously reduced, by exposure to exceptionally low temperatures. The
remedy, or rather preventive, is to remove to deeper water in the fall,
and seed oysters on natural spatting-grounds may often be saved by
this means.
In deeper water, such as is found on the offshore beds of Long Island
Sound, they are not subject to such severe trials, but are nevertheless
called upon to withstand, during several months, a temperature not far
from 32° F. In the Long Island oyster region the summer temperature
of the water reaches 75° F., and from May 1 to November 1 probably
never falls below 00° F. On the South Carolina oyster-beds the tem-
perature appears to rarely fall below 55° F., but, on the other hand,
the exijosed banks of that region are subjected to the direct rays of the
sun and therefore withstand a temperature considerably higher than
that to which submerged oysters are liable.
The temperature has an important bearing upon the food supply.
When the water is warm there is a rapid multiplication of the small
forms upon which the oyster feeds, and at the same time the activities
of the oyster itself are quickened. The two facts taken together result
in a more rapid growth of the oyster than is likely to take place in
colder waters.
It is often said that "plants do not spawn," and there appears to be
some truth in the statement if we apply it to a period of a year or so
after planting, and refer to cases in which the transplanting has induced
considerable modification in the conditions under which the oyster is
placed. This fact is no doubt largely due to the changes in temperature
to which the oyster is subjected when transplanted. Dr. Ryder says :
A very short exposure of the animal to water of an increased temjierature caused
a deterioration of the generative matter. I have tried to fertilize the eggs of num-
bers of oysters that had lain over night in the Quinnipiak River aud invariably
failed; the eggs m every case appeared to be overripe. Oysters taken from the bed
at the same time and from the same locality, but kept in a basket over night, gave
good results.
The same investigator found that at Beaufort, N. C, the best results
in fertilization were obtained the nearer the temperature was to 70° F.
Both at Beaufort and in Chesai^eake Bay the embryos develop most
OYSTERS AND METFIODS OF OYSTER-CULTURE. 281
rapidly in waters between 74° and 80° F., although the mortality is
greater than at a sliglitly lower temperature. Under such conditions
the embryos reach the swimming stage in from 3 to 10 hours, a fact
which is, of course, advantageous to those undertaking artificial propa-
gation. When the temperature falls to below 65° F., development
almost ceases, and when it rises above 80° F. but few of the embryos
reach the swimming stage. Sudden changes are usually fatal, and cold
rains kill great numbers of the swimming fry.
Dr. Ryder recommends ''that the prevalent temperature of the water
during the spawning season shall range from 68 to 80° F." It is quite
possible that in other regions, with oysters native thereto, or even those
which have been acclimated therein, some other temperature may be
found more favorable, but no data bearing upon the matter have been
published.
TEMPERATURE; PLANTED BED^^ IN SAN FRANCISCO BAY.
The temperature at San Francisco is usually not much higher in
summer than in winter, but information upon the subject is limited.
Upon the oyster-beds at Millbrae it is said to vary from 58° to 05° F.,
but at the extreme southern end of the bay it ranges from 67° to 74° F.
In October, 1890, Mr. C. II. Townsend found 61° F. at Belmont; at San
Mateo, nearer the sea, 60° F., and at California city, 57° F.
In midsummer the temperature M^as considerably higher; between
July 12, 1891, and September 7, 1891, it ranged from 67° to 74° F., the
means for 10 day periods during the same time being between 69.1°
and 72° F. As Mr. Townscnd points out, there is, therefore, a con-
siderable period during the snmmer when the temperature, in portions
of the bay at least, is favorable for spawning of the planted eastern
oysters. The portions of the bay near the sea appear to have a tem-
perature several degrees cooler than in the southern portions.
DENSITY OF WATER.
Oysters are found living in water ranging in salinity from 1.002* to
1.025, but the lower densities are always injurious, and prolonged
exi)osure to their influence is fatal to oyster life. It is not possible to
l)rofitably maintain oyster-beds in waters where the density falls below
1.007 for any length of time, the oyster, if not killed, becoming poor in
(juality, pale, watery, and tasteless. Heavy freshets, such as occur in
the rivers discharging into Chesapeake Bay and at various places on
the Gulf coast, frequently so lower the density of the water as to prac-
tically exterminate the oysters on certain beds. Experience apparently
indicates that the best oysters are grown in densities between about
1.011 and 1.022, the former being approxinuitely the specific gravity
over the Tangier Sound beds, the latter that over the deep-water
oyster-grounds of Long Island Sound.
"The figures represent the specific gravity as measured with the salinometor, that
of pure water being 1.000.
282 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
Change of density lias an important efiect upon the spawning of
oysters. At St. Jerome Creek, Dr. Ryder found that the eggs could
not be impregnated in a density much exceeding that in which the
parent animals live. With oysters raised in water ranging from 1.007
to 1.0095 it was found that the milt was killed by a density greater
than 1.013, the individual spermatozoa losing their mobility in a few
moments when exposed to the greater density. The frequent failure
of oysters to spawn in the season in which they are transplanted is
perhaps in a measure owing to this cause. In Chesapeake Bay they
are usually transplanted from deeper, denser water to more shallow
and less dense, and when taken from the Chesapeake to Long Island
Sound they go through a similar experience. There is at the same
time, however, usually a change in temperature, and doubtless both
factors combine to produce the effect noticed.
It has been suggested by Lieutenant Piatt that the density of the
water has an effect on the distribution of the set; that is, the specific
gravity of the swimming embryo is such that it can not sink in
dense water and therefore must become attached in marginal beds
between tide marks, as is seen on the "raccoon" oyster-beds of South
Carolina.
In some places it has been found that the best results in oyster-
culture are to be had in brackish water, and Dr. Kyder suggests that
this may be largely due to the fact that water of the lower densities
is usually shallower, and consequently warmer and better adapted to
the production of an abundant supply of the minute organisms which
constitute the principal source of the oyster's food. There can be no
doubt, however, that the eastern oyster is distinctively a brackish-
water form. It has been found that it will not thrive in French waters
l)erfectly adapted to the culture of the European species, and there is
reason to believe that it will reproduce itself in a lower density than is
necessary for the native oyster of California.
For determining the temiierature and the density of sea waters the
apparatus shown in plate ii is used. It consists of a glass float with a
long stem and a large bulb, weighted so as to sink in fresh water to a
point near the top of the stem. The stem is graduated to read between
1.000 and 1.031, the figures representing the specific gravity; that is,
they show the weight of the salt water, an equal body of fresh water
being supposed to weigh 1.000.
In practice a scale having the entire range would be too long for
safety and convenience, and therefore the salinometers are made in
sets of three, reading from 1.000 to 1.011, from 1.010 to 1.021, and from
1.020 to 1.031, respectively.
There is also provided with them a deep copper cup or cylinder,
at one side of which a thermometer is attached (plate ii). The method
of using the salinometer is as follows: Tlie cup is filled with the water
to be tested, the appropriate float is placed in the water, the density of
Fish Manual. (To face page 282.)
Plate II.
Scale
> . '
INCh£3
SALINOMETER AND SALINOMETER CUP.
The bcale opposite tlie steui of the saUnoineter represents that of the liiRh readiiiK spiucile as if unrolled.
It registers densities between 1.020 and l.ii3I.
OYSTERS AND METHODS OF OYSTER-CULTURE. 2^3
which will be the reading of the scale nearest the point where the sur-
face of the water touches the stem. For purposes of oyster-culture the
finer graduations may be neglected. To show the specific gravity, the
number "1.0" should always be placed in front of the scale reading;
for example, if the surface of the water should stand opposite the scale
reading "If)," the density would be 1.015. The test should be made
imniediately after the water specimen has been collected and a reading
of the thermometer should be taken at the same time.
For practical purposes on the oyster-beds, a bottle or jar not less than
10 inches deep may be used instead of the copper cup, and any ordinary
thermometer may be used for obtaining the temperature. The cheap,
wooden-cased instruments known as "bath thermometers" serve very
well, as they have no metal parts to be corroded by the salt water. In
most oyster regions the salinometer reading from 1.020 to 1.031 will
not be necessary, as the density on the oyster-beds rarely falls within
its range.
The specimens of water should be from the bottom, or near it, and
may be conveniently obtained by the following rough method: An
empty jug or large bottle weighted and corked is lowered to the bottom
by means of a line. The cork is then pulled out by jerking on a cord
previously attached to it, the receptacle fills with a sample of water
from or near the bottom, and if hauled rapidly to the surface it answers
the practical purposes of more scientific and accurate apparatus.
SILT, MUD, AND SUSPENDED MATTER.
A bottom composed of soft mud, into which the young oysters would
sink and become stifled, is unfavorable to oyster- culture or to the de-
velopment of natural beds. If, however, hard objects are distributed
over the bottom they will become collectors of spat so long as the
surface remains clean and free from slime and sediment, and the
importance of having water containing as little sedimentary matter
as possible is manifest if it is desired to produce permanent beds or
catch the floating fry.
Oysters will grow more rapidly on muddy bottoms, or in their vicinity,
than they will elsewhere, as such situations are usually more pro-
ductive of food materials. This food is in the form of suspended or
swimming organic particles, and, therefore, filtered water, or that which
is <levoid of suspended matter of all kinds, lacks one of the essential
recjuirements of successful oyster-culture. The most desirable water
is that which contains an abundance of minute living particles with a
minimum of suspended inorganic matter. An organic slime, however,
such as rapidly forms on exposed surfaces in some localities, is as
eflectual in i)reventing fixation as is inorganic; sediment. In many
places in Chesapeake Bay and in the bays on the New Jersey coast the
sediment, as well as the bottom mud, is largely composed of the finely
comminuted fragments of vegetable matter, seaweeds, etc., the rapid
deposit of which soon covers with a soft film the surface of all objects
284 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
exposed to it, except when the currents are sufficient to exert a scouring
influence.
Large oysters are not so susceptible as small ones to the effects of
mud, but even those full grown may be stifled or buried by the rapid
deposit of mud or sediment, whether this be of organic or inorganic
origin. Freshets and heavy seas often cause great damage by the
amount of mud, sand, and other debris which they carry upon the beds.
The question of the physical characters of a suitable bottom for
oyster-culture is considered in another connection.
TIDES AND CURRENTS.
Tides and currents are important factors in tlie growth and culture
of the oyster. They bring about the aeration of the water and oxida-
tion of its dead organic ingredients; they have a scouring action upon
the bottom and thereby cleanse the cultch, and at the same time serve
as the vehicles for the transportation of food, of the genital products,
and of the young. Stagnant water tends to become exhausted of its
oxygen; it is heated by the sun, and the contained organic matter
undergoing death and decomposition causes it to become foul and fatal
to the oysters in the vicinity. With currents, however, a fresh supply
of oxygen is constantly being supplied for respiration and for the
combustion of the effete matter, which is thus rendered harmless.
Over densely-populated beds the food suj^ply, unless unusually pro-
lific, as in claires, would in time become exhausted. The oyster can
not, of course, change its location, but the same purpose is subserved
by currents constantly bringing a fresh supply of food-laden Avater
within the influence of the ciliary action by which the oyster cai^tures
its food.
Tlie genital products of the oyster, both male and female, are simply
discharged into the surrounding water. The eggs are absolutely immo-
bile, and while the spermatozoa, or male elements, possess the power of
locomotion to some extent, they are obviously incapable of moving very
far during the limited period of their mobility. In densely-crowded beds
no doubt a considerable proportion of the eggs may become fertilized
even without the agency of currents; but where, as upon most oyster-
grounds, the oysters are scattered, the proportion must be exceedingly
small. Oysternien are well acquainted with the fact that upon beds
removed from the influence of the tides the rate of reproduction is
very low.
Currents, however, will bring about a distribution of the genital
products, more particularly the almost impalpable milt, and thus give
an opportunity for obtaining better results by increasing the chances
for spawn and milt to come into contact. Although the young spat is
a free-swimming organism, yet its powers are not sufficient to carry it
to any great distance from its original scmrce. It is transported mainly
by tidal currents, and, as a general rule, the more widely distributed
a given lot of spat, the greater is the number liable to become success-
OYSTERS AND METHODS OF OYSTER-CULTURE. 285
fully set. Currents, even of considerable strength, do not prevent the
settling down of the larval oyster and its fixation upon a proper
surface.
In the preparation of this surface the (nirrents are also effective,
injisniuch as by their scouring action they prevent the deposit of sedi-
ment and slime, which soon render collectors unsuitable for the fixation
of the young oyster. Finally, where the fry are uniforndy distributed
in a body of water a collector placed in a current will (;olkct more spat
than one in quiet water, because a greater quantity of water and con-
sequently a larger number of fry will be brought into contact with it.
Points around which fry-charged water sweei)S with sufficient velocity
to prevent the deposit of sediment are good places for the location of
collectors.
Freshets, for several reasons, usually have a bad effect upon the
oyster-beds. When the volume of fresh water is large, the oysters
suffer from the decrease in the density. Large quantities of mud and
sediment are brought down by the floods and often deposited on the
beds, covering up the cultch and smothering the young spat, and, if
the amount of sedimentation is very great, even injuring or killing
the adults.
DEPTH OF WATER.
The vertical range of the cultivated oyster beds is from the shore
line to a depth of 15 fathoms. In New Jersey, Chesapeake Bay, South
Carolina, and other places, there are beds which are partially exposed
at low water, while in Long Island Sound successful oyster-culture
is carried on in depths as great as 15 fathoms, the average over i)lanted
grounds in that region, however, being from 5 to 6 fathoms. In most
places, however, the planting is done in shallow bays and coves.
WEATHER CONDITIONS — STORMS, G^ALES, AND ICE.
Gales rarely have any influence upon adult oysters in deep water,
but they sometimes seriously affect shallow-water beds. Heavy surf
occasionally carries away the oysters and throws them upon the beach,
or they may be buried in situ by the sand and seaweeds which the
waves lodge ui^on the beds. Sometimes, after the lapse of a short time,
the beds are again uncovered by the eroding effects of currents, but in
many cases they are practically destroyed, both old and young being
smothered by the overlying deposits.
In winter, ice often grounds upon the beds during gales and does
considerable damage. The oyster ai)pears also to be tenqjorarily
affected by the mere freezing of the waters, and it is said that, in the
Chesapeake, oysters on the deeper beds are more affected than those in
shoal and brackish water, becoming dark, slimy, and worthless for the
market. Ten days or a fortnight must elapse after the disappearance
of the ice before they become again fit for use.
The fry are more affected by the weather than are the adults. Dr.
Ryder found that in the swimming stage they were killed by thunder-
286 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
storms, by cold rains, and by sudden falls in temperature, and the
prevalence of such weather during the spawning season must have au
important effect upon the set of spat.
FOOD.
The oyster feeds upon both animal and vegetable food, the particles of
which are of microscopic dimensions. The fry and young spat consume
relatively large quantities of bacteria and monads, among the most
minute organisms known to microscopists. According to Dr. Eyder:
Many of the food balls found in the intestine of the recently attached spat will
measure under tjtJ(Ttt inch in diameter. The cavity of the little creature's stomach
measures only —^v-n inch. Yet in this minute digestive cavity the food is actually
found rotating in tbe form of minute rounded and oval bodies, which are kept in
motion by the action of the cilia which line the stomach. That these bodies must
have been of about the size noted when they were originally swallowed and as seen
rotating in the stomach is evident fr9m the fact that the young oysters, like the
adults, are wholly without teeth or triturating organs of any kind.
This minute kind of vegetable and animal food is found more or less abundantly
in all sea water, and is especially abundant during the spawning season, when the
decomposition and disintegration of all kinds of minute organic debris floating about
in the water is in rapid progress, owing to the prevalent high temperature of the
air and water. It is, therefore, probable that very few otherwise suitable locations
exist where it is not possible to find an abundance of the proper sort of food for the
oyster during its very earliest stages of growth.
The food of the slightly more advanced spat and the adults is found to consist of
diatoms, rhizopods, infusoria of all kinds, monads, spores of alg;e, pollen grains
blown from trees and plants on shore, their own larvaj or fry, as well as that of many
other mollusks, of bryozoa and minute embryos of polyps and worms, together with
other fragments of animal or vegetable origin, and sometimes even minute crusta-
ceans. In variety of food the oyster, therefore, has a wide range of choice. There
are also few locations otherwise well adapted which will not supply an abundance
of food for the animal, which, it is to be remembered, captures and hoards millions
of these minute plants and creatures in its stomach, where they are digested and
incorporated into its own organization. It therefore follows that when we eat an
oj'Ster we are consuming what it required millions of the minutest organisms in the
world to nourish. The oyster is consequently a sort of living storehouse for the
incorporation and appropriation of the minute life of the sea, which could never be
rendered tributary to the food supply of mankind in any other way except through
the action, growth, and organization of this mollusk.*
The quantity of young oysters consumed by the adults is doubtless
enormous, 200 fry having been found in the stomach of single individ-
uals. Not only the free-swimming fry, but eggs and spermatozoa are fed
upon, and an insight Is here gained into the ultimate fate of some of the
vast numbers of genital elements which the parents shed into the water.
While the oyster feeds upon both plant and animal organisms, it
must be remembered tliat it is primarily dependent ui)on the former.
That not only is the major portion ol the food of the oyster itself of
vegetable origin, but the minute animal forms are dependent for their
sustenance upon the plants and are not to be found in abundance far
removed from them.
Kept. U. S. F. C. 1885, pp. 387-388.
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OYSTERS AND METHODS OF OYSTER-CULTURE. 287
lu most regions which have been investigated the phiuts constitute
by far the most important item of diet, usually over 90 per cent of the
food contents of the stomachs being composed of vegetable matter.
Of this diatoms are the chief constituents, and to a certain extent the
food value of any given oyster region may be measured by the quantity
of these minute plants which it is capable of producing.
Diatoms are numerous both in species and individuals, and all possess
two interesting peculiarities: They are incased in a siliceous or Hinty
box and they possess the power of locomotion, the first permitting their
ready identification in the stomach contents and the second aiding in
their distribution. More or less regular diurnal migrations of swarms
to and from the surface of the water take place with the variations in
the light. During sunlight they rise from the bottom, and are then
readily transported by the currents, again settling down as darkness
comes on. They feed and grow in size most actively during the day, but
multiply in number principally at night. Diatoms are important, not
only in fattening the oyster, but they also have a i^rofound influence
upon its flavor and color.
The oyster is said to feed mainly during flood tide, opening its shell
at that time to admit the influx of water with its contained organisms.
Investigation by Dr. Bashford Dean showed that the stomachs were
practically foodless in the morning, contained most food at midday,
and a somewliat reduced quantity at evening, thus suggesting that
feeding was most active during intense daylight.
Dr. Dean remarks :
This suggestion, as to the feeding habits of the oyster, is not a surprising one
when wo remember that it is during the strongest sunlight tliat diatoms, as plants
keenly sensitive to the sun, are most active and are known to migrate in floating
clouds from the bottom of the surface.
As is mentioned in the section relating to the anatomy of the oyster,
the water drawn into the mantle cavity by the action of the cilia is
filtered through the rectangular openings in the gills into a chamber or
tube lying above each gill, whence it passes backward and out of the
shell in a current dorsal to the entering stream. The particles of food
in the inflowing stream become entrapped in a sticky mucus covering
the gills, and, together with this mucus, in part, are carried in a steady
stream toward the mouth, the motion being imparted to the mass by
the rhythmic action of the cilia. The palps and mouth are also
ciliated, which insures the continuance of this current into the stomach,
where the food particles undergo digestion. A very considerable pro-
portion of inert matter, sand, mud, etc., of no nutrient value passes into
the alimentary tract along with the food, the oyster having no means
of making selection.
The temperature, depth, and density of the water have considerable
effect upon the food supply. In clear, warm weather the amount of
food matter is increased by the natural multiplication of the minute
288 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
organic bodies which find such conditions favorable, but at the same
time many of these organisms, particularly the diatoms and zoospores,
are attracted to the surfacie by the sunlight and are thus placed beyond
reach of the oyster. In rainy or stormy weather, however, they are
driven down toward the bottom, where tliey may be brought within the
inriuence of the cilia, and at the same time there is an increase in the
amount of other organic sediment, much of which is available as food.
Shallow water, as a rule, produces more food than the greater
depths, owing largely to the fact tluit it warms more (juickly and thus
increases the vitality of both the oyster and its food. The latter shows
its greater vigor by a more rapid multiplication, and the former by its
greater consumption of the food which is thus provided for it. In other
words, the chemical aiul physiological changes resulting in the conver-
sion of inorganic matter into oyster tissue through the medium of i)lant
life go on more rapidly in the presence of warmth. It must also be
remembered that the shallow waters are generally of a lower density
than the deeper ones, and this approach to brackishness appears to be
also favorable to the production of food.
Summer and fall, the seasons of most vigorous growth of aquatic
vegetation, are in most localities likewise the best seasons for the
growth of the oyster, while in winter the food supply is at a minimum,
the vital activities of the oyster are much reduced, the ciliary action is
weak, and the oyster in a state of semihibernation, both the waste and
repair of tissue being reduced to a minimum.
That the oyster in many place's reaches its greatest fatness and per-
fection late in fall is due partly to the quantity of food produced during
the summer and partly to the cessation of the drain which the act of
spawning entails. Shortly before and during the spawning season
most of the nutrient matter in the food is utilized in the rapid growth
of the sexual products, but after the cessation of spawning it is con-
verted into surplus protoplasmic matter, which is stored up in the
tissues and thereby renders the oyster fat and well flavored.
ENEMIES.
At all stages of its career the oyster is preyed upon by more or less
dangerous foes. It might be supposed that an animal inclosed in a
ponderous armor, which in times of danger is a complete encasement,
would be free from the attacks of enemies, but no organism has ever
evolved a protective device which some other organism has not found
partially vulnerable; and it must be remembered that the oyster is not
always as well protected as we find it in the adult and marketable con-
dition. In the young state, before attachment, the minute and delicate
fry is fed upon extensively by the adult oyster and by other mollusca,
lingulas, worms, sponges, and hydroids. Upward of 200 young have
been found in the stomach of an oyster, and there is but little doubt
large numbers are so consumed on every oyster-bed. Probably the
OYSTERS AND METHODS OF OYSTER-CULTURE. 289
nienhaflen, the alewife, and other fish equipped with delicate sifting
devices at times llnd the oyster fry of some im])ortance in their dietary.
After the attachment of the spat other enemies, active and passive,
wage war upon it. The passive enemies aft'ect its welfare by consum-
ing its food or by smothering it beneath their own more active growth.
Of the former class, mussels, lingulas, etc., are examples, but as the
food upon an oyster-bed is usually sufficient for all, this is not a very
important consideration, particularly as in the end an equilibrium is
established through the intimate reciprocity which exists between the
various forms of life.
The conditions of life upon an oyster-bed are favorable to the rapid
growth of dense sponges, mussels, barnacles, hydroids, and tube-build-
ing worms, which establish themselves upon the young growth, often
increase more ra])idly than their hosts, and, in many cases, overgrow
them to such an extent as to cut oft" the supply of food and oxygen.
(Plate XVII). Aquatic vegetation sometimes has the same eftect when
its growth becomes extensive. Certain worms, such as Seypula, and
especially 8ahellnri<i (plate xv, fig. 3), often build their tubes of lime or
sand so rapidly as to produce dense accumulations upon the surface
of the shells, thus forming a nidus for the collection of sand and mud.
Considerable loss has at times resulted from the suffocation of oysters
by sponges, worm tubes, and vegetable growths, but most of these
passive forms have a compensatoiy use in the food which their spores,
eggs, and young furnish to the oysters.
The active enemies of the adult oyster are those which injure it by
direct attacks, such enemies being found in most of the classes of
zoological life having aquatic representatives.
Fishes of several kinds are found habitually on the oyster-beds.
Most of these otter no direct injury and they may even benefit the
oyster by keeping down the crowding masses of hydroids and vegetable
life, but a few species, of which the drumfish is apparently the most
destructiv^e upon the Atlantic coast, consume considerable quantities
of oysters as food. At times mu(;h damage has thus been wrought to
the beds in the vicinity of New York and along the New Jersey coast.
In San Francisco Bay the stingray is the most feared enemy of the
oyster, and schools of them fre([uent?ly "clean out" the beds to which
they gain access, their teeth bemg such that the shells are crushed into
fragments in their grasp. Some of the skaies and rays on the eastern
coast no doubt have similar habits, but they do not appear in sufficient
numbers to cause much harm.
The drills are the most destructive enemies of the oysters in the
Chesapeake and adjoining regions, as well as upon most of the more
inq)ortant inshoie beds northward. There are, perhaps, several species,
but the most destructive is the form known to naturalists as Urosalpinx
cinered (i)late xv, fig. 1). It is a snail-likemollusk, which, by means of its
rasping tongue, drills a tiny hole in the shell of the oyster, through which
it extracts the soft parts. It is only the younger oysters Avhich are thus
r.^r. — 19
290 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
attacked, as after they become about 2 incbes long the shell is stout
enough to resist this foe. The loss sustained from this source is very
great, as the drills are often present in large numbers and continue
their work throughout the year.
The two large conch-like gasteropods of the Atlantic coast, Sycoty-
pus canaliculatus and Fulgiir cariea (plate xv, fig. 4), also feed upon the
oyster, from their size being capable of attacking the largest individ-
uals. These periwinkles, " winkles," or conchs, as they are variously
called, appear to do comparatively little damage, as they are not pres-
ent in sufficiently large numbers anywhere except perhaps on the coast
of Florida.
Other gasteropods doubtless feed upon tlie oyster, but not to an
extent worthy of consideration.
Upon brackish-water beds the starfish (plate xvi) is not usually
troublesome, and in Chesapeake Bay it is practically unknown, but in
Long Island Sound, and especially upon the offshore beds in the more
saline waters, it is the most destructive enemy with which oystermen
have to contend. It is there extremely abundant at times, "but it is a
migratory form, and sometimes certain beds are unmolested while others
nearby are almost ruined by its inroads. The appearance of this i^est
upon the beds is without warning, and frequently the ground is almost
devastated before the owner is aware of their presence. Vast swarms
or schools sweep across the beds, devouring the oysters in their path.
The migration is said to take place in the form of a "winrow," moving
in some cases at the rate of about oOO feet per day. Apparently the
only way to stop the march of these hordes is to catch them up by some
of the methods indicated in pp. 313-310. By energetic work the damage
may often be confined to the beds at the edge of a cultivated area.
The starfish begins its destructive work soon after it abandons its
free-swimming larval condition, at a time when it is hardly larger than
a pin's head, and continues it through life. At first it feeds upon the
tiny spat, but as it grows it increases the size of its prey, though even
the full-grown stars rarely feed upon oysters over two, or, at most,
three years old. Small oysters are often taken bodily into the stomach
of the starfish, a proceeding which is of course impossible with large
ones or those firmly attached to large cultch. It is not definitely known
how the oysters are opened, but Dr. Paulus Schiemenz has pretty con-
clusively demonstrated the probability that they are actually pulled
open by muscular effort on the part of the starfish.
If the common starfish be examined there will be found on the under
surface of each arm four rows of closely c-rowded suckers or feet extend-
ing from the mouth to the tips of the arms. These feet are tubular
and are extended by having a fluid pumped into their cavities by a
special apparatus in the body of the starfish. The suckers at the ends
may be caused to adhere to foreign bodies with great tenacity, and if
the hydrostatic preSsnne be tlien nplievfed and tire mUScles of th6 atalfcB
of the feet contract^ a strong {lull mity be fexerted hf each l"oot, eithet
OYSTERS AND METHODS OF OYSTER-CULTURE. 291
independently of its fellows or iu conjunction with them. As shown
in plate xvi, the starfish feeding upon oysters or other laniellibranchs
arches itself over the nibs or lips of the mollusk so that some of its arms
are on one side and some on the other. In this position a large number
of the sucker feet are attached to each valve, and when they contract
a stress is produced in opposite directions and opposed to the force of
the adductor muscle which tends to keep the valves of the oyster
closed. Dr. Schiemeuz has shown by actual measurement that in this
manner there is exerted a force sufficient to overcome any resistance
which the oyster may ofl'er. It is eventually tired out by the persist-
ence of its enemy, its shell is forced open, the stomach of the starfish
is inserted, and within a few hours the valves only remain.
Another annoying and frequently very destructive enemy of the
oyster is the boring-si^onge, Cliona sidphurea. It differs from the
enemies before enumerated iu that it consumes the shell and not the
soft parts of the unfortunate oyster. The young si)onge lives in galleries
excavated in the substance of either dead or living shells which are
soon reduced to a honey-combed coiulition, when they may be crumbled
to powder between the fingers. Wben they attack a living oyster,
as the galleries penetrate the inner face of the shell, an irritation of
the mantle is produced, causing an increased amount of shell deposit
at that point. If the inside of such a shell be examined it will be found
to be covered with blister-like shell deposits, sealing up the openings to
the galleries, and many curious distortions follow from the destruction
of the hinge area and the portion of the shell to which the adductor
muscle is attached. Although the oyster itself is not attacked, j^et it
becomes poor, thin, and watery and often dies from the exhaustion
induced by the constant effort to keep its shell intact.
The older specimens of the boring-sponge are large, dense, yellow
masses, often 6 or 7 inches in diameter and usually inclosing the shells,
etc., to which they were originally attached. All stages intermediate
between those described can usually be found upon infested oyster-
beds. The older, more massive forms often suffocate the oyster through
the denseness of their growth.
In addition to the various forms already enumerated there is a large
population upon the oyster-beds which is not injurious. This, of course,
includes many of the minute food forms, together with some of the fishes
and crabs. The latter, at least on the Atlantic coast, can not be
regarded as very destructive, but on the contrary tliey serve as scav-
engers, removing dead matter from the beds when it miglit otherwise
become foul and fatal to the oysters. It will be seen that the popula-
tion of the oyster-beds is large and extremely complex. The social
relations of the various forms are exceedingly intricate and have, iu
the course of evolution, become nicely adjusted in a system of recii)rocity.
The hiw of the oyster beds is "give and take,'' eacli of a large number
of organisms giving something for the general welfare and taking what
it needs for its own well being.
292 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
DESCRIPTION OF NATURAL BED.
Dr. Brooks thus describes a natural oyster bank:
Au examinatiou of a Coast Survey chart of auy part of the Chesapeake Bay or of
any of its tributaries will show that there is usually a inidchauiiel or line of deep
water where the bottom is generally soft and where no oysters arc met with, and on
each side of this an area where the bottom is hard, running from the edge of the
channel to the shore. This hard strip is the oyster area. It varies in width from a
few yards to several miles, and the depth of water varies upon it from a few feet to
5 or 6 fathoms or even more. But there is usually a sudden fall at the edge of the
channel where the oysters stop, and we pass onto liard bottom; and a cross-section
of the channtd would show a hard, flat plane with oysters on each side of the deep,
muddy channel. Tlie oyster bottom is pretty continuous, except o])i)osite the mouth
of a tributary, where it is cut across by a deep, muddy channel. The solid oyster
rocks are usually situated along the outer edge of this plateau, althougli in many
cases they are found over its whole width nearly up to low-tide nuirk or beyond.
As we pass south along the bays and sounds of Virginia and North Carolina, we find
that the hard borders of the channel come nearer and nearer to the surface until in
the lower part of North Carolina there is on each side of the channel a wide strip of
hard bottom, which is bare at low tide and covered with oysters up to high- water
mark, although the oysters are most abundant and largest at the edge of the deep
water, where they form a well-delined reef. In our own waters there is usuallj^ a
strip along the shore where no oysters are found, as the depth of water is not great
enough to protect them in winter. The wliole of the hard belt is not uniformly
covered with oysters, but it is divided up into separate oyster rocks, between which
comparatively few can be found.
The boundaries of a natural rock which has not been changed by dredging are
usually well defined, and few oysters are to be found beyond its limits. The oysters
are crowded together so closely that they can not lie flat, but grow vertically upward,
side by side. They are long and narrow, are fastened together in clusters, and are
known as "coon oysters."
When such a bed is carefully examined it will be found that most of the rock is
made up of empty shells, and a little examination will show that the crowding is so
great that the growth of one oyster prevents adjacent ones from opening their shells,
and thus crowds them out and exterminates them. Examination shows, too, that
nearly every one of the living oysters is fastened to the open or free end of a dead
shell which has thus been crowded to death, and it is not at all unusiuil to Hud a
pile of five or six shells thus united, showing that number two has fastened, when
small, to the open end of numlx-r one, thus raising itself a little above the crowd.
After number one was killed, number two continued to grow, and number three fast-
ened itself to its shell, and so on. Usually the oysters upon such a bed are<small, but
in some places shells 12 or 14 inches long are met with. The most siguificaiit cliarac-
teristic of a bed of this kind is the sharpness of its boundaries. In regions where
the oysters are never disturbed by man it is not unusual to lind a hard bottom
extending along the edge of the shore for miles and divided up into a number of
oyster rocks, wheie th(^ oysters are so thick that most of them are crowded out and
die long before they are full grown, and between these beds are areas where not a
single oyster can be found. The intervening area is perfectly adapted for the oyster,
au'l when a few bushels of shells are scattered upon it they are soon covered with
young, and in a year or two a new oyster rock is established upon them, but when
they are left to themselves the rocks remain shari)ly defined.
What is the reason for this sharp limitation of a natural bed ? Those who know
the oyster only in its adult condition may believe that it is due to the absence of
powers of locomotion and may hold that the young oysters grew up among the old
ones, just as young oak trees grow up where the acorns fall from tlie branches. This
can not be the true explanation, for the young oysters are swiiiuning animals, and
OYSTERS AND MI THODS OF OYSTER-CULTURE. 293
they are discharged into the water in countless numbers, to be swept away to gieat
distances by the currents. As they arc too small to be seen at this time without a
microscope it is imj)Ossible to trace their wanderings directly, but it is possible to
show indirectly that they are carried to great distances and that the water for miles
around the natural bed is full of them. They serve as food for other marine animals,
and when the contents of the stomachs of these animals are carefully examined with
a microscope the shells of the litthi oysters are often found in abundance. While
examining the contents of the stomach of lingula in this way I have found hundreds
of the shells of the young oysters in the swinnning stage of growth, although the
specimens of lingula were cajjtured several miles from the nearest oyster-bed. As
lingula is a lixe<l animal tlie oysters must have been brought to the spot where the
speciniens were found, and as the lingula has no means of capturing its food, and
subsists upon what is swept within its reach by the water, the presence of so many
inside its stomach shows that the water must have contained great numbers of them.
It is clear, then, that the sharp limitation of the area of a natural oyster bed is not
due to the absence in the young of the power to reach distant points. There is
another proof of this, which is familiar to all oystermen — the iiossibility of estab-
lishing new beds without transplanting any oysters. The following illustration of
this was observed by one of your commissioners: On part of a large mud fiat which
was bare at low tide there were uo oysters, although there was a natural bed u])on
the same Hats, about half a mile away. A wharf was built from high-tide mark
across the Hat out to the edge of the channel, and the shells of all the oysters which
were consumed in the house were thrown onto the mud alongside the wharf. In the
third summer the Hat in the vicinity of the wharf had become converted into an
oyster-bed, with a few medium-sized oysters and very great numbers of young, and
the bottom, which had been rather soft, had become quite hard ; in fact, the spot
presented all the characteristics of a natural bed. Changes of this sort are a
matter of familiar experience, and it is plain that something else besides the absence
in the oyster of locomotive power determines the size and position of a bed.
Now, what is this somcthirKj else? If the planting of dead shells will build up a
new bed, may we not conclude that a natural bed tends to retain its position and
size because the shells are there? This conclusion may not seem to be very import-
ant, but I hope to show that it is really of fundamental importance and is essential
to a correct conception of the oyster problem.
Why should the presence of shells, which are dead and have no power to multiply,
have anything to do with the perpetuation of a bed?
We have already called attention to the fact that oysters are found on the hard
bottom on each side of the channel, while they are not found in the soft mud of the
channel itself, and it may at first seem as if there were some direct connection
between a hard bottom and the presence of oysters, but the fact that uo oysters are
found upon the hard, firm sand of the ocean beach shows that this is not the case.
As amatter of fact, they thrive best upon a soft bottom. They feed upon the floating
organic matter which is brought to them by the water, and this food is most abun-
dant where the water flows in a strong current over soft organic mud. When the
bottom is hard there is little food, and this little is not favorably placed for ditiusion
by the water, while the water which flows over soft mud is rich in food.
The young oysters which settle u])on or near a soft bottom are therefore most
favorably placed for procuring food, but the young oyster is very small — so small
that a layer of mud as deep as the thickness of a sheet of paper would smother and
destroy it. Hence the young oysters have the habit of fastening themselves to solid
bodies, such as shells, rocks, or ])iles, or floating bushes, and they are enabled to
profit by the soft bottoms without danger.
Owing to the peculiar shape of an oyster shell, some portions usually project above
the mud long after most of it is buried, and its rough surface furnishes an excellent
basis for attachment. It forms one of the very best supports for the young, and a
little swimming oyster is especially fortunate if it finds a clean shell to adhere to
when it is ready to settle down for life. Then, too, the decaying and crumbling
204 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
shells are j^radnally dissolved in tlie sea water, and thus furnish the lime which the
growiiiii; oyster needs to build up its own shell. As long as the shell is soft and thin
the dant^er from enemies is very great, and this danger is greatly diminished as
soon as the sliell becomes thick enough to resist attack. It is, therefore, very neces-
sary that the shell should be built up as rajjidly as possible, and an abundant supply
of food in general will be of no advantage unless the supply of lime is great enough
for the growth of the shell to keep pace with the growth of the body. All sea
water contains lime in solution, but the percentage is, of course, greatest near the
sources of supply. It is well known that on coral reefs, which are entirely made of
lime, all kinds of shelled mollusks flourish in unusual abundance and have very
strong and massive shells, and our common land and fresh-water snails are much
larger and more abundant in a limestone region than in one where the supi^ly of
lime is scanty. In such regions it is not unusual to iind the snails gathered around
old decaying bones, to which they have been drawn in order to obtain a supply of
lime for their shells.
From all these causes combined it results that a young oyster which settles upon a
natural oyster-l)ed has a miich Ijctter chance of survival than one which settles
anywhere else, and a natural bed thus tends to perpetuate itself and to persist as a
definite, well-defined area; but there is still another reason. As the flood tide rushes
up the channels it stirs up the fine mud which has been deposited in the deep water.
The mud is swept up onto the shallows along the shore, and if these are level much of
the sediment settles there. If, however, the Hat is covered by groups of oysters, the
ebbing tide does not flow off in an oven sheet, but is broken np into thousands
of small channels, through which the sediment flows down to be swept out to sea.
The oyster-bed thus tends to keep itself clean, and for these various reasons it
follows that the more firmly established an oyster bed is the better is its chance of
perpetuation, since the young spat finds more favorable conditions where there are
oysters, or at least shells, already than it finds anywhere else.
Now, what is the practical importance of this description of a natural bed ? It is
this: Since a natural bed tends to remain permanent, because of the presence of
oyster shells, the shelling of bottoms where there are no oysters furnishes us with a
means of establishing new beds or of increasing the area of the old ones.
The oyster-dredgers state, with perfect truth, that by breaking up the crowded
clusters of oysters and by scattering the shells the use of the dredge tends to enlarge
the oyster-beds. The sketch which we havejust given shows the truth of this claim,
but this is a very rough and crude way of accomplishing this end.*
This description, so far as it relates to the oysters themselves, gives
a good idea of the average oyster-bed, though they differ somewhat in
details in different localities. But, as shown in the sections which treat
of the enemies and the food of the oyster, the latter is very far from
constituting the entire population of the beds. The same causes which
induce the growth of the oyster, the firm basis of attachment, the sur-
rounding food-producing mud, the favorable density and temperature,
all tend to make the oyster-bed a center teeming with aquatic life.
Thus a single point of attachment, a firm nucleus projecting naturally
above the surrounding mud, or a few shells thrown upon the muddy
bottom may give rise to a community where life is as abundant and the
struggle for existence as complex and strenuous as is anywhere found
in nature.
* Brooks, W. K., Maryland Oyster Report, 1884, pp. 86 to 88, inclusive.
OYSTERS AND Ml.TFIOl^S OF OYSTER-CULTURE. 295
DESTRUCTION OF NATURAL BEDS— CAUSES AND REMEDIES.
Until a comparatively receut date our supply of oysters was drawn
almost entirely from the natural beds, wliicli were originally so vast that
it was a common saying that they were inexhaustible. Tlie fallacy of
this view has been abundantly proven, and wherever reliance has been
placed upon natural beds solely there has been a decreasing supply to
meet an increasing demand. Many causes have been cited to account
for the decrease in t-he productiveness of the oyster-beds, but wherever
unprejudiced investigation has been brought to bear upon the subject
tlui verdict has always been that the fishing upon the beds has outgrown
their fecundity.
Vast as is tlie production of spawn, the chances against its growth
to maturity are such as to limit the productiveness of the beds. Much of
it fails of fertilization. Most which passes that critical stage becomes
a prey to enemies or falls upon unsuitable bottom, where it fails of
attachment and sinks in the ooze. Even after the vicissitudes of
larval life are passed the infantile si)at may be buried in an accumu-
lation of organic or inorganic sediment, or it may be devoured by
enemies against which it can i^resent no adequate defense. Storms
may tear the adult oysters from their attachment and cast them upon
the shore, or they may become covered by sand and seaweeds drifted
in by the waves ; or, again, excessively cold weather may cause their
death in exposed places by freezing.
Numerous as are the perils which beset them under their natural
surroundings, they have, upon the whole, found the conditions favorable
for their maintenance and increase until civilized man began his syste-
matic attacks. It is true that before the appearance of the white man
upon the scene they had disappeared from regions where they were
formerly found, but upon our coasts such cases are isolated and rare.
Without here going into the evidence, it may be asserted as a dem-
onstrated fact that overfishing is the cause of the depletion of our
oyster-beds, and that it produces its damaging effect in several ways:
1. It removes the adult oysters, which are either spawning or are
capable of spawning, and thereby reduces the reproductive power of
the bed as a whole.
2. It removes the shells, and therefore decreases the available points
of attachment of the spawn. When the oysters are not culled on tiie
beds this effect is aggravated by the removal of the dead shells.
3. Spat and young oysters attached to the shells of the adults are
removed from the beds, and as it is impracticable in many cases to
detach them they are of necessity destroyed.
4. The quantity of oysters taken and destroyed from the several
causes mentioned is greater than that which is permitted to annually
grow up to take their places.
Many causes have been assigned as tending to deplete the oyster-
beds, and many remedies have been proposed. Various phases of the
206 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
oyster business have beeu cited to show cause why they shouhl not be
curtailed or abolished as destructive. It has been proposed to restrict
the demand by pi'ohibiting canning; to luohibit the use of this or that
kind of apparatus, or to interfere in various ways, with more or less
legitimate methods of meeting and increasing the demand.
The attempts that have been made to keep the demand upon the beds
within the limit of their fecundity have so far been failures, and such
attempts are also seen to be illogical when it can be shown that the
reciprocal measure, increasing the supply, is perfectly feasible.
The dictates of sound economics require that no eftbrt be made to
restrict the demand until it can be shown that efforts to increase the sup-
ply are futile. A growing demand for a product is the most trustworthy
indication of an industry's prosperity, and the only rational manner in
which to bring the supply and demand into equilibrium is to increase
the former. Only after the failure of all efforts to save the supply from
total extinction, should a restriction be placed upon the demand.
The close season has beeu a favorite measure in protective legisla-
tion, as it has been in most legislation looking to the perpetuation of
game and fish. It is usual to fix the close season during the spawning
mouths, upon the theory that the reproductive act should be allowed
to proceed unmolested. It really matters but little whether the oyster
is taken during the season of spawning or a month or two before; the
effect upon the fishery is the same, as in either case the bed is deprived
of an individual capable of reproducing its kind. The only effect of a
close season, whenever occurring, is to reduce the time during which
the oyster is subject to attack from the oystermen. Even this is of
little avail with the sedentary oyster, for it is jwssible for 3G5 men,
fishing ten days, to as effectually "clean up'' a bed as can be done by
10 men fishing throughout the year. This has been found to be the
practical result of a close season in some places; the first few days of
fishing removing so many oysters as to make it unprofitable to work
the beds during the rest of the year.
The methods by which the increased demand resulting from a widen-
ing of the markets may be met will be treated of in another connection.
It may become necessary in some parts of this country, as in Europe,
to reserve the natural beds for the production of seed. Such a reser-
vation would naturally excite the strenuous opposition of the oystermen ;
but should the industry ever be reduced to the desperate condition at
one time found in France, correspondingly desperate remedies must be
invoked.
INCREASE OF SUPPLY BY ARTIFICIAL MEANS.
In many countries in which oysters are an imi)ortant item of food it
has been found necessary to give nature some assistance in order to
maintain or increase the supply of oysters available for the markets.
The direction in which this as sistance is rendered is governed by local
conditions, but in general it may be stated that all methods of oyster-
culture depend for their success upon the modification of the natural
OYSTERS AND METHODS OF OYSTER-CULTURE. 297
conditions in sncli a uuuiuer as to bring about one or several of the
following results:
1. An increase in the number of eggs successfully fertilized.
2. An increase in the surfaces available for fixation, and consequently
an increase in the number of spat which become fixed and pass through
the early stages of spat existence.
3. The utilization and salvage of spat, which would otherwise fall
victims to the several vicissitudes of their careers — storms, frosts,
crowding, etc.
4. A decrease in the liability to attacks from enemies.
5. The utilization of otherwise neglected bottoms and food supplies.
Upon our coasts the objects set forth above, or some of them, have
been best realized by the process of "planting.'' This consists in
placing firm bodies in the water for the purpose of catching the spat
or in spreading young oysters upon tlie bottom in ])laces suitable for
their growth. Vast as are our oyster-fields, but a small portion of the
bottom available for the growth of this mollusk has been utilized by
nature. This has arisen from the fact that in many cases where the
other conditions are favorable the bottom is of such a character as to
l)revent the attachment of the young, though perfectly adapted to the
rapid growth of the adults. If then the spat be caught on planted
cultch, or partially grown oysters be placed upon such bottoms, the
difticulty is overcome and nature has been assisted to the degree
necessary and all or some of the conditions mentioned above are more
or less completely fulfilled; the first by increasing the number of
adult oysters in any region, and by their closer aggregation ; the second,
by the process of preparing the ground and sowing the shells; the
third, by the use of seed from regions less favorable to its maturing;
the fourth, from the greater care with which a bed under private owner-
shi}) will be watched and guarded, and the fifth by the very act of
planting upon virgin or depleted bottom.
Other and more complex plans of oyster-culture are employed in the
countries of Europe, but have not yet been adopted in the United
States. There are indications, however, that in certain portions of our
oyster belt it may be necessary to follow some method of pond culture,
not so much for the i)urpose of growing the oysters, but to fatten them
for market. Should the feasibility of this be demonstrated under the
conditions prevailing in the United States, a vast inciease could be
nuide to our oyster supply, as it is a well-known fact that certain large
areas are capable of raising oysters which they rarely fatten and for
which, therefore, no market can be found.
P>y some modification of pond culture it may also be possible to
raise seed oysters in regions in which few or none are now ])roduce(l,
thus adding another considerable item to the wealth giving powers of
our coasts.
These several subjects are treated under their appropriate headings
in the following pages.
298 REPORT OF COMMISSIONER OF FISH AKD FISHERIES.
PLANTING WITH SEED.
PRELIMINARY CONSIDERATIONS.
Preliminary to planting, the first essential is to determine whether
private rights in oyster bottoms are recognized by law or countenanced
by i^ublic opinion. Unless the planter is assured of exclusive owner-
ship in the product of his labor and enterprise he will find more profit
and peace of mmd in devoting his energies to some other calling.
Unless the law, backed by the public sense of justice, makes the theft
of oysters from planted grounds i)uiiishable like theft of any other
kind, it will be impossible to expect success in oyster-])lanting. Very
remarkable views obtain in some places concerning the right to property
beneath the sea, and in such places the planter will find it impossible
to protect his interests.
Having determined that his rights in his riparian property may be
successfully maintained, the next step is to select beds that present the
proper conditions of temperature, density, bottom, food, etc.
Temperature. — If it is desired to establish a self-perpetuating bed
the temperature should rise for a considerable time during the spawn-
ing period to between 68 and 80 degrees. If it be desired to merely
increase the size of seed oysters obtained elsewhere, it is not necessary
that the temperature should ever rise so high, although, as a rule,
wann waters induce more rapid growth. The range of temperature to
which adult oysters are subject will be seen on page 280.
Density. — The density should be above 1.007 at least, and the beds
should be so located as not to be subject to the influence of freshets
■which would reduce the density below that degree for any length of time.
A density over 1.023 is not advisable, although oysters grow in places
in a somewhat greater salinity. (See p. 281.)
Bottom. — The character of the bottom is the most important consid-
eration, and it is probable that, upon our coasts, the other conditions
will be fairly met in any locality where suitable bottom is available.
The selection should be made with care, and the methods employed
should be adapted to the character of the ground. Otherwise the
planter may be imt to labor and expense without return.
Hard, rocky bottom is in general unsuited for the cultivation of the
oyster. Such ground, while affording facilities for the fixation of spat,
does not supply suflScient food to cause a rapid growth, such as is desired
by the planter, unless there is abundant muddy bottom in the vicinity.
Heavy clay is open to the same objection. Loose sand is liable to drift
and bury the oysters, and deep, soft mud is absolutely fatal, as it allows
even adult oysters to sink to such a depth that they are smothered.
The best bottom consists of a firm substratum, above which is a layer
of soft flocculent mud. In Long Island Sound, firm, sandy bottom is
often used with great success. The oysters do not grow so rapidly
there, however, as they do upon the soft mud of Jamaica Bay and other
places on the south shore of Long Island.
OYSTERS AND METHODS OF OYSTER-CULTURE. ^99
Food. — The question of food is a sine qua non iu oyster-culture.
Without a supply of suitable and proper food it is useless to attempt the
growth of oysters. As a general rule, it will be found that where the
pio])er conditions of temperature obtain the vicinity of a muddy bottom
will be well stocked with the minute organisms upon whicli the oyster
feeds, Keliance upon this fact, however, is placing dependence upon a
"rule of thumb," never a profitable method where more accurate and
scientific information can be obtained. Oystermen usually determine
the best growing and fattening grounds by actual experiment, a pro-
ceeding often entailing the wasteful expenditure of time and capital,
and the small cost which would be involved in making a preliminary
biological survey would be, in most cases, well expended. The currents
may be such as to carry the food organisms away, or for other reasons
beds, apparently well situated, maybe lacking in food, a fact usually not
discovered until lime and money have been wasted in experimental
planting.
Marking bed, etc. — The boundaries of the planting-grounds should be
marked with stakes in such a way that each planter will have no diffi-
culty in distinguishing his own ground from that of his neighbor. In
order to recover the boundary, should the stakes be carried away by
storms or ice, it -is usual to have ranges locating the most important
marks, such as those at the corners of the beds, these ranges being
either conspicuous natural objects, buildings, etc., or, preferably, signals
erected especiallj^ for the purpose. In deep water, or upon bottoms
where stakes can not be driven or held, buoys are commonly used for
locating the beds. Some of the States have laws regulating more or
less strictly the manner of describing and marking the private oyster-
grounds, and to avoid trouble and disputes these should be strictly
complied with.
It should be remembered that it is more difficult to lay out and mark
areas beneath the water than upon the land. It sometimes happens
that the planter is able to get control of an entire cove or brackish-
water creek, in which case the question of marking the beds and of
protecting them from poachers is much simplified. In some places it is
customarj^ for owners to subdivide their beds for purposes hereafter
mentioned, and such subdivisions may be marked in the manner adopted
for indicating the boundary of the right.
PREPARING BOTTOM.
Having located and marked the beds, the ground should be prepared
for i^lanting. In places such as San Francisco Bay, where the oysters
are placed on beds which are more or less exposed at low tide, this
usually consists of clearing away the snags and other debris at low
water and leveling oft the mounds and filling up the hollows. If it is
necessary to build stockades to protect the oysters from fish, this should
also be done before planting is begun, as otherwise the bed may be
ruined before it is fairly planted.
300 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
In deeper water the clearing np of the grounds is usually done by
means of the dredge, all debris being carefully removed. This work is
best performed by steam, the larger planters owning vessels and the
smaller ones hiring them for the purpose. The work with sailboats is
more laborious and less rapid.
If the bottom is firm, or if there is a firm substratum an inch or two
below the soft surface-layer, no further preparation is needed. When
there is a soft mud of some depth, however, it is absolutely necessary
that the surface be prepared in some way which will prevent the oysters
from becoming completely submerged and suffocated in the soft deposit.
This is usually done by distributing over the soft places various hard
substances, which, resting upon the mud, give it a firm surface upon
which the oysters may repose in safety.
In France, where the lack of suitable grounds frequently requires
the use of very soft bottoms, this difficulty is sometimes overcome by
the expensive means of macadamizing the bottom with gravel and
clay. While this, of course, forms an excellent bottom, hard and
smootli, it can only be used on grounds exposed at low tide.
American planters usually provide a firm surface by strewing oyster
shells, clam shells, gravel, or sand over the bottom in such quantities
as to have the desired effect. When shells or gravel are used the double
purpose is often served of preventing the submergence of the adnlt
oyster in the mud and offering a place of attachment for the spat. In
certain places sandy and gravelly material resulting from dredging for
harbor improvements has been utilized for this purpose, and much soft
bottom, before valueless, has been made to yield a profitable return to
the planter. Such material can often be obtained at a very small cost,
sometimes merely for the expense of transportation to the beds.
In surfacing, care should be exercised that the firm layer be deposited
uniformly, as otherwise the muddy bottom will be exposed in places
and the oysters falling thereon in planting will be engulfed in the mud.
Plenty of material should always be used, as it is poor economy to
spend money for work and material which is insufficient to accomi)lish
the end sought. The exact amount necessary will depend upon the
character of the bottom. Where it consists of a very deep, pulpy or
flocculent deposit it is useless in most cases to attempt to improve it,
as the surfiicing material will sink almost as fast as it is deposited.
In j>laces perhaps this might be overcome by the French system of
macadamizing, but as more suitable bottom is abundant on our coast
such an expensive procedure would be unnecessar3\
When the bottom is jiroperly surfaced with coarse sand or gravel it
does not as a rule require another coat for four or five years. When
there is a rapid deposit of mud it will, of course, soon become covered
up, but a location where this takes place with much rapidity should
perhaps be better left alone, as the seed oysters are liable to suffocation
by the deposit of matenal upon them. A strong current will pi-event the
deposit and keep the surface scoured after it has been once prepared.
OYSTERS AND METHODS OF OYSTER-CULTURE. 301
SEED.
After the ground has been thoroughly prepared according to its
requirements, the next consideration is the actual planting of the
oysters. Planters follow one of two methods, as their interests and
experience may dictate; they either plant seed oysters and raise them
to an adult or marketable size, or they use cult<!h to catch the spat,
which may be either sold as seed or retained until it has grown. The
former method is perhaps the simpler and more uniformly successful in
most localities, and it will be, therefore, first discussed.
Seed oysters are young or immature oysters suitable for planting.
They vary in size from minute "blisters" uj) to well-grown oysters,
which will be read}^ for market in six months after they have been
bedded. In most cases they run in size between 1 and 1 J inches, or
from about the size of a silver (quarter up to the size of a silver dollar.
The seed is obtained either from planters who make a specialty of
raising it, or from the natural reefs, or from various places along shore
where there may be an abundant set of spat. In certain localities
gravel beaches often show a strong set in the aiea between tides, where
it may be collected at low water, or beyond low- water mark, where it
may be dredged or tonged from boats. In some parts of Long Island
Sound there is an extensive fishery for seed oysters in localities such
as described.
Some planters collect seed for themselves, but most of them prefer to
buy from those who make a specialty of that branch of the industry.
The piiice varies in difiVrent localities and with the character and size of
seed, from 10 cents to |1 i^er bushel. The larger growth of seed brings
a better price than the smaller, as it takes a shorter time to bring it to
maturity and it is less susceptible to the attacks of enemies. The care
with which the seed has been sorted is also a prime factor in the cost.
Seed, Just as it comes from the beds, contains much besides oysters;
sometimes as much as 7.1 per cent consisting of old shells, sp<mge, and
other rubbish. Though such material may be obtained at a low i)rice,
it is not generally regarded as economical, as a larger (quantity must
be planted than when good seed is used, the bed is littered with unde-
sirable rubbish of all kinds, and is liable to become stocked with
enemies which will cause trouble in the future. The unculled seed is
liable also to grow into rough oysters, crowded into bunches and of
undesirable shapes, which briug a smaller price when put upon the
market.
When culled stock is selected — that is, seed consisting of separate
individuals of good shape and uniform size — it is said to generally give
satisfactory results. It is free from rubbish and enemies, and, being
vigorous, it is able to at once avail itself of such advantages as the
beds x)ossess and its growth is correspondingly rapid. The oysters
being separate froin' the beginning, when they reach nuiturity they are
shapely and in good condition. .
302 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
It has sometimes happened that good results have followed the
sowing of spat-covered shells purchased from the canneries, but this
method is precarious unless the shells are used in the process of spat-
collecting to be explained hereafter.
The locality whence the seed is derived is also important. Oysters
taken from a warm region, where food is plenty and growth rapid, to a
colder region, where food is more scanty, are, it is stated, not always
successfully acclimated unless the transfer is made when the oyster is
very young. Some planters say that when southern oysters just about
to spawn are taken to Long Island Sound, the generative products are
not discharged and many of them die in the course of the season. The
seed obtained from southern '^ plants,-' however, is as hardy as that
obtained from the "natives," from which it can not be distinguished in
either appearance or growth. The planting of southern seed oysters
was formerly an im^iortant industry in Long Island Sound, but it has
been almost entirely supplanted by shell culture. Each spring a com-
paratively small number of Chesapeake oysters are set down, as they
have been found to fatten earlier in the fall than the native stock.
There is no complaint of excessive mortality among the " Virginia
plants," and it is claimed that they spawn freely in summer even if
bedded in the preceding spring.
SOWING THE SEED.
The seed oysters are usually scattered over the beds from boats or
scows. Care should be exercised to get them as equally distributed as
possible, as experience has shown this to be advantageous to their
growth. When thrown into heaps many are prevented from getting a
proper supply of food, and the crowding may also cause irregularities
in the shape of the shells, thus reducing their market value.
In order to secure a proper distribution over a bed, it may be roughly
marked out into areas, say 50 feet square, in each of which an equal
amount of seed should be planted, by scattering it broadcast with
shovels or scoops from the boat or scow. In subdividing the bed a few
rough stakes or buoys may be used as temporary guides.
Another method is to anchor the boat upon the bed, distribute the
required amount of seed over the area which can be reached by throw-
ing the oysters from a shovel, and then move on to the next station,
where the boat is again anchored and the operation repeated. When
the scow is emptied a buoy or stake may be used to mark the position of
the last deposit, and operations can be resumed from that point with
the next boat load. By such means the seed is rapidly and evenly
spread over the bottom.
In planting on extensive beds where steam power is used the seed is
distributed from scows, which are slowly towed back and forth, while a
gang of 8 or 10 men shovel the oysters overboard as rapidly as possible.
That is the most rapid and economical method, and is the t)ne usually
employed on the tleep-water grounds of Long Inland Sound.
OYSTERS AND METHODS OF OYSTER-CULTURE. 303
It is not well to deposit the oysters very thickly. About 300 to GOO
bushels per acre appears to be the usual amount in most places. The
ground will, of course, support a larger number of yearling seed, but as
they grow larger there will be more or less crowding and the demand
for food will be greater.
In certain places where oyster-planting has greatly increased within
recent years it is found that the oyster neither grows as rapidly nor fat-
tens as readily as formerly, and it is supposed by many that the quantity
of oysters has outgrown the ability of the region to supply them with food.
The matter has not yet been investigated and the facts in the case are
not definitely known, but the theory proposed is a plausible one to
account for the difficulty with which the planter is beset in fitting his
stock for market. It is well known that when the seed is sowed too
closely upon a given bed the oysters grow and fatten more slowly than
upon less thickly populated ground, and only in waters exceptionally
rich in food can the quantity of seed planted exceed with safety the
number of bushels stated. When the seed is sowed too thickly there
is also a tendency to distortion from crowding.
WORKING THE BEDS.
When seed oysters of good quality are used it is generally not
regarded as necessary to "work the beds," although care should be
taken to prevent, if possible, the inroads of enemies. The various
methods of attempted protection from enemies have been discussed in
another connection.
It is sometimes advantageous to dredge over the planted beds to
remove debris, seaweed, etc., which has drifted upon them, and which
of itself and by the collection of sand, etc., would smother the oysters
if allowed to remain. If the bottom is not perfectly fixed it may be
necessary to shift the oysters during their growth in order to prevent
"sanding," i. e., being covered with sand, etc., from the drifting bottom.
While oysters grow most rai)idly upon or near nuiddy bottom, they
are often in some respects objectionable if placed upon the market
directly from such beds. Some planters, therefore, transplant them to
hard bottom for several months before sending them to market, it being
said that this improves their flavor and appearance by causing the
muddy matter in the gills and mantle cavity, as well as in the Intestine,
to be gradually cleared out and disgorged.
In parts of Long Island Sound many of the planters take up a jior-
tion of their sto{!k in spring and transplant it to such ground as may
be available in the bays and harbors. Such transplanted oysters fatten
and grow more rapidly than those left in the deeper water; the differ-
ence in condition is manifest to even the inexperienced, and a higher
price is obtained and a more ready market found for the '' harbor
plants." The area available for tiiis purpose, however, is insufficient to
fjefiiiit of the transplanting of more than a ver^^ small proportion of
the ''Sontul stock."
304 REPORT OF COJ'MISSIONER OP FISH AND FISHERIES.
The bottom from which tlie oysters have been shitted is, of course,
cleansed of rubbish when the oysters are taken up and nuiy be at once
utilized for fresh seed. Some oystermen prefer to let it lie idle for a
year, supposing that this increases its fitness for a further crop, but
there appears to be uo good reason for this, though it may be that this
course liermits of a recuperation of the food supply on the fallow beds.
The length of time during which the jdants are allowed to lie de})ends
upon the location of the beds, as affecting the rai)idity of growth, upon
the size of the seed planted, and upon the judgment of the planter. In
many places "yearling" seed will be ready for the market in two or
three years after being i>lanted, i. e., when the oysters are 3 or 4 years
old, but in exceptionally favorable localities, such as Jamaica Bay,
Long Island, such seed is said to grow, to marketable size in six months
or a year. In some places it is said to now take a year longer lor the
oysters to mature than when planting was first i:)racticed.
As large oysters bring a better price than small ones, it generally
pays to allow them to grow for a year or two after they reach a market-
able size, but this is a matter which the planter will determine for
himself, as conditions vary with the locality.
As the planter generally wishes to harvest a portion of his crop each
year, it is customary to divide the beds into sections, which are i)lanted
in successive years in such a manner as may suit the plan of operations
of the particular grower concerned.
PLANTING WITH CULTCH OR STOOL.
PRELIMINARY CONSIDERATIONS.
This method of oyster-culture is that which was first adopted, and to
it and its modifications we must doubtless look for future gTOwth in
the oyster industry. The method of planting seed oysters improves
the size, shape, and flavor of the plants, and to some extent increases
the quantity of oysters available for the markets, but, nevertheless,
many of those which are raised from seed derived from the natural
beds would have reached a marketable size if left to renuiin. Moreover,
the natural beds are now being depleted at a rapid rate by the drain
which has been made upon them, Not only are they (;ompelled to
supply oysters for market, but the young growth is now carried off to
be jdanted elsewhere. As the number of spawning oysters on the beds
is reduced and as the spawners become more scattered, the reproduc-
tive capacity of the beds is being lowered, and at the same time the
removal of both oysters and shells leaves fewer points of attachment
for the young spat. As the seed-producing power of the natural beds
becomes reduced from these various causes, the planter must have
recourse to other methods for obtaining his set of young oysters.
Fortunately, there is a well-trietl method which may be adopted. Tlie
oystermen long ago noticed that under certain conditious.uot only did
natural objects of various kinds become covered with young oystei\s,
OYSTERS AND METHODS OF OYSTER-CULTURE. 305
but other objects accideutally dropped overboard would often, wlien
recovered a few weeks later, show a heavy set of spat. !Raturally tliey
began to throw objects into the water for the exi)ress purpose of
collecting the spat and thus increasing- the amount of seed available,
and from this beginning the j)rosent system of spat-collecting now in
use in our waters was developed.
For this method of planting it is, of course, essential that there
should be in the vicinity of the beds spawning oysters, either of volun-
teer growth or planted, and that the temperature of the water should
be between 68° and 80° F. during a period of some weeks' duration,
PREPARING BOTTOM.
The bottom used for this method of cultivation shoiild be firmer than
that which will suffice for bedding well-grown seed, though soft bottom
may be prepared so as to be satisfactorily used. If the bottom is very
soft it may be overlaid with gravel or sand in the manner before
described (p. 300), and upon this the collectors or cultch may be depos-
ited. In a moderately soft bottom the cultch can be applied without
previous preparation other than to clear the ground of all debris which
would interfere with working it. Hard, gravelly bottom in shoal water,
whicli may be of little use for the raising of adult oysters on account
of the absence of food, may prove an excellent place for the collection
of spat, and the same may be said of some places with a stiff" clay soil.
One of the great difficulties in spat-collecting is to avoid the deposit
of sediment upon the cultch, as an amount of sedimentation which
would have no effect whatever upon the adult oyster w^ould prove
absolutely fatal to the young spat. At the time of attachment the
infant oyster is about one-ninetieth of an inch in diameter, and the
deposit of a very slight film either before or immediately after the
falling of the spat would be sufficient to cause its suffocation. It will
be seen, therefore, that a soft bottom upon which the large oysters will
thrive, or an amount of sedimentation which may favor the rapid growth
of the adults from the food matter which it contains, will effectually
prevent, in many instances, the cultivation of spat.
CULTCH, COLLECTORS. STOOL.
By these terms is understood any firm and clean body placed in the
water for the purpose of affording attachment to the apat or young
oyster. A great variety of objects have been suggested and used for
this purpose, both here and abroad, and some of these will be now
discussed.
Oyster shells. — In this country oyster shells are the oldest and most
generally used form of cultch. They are usually merely spread upon
the bottom, being thrown broadcast from boats in the manner which
is described for planting seed oysters (p. 302). When the bottom is
sufficiently hard to prevent the submergence of the shells, it is custom-
ary to ai)read them as uniformly as possible over the ground, so as to
F. M 20
300 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
ofiev tlie largest available area for the attachment of the spat. Where
the bottom is so soft, however, that the shells would tend to sink before
the young oysters have reached a size to enable them to successfully
combat such <;onditions, it is preferable to surface the bottom in the
manner described ior planting seed oysters, or the shells may be thrown
over so as to fall in <!at heaps, those at the base forming a foundation
support lor those above, leaving only the upper shells available for the
set of spat, those below soon becoming buried in the mud.
Shells may be planted in all depths of water with equal facility.
They are cheap and readily obtainable in all oyster regions. Clam and
scallop shells are also used in the same manner. The quantity required
to properly "shell "a bed depends ui>on the nature of the bottom.
When the ground is soft a larger number is necessary than upon hard
ground, because in the former case many become buried in the mud or
covered up by the others, whereas in the latter instance they all become
available as collectors.
Upon soft ground some planters, instead of preparing the bottom
with sand or gravel, apply a layer of oyster shells a coui)le of months
before it is time to distribute the cultch proper. Those tirst applied
sink a short distance into the mud where they become suspended so as to
form a more or less solid substratum which supports the cultch applied
later. A bed so prepared simulates the natural banks, which in most
places overlie a mud bed that, in its upper portions, has accjuired some
consistency and firmness by the shells lying buried in it.
After a muddy bed has been shelled for a number of successive years
it will be found to become gradually firmer. Each year some of the
planted shells become covered up and are left remaining when the
oysters are removed and thus it happens that the bottom of a well-
handled planting-ground improves with use.
When the oyster or clam shells are thrown from the boats they will
be found to fall so that the convex side rests ui)on the bottom. There
is nothing very remarkable or inexplicable in this, as it is entirely iu
accordance with the ordinary laws of the resistance of fluids to the pas-
sage of a solid body through them; but in sowing the shells, however,
it is important that they so fall. In most cases, if such cultch be
examined, it will be found that nearly or quite the entire set of spat is
upon the convex or lower side. As the shell falls its greatest convexity
rests upon the bottom, its edge being held clear of the mud in the forui
of a i^rojecting ledge, sheltered on its under side from the suffocating
sediment deposited upon the upper surface. In ordinary situations
perfectly flat pieces of tile, shale, etc., would be vastly inferior to shells,
for the lower surface would lie close to the bottom while the upper
would become covered with a muddy deposit from the water, between
the two the young oyster having but scant opportunity tor fixation.
It has been observed that when shells and gravel are spread upon
the same beds the former usually catch the larger amount of s))at,
esi^ecially in years in which there is but a moderate set. The planters
OYSTERS AND METHODS OF OYSTER-CULTURE. 307
and oystermeii attribute this to the fact that the shells project a greater
distance above the bottom and that therefore the fry come into contact
•with them first in their descent for attachment, but as the set is mainly
upon the convex side of the shell and therefore underneath, it will be
seen that the true explanation of the superiority of the shells is that
given above.
The (quantity of shells sowed upon any given bottom will depend upon
the judgment of the i)lanter, the general rule being to sow more on soft
than upon hard bottom, for the reasons before stated. The usual quan-
tity appears to be from 250 to 500 bushels of shells per acre, most of the
planters using about 400 bushels per acre, excei)t upon very muddy
bottom 5 but in Long Island Sound there is an increasing tendency to
use greater quantities.
In some places the shells may be obtained for the cost of transporta-
tion. This was the general rule years ago, but with the increase in
planting a charge of from 2 to 5 cents per bushel is now made for them.
Many planters who operate canneries or ship "shucked" oysters have
ready at hand an abundant supply of shells for use as cultch. The cost
of spreading ranges from ^ to 2 or 3 cents i)er bushel, according to the
location of the beds and the cost of labor, etc.
The principal objection to the use of oyster shells is that they are of
such large size that many more spat attach themselves than have room
to grow and, at the same time, they are so strong and massivcthat it>is
dififlcult to break them in pieces so as to allow for the expansion of the
young. As a consequence many young oysters which have successfully
passed through the early stages of their fixed conditions are smothered
or overgrown by their more vigorous fellows, which are themselves dis-
torted by the crowding to which they are subjected. Many are thus
wasted which would, under better conditions of attachment, have grown
to a marketable size. (Plate ix.)
For the reasons mentioned scallop, "jingle," and other fragile and
friable shells (plate xviii, figs. 1 to G) are, when they can be obtained in
quantities, to be preferred. Such shells will break up under the mutual
pressure exerted by the oysters during their growth and the latter will
then be liberated from the bunches and will tend to grow into shapely and
desirable forms, with a smaller rate of mortality. When the currents or
waves are very strong such frail shells as jingles may prove too slight
to withstand their action and the planter using them may find, to his
suri)rise, that much of his cultch has been carried away. Upon some
portions of the Pacific coast it is said that the wave action and the
currents are so strong that the light, thin shells of the native oyster are
swept away or thrown upon the shore. Otherwise, and for the reasons
before stated, these shells appear to be well adapted to the process of
sowing and they can also be obtained cheajjly and in large quantities.
Other methods of using shells. — It has been recommended or suggested
that shells of various kinds could be strung upon wires, etc., and sus-
pended in festoons from stakes planted in the bottom. This would, of
308 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
course, prevent tlieir submergence in places where the mud was very
soft, but as each shell would have to be separately handled it will be
found that this method is too expensive to be warranted by the present
condition of the oyster business. Another method of utilizing oyster
shells as cultcli is treated of in connection with the subject of pond
culture (pp. 322-330).
Gravel and pebbles. — This is a form of cultch which is nuich favored
by the planters in some parts of Long Island Sound, its principal
advantages being the small size of its constituent particles and its
cleanliness. As a rule the pebbles are so small that but few spat fix
themselves to each (plate xviii, fig. 7) and, consequently, there is little or
no danger of crowding. Not only do a larger proportion of the young
oysters survive their infancy, but they develop into deeper, more regular
shapes, are free from bunches, and, consequently, bring a higher price in
the markets. Where the.trade in " shell stock " is large the shape of the
oysters is a consideration of importance, but where only shucked oys-
ters are shipped irregularities in shape are less undesirable. The gravel
is more* cleanly than shells, because it is not attacked by the boring
sponge, which gives rise to much of the debris found upon the oyster-
beds. There is also less liability to the introduction of oyster enemies
than when shells are utilized.
The bottom used for obtaining a "pebble set" must be firmer than
that which will suffice for the sowing of shells, the gravel being heavier
in proportion to its surface and therefore more liable to sink. It also
presents less surface on muddy bottoms, where the pebbles will soon
become buried to their equators, and if there is any sedimentation there
is left no surface available for the attachment of the fry. Bounded,
water- worn pebbles are usually preferred, such offering more surface
free from sediment than flat stones. They afford, perhaps, the best form
of cultch for use upon firm bottoms, when there is sufficient current to
prevent the rapid deposit of sediment. It is observed that gravel
beaches, when these conditions, obtain, are often the most valuable of
natural spattmg-grounds. In some i)laces gravelly material dredged
from harbors and channels during the imj^rovement of waterways is
used to advantage. Crushed stone, averaging about the size of a wal-
nut, is also an excellent collector. Gravel or crushed stone is generally
more expensive than shells, costing from 5 to 7 cents per bushel. The
custom is to sow from 25 to 30 cubic yards (from 500 -to GOO bushels) per
acre when used alone, but a smaller quantity if shells are also used.
Scrap tin, tin cans, etc. — In some places old tin cans and scrap tin of
various kinds is found to give good results when used as cultch. It
has the advantage of becoming corroded and gradually dissolving in
the salt water, thus releasing the young oysters before tliey begin to
crowd one another and allowing them to grow into well shaped adults.
Moreover, as the cultch each year disappears in solution, there is no
debris from this source to litter the ground and to cause the expense
of culling. It seems that, in the form of old tin cans, this type of cultch
OYSTERS AND METHODS OF OYSTER-CULTURE. 309
miglit have some advantage on muddy bottom where there is a rather
rai)id sedimentation. Such cultch is light in proportion to the surface
presented, it wouhi not i^eadily sink, and the upper half of the interior,
and to some extent the lower half of the exterior would present sur-
faces protected from sedimentation upon which the young oyster could
lodge itself. By the time the can disintegrated tlie oysters would no
doubt be suflBciently grown to withstand the action of the mud. The
tin is distributed over the bottom as in the case of shells and gravel.
Brush for soft bottom. — Where the bottom is so soft that ordinary
methods can not be used, it will sometimes be found that fagots and
brush make most efficient collectors. The brush is thrust firmly down
into the mud in such a manner that the small branches are at some
distance above the bottom. They will offer a large surface to the
water, a slight current will tend to keep them free from destructive
deposits of sediment, and in water well charged with the swimming fry
will almost certainly jdeld a full set of spat. The brush is lifted at the
I^roper time by means of a crane or boom and windlass. This method
was used with some success at the town of Groton, Conn. The seed
was left to grow to a marketable size on the brush, but owing to the
liability of the large oyster to drop off: into the soft mud below, it was
sold as soon as possible.
Brush, straw, etc., may also be used by collecting the material into
bundles, sheaves, or fagots, wdiich may be anchored by stones or sus-
pended from stakes. As it is usually unnecessary to resort to such very
soft bottom, it Avill be found in most cases that shells, gravel, or scrap
tin will be more serviceable and satisfactory. Brush collectors would
be difficult to use in regions of violent wave action.
Other collectors. — Many materials have been suggested as suitable for
collectors, but the foregoing api)ear to be the only ones which have
proven i)ractical on a large scale in our waters. Tiles and rooting slates
arranged in various forms have been found satisfactory by European
culturists, but are apparently not adapted to use here where labor is
high and oysters are cheap. These collectors will be discussed in
another connection. Pieces of bricks, broken pottery, and similar
materials may suggest themselves to the planter as local substitutes
for shells and giavel. Hard-wood chips and bark might prove useful,
but are hardly to be recommended.
COATING CULTCH.
To overcome the difficulty, which has been mentioned, of the set upon
collectors being so dense as to interfere with its subsequent growth, it
has been i)roposed to coat the cultch with some material which will
flake off", either under the mutual pressure exerted between the grow-
ing oysters, or when it is scraped with a suitable instrument. This
device was apparently first used in France, where it was adopted to
avoid the theretofore necessary breakage of the tile collectors. The
coating is detached from the tiles with a chisel-shaped instrument,
somewhat resembling a putty knife.
310 REPORT OF COMMISSIONER OF FISH AND FISHERIES^
Appjirently this metliod has never been used in our waters, but where
it is necessary to use oyster shells for cultch it might perhaps be
applied to advantage. In this case the fry could not be economically
detached by hand, but there is little doubt that the growing oysters
would automatically liberate themselves. The coating used in France
consists of a mixture of sea water, lime, and sand, or hydraulic cement,
"stirred to the consistency of thick cream." Various formului are used
by <lifterent culturists, three of them being as follows:
1. One part quicklime, 3 parts fine sand.
2. One part quicklime, 1 part tine gray mud.
3. First a light coating of quicklime, and, after drying, a coat of
hydraulic cement.
The coating should be such as not to readily wash off, yet sufiBciently
brittle to flake under the mutual pressure exerted between the growing
oysters, and about -gVi^ch in thickness.
For convenience in coating, Dr. Eyder recommended that the shells
be placed in a wire basket and dipped into the cement vat, the mixture
being then allowed to set before the shells are used.
GENERAL CONSIDERATIONS ON SPAT- COLLECTING.
Whatever may be the character of the cultch, it should invariably
be clean and without any surface deposits which might tend to prevent
the fixation of the spat. For the same reason the cultch should not
be placed upon the beds long before the season for setting.
In almost any body of water, except where the currents are swift,
there is more or less sedimentation, and it is obvious that the shorter
the time that a body is exposed to such action the thinner must be the
deposit. If the cultch is placed in the water long before it is needed
the deposit of sediment is often so thick as to stifle the young oyster,
but on the other hand if the time be well chosen a practically clean
surface is presented and a good set is more likely to reward the planter.
The latter's aim should, therefore, be to determine as nearly as possible
the time when the maximani amount of spawn falls, and to so regulate
his operations that his cultch is laid down but a few days before. The
time will vary somewhat with the locality, and if there is no local expe-
rience to guide the beginner he may be compelled to experiment a little
to find the most favorable time for exi)osing his collectors. It should
be remembered that while the spawning season in any given locality
extends over a number of months, the majority of the oysters spawn
within a more circumscribed period, usually about midway between the
two extremes.
If the time at which the collectors are exposed be well chosen, and
the location of the beds properly selected, the planter may or may not
obtain a good set. Sometimes one bed will show a strong set, while its
neighbor appears to have been entirely passed over by the fry. Often
the cultch in one part of the bed is thickly incrusted with spat, while
another portion, apparently equally well located and upon which an
OYSTERS AND METHODS OF OYSTER-CULTURE. 311
equal iiiuoiiiit of care has beea expended, will i^rove utterly sterile.
While in many such cases the causes are not known, yet the experience
of planting has thrown some light upon the matter. It is known that
cultch can not be thrown down at random with any strong expectation
of success. The water is not everywhere charged with the swimming
fry, and the experience of planters has shown that they are often dis-
tributed in streaks or belts, which appear, to some extent, at least, to
be conditioned by the currents. If cultch be placed in a current it will,
other things being equal, be more likely to catch a set than when in
still water. Even a strong current does not appear to interfere with
the fixation of the young, and as it brings a greater body of water into
contact with the collecting surface, some of it is more likely to contain
fry at the stage for fixation.
It is also obvious that the water is not likely to contain many fry
unless there are spawning oysters in the vicinity, and it is, therefore,
the part of wisdom to locate the collectors in the vicinity of natural
or artificial beds ooutaining mature oysters. Even where the oysters
are so scattered as to hardly pay for working, it will be usually found
that there is sufficient spawn fertilized to provide considerable seed if
it be given x)roper facilities for attachment. For reasons readily seen,
it will be advantageous to locate the collectors so that the predominating
current sweeps from the spawning oysters toward the collectors. In
some lo(!alities it will be found that the entire set occurs in the tidal
zone; that is, in the area between low and high water. The reason for
this is not yet fully understood, but if it should prove to be because the
embryo oyster is lighter than the dense sea water, and therefore can
not sink to the bottom, or because the sedimentation is too rapid
below low-water mark, or almost any other reason except the softness
of the bottom, then the cultch must be confined to the area between
tides if it is to be effectual as a collector of spat. The most careful and
uniformly successful oyster-culturists do not depend entirely upon the
spawn derived from neighboring beds, but usually distribute over the
spatting-beds a number of mature spawning oysters in the proportion
of 30 to (50 bushels per acre, these being usually put down before the
cultch, so that the oysters will become to some extent acclimated before
the spawning season.
As the cultivated area increases it becomes unnecessary to use so
many brood oysters, and in some places where they were formerly used
reliance is now placed solely upon the floating fry derived from the
mature oysters on neighboring beds. Upon theoretical grounds it would
appear to be preferable not to scatter these '' mother oysters" too widely.
There would seem to be greater certainty of fertilization when the
oysters are grouped, and there are ami)le time and superior facilities
for securing distribution over the beds in the embryonic condition.
The embryo exists for a period as a free-swimming form, and during
that time it may be carried considerable distances by its own exertions
312 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
and by the action of the currents. On the other liand, the eggs, and
especially the spermatozoa, will probably die unless they fulfill their
destiny within a much shorter period, and the sooner they are brought
into contact with one another the better, and the smaller the bulk of
water through which they are at first distributed the larger the number
which will accomplish successful union.
Upon these considerations is based the advice not to scatter the
"mother oysters" too widely. Fifty bushels of oysters, 250 to the
bushel, scattered evenly over an acre would allow one oyster in every
22J linear inches in each direction, i)lenty near enough if they were to
all spawn at one tiiue, but it must be remembered that the proportion
ripe at any one time is not so large, and there is a possibility of all of
the oysters over a considerable space being of one sex.
The "mother oysters" used for this purpose are preferably obtained
from the neighborhood of the plantiug-ground. It has been remarked
in another connection that transplanting mature oysters, esjiecially
from a warmer to a colder region, may have the effect of checking the
development of the genital products, and Dr. Ryder has commented
upon the fact that the spermatozoa of ripe oysters are killed by being
changed to much denser or warmer water than that in which they have
been living. The eodeavor should be, therefore, to study the con-
ditions on the planting-grounds, and to procure the spawners from
beds as nearly as possible similar in the conditions of temperature and
density. Where this consideration can not be closely followed, as for
instance in the shipment of eastern oysters to places on the Pacific
Coast, the brood oysters should be sent during the fall preceding the
season at which the cultcli is to be put down. They Mill then be pretty
well disgorged of their ripe genital products and the time intervening
befor-e the next period of sexual activity will probably be sufiicient to
acclimatize them.
WORKING THE BEDS.
Many planters are content to allow their beds to remain nnworked
until they are ready to market their crop, whether this be one, two,
three, or more years. In some instances this may be satisfactory, but
ofteu, and perhaps nsually, it is better to go over the beds with tongs or
dredges, cleaning up the debris and separating the oyster clusters or
even in some cases removing the seed to localities in which the condi
tions are more favorable for rapid growth, for in many cases the best
spatting- grounds are not the most favorable for subsequent growth.
The stage at which the planter will find it most iirofitable to sell his
oysters will depend much upon circumstances. Sometimes the set of
spat will be greater than could be advantageously grown ui)on the area
covered and some of it could be manifestly removed to advantage.
Some planters find it more profitable to sell their oysters as seed, thus
receiving (piicker returns for their investment and also lessening the
possibility of losses due to the appearance of enemies or the advent of
OYSTERS AND METHODS OF OYSTER-CULTURE. 313
untoward conditions. In many cases it will pay the planters to spe-
cialize, some raising seed fdr sale to others who devote their capital and
enterprise to the work of raising the oysters to a marketable size.
Even if the oysters are to be left upon the spatting-bed, it is often
better to work over the ground during the first year, removing the
debris and breaking up the clusters of young oysters, so as to insure a
greater survival and superior shape. As has l)een already mentioned
in treating of the planting of seed, it is often advisable to shift the
oysters to other ground during the last few months before marketing
in Older to fatten them, improve the flavor, and cause the gradual dis-
gorgement of mud from the intestine and mantle chamber.
A keen watch should be kept at all times to detect the presence of
enemies, some of which may be with more or less success combated by
the methods mentioned on pp. 313-319. The spatting-beds are espe-
cially subject to the attacks of various enemies which find in the vast
numbers of thin-shelled young an abundant and readily obtained food
supply. The starfish, especially, at times appear in vast schools or
swarms, and often a bed is almost completely destroyed before the
idanter is aware of what is taking place.
PROTECTION FROM ENEMIES.
In the case of most of the enemies of the oyster it is impossible to
indicate efficient means of protecting the beds from their inroads. The
impossibility of knowing at all times the exact conditions prevailing
upon the bottom, the suddenness with which many of the enemies
ajipear upon the beds, and the insidious character of their attacks all
add to the difficulty which the planter finds in preventing the destruc-
tion of his property.
PROTECTION FROM FISH.
It is possible to protect oysters in shallow water from the attacks of
fishes by surrounding the beds with palisades of stakes driven into the
bottom at sufticiently close intervals to prevent the passage of fish
between. Upon the Atlantic coast the inroads of fish are not suffi-
ciently formidable to reciuire such protection, although the drumfish
causes some loss to i)lanters in the vicinity of New York. Upon the
Pacific coast, however, and especially in San Francisco Bay, stockades
are necessary to prevent the absolute destruction of the planted beds
by tlie stingray, the stakes being driven at intervals of about 4 inches.
It is necessary to keep the inclosure in good repair, as a school of rays
entering through a small brea{di may utterly ruin the bed.
PROTECTION FROM STARFISH.
Many methods have been suggested for combating this destructive
enemy of the oyster, most of them being of no practical utility. Bar-
riers are utterly useless, for the very small starfish are among the most
destructive and the largest ones are able to pass through an orifice of
314 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
siuli small (limeusioiis that it is impracticable, for manifest reasons, to
build a barrier so close in structure as to exclude them. Some attempt
has been made to catch them in traps, made of laths and baited with
fish, crab meat, clams, etc. These traps are constructed and tended
like lobster pots, and while it has been found that the starfish can be
taken through their agency, the method is too laborious and inefficient
to be used for the protection of extensive beds. Various devices for
catching starfish have been patented from time to time, but none of
them a])pear to have been of practical value.
Upon the theory that the starfish prefers the mussel to the oyster as
food, it has been proposed to surround the oyster-beds with a growth
of mussels with the expectation that the starfish will not pass over the
mussel bed to obtain the less desired oysters. Investigations in Long
Island Sound show that this expectation is not realized in practice,
and, moreover, in favorable locations, the growth of mussels is so rank
that they themselves become a menace to the planter by overgrowing
his beds and suffocating the oysters. This method of protection is also
wrong in principle, for by supplying the starfish with additional food
we better its conditions and thereby aid in increasing its numbers.
For catching starfish some planters use the ordinary oyster-dredge,
an implement which has some advantages when it is desired to cull the
stock, but, in general, it involves unnecessary labor and also crushes
and kills many young oysters. A lighter dredge of similar construction
is also used, and on the shallow beds tongs may be sometimes employed
to advantage.
The oyster-growers of Long Island Sound, who have had more expe-
rience in fighting starfish than those of any other section, find that
eternal vigilance is the price which they must jjay for even the compara-
tive safety of their beds. The beds are closely watched and worked
over with dredges and tangles. Tugs are kept more or less constantly
at work, and all starfishes taken, either in the ordinary work of oyster
dredging or during "starring," are carefully destroyed. Thousands of
bushels are caught during the year and much money is expended in
the work, the result being that many beds, through timely and unceas-
ing attention, are saved from utter destruction. The tangles or mops
employed are an adaptation of a device long used by naturalists for
collecting spiny forms from the sea bottom, and their use in fighting
the starfish was first suggested by the United States Fish Commission.
They consist essentially of an iron bar to which small chains or wires
are attached at intervals of about a foot, mops or bundles of rope yarn,
cdtton waste, or similar material being distributed at short distances
along the chains. The bar is fastened to the ordinary dredge line or
chain and is dragged over the bottom, being hauled in at frequent
intervals for the removal of the starfish which have become entangled.
Most of the tangles used in Long Island Sound have frames weighing
from 100 to 150 pounds, and to prevent this heavy mass of metal from
crushing small and thin-shelled oysters they are provided with a hoop,
OYSTERS AND METHODS OF OYSTEK-CULTURE.
315
12 or 14 inches in diameter, at or near eacli end of the bar. These
hoops ride over the bottom Hive runners and tlie crushing surface is
thus much reduced. The general construction of these tangles is shown
in cut 2. The weight ai)pears to be unnecessarily great, all that is
actually required being that which is sufficient to hold the tangles
upon the bottom when in motion, a condition which is largely insured
by the sagging of the chain used in towing.
A vessel-owner at Kew Haven, Capt. Thomas Thomas, who has been
very successful in "starring," uses a much lighter tangle constructed
as follows: To a half-inch chain, about 8 feet long, stout wires 12
Cut 2.— Tanffle.
Cut 3. — Tackle.
or 14 feet long are attached at regular intervals, and to these wires
are fastened mops or swabs of cotton waste. The chain is securely
lashed to a bar about 7 feet long by lA inches wide and half an inch
thick, provided with a bracket and eye for the attachment of the drag
chain, as shown in cut 2.
When in use this tangle covers an area about 7 feet wide and 12 feet
long, forming a dense mat of snarled cotton threads. One of these is
tow- ed on each side of the vessel, like a dredge, and, sweeping over the
bottom, entangles the starfish with w^hich it comes into contact. The
length of time during which the mops are towed depends upon the
31 n REPORT OF COMMISSIONER OF FISH AND FISHERIES.
abundance of the stars, being greater when they are few than when
they are i)lenty. The starfish are killed by i)eing momentarily immersed
in a tank of boiling water, the bath being heated by a steam tap con-
nected with the boiler. The tanks are about 7 feet long by about 18
inches wide and deep, and are located one on each side of the main
deck, just inboard of the roller over which the tangle chain runs. To
facilitate the iiuniersion aiul handling of the tangles, a davit, with block
and fall, is rigged on the hurricane deck over the tank, as shown in
cut 3. A lanyard is rove through an eye welded to the back of the
hook on the fall and the other. end is fastened to the davit, its length
being so adjusted that the hook is automatically tripped by the weight
of the tangle when the hauling part of the tackle is eased and the mops
lowered to near the surface of the water. .
Cut 4. — Drill-dredge in position for work.
Some of the oystermen pick the starfish out by hand, but this is a
slow and laborious process and, moreover, it is almost an impossibdity
to so remove all of the small ones. By using the arrangement just de-
scribed the labor is lightened and the killing of the stars assured. By
using a tangle on each side of the vessel one is always at work wdiile the
other is being hoisted. It is stated that upw^ard of 10(),()()0 starfish
havebeen caught in a single day by a boat using the apparatus described.
It is usual to work on the beds until not over half a bushel of starfish
can be caught in a day, the beds then being considered safe, although
at any time a host may arrive from a neighboring bed.
United effort on the part of the planters is necessary for su(;cess in
fighting starfish. A neglected bed is, in a measure, a menace to others
in the vicinity: for if starfish are left to multiply without hindrance
they will move to neighboring beds as soon as they have exhausted
the supply of food upon the first.
OYSTEKS AND METHODS OF OYSTER-CULTURE.
317
PROTECTION FROM DRILLS.
No melhod of i)roved etliciency lias yet been devivsed for i)rotectinff
oyster-beds from the inroads of the drill, but by systematic; attentiou
something could, no doubt, be done to lessen its destructive effects.
In culling the oysters brought up in the dredge or tongs care should
be exercised to destroy the drills. Most of them, however, will pass
through the intervals of tlie ordinary oyster-dredge, and to obviate this
a finer bag might be used within the dredge. This could be used
especially in cleaning up the beds preparatory to planting. It should
be remembered, in this connection, that it is possible to infect new
grounds with the drill by its transportation thereto with the seed. The
deep water beds of Long Island Sound bave of recent years suffered
more and more from this pest, and it is supposed that this is accounted
CiT 5. — Drill-dredge open for emptying.
for by the use of seed from the drill-infested beds in the less saline
inshore waters. The use of tangles for catching starfish also, no doubt,
aids in the distribution of the drills by dragging them from place
to place.
The most promising method which has yet been proposed for catch-
ing this enemy is the invention of Capt. Thomas Thomas, of New Haven,
Conn., who has applied for letters jiatent thereon. It consists of a rec-
tangular frame of iron bars about 4 feet long, L* feet wide, ami 18 or 20
inches deep. The bottom, ends, and rear are covered with an iron wire
screen, having a mesh of about half an inch, the top and front being
left oi)en. To the ui)i)er rear edge of the frame is hinged a stout
wire screen of about 1-inch mesh, its length being such that it may
fall between the ends and its breadth being ecjual to the diagonal
of the end pieces when in place; therefore it extends from the lower
318 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
front edge to tlie upper rear edge of the frame. Attached to the
lower front bar is a broad blade of iron or steel, inclined somewhat
downward and forward from the plane of the bottom of the box. The
whole is attached to a dredge frame, to which the chain used in
dragging is made fast. (See cuts 4 and 5.)
When this appliance is dragged over the bottom the oysters and other
inhabitants of the beds, together with shells and debris of all kinds,
are lifted from their resting-places by the blade and deposited upon the
inclined screen or apron. The motion of the trap and the pressure
exerted by the accumulating material in front gradually pass the mass
backward across the screen, the smaller particles, drills, etc., sifting
into the box, while the oysters, being too large to pass through, finally
fall over the edge behind.
By this means the varied material on the beds undergoes a process
of screening, the oysters being automatically returned to the bottom,
while a large ])art of the debris is held and brought to the surface.
That the device will accomplish this has been demonstrated, but whether
the drill can be successfully fought by this means has still to be shown,
although the prospects are favorable.
PROTECTION FROM WINKLES.
The conchs or winkles have never been a serious menace to our
oyster-beds. Their small numbers and large size and the large size of
their egg cases make it possible to successfully fight them by destroy-
ing all winkles and egg cases brought up in the process of dredging or
tonging.
PROTECTION FROM SPONGES, HYDROIDS, MUSSELS, ETC.
The growth of sponges, hydroids, etc., when so rank as to threaten
the welfare of the oysters, may be kept down by working over the beds
with the oyster dredge and culling out the debris. A thorough cleaning
up of the ground before i)lanting and the use of clean seed and cultch
go far toward the prevention of trouble from this source.
PROTECTION FROM STRONO VEGETABLE GROWTHS.
In places where eelgrass (Zostera)', etc., grow so rapidly as to cause
stagnation of the water and suffocation of the oysters some means must
be adopted for its removal. Sometimes it may be removed with an ordi-
nary scythe at low water. A grower in ]S"ew Jersey has invented for
this purpose what has been termed an "aquatic mowing machine."
It is described as follows:
Eelgrass grows abundantly in some parts of the Navesink River and, as in other
localities where it is found, acquires in due time full possession of the areas where
it grows, rendering them useless for oyster-culture. In combating this enemy of
the oyster-plantiug industry, Mr. Charles T. Allen, of the firm of Snyder & Allen,
Oceanic, N. J., has achieved a degree of success heretofore unequaled. After
expending much fruitless labor in ellorts to mow the eelgrass with a scythe, a method
which proved impracticable because the water was sometimes too deep and also im
OYSTERS AND METHODS OF OYSTER-CULTURE. 319
account of the difficulty of cutting grass growing under water, ho invented in 1885
and Las since used a device which may be termed an aquatic mowing machine.
The machine is rigged on a square-ended scow 20 feet long by 8 feet wide. On the
forward end of the scow is suspended, by a framework, a double set of knives, each
set being similar to those of mowing machines used by agriculturists. The object
in having double knives is to enable the machine to cut when moving backward as
well as when moving forward, thus avoiding the necessity of having to turn the
scow around when the end of tlie swath is reached. The knife bar is 12 feet long
and consequently cuts a swath 12 feet w ide. The power of propelling the machine
is supi)lied by a 6-horse])ower high-pressure condensing engine, which is located in
the middle of the scow. A line 1,000 feet in length is passed with three turns around
a winch head and drawn taut by an anchor at each end, placed a short distance
beyond the extreme boundaries of the area to be mowed. It is held in position by a
fair-leader or chock having a shive on each side similar to the shive of an ordinary
tackle block. The shives facilitate the passage of the line through the leader by
lessening the friction and correspondingly decrease the wear upon it. The leader
or chock is i)Iaeed on the forward end of the scow, and not only serves to hold the
line in position, but also keeps the scow straight in its course.
When the engine is started, the winch-head revolves, and the pressure of the line,
encircling it in three turns tightly drawn, forces the scow through the water. The
rate of speed at which it can be operated is 1,000 linear feet in 5 minutes, thus
enabling it to mow an area of 2,000 square feet or more per minute, or 1 acre in from
20 to 22 minutes, making allowance for time spent in moving anchors or otherwise
adjusting the machinery.
When fitted for work, with coal and water, and manned with three men, including
an engineer, which is the number requisite to operate the machinery and attend to
shifting the anchors, the draft of the scow is about 8 inches of water. When the
anchors have once been adjusted, several swaths can be mowed before they require to
be shifted over toward the uncut grass, as the line can not easily be drawn so taut —
nor does it need to be — as not to allow the scow to be moved (]nished with a pole)
sidewise for a short distance. When necessary, the anchors are shifted by tlie use of
a small boat. Thus the scow is guided back and forth across the lot, cutting the
grass with ecjual facility in both the forward and backward movements. When the
grass is cut, it lloats to the surface of the water and is carried away by the current.
The knives are set in motion by a vertical iron shaft which passes through a hori-
zontal cogged wheel. This wheel is geared to a pulley which is run by a belt from
the engine. The vertical shaft is so arranged as to slip up or down in order to gauge
the machine to any depth of water within the range of its capacity. The extreme
depth of water in which mowing can be successfully done, as it is now adjusted, is
about 8 feet. It could doubtless be so arranged as to operate in deeper water.
If there are no obstacles in the way, the grass can be cut within 1 inch of the bottom.
If there are oysters on the ground, some allowance for that fact has to be made,
and wliilo the grass can not be sheared so close to the bottom, it can be mowed
snfliciently close to the oysters to answer all practical purposes. Tlie only thing
requisite is to mow it short enough to preclude the possibility of any large (juantity
of sediment settling in it and choking the oysters. This object is easily attained, as
grass a few inches long will not injure the oyster crop. It is when its length is
measured by feet and it is filled with sediment that it becomes dangerous.
In the locality where this machine is used the water is about 6 feet deep. It
has been customary to mow the oyster-beds quite fri-quently, five or six times,
perhaps, during the growing season, from the lirst of May to the last of October. The
result has been that tracts of bottom that would have otherwise been worthless for
oyster-growing purposes have Ix^en converted into beds as productive as any iu the
river. The coat of building a similar machine is estimated by Mr. Allen to be from
$450 to $500.*
* Hall, Aneley, Rept. U. S. Fish Commission 1892, pp. 477 and 478.
320 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
INCREASE ON PLANTED BEDS.
The percentage of seed oysters which reach maturity depends upon
local and seasonal conditions, upon the care with which the oysters
have been planted and worked, tlie size of the oysters when planted,
and the length of time which they have been left to lie. Under the
very best conditions there is a considerable mortality among the plants,
and while the individual oysters have increased greatly in size the loss
from one cause or another is such that there is by no means a corre-
sponding increase in the total quantity as measured in bushels. In some
places the planter is satisfied if he can market a bushel for each bushel
planted, depending for his profit upon the increased price brought by
the larger growth, but the usual average yield in many localities is two
or three times this amount, and cases are known where 500 bushels of
shells yielded 3,000 bushels of salable oysters.
GROWING OYSTERS IN PONDS.
In Europe pond culture has been commercially successful for many
years, and in some countries practically the entire product of oysters
has been derived from this source. Small inclosed ponds, claires, have
been used in France for greening and flavoring the oysters and i^arks
or partially inclosed ponds, admitting the tides, are used for growing
the oysters from seed, but all experiments heretofore made with a view
of raising the seed in closed ponds have been attended with failure or
scanty success.
Over a large area of our oyster-producing territory the difficulty of
obtaining seed is usually not a pressing one and an utter failure to
secure a set is rarely confronted upon more than occasional years.
Under such conditions, in several regions, the practice of sowing shells
has grown to great proportions, but with the vast increase in the planted
area an increasing difficulty has arisen in preparing the oysters for
market. Growth is slower than formerly, and during some seasons the
oysters either do not fatten at all or else so slowly that months are
wasted before they can be brought into i^roper condition. It is signifi-
cant that complaints of this difficulty come from regions which were at
one time famous for the fiitness and flavor of their product and that
the trouble was not manifested until the population of the beds far
outgrew that which was found in their natural condition. The causes
leading to the difficulty complained of have never been studied, but
the explanation will probably be found in the fact that the quantity of
oysters in such regions has outgrown the ability of the M^aters to supply
them with food.
As is elsewhere pointed out, the rate of the growth depends ])rimarily
upon the relative richness of the food su])ply, and a quantity which
may be sufficient to cause a moderate growth may still be inadequate
to produce the degree of fatness upon which the oyster's toothsomeuess
so largely dex)euds.
OYSTERS AND METHODS OF OYSTER-CULTURE. 321
It is manifestly impossible to propose efficient means for increasing
the abundance of the food organisms over any very extended area of
open waters, where ownership is vested in the many and the conditions
are not subject to control. Only in inclosed or semi-inclosed bodies
of water could there be any hope of such regulation of temperature,
density, and other factors as to conform to the best conditions for the
rapid multiplication of such organisms as constitute the preponderance
of the oyster's food. If it were possible for the })lanter to have at his
command a body of water extremely rich in food he could, in a short time
and at will, fatten oysters which had grown to a marketable size upon
other and less favorably situated beds. It is probable that under intelli-
gent direction a comparatively small area could be made to serve as a
fattening bed for all of the oysters ])roduced on a great area of ordinary
shelled ground, and that the cost of preparing and maintaining the rich
food producing beds would be returned many-fold in the ready sale and
high price which the superior product would be able to command. In
many places in the United States this plan is followed with success by
transplanting the oysters from offshore beds to harbors and coves, but
so far as known no practical and conclusive test of culture in artificially
prepared i)onds has been made, and it is therefore not ])ossible to give
full and practical directions concerning the method to be followed in
attempting it.
The European methods are generally not economically adapted to
use in our waters, but the experience of French culturists has estab-
lished certain principles which are of general application, and may
serve as a guide to those working upon somewhat similar lines here.
There are many localities witliin the limits of the oyster-producing
region of the United States where ])ond culture for the jjurpose of
growing and fattening oysters would probably prove successful, and salt
l)onds, connected with tide water by natural or artificial channels, could
often be made to return a good dividend to their owners if converted to
the uses of oyster culture. In other cases low and swampy land might
be dredged or excavated so as to answer the i)urpose, and thus be made
to return a revenue in perhaps the only possible manner. Such ponds
should be well protected by embankments sufficient to prevent the
entrance of water except when desired, the sup])ly being regulated by
flood gates which can be opened or closed at will, or the height of the
embankments luixy be so adjusted that the water from the sea will enter
during very high tides only, say once or twice a month. When the
p(mds are large it has been found that the surface aeration is sufficieiit
to siipi)ly the oxygen reipiired, but in smaller ponds it is necessary to
attain this end by more or less frequent interchanges of water between
the pond and the main body of salt water with which it is connected.
In the case of practically inclosed i>onds it is necessary to provide for
the addition of fresh water to make good the loss occasioned by evaj)-
oration. If this precaution be neglected the density of the water will
rise above the maximum in which the oyster flourishes.
KM. 21
322 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
• It may be advisable in some places to reduce tlie density in the ponds
below that of the open waters, as it is well known that the more brack-
ish waters are generally most favorable to the rapid multiplication of
diatoms and other minute vegetable forms valuable to the oyster-grower.
Experiment could be made to demonstrate approximately the best
density for the piirpose, and where tlie water supply is under control
the poud could be maintained at nearly or (]uite the degree of salinity
required. The ordinary surface drainage into many natural salt ponds
is sufficient to reduce the density below the level in the main waters,
and by merely regulating the inflow of sea water the grower will prob.
ably find that almost any degree of brackishnessmay be maintained at
will. Such ponds will be found to possess all the requirements for the
production of food in abundance, the density will be favorable, their
shallowness will cause them to warm early in the season, and thus
stimulate the growth of microscopic vegetation, and their immunity
from the influences of tides will prevent the carrying away of the food
which they produce.
There are, of course, many places where the natural conditions for
the production of oyster food are all that could be desired, and there
pond culture would doubtless be unnecessary, but in other localities,
such as are mentioned at the beginning of this section, it seems to offer
the most promising field for experiment.
BREEDING OYSTERS IN PONDS.
While in some of our most important planting regions there is rarely
any difficulty in obtaining seed oysters, there are places, otherwise
admirably adapted to the industry, in which the supply of seed is
extremely precarious. The most remarkable fluctuations in the set of
spat take place, and often where there is one year an abundance the
following season may exhibit a dearth. In certain localities on Long
Island a set of spat rarely occurs, and the x)lanters long ago abandoned
the attempt to raise seed and now procure it from some other region
more favored in that respect. In still other places, as over the larger
part of Chesapeake Bay, the seed oysters are obtained mainly from
the natural beds, but with the dej)letion of these there will be an
increasing difficulty in obtaining it, and before long it will no doubt be
necessary to derive it from some other source. There is an increasing
tendency in the region last mentioned to follow more closely the method
of sowing shells practiced in Connecticut; in some places the experi-
ment has met with great success so far as the procuring of a set is con-
cerned, but in other localities the results are too uncertain to permit it
to be followed with profit.
Where a "strike" occurs each year with tolerable certainty this
method is without doubt the best available to our oystermen, but where
the spat may fail to set for several years in succession, the expense of
putting down the shells without return will soon eat up the profits of
P'ish Manual. (To face page 323. J
'^
1
J
Spawning Pond X.
rt rTTirrvinrvlnrirw-innrinnnnrrinnnnnnri
-innr'"'~"TirvinmTnnnnr"~«nnni
mm.
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Section on Line A-/
. c«. .'
• ■ '^ ■<• " ' *^ ' /^/ .' ** '^
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OYSTERS AND METHODS OF OYSTER-CULTURE. 323
more successful years, aud the irregularity of his crop may cost the
j)lauter his market.
It is obvious that iu order to obtain more certain results the con-
ditions upon ^vhich the spatting depends should be subject to some
control. It is useless to exi^ect such control in any adaptation of the
ordinary method of planting shells, and the only direction which prom-
ises success in such an attempt is some modiftcation or form of pond
culture. The culturists of Europe have shown that a very considerable
control can be exercised over the conditions in parks used for growing
oysters from seed, and with proper modifications the same success
could doubtless be attained with breeding ponds for raising seed.
"To actually come into competition with the system of shell sowing in
deep water we must proceed to abandon all old methods, condense our
cultch so as to have the greatest possible quantity over the smallest
possible area, and finally have that so arranged that the currents devel-
oped by the tides, in consequence of the peculiar construction of a system
of spawning ponds and canals, will keej) the cultch washed clean auto-
matically. Unless this can be done, all systems of pond or cove culture
for the i)urpose of obtaining spat must unhesitatingly be pronounced
failures."*
Impressed by these facts. Dr. Ryder, in 1885, devised a very ingenious
method of spat-culture, which he described as follows :
(A) The method as adapted to canals or sluices in which the cultch is placed in masses,
with jetties at intervals.
The first form in which I propose to inaugurate the new system of spat-cultiire
which has grown out of the principles already developed consists, essentially, iu
condensing the cultch or collecting apparatus in such a way as to expose the maxi-
mum amount of collecting surface for the spat to adhere to within the least possible
area. This may be achieved in the following manner: A pond, X, as shown in plan
and elevation iu jilate iii, is constructed with a long zigzag channel, s, connecting it
with the open water. The pond ought to be, say, 40 to 60 feet square; the channel,
s, may be, say, 3 feet 3 inches wide, as shown in the diagram. The vertical banks,
z, between the zigzag canals running to the open water might be 3 feet in width.
The sides of the canals ought to be nearly or quite vertical, and the earth held in
place with piles and rough slabs or planks. The direct inlet to the pond at _ might
be provided with a gate, aud the outlet of the canal, where the latter connects with
the open water at o, might be provided with a filter of moderately fine galvanized
wire netting and a gate; the first answering to keep out large fish and debris and
the latter to close under certain circumstances, or when violent storms develop
strong breakers. The accompanying plan and sectional elevation, as shown in plate
III, will render the construction of such a pond and system of collecting canals clear.
Into the pond, A', I would put an abundance of spawning oysters, say 100 bushels,
if the pond were 40 feet square, and 200 bushels if it were OO feet square. But
instead of throwing the oysters directly upon the bottom, I would suggest that a
platform, of strong slats be placed over the bottom of the pond at a distance of
8 to 10 inches from the earth below, upon which the oysters should be evenly dis-
tributed. This arrangement will prevent the adult oysters from being killed by
sediment, and also afford a collector, in the form of a layer of shells, to be spread
.^
* Rept. U. S. F. C. 1885, p. 392,
pish Manual. (To f»ce p»ge 323. J
^
Spawning Pond X.
f
Plate III.
Section on Line A-A.
Section on Line B-B.
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GROUND PLAN AND SECTIONS OF PONDS FOR SPAT-CULTURE.
Adapted from John A. Kyder
o
OYSTERS AND METHODS OF OYSTER-CULTURE. 327
labor to be expended iu making the necessary excavations will be proportionally
diminisLed, and no assistance from a skilled engineer will be reciuired.
Whether the si)awning pond is excavated or not, the principle npon which the
system is constructed and operated remains the same, namely, that the area of the
canal systems and the ponds be about the same. In order that the fry be not car-
ried past the collectors, the area of the pond should not much exceed the total area
of the canals. In order that the fry may be wafted to the outermost collectors, the
area of the canal system ought not to greatly exceed that of the pond or ponds.
Canals constructed between a series of spawning ponds may also bo utilized; in
fact, a great many other modifications of tlie system are available, which would
become ai)pareut only after a study of a given location. The plans for carrying out
this system would, in fact, have to conform to the demands of the location, so that it
maj- be said that each establishment would have to be designed in conformity with
local conditions.
If cultch in the form of shells is the best (for which conclusion we have assigned
reasons), it follows that such material should be so utilized as to obtain the largest
possible return for the least possible outlay. In other words, if shell cultch is to be
used at all, let it be expeditiously and economically, and not wastefully and
unscientifically, employed. It has been found that even the sowing of shells is
profitable, as has been conclusively demonstrated, and in one type of culture,
namely, that which is practiced in deep water, it is probable that it is the only
practicable method which will be devised for a long time to come. While it is to a
great extent wasteful and at times uncertain, for the present, at least, there seems
to be no other which can bo so economically and successfully operated over large,
open, navigable areas. Largo areas operated by one individual or corporation can
not always be commanded, or only exceptionally, under the existing laws of the
States of Maryland and Virginia. In those States, however, where it is possible to
command the right to natural areas of water which are more or less nearly land-
locked, the system of merely sowing shells would be positively wasteful and not iu
conformity with the results attainable under the guidance of the proper knowledge.
It is found in the practice of shell sowing that extensive areas will sometimes fail
to iiroduce anj' spat. This is apparently due to the presence of currents which have
swept the fry oif the beds, or to the presence of sediment, which has put an end to
the first stages of its fixed career. Even after the spat is caught, great destruction
may occur through the inroads of starfishes, or a too rapid multiplication of worm
tubes over the cultch and spat. The latter is sometimes smothered in vast numbers
from the last-mentioned cause, as has been recently discovered by Mr. Rowe. Such
casualties are rendered either impossible or readily observable during their early
stages by the method of inclosing the cultch in suspended receptacles, as suggested
in this paper. The netting will efi'ectually protect the young spat against the attacks
of large starfishes, and no growth of barnacles or tunicates, worm tubes or sponges,
would be rapid enough during the spatting period, judging from an experience
extending through several seasons, to seriously impair the spatting capacitj' of the
cultch used in the suspended receptacles. Any of the larger carnivorous mollusks,
fishes, or crustaceans which could prey on the young oysters can also be barred out
and kept from conmiitting serious depredations by means of the netting around the
cultch, as well as by means of screens placed at the mouth of the canal.
The maximum efficiency of the cultch is not realized in any of the old forms of
collectors, for the reason that the cultch can not be kept clean ; secondly, because
both sides of the cultch can not be exposed to the passing fry ; thirdly, because the
fry can not be compelled to pass over and amongst the cultch repeatedly; fourthly,
because the cultch is scattered over too great an area and throughout onlj two
dimensions of a body of water, namely, its horizontal extent, where it is possible, as
I have showu above, to do all this and more— that is, to avail ourselves of the possi-
328 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
bility of obtain inj^ spat througli the tliiee dimensions of a body of water charged
with embryo oysters in their veliger condition. These are good and sufticient
reasons lor my asstrtion that cultch has hitherto been wastefnlly ;ind niiscientifically
applied. With this I must conclude this exposition of the princijjles of a rational
theory of oyster-culture, a subject which has jeceived the attcutiou of many investi-
gators, none of whom have, however, struck at the root of the question and allowed
themselves to be guided by readily verifiable facts. In the hope that I have made
both the theory and the i>ractice of luy new method clear to the reader, who, if he
should happen to 1)6 an oysterman, will, I hope, at least give me the credit of being
honest and sincere in my intentions, and, whether he feels inclined to ridicule or to
adopt my conclusions, I feel very certain that what I have formulated in the preced-
ing Images will become the recognized doctrine of the future. *
A trial of this method was made by the Fish Commission at St.
Jerome Creek, Maryland, but it was found that Dr. Ryder's expecta-
tions regarding the freedom of his apparatus from sedimentation were
unfounded. St. Jerome Creek is admirably adapted, from its rich food
supply, to growing oysters from seed, but its very advantages in this
respect militated against the success of the experiment of spat-raising.
A small set was obtained upon some of the cultch exposed, but the
deposit of sediment was so rapid that the young oysters were unable
to fix in quantities sufficient to make the experiment a commercial
success.
It seems probable that under more favorable conditions with respect
to sedimentation the apparatus would prove a useful one, and it is to
be hoped that it will be given a further trial. The writer witnessed
Dr. Ryder's experiment at Sea Isle City, N. J., with a modification of
this arrangement, and, although the trial was made on a scale too
small, the results were such as to impress him with the feasibility of
the device under more favorable conditions than existed at St. Jerome
Creek.
One of the principal defects in Dr. Ryder's apparatus appears to be
the lack of suitable arrangements for flushing the cultch with currents
of water sufficiently strong to scour away anj^ sediment which may accu-
mulate. It was supposed that this (iould be accomplished by means of
jetties, but the current induced in the long canal by the ebb and flow
of the tide is apparently too gentle to have the eflect sought. This end
might be gained by providing the inner loops of the canal with gates
communicating with the pond, the outer loops having similar means
of communication with the exterior waters, as shown in plate in,
which is adapted from Dr. Ryder's plans. If the water in the pond at
high tide be held back until the canal has nearly emptied, a strong cur-
rent could be directed into any loop by opening the appropriate gates.
On the other hand, if the gates at the outer end of the loops be closed at
low water, a strong current could be thrown into the canals by opening
them at high water. By thus occasionally flushing each pair of loops
in succession it is believed that the injurious collection of sediment
can be prevented in even quite muddy water. The end is accomplished,
Rept. U. S. F. C. 1885, pp. 381-423, pis. i-iv.
OYSTERS AND METHODS OF OYSTER-CULTURE. 329
however, by some loss in simplicity of construction and operation of
the apparatus and at the expense of the escape of some of the embryos.
Plate III shows the original plans modified by the addition of sluice-
gates.
It is thought that this method of utilizing eultch may solve the
problem of the culture of the eastern oyster upon the Pacific coast.
Two chief difficulties there interfere with the obtaining of a strong set:
the temperature of the water is in most places too low to insure active
spawning, and, secondly, the young of the imported spe(;ies is crowded
out by the rank growth of the native oyster. It is probable that both
of these difficulties might be overcome by the use of Dr. Ryder's method
or some modification thereof. There is little doubt but that the ebb
and How of the tides through the channels could be so regulated that
a sufficient quantity of water would remain at low tide to temper that
which would ilow in at flood tide. The shallowness of the pond should
render it so susceptible to the effect of the sun's rays that a tem-
perature several degrees higher than that of the neighboring Avater
could be maintained, and in some places these two or three degrees
are perhaps the measure between success and failure in obtaining a set
of spat.
The eastern oyster spawns at 67° or G8° F., but does better at 70°.
Ponds such as that described might be located in connection with the
sloughs communicating wil!h the bays, and, as Mr. C. H. Townsend
says that the native Pacific coast oyster does not flourish in such
places, the imported species would doubtless have a better opportunity
of survival during its early career, the period when it is especially
liable to sutt'ocation by foreign organisms. If necessary, a filter, such
as is described on pp. 330-332 of this paper, might be introduced into
the mouth of the canal. This would to some extent interfere with
the ebb and flow of the tides between the pond and the slough or bay,
but it might be the very thing necessary to retard the interchange
sufficiently to allow the Avater in the pond to become warmed by the
sun.
The experiment is at least worthy of a trial, and it may be the means
of saving to the planters of the Pacific coast the large sums of money
which are now annually expended in transporting seed oysters across the
continent. The experimenter, if successful, would reap the benefit of
his own success. The brood oysters used in stocking the pond should
preferably be i)lants of several years' standing, as such Avould be more
likely to be acclimated than those brought from the East but a short
time prior to the experiment.
330 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
ARTIFICIAL PROPAGATION.
Artificial propagation in the fish-culturist's sense, the raising of
oyster fry from artificially fertilized eggs, has, at the present time, no
I)lace in practical oyster-culture. It may perhaps sometime demon-
strate its applicability to a system of spat production in small closed
ponds, but it can have absolutely no use in the present methods of
oyster- growing. It is futile to expect any results from deposits of the
swimming fry upon beds planted in the open waters of the bays and
sounds where the conditions are usually such as would bring about a
wide distribution. Fry so deposited would be, no doubt, largely carried
to other beds, and be lost to the man who planted them, or else would
fall upon unsuitable bottom. Their fate after being deposited in the
water is so uncertain that, in our present state of knowledge, it
would be a waste of effort for either Government hatcheries or private
individuals to attemj)t to increase the oyster by such means.
If, however, there can be devised some successful method of closed-
pond i^roduction, then artificial propagation may find a field of useful-
ness. Dr. Eyder suggested that the available amount of fry in his
method of spat-culture might be increased by adding embryonized
water to the inlet to the sluice at the beginning of flood tide, the
embryos being carried up through the cultch upon the flood and back
again upon the ebb, thus giving a double chance for fixation. There
is no doubt but that the proportion of eggs successfully fertilized can
be increased by the artificial mixture of the ova and spermatozoa
according to methods which science has demonstrated.
Another experiment by the same investigator showed that spat could
be raised in a practically closed pond from artificially fertilized eggs.
The experiment was briefly as follows: The pond was excavated in the
salt marsh on the shore of Chincoteague Bay. It was about 20 feet
square and 3i feet deep, and communicated with the bay by a canal 10
feet long, 2 feet wide, and the same depth as the pond. The mouth of
the canal was closed with a filter composed of boards perforated with
auger-holes and lined inside with gunny-cloth or bagging. The boards
constituted two diaphragms, an inner and outer, the interval of 2 inches
between being filled with clean sharp sand. Through this the tide
ebbed and flowed, giving a rise and fall of from 4: to G inches during
the interval between successive tides.
This filter, like most structures of its class, showed a tendency to
clog after it had been in use for some time, and as, from its shape, it
was difficult to cleanse, Br. Ryder devised the following arrangement,
which is accessible at all times and in which the sand may be renewed
at will:
My improved permeable diaphragm is placed horizontally withiu an oblong
trunk or box, A, tig. 1, of plate iv. The box is made of inch planks, to which strong
horizontal sidepieces, a, tigs. 2 and 3, are secured, and to which are fastened the
Fish Manual. (To face page 330.)
Plate IV.
Fig.^
Tig.Z.
Tig .3.
J -
,-ii';-'..i ;• ■;
't
J£J±
i^fr-
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1*' -"■••I'l
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■"-■'.'■ij.
i.'»;'\'«'
ngA.
DETAILS OF FILTER FOR PONDS USED FOR OYSTER-CULTuRE.
After John .\. Ryder.
OYSTERS AND METHODS OF OYSTER-CULTURE. 331
transverse crossbars h b, of ligs. 1, 2, 3, and 4, upon which the pormeabh) diaphragm
rests. Fig. 1 represents the trunk A secured within a pair of quadrangular frames,
F F, and partially in sectional elevation in jdaco in the trench or canal leading from
the pond to the open water; tig. 2 represents the construction of the end of the trunk
next the open water, and tig. 3 that of the end next the pond, while lig. 4 shows the
trunk as viewed from above.
Oti the crossbars b b a single screen of galvanized wire cloth, W, fig. 1 (galvan-
ized after it is woven), is superimposed, having meshes, say, one-half inch in diameter;
njion the wire screen a layer of gauuy-cloth, C, figs. 1 and 4, is laid, upon which a
layer of fine, clean sand, S, is sjnead evenly from one end of the trunk to the other.
The end board e, extending halfway up at the outer end of the box, runs up past
the level of the wire and cloth to contine the sand at that extremity, as shown in
fig. 2, while the sand is confined by the board i at the other end of the trunk next
the pond, as shown in fig. 3. Tlie wire cloth and bars bb constitute the support
for the sand as it lies upon the gunny-cloth, which is supported in turn by the wire
cloth or screen W. This is essentially the construction of the filtering apparatus in
which the layer of sand, S, is at all times accessible, so that it can be removed if it
becomes clogged with ooze carried in by successive tides under the gate G, figs. 1,
2, and 4. This layer of sand can also be increased or diminished in thickness so as
to strain the inflowing and outflowing water more or less eff"ectually, as may be
desired, or in order to more or less efieitually prevent the escape of any eggs or
embryos of oyster which may be developing within the pond and wafted to and fro
by the ebbing and flowing currents which are carried in and out of the pond through
the diaphragm by tidal action. The gunny-cloth, C, fig. 4, may possibly be replaced
by, first, a layer of coarse gravel, then a layer of finer gravel superimposed upon
that, which would prevent the fine sand from sifting through the supporting wire
screen W. Gravel would be more durable than gunny-cloth or sacking, which, like
all other textile fabrics, will rot if immersed in salt water for a few weeks. In
practice, however, a mode of getting over all such difficulties would soon be devised.
A coarse sacking to be used for the purpose might be saturated with a drying oil or
with tar diluted with oil of turpentine, which when dry would act as a preservative
of the material, but not cause it to become impervious.
^ * * # * -v ^*
When the trunk A is put in place (which should be done before the water is let
into a freshly excavated pond, and also before the water is let iuto the trench from
the sea end), it should be securely placed in position and the earth tightly rammed
in along the sides so as to prevent any sea water from finding its way into the pond,
except such as passes through the filtering diaphragm. It is also unnecessary to
insist that the trunk be constructed in such a way that it will be practically water-
tight, and not liable to leak between the planks or at the corners. The wire cloth,
sacking, or gravel, and sand having been got into place, and when complete forming
a stratum having a total thickness of 5 or 6 inches, the operator is ready to cut
away the barrier at the sea end of the trench and let in the water.
If then the truuk .i has been let down iuto the trench deep enough the sea level
at low tide ought to be somewhat above the np])er edge of the board e. The water
will then, as the tide rises, flow back over the sand as far as the board i, aiul will per-
colate through the diaphragm into the space /, under the latter, and so find its waj^
into the pond. After a day or so the pond will be filled with sea water which has
practically been filtered, and filtered more or less effectually in pro])ortion to the
thickness of the stratum of sand constituting the diaphragm. After the pond lias
once been filled with the rise and fall of the tide in the open water the level of tho
latter andiihat in the pond will be constantly changing ; in other words, when the tide
is ebbing the water level in the pond will be higher than that of the water outside,
as in fact represented at ivl and tl in fig. 1. Under these circumstances there will
be a supply of water flowing out through the under division I of the trunk A, up
through the sand and out over its surface through the outlet O under the gate Cr.
After the ebb tide is over and flood tide begins these levels will bo reversed and wl
332 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
in the pond will be lower tlian 11 in the open water, and under those circniustancea
there will be an inllow of sea water into the pond throngh the diaphragm instead of
an outflow, as is the condition of the water level during ebb tide. Under such condi-
tions there will be four alternating periods during every twenty-four hours of inflow
and outflow, lasting, we will say, four hours each, not reckoning the nearly stationary
intervals between tides or during slack water. This almost constant partial renewal
of the water will unquestionably maintain the water inclosed in the pond or ponds
by means of diaphragms in a condition fitted to supjyort oysters colonized therein,
provided its density is not too great or too slight, and if there is also some micro-
scopic vegetation present.
It will be readily understood from the preceding description how it is intended
that the apparatus is to bo operated. The figures also give a very good idea of how
the diaphragm and trunk are to be constructed, the first four figures being drawn
to a common scale of 1 inch to 3 feet.*
I The water in the pond reuiained at about the same density and tem-
perature as that in the open bay and soon developed a greater abun-
dance of food organisms, both plants and animals. Artificially fertilized
ova were placed in the pond at intervals during the spawning season,
and forty-six days after the beginning of the experiment young spat
from one-fourth to three-fourths of an inch long were found attached
to the bunches of shells which had been hung upon stakes to serve as
collectors. Great difficulty was experienced from sedimentation. The
experiment demonstrated that spat could be raised in ponds from
artificially fertilized eggs and that it would grow as rapidly as the spat
reared in the open bay. As the conditions are stated by Dr. Ryder, it
appears probable that equally good or better results might have been
attained with less labor by placing a quantity of spawning oysters in
the X)ond.
Not only would there be a saving of labor in the direct use of the
spawning oysters, but there would also be no necessity for the sacrifice
of the parents, as must be done under the method of artificial fertiliza-
tion. The increase in the size of the spawners under the favorable
conditions of growth would probably go far toward the payment of
expenses.
The method which promises the best results is that in which the eggs
are deposited in the pond within from three to five hours after fertili-
zation. There is apparently nothing to be gained in holding the eggs
a longer time, the chief gain of the culturist being not in the protection
of the embryo, but in the increase of the proportion of eggs fertilized.
The method of fertilization used by Dr. Eyder was as follows:
The method formerly used was to first learn the sex of a number of adult oysters
■with the microscope, then cut out the generative glands with their products and
chop up those of ditterent sexes separately in small dishes with sea water. This
system we may now say is barbarous, because it is crude. Large numbers of eggs are
destroyed by crushing, or are injured by the rough usage to which they are subjected,
and, besides, there is no assurance that the eggs or milt operated with are quite
matui'e. It is also troublesome to free the generative gland from fragments of the
hver, which help to pollute the water in the incubating vessels with putrescible
* Bull. U. S. F. C. 1884, pp. 19, 21, 22, 23.
OYSTERS AND METHODS OF OYSTER-CULTURE. 333
organic inatter, and thus interfere greatly with the life aud healthy development of
the embryos.
By our method the ohjectionablo features of the old plan, as stated above, are
overcome. If possible select good-sized oysters; open them witli the greatest possi-
ble care so as not to mutilate the mantle and soft parts. Carefully insert an oyster
knife bet^veen the edges of the valves and cut the great adductor muscle as close as
possible to the valve which you intend to remove, leaving the animal attached to
the other valve, which, if possible, should be tlie left or deepest one. The soft parts
being firmly fixed or held fast by the great adductor muscle to the left valve pre-
vents the animal from slipping under the end of the pipette, held flatwise, as it is
gently aud firmly stroked over the generative gland aud ducts to force out the
generative products.
To ])repare the animals to take the spawn from them after opening, the following
precautious are to be observed : Note that the reproductive gland in great part
envelops the visceral mass and extends from the heart space, just in front of the
great adductor, to within a half inch orso of the head or mouth end of the animal,
which lies next to the hinge. Note also tliat both sides of the visceral mass which
incloses the stomach, liver, and intestine are enveloped on either side by a membrane
which also lies just next the shell and is garnished by a fringe of purplish, sensitive
tentacles along its entire border except at the head end, where the mantle of the left
side passes into and is continuous with tliat of the right side of the animal. The
ventral or lowermost side of the animal, anatomically speaking, is macked by the
four closely corrugated gill plates or pouches, which are preceiled in front by the
four palps or lips, but both the gills and palps depend downward between the lower
borders of the mantle of the right and left sides. Note, too, that if the mantle is
carefully cut and thrown back on the exposed side of the animal between the njtper
edges of the gills and the lower edge of the cut or exposed end of the great adductor
muscle, the lower and hinder blunted end of the visceral mass will be exposed to
view. It is on either side of this blunted end of the visceral mass between the upper
edge of the gills and lower side of the great muscle that the reproductive glands
open almost exactly below the great adductor. From these openings we will after-
wards find, if the animal is sexually mature and the operation is properly conducted,
that the spawn will be forced out in a vermicular, creamy white stream. But in
order to fully expose the reproductive organ we should carefully continue to s(!ver
the mantle of one side with a sharp jjcnknife or small scissors some distance forward
of the great muscle toward the head, cutting through the mantle just above the
upper borders of the gills and following a cavity which lies between the latter and
the lower border of the visceral mass.
A little experience will teach one how far it is necessary to carry this incision of
the mantle. For some distance in front of the heart space the mantle is free or
detached from the visceral mass and reproductive organ, which lies immediately
beneath, and this enables one, if the last- described incision has been properly made,
to almost completely expose the oTie side of tlie visceral mass and the richly tinted,
yellowish-white reproductive gland which constitutes its su])erficial portion. The
opening of the gland and its superficial ramifying ducts being laid bare on the
exposed side ot the animal, we are rcadj^ to press out the spawn on that side. Before
beginning this, however, it is important to observer that tlie jjiincipal duct passes
down just along the edge of the visceral mass where the latter bounds the heart
space, in which the heart may be observed to slowly pulsate, and that this great duct
ends somewhere on the surface of the ventral blunted end of the visceral mass (plate i,
tig. 2 d). To ex])ose the great or niaiu generative <luct it may be necessary to cut
through or remove the pericardial membrane which incloses or covers the heartepace
on the exposed side. If tlie oyster is sexually mature, the main duct will be observed
to be distended with s])awu, and that, originating from it and branching out over
almost the entire surface of the visceral mass, there are minor ducts given off, which.
334 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
again and again subdivide. If these are noted and it is observed that they are
engorged, giving them the appearance of a simple series of much-branched great
veins filled with creamy white contents, it may be certainly presumed that your
specimen is mature and that spawn may be readily pressed from it.
The operation of pressing the spawn out of the ducts requires care. The side of
the end of the pipette may be used, being careful not to crush or break open the
ducts as you gently and iirmly stroke the pipette flatwise over the side of the
visceral mass backward from the hinge toward the heart space and over the great
duct at the border of the latter diagonally downward and backward to tlie opening
of the reproductive organ. If this has been properly done it will be found that the
generative products are being pushed forward by the pipette through the ducts, as
the pressure will be seen to distend the latter, the contents of the branches flowing
into the larger and larger trunks until they are forced outward through the main
duct and opening below the great adductor, where they will pour out in a stream
one-sixteenth of an inch or more in diameter if the products are perfectly ripe. The
sexes may be discriminated as described at the outset, and it is well to first find a
male by the method already given and proceed to express the milt as described
above into, say, a gill of sea water, adding pijietteful after ])ipetteful until it acquires
a milky or opalescent white color. As the milt or eggs are pressed out of the open-
ing of the ducts, they are to Ije sucked up by the pipette and dropped into the water,
the mixture of milt being first i)repared, to which the eggs may be added as they
are expressed from the females. The judgment of the operator is to be used in mix-
ing the liquids; in ])ractice I find that one male Avill supply enough milt to fertilize
the eggs obtained from three or four females, and it does not matter if the ojieration
takes from twenty to thirty minutes' time, as the male fluid, which it is best to
prepare first, will retain its vitality for that period.
It is always desirable to be as careful as possible not to get fragments of other
tissues mixed with the eggs and milt, and the admixture of dirt of any kind is to be
avoided. To separate any such fragments nicely, I find a small strainer of coarse
bolting or cheese cloth to be very convenient.
In the foregoing descriiition we have described the method of obtaining the spawn
only from the side of the animal exposed in opening the shell. A little experience
will enable one to lift up the head end of the animal and throw it back over the great
adductor muscle, expose the opening of the reproductive organ on the left side,
or whatever the case may be, and also express the spawn from that side, thus as
eft'ectiially obtaining all of the ripe eggs or milt as is possible in the process of
taking the same from fishes.
It is remarkable to note the success attending this method, since almost every egg
is perfect and uninjured, the percentage of ova, which are impregnated, is much larger
than by the old method, reaching, I should say, (juite 90 per cent of all that are taken
when the products are perfectly ripe. It is also found that the products are not so
readily removed by my process if they arp not perfectly mature, which is also to
a certain extent a safeguard against poor or immature spawn. In the course of
an hour after the products of the two sexes have l)een mingled together it will
be found that nearly every egg has assumed a globular form, has extruded a polar
cell, lost the distinct germinative vesicle and sjiot in the center, and begun to develop.
It is noteworthy that our practice as herein described has completely vindicated
the statement made by the distinguished French anatomist and embryologist, M.
Lacaze-Duthiers, that there is but a single gener.ative opening on each side of the
visceral mass of the oyster, and that, as we have«tated, it is found to open just below
the great adductor muscle.
We have also discovered, since the foregoing was written, that the use of an
excessive amount of milt is of no advantage. The water in which the eggs are to be
impregnated only requires to be rendered slightly milky; a very few drops of good
milt is sufficient to make the impregnation a success. Too much milt causes the eggs
OYSTERS AND METHODS OF OYSTER-CULTURE. 335
to be covered by too large a uiimber of spermatozoa ; tbonsands more tban are
required if too mucb is used. These superfluous spermatozoa simply become the
cause of a putrescent action, which is iujurious to the healthy development of tlie
eggs. A drop of milt to 20 drops of eggs is quite suflicient.
Immediately after the ova have been fertilized it is best to put them into clean
sea Avuter at once, using water of the same density as that in wliich the adults grow.
If the attempt is made to impregnate the eggs in water much denser than tliat in
which the adults lived, it is probable tliat the milt will be killed at once. This
singular fact, which was accidentally discovered by Colonel McDonald and myself,
shows how very careful we should be to take into consideration every variation in the
conditions aftectiug a biological experiment. If sufficient water is used no trouble
will be experienced from the pollution of the water by dangerous micro-organisms,
which are able to destroy the oyster embryos. From 50 to 200 volumes of fresh,
clean water may be added to the volume in which the eggs were first fertilized.
This may be added gradually during the first twenty-four hours, so as to assist
aeration and prevent the suffocation of the embryos. *
ARTIFICIAL FEEDING.
There is uo practical way now known of furnisliing oysters with an
artificial food supply.
Experiments have been made with a view to feeding the adnlt oysters
upon corn-meal or some similar substance, but such attempts have been
of no practical value. There is no doubt that they would eat corn-meal
or any other substance in a sufficiently fine state of division to be acted
upon by the cilia. The oyster is incapable of making a selection of its
food, and probably any substance, nutritious, inert, or injurious, would
be swept into the mouth with complete indifference except as to the
result. Corn-meal and similar substances would doubtless be nutri-
tious, but their use must be so wasteful that the value of the meal
would be greater than that of the oyster produced.
The only way in which the amount of oyster food can be increased is
by so regulating the conditions in ponds or parks that the natural food
may grow in greater luxuriance. In artificial propagation the life of
the young lias been prolonged beyond the early embryonic stages by
feeding upon certain marine alga', reduced to a powder by pounding
them in a mortar, but such successes have been purely experimental
and are of no significance from a practical standpoint. Even if artificial
propagation were to obtain a place in practical oyster-culture, the fry
would doubtless be liberated before resort to artificial feeding would
become necessary.
* Fisheries Industries, Sec. I, i)p. 723, 724, 725.
336 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
FATTENING, PLUMPING, FLOATING.
As has been frequently pointed out, the so-called "fattening" of
oysters for a short time previous to sending them to market is not a
fattening process at all, but is a device of the trade to give to the
oysters an illusive appearance of plumpness. It adds nothing whatever
to the nutritive qualities of the oyster, but on the contrary injures its
flavor and extracts certain of its nutritious ingredients. However, as
long as the public desire such oysters the dealers can not be blamed for
supplying them.
The process of plumping consists in changing oysters from denser to
less dense water, causing an interchange of fluids through the walls of
the animal, the denser fluids in the tissues passing slowly outward, the
less saline water in which the animal is immersed passing more rapidly
inward. The net result is to cause a swelling of the tissues by an
increase in the fluid contents, in much the same manner as a dry
sponge swells when moistened. The oysters are not usually placed in
absolutely fresh water, which would kill them if exposed too long,
but in fresher than that in which they have been living. The fluids
which have passed out from the tissues carry with them salts and some
fats, chemical experiment showing that the oyster, although larger after
plumping, has lost 13 per cent of its original nutritious substances,
protein, fats, carbohydrates, and mineral salts.. Sufficient water will be
taken up, however, to increase the total weight of the oyster from 12 to
20 per cent. The same result is produced by i)lacing the oysters in fresh
water after they have been removed from the shell. It will be seen that
what the oysters have gained is simply water, of no value as food.
If the living oysters are left too long on the floats they will again
become "lean," leaner than before, in fact, owing to the state of equi-
librium which is finally established between the density of the juices
within the tissues and without. If oysters are taken from brackish
water to that which is considerably more saline they become shrunken,
tough, and leathery, owing to the converse process to that of plumping.
Various forms of floats are used. One of the simplest consists of
trays 8 feet by 10 feet by 2 feet deep, with perforated bottoms, these
being raised from the water for filling and emptying by means of a chain
attached to each corner and a pair of windlasses supported upon piles.
While not harmful in itself it may be well in this connection to sound
a word of warning. Oysters may, and no doubt sometimes do, consume
pathogenic bacteria, or disease germs, with their food; and such germs,
transferred to the human economy with vitality unimpaired may upon
occasions have serious results. Care should be exercised to construct
the floats in such places as are free from the contaminating influences
of sewer discharge and other sources of i)ollution.
In France the oysters are subjected to a true fattening process in
inclosed ponds or claires, their flavor and appearance being much
improved thereby.
OYSTERS AND METHODS OF OYSTER-CULTURE. 337
GREENING.
!N'otwitlistaiuliiig that almost every recent writer ui)on the subject
has insisted upou the harmlessness of the green coloration which is
frequently observed in certain portions of the oysters, there is still con-
siderable misapprehension of the subject by consumers and oystermen
alike. The prejudice is confined to America, in Europe such oysters
being regarded as superior, and much trouble being taken to impart to
them their peculiar viridity. In our waters the greening is liable to
occur in certain localities and at irregular times. Rather shallow
waters appear to be more susceptible to the production of this effect
than the greater depths, but it has recently appeared on the deep-water
beds of Long Island Sound.
When oysters become so colored the oystermen find great difficulty
in disposing of them, owing to the poj^ular belief that they are unfit for
food, or even poisonous. They often have what is described as a cop-
pery taste, and uninformed persons usually assume that the green color
is due to the presence of copper. A number of careful investigations
have shown that such oysters contain no copper whatever, but that the
green color is derived from a harmless blue green substance, idiyco-
cyanin, which is found in certain of the lower plants.
Under proper conditions these unicellular vegetable organisms mul-
tiply in brackish or saline water with great rapidity and provide an
important item of food to the oyster. The green matter is soluble in
the juices of the oyster and passes into the tissues, affecting principally
the blood corpuscles.
An oyster usually shows the first indication of greening in the gills
and palps, and frequently this is the only portion of the animal which is
colored, a fact which is explained when we remember that this is the
most highly vascular portion. When the supply of greening food is
abundant and long continued, the mantle, liver, and eventually the
entire organism, with the exception of the muscle, acquire a green
hue. Such oysters are usually, but not always, fat and well fed, the
result of the abundant supply of nutritious food, and such a condition
could hardly obtain were the dye a copper product, such as has been
popularly supposed.
The color may be removed from the oysters by transferring them for
a short time to waters in which the green food is deficient, a fact
which may be available in preparing for market oysters which popular
prejudice refuses to use in the green state.
In conclusion, it may be again insisted that the greening is not a
disease, nor a parasite, nor a poisonous material in any sense.
F. M. 22
338 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
TRANSPORTATION AND LENGTH OF LIFE WHEN REMOVED
FROM THE WATER.
Under proper couditions the oyster will live for a long time after its
removal from the water. Professor Verrill records a case in which
marketable oysters survived for over ten weeks while hung up in the
window of a shop, during the months of December, January, and
February. The temperature was variable, but upon the whole rather
cool. He says :
The remarkable duration of the life of these oysters is unclonbtedly due to two
causes :
1. The perfect condition of the edges of the shells, which allowed them to close
up very tightly.
2. The position, suspended as thej* were with the front edge downward, is the
most favorable position possible for the retention of water within the gill cavity,
for in this position the edges of the mantle would closely pack against the inner
edges of the shell, eft'ectually closing any small leaks, and the retained water would
also be in the most favora'ble position to moisten the gills, even after part had
evaporated. It is also possible that when in this position the oyster instinctively
keeps the shell tightly closed, to prevent the loss of water.
This incident may give a hint as to the best mode of transporting oysters and
clams long distances. Perfect shells should be selected, and they should be packed
with the front edge downward and kept moderately cool in a crate or some such
receptacle which will allow a free circulation of air. Under such favorable condi-
tions selected oysters can doubtless be kept from eight to twelve weeks out of water.
So far as is known, Professor Verrill's suggestion has not been fol-
lowed by shippers, who seem to have no difficulty in making shipments
to distant points.
Oysters are usually transported in barrels or sacks. To far inland
or transcontinental points shipment is made in refrigerator cars. In
the transportation of American oysters to Europe the same method of
packing is followed, and they are carried in the cold-storage chambers
of the vessels.
Several devices for locking the oysters, so as to prevent the gaping
of the valves and the escape of the fluids, have been patented, but
they do not appear to be in extensive use at the present time.
It is stated by some dealers that oysters which have been "plumped"
or "fattened" stand shipment better than those which have not been
subjected to the process.
The oyster, of course, can not feed during the period of its depriva-
tion from water, and to maintain its vitality it makes draft upon its
own tissues and gradually becomes poorer in quality. As the vital
activities are apparently reduced at such times, the waste of tissue is
small.
NOTES ON CLAM-CULTURE.
Owing to the importance of several species of clams as food for man
and as bait in tbe line fisheries, it is deemed desirable to append a
few facts relating to them and to their culture.
Two species are in common use upon the Atlantic coast, one of them
also being an introduced species upon the Pacific coast. The quahog,
hard clam or round clam {Mercenaria mercenaria)^ is perhaps the more
important. It is the "clam" of the markets of New York, Philadel-
phia, and southward, and it is also utilized to some extent in New
England. It is a heavy-shelled form living on the nmddy bottoms,
principally below low- water mark, where it is taken by means of rakes
or by the process of " treading out,'' the clammer wading about and
feeling for the clams with his toes and then i)icking them up by hand
or with a short rake.
The long clam or mananose {Mya arenaria) is the principal sjiecies in
the markets north of New York, and, on account of the comparative
lightness of its shell, is often called the "soft" clam. This species was
introduced on the Pacific coast with oysters brought from the East,
and has now become widely distributed there and an important food
product. It is found principally on sandy shores or in a mixture of sand
and mud, between tide marks. Its long siphons permit it to burrow
to a considerable depth, and it is dug from its burrows by means of
spades, stout forks, or heavy hoes or rakes.
The soft clam appears to be the only sjiecies which has been the
object of attempted cultivation, although no doubt the quahog is
equally favorable for the experiment.
In Chesapeake Bay the. soft- shell clam spawns from about September
10 to October 20. The eggs are of about the same size as those of the
oyster, and in their early development pass through practically the
same stages. At the end of the free-swimming stage the clam is still
very small. It settles to the bottom, but instead of becoming attached
to shells or other firm bodies in the water it soon burrows into the bot-
tom until it is completely hidden with the exception of the tips of the
siphons, throngh which it derives its supply of food and oxygen from
the currents of water induced by the action of cells provided with hair-
like processes (cilia). Upon very soft bottom the young clam, like the
young oyster, is liable to become sufibcated in the mud, but as it grows
339
340 REPORT OF COMMISSIONER OF FISH AND FISHERIES.
larger its powers of locomotion, which, though limited in degree, persist
throughout life, enable it to extricate itself.
Owing to its free-living habit, the methods in use for catching oyster
spat can not be utilized for the growing of seed clams. Although so
far as known no successful attempt has been made to obtain clam spat,
it seems probable that a moderately soft bottom naturally devoid of
clams could be made available by covering it with a coating of sand of
sufficient depth to prevent the sinking of the young during the early
stages after it falls to the bottom. Later in life they are better able to
care for themselves.
In certain places the planting of seed clams has been attended with
some success, as is shown in the following account:
Quite an interesting feature in connection with the clam fisheries at Essex, Mass.,
was found in the shape of clam-culture. In 1888 an act was passed by the legislature
authorizing the selectmen of the town to stake off in lots of I acre or less each of
the flats along the Essex River, and let them to persons desiring to plant clauis for a
rental of $2 per acre or lot for five j'ears and an additional fee of 50 cents. Thus
far 37i acres have been taken up and seeded witli clams. Small clams are dug on
the natural beds and planted on these hitherto uuiiroductive flats. About 500
bushels are required to plant an acre properly. During the first two years (1889 and
1890) the people were slow to avail themselves of the privilege of planting for fear
that after they had spent their time and labor they would not be al)le to secure i)ro-
tection from trespassers. But in 1891 and 1892 lots were obtained and planted.
The principal difficulty encountered has beeu the loss of the clams by the sand
washing over them, the bottom in some localities being soft and shifting. In 1892
there were 25 acres that wore quite productive, about one-third of the entire catch
of the section being obtained from them. The catch from these lots is not definitely
known, but is estimated at al)out 2,500 barrels.
The cultivated clams possess some advantage over the natural growth from the
fact that they are more uniform in size and are as large as the best of the natural
clams. They bring $1.75 per barrel, while the natural clams sell for $1.50 jier barrel
This is the price received by the catchers. One acre of these clams is considered to
be worth $1,000 if well seeded and favorably located so as not to be in danger of
being submerged with sand. This valuation would be too high for an average, since
all the acres are not equally well seeded and located. The clamraers are generally
impressed that the industry can be extensively and profitably developed, and their
only fear is that they will not be able to secure lots i^ermanently. The greater part
of the land available for this purpose is covered by the deeds of i)eople owning farms
along the river, and the consent of the land-owners has to be obtained before lots
can be taken up. It seems probable, however, that the business will continue to
l)rogress unless checked by complications that may arise relative to the occupancy
of the grounds. — Report U. S. Fish Commission, 1894, iip. 139. 140.
It was hoped that these planted clams would propagate on the new
beds, but the exi^ectation has not been realized, owing, no doubt, to the
unsuitableness of the bottom, a fact which would also account for the
absence of the si^ecies in the first place.
The growth of the soft clam is quite rapid, and Dr. Eyder has shown
that at St. Jerome Creek, Maryland, the shells reach a length of between
1^ and 1§ inches within several months of the time of spawning.
Fish Manual. (To face page 340.)
Plate V.
FIG 1, INNER FACE, AND FIG. 2. OUTER FACE OF SHELL OF TYPICAL AMERICAN OYSTER.
From Fourth Autmal Report, l*. S. Gfolofjical Survey.
Fish Manual. (To face page 340.)
Plate VI.
Fig. 1. Upper view of clcsed valves of I'acitii- oyster. Ostrcd lurkla.
Fig. 2. Inner face of ventral valve of .same specinieii
Fig. 3. Outer face of ventral valve of same specimen.
Fish Manual. (To face page 340.)
Plate VII.
Fig. 1. Unfertilized egg shortly
after mixture ot spawn and milt;
spermatozoa are ailherinf^ to the
surface.
Fio. a. EgK after fertilization.
Fig. .3. Same ey;g --i minutes later.
Polar body at broad end.
Fig. 4. Same egg (> minutes later.
Fig. 5. AlKHit t5.J hours later.
Fig. fi. Another egg at about the
same stage. Mass cf small cells
growing over large cell or mae-
romere n.
Fig. 7 Egg ."j.'i mimites later. Mac-
roinere almost covered by small
cells of ectoderm.
Fig. 8. 6ptical section of egg 27
hours after imi)reguation, show-
ing two large cells, derived from
(/ m tig ti, <-overed by a layer of
small ectodermal cells.
Fig. 9. Egg a few hours older.show-
ing large cells viewed from below.
Fig. 10. An egg somewhat older
viewed from above, showing fur
ther subdivision of large cells as
seen throuirlu-ellsof ui)per layer.
Fi(i. II. An older >'tiSi- now become
flattened from above downward.
Viewed in optical section.
Ki(i. 1-' .Surface view of an embryo
just begiiming to swim.
After \V K. Rrooks.
Fig. 13. Optical section of same.
Fig. 14. Surface view of same from
another position.
Fig. 1."i. Surface view of same from
another ixisition.
Fig. hi. An older eml)ryo in same
position as in tig I"J
Fig li. A still older embryo show-
ing sjiherical ciliated digestive
cavity opening by mouth, m.
Fig. IK. An embryo with well-de-
veloped larval shells, older than
tig. 1, Plate VIII. ;-.s, right .shell;
/.S-. left shell; i7, velum; m,
mouth.
Fish Manual. (To face page 340.)
V,
Plate VIII.
am
Flfi. 1. View of right side of embryo about (i days uM. m. iiiouUi; r. vent; /, rifjht lobe of liver; vt, vchi;ii.
1- iG. •^. (Jlder larva of European oyster, Ustrca liiiidd. L, shell; h. hiuyre; r.s- ami ri, retractor iiuiseles of
the velum, li; s. stomach; /, intestine; aiti. larval adductor muscle: h. lioily <'avity. ( )ther letters as in
the preceding.
Fig. 3. Altaclied spat of Ontrea viryinica. •S', shell of spat with larval shell. L, at the beak or umbo; 7;,
palps; g, gills; c, diagrammatic representation of a single row of cillia extending from the mantle border to
the mouth m: 1; radiating muscle fibres of mantle; t. rudimentary tentacles of mantle bordei-; .U, perma-
nent adductor muscle: C. cloaca: re and an. ventricle and auricle of the heart: .'/. i)osterior extremity of
the gills and junction of the mantle folds. ( )ther figures as above. Compare this figiu-e with I'l. 1, fig. ].
Fig. 1 after W. K. Urook ;. Fig. -i after Thomas H. Huxley. Fig. 3 after John A. Ryder.
Fisn Manual. (To face page 340 )
Plate IX.
SET OF OYSTERS ON RACCOON OYSTER SHELL, SHOWING CROWDING. NATURAL SIZE.
Fish Manual. (To face page 340.)
Plate X.
OYSTER SPAT TWO OR THREE WEEKS OLD ON INSIDE OF OYSTER SHELL.
NATURAL SIZE
Fish Manual. (To face page 340.)
Plate XI
OYSTER SPAT ABOUT TWO MONTHS OLD, ON A STONE. NATURAL SIZE.
Fish Manual. (To face page 340.)
Plate XII.
FIGS. 1, 2, AND 3, OYSTERS ONE, TWO, AND THREE YEARS OLD, RESPECTIVELY. NATURAL SIZE.
(imwii nil liarcl liottmn in Long Islainl .Sound.
Fish Manual. (To face page 340.)
Plate XIII.
1t^ If
FIGS. 1 AND 2, OYSTERS FOUR AND FIVE YEARS OLD RESPECTIVELY. NATURAL SIZE.
Grown on liard bottom in Long Island Sound.
Fish ManOal. (To face page 340 )
Plate XIV.
Fig. 1. PHOTO-MICROGRAPH OF THE DIATOM. SURIRELLA GEMMA, ENLARGED ABOUT 1,600
DIAMETERS.
The tip of the frustule is alone piven. to indie ite the character and texture of the glassy surface.
Fig. 2. FOOD OF SOUTH CAROLINA OYSTER A FEW TYPICAL ORGANISMS ( x 225>.
Numbers 1 to 20 are diatoms.
1-."). Xavicula (BoryV
6. N. didyma(K.>.
7. Pinnuiaria radiosa (?) (K. S.).
8. Amphora sp. ( K.)
9. Pleurosifrma faseiola (E. S.).
10. P. littorale iS. >.
11. P. stri(josum (S. i.
12. Actinocyclus uudulatus (K.).
1.'^. Coseinodiseus radiatus(E.).
14. Cyclotella rotula (E.).
1.5. Synedra sp. (E. ).
Ifi. Diatoriia sp. (l)e C.V
17. ("jMiihella sp. iAj:->-
18. Masto(.'loia sniithii (Tliw. i.
19. Triccratiiitii alteriians (Br.
Bai.).
20. Biddulphia sj). ((Jr.).
-'1. drain of phu- ])ollen (Pinus
ritcida i.
2-i. Foraiiiinifera (Rotalia).
'£i. Zoiispore i I'lva '/l.
24. S])ioules.
(After Basliford Dean.'*
Fish Manual. (^To face page 340.)
Plate XV.
SOME ENEMIES OF THE OYSTER.
Fig. 1. Drill. friixft^jiiH-c fi-H*fi^t.
Fig. •>. .Mussel. Mi/li/un cduliis.
Fig. ;i. Sabiilnrio rtilgnri.<i.
Fig. I. I'eriwiiiklc. Fiilf/iir cwica.
Fish Manual. (To face page 340.)
Plate XVI.
fD
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Fish Manual. (To face page 340.)
Plate XVII.
BUNCH OF OYSTERS FROM GREAT POINT CLEAR REEF SHOWING GROWTH OF MUSSELS AND
BARNACLES.
From Bulletin U. S. Fish Commission, 1895.
Fish Manual. (To face page 340.)
Plate XVIII.
MATERIALS FOR CULTCH.
Fl<i. 1. '• QiiarliT-ilcckcr." Cri piiliiln funiii'iitd. Kl<;. •'). Tlii' siuiic. lower Milr
Fk;. 2. '■ Qiuirtcr-dcckcr," Cnpidiild pl(uiii. Kk;. (i. i^callop, I'n-ti n ii-nnliiiini.
Flu. 3. "Quiirtfr-iU'ckcT," Crfpididti omvij-n. Fi«. 7. Oystor attached to pebble.
Fk;. -4. Jingle, Aiioiiiia <ilnbm. i)r()(ile view.
DATE DUE
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OCT 2 4
1S96
DEMCO 38-297
3 1197 00553 6047
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