ae : * as oe : zy a eat \ uit Heel hy ‘ U. S. COMMISSION OF FISH AND FISHERIES, JOHN J. BRICE, Commissioner. MANUAL OF FISH-CULTURE, BASED ON THE METHODS OF THE UNITED STATES COMMISSION OF FISH AND FISHERIES, WITH CHAPTERS ON THE CULTIVATION OF OYSTERS AND FROGS. Extracted from U. 8. Fish Commission Report for 1897. Pages 1 to 340, Plates 1 to 62 and I to XVIII. WASHINGTON: GOVERNMENT PRINTING OFFICE. 1897. “A MANUAL OF FISH-CULTURE, BASED ON THE — METHODS OF THE UNITED STATES COMMISSION OF FISH AND FISHERIES. PREPARED UNDER THE DIRECTION OF JOHN J. BRICE, UNITED STATES COMMISSIONER OF FISH AND FISHERIES. TABLE OF CONTENTS. Page Imtro diction= seme see ee Sen eee eae eee en eee ene 5-6 ithe Salmonsroteuhesbaciie | Coastasssee ese eee eee eee 7-26 The Atlantic and Landlocked Salmons. ......-.........---- 27-70 AMOR LRH Hal AKO aed BE ROMOL Rees hea cies Pr epee mes a SL SA 71-89 DheyBrooksLrouibsss2 see sos See Sees ee aoe See oe 91-101 Thesvakeulro mts cooaerecec eee ve Seas eee wel ae ete ne eee ne OS =, ABO NA OUR Te) TIS) ert Saat a ae are reer a ee ee ed Mee Tae ah AM oven Shak i0 eee eae Ans Se mene aa ree he ae se a we ee Ae eee Tee liats The Black Basses, Crappies, and Rock Bass..-...........-. 159-177 Miscellaneous Fresh-Water Fishes.....................--.. 179-191 Minor routs/and ithe Grayling 22a) 22220 see ee 179 Lake Herring and other Whitefishes .--..-.......-..... 180 Musikkelilmm ge o25 52 361s oi22 fects enw de ee s see eee 181 Vellow, (Perches oe See Lich ets etic se ee ees 182 SiripedeBassandanjhitesPerch®esa=-s eee se eeeeeee sees 185 ING ARYES. Ow Ihyeie Ielepebveyss 655565 Gace boos coon cocuse 186 SHG. coat deen Gbooo sre denon des okesaasanoenioboaooccoD ed 188 Goldenthdere se: cscessccce nee samsise = see reece eee 188 SINMODHEEOUS SSo Gan Soaqda co decons Gancad GonCOS FeSose naoouE 189 Wing) Oil ss6dac cans so cadecses céee cs ceases sodeoses susaassoes GREAT herC omnton-Mackerela: << =a saememeeee see se asa ee 209-213 ihe Mattsh or Winter hloundersseees.- oss lomo Miscellaneous Salt-Water Fishes ....-...-...---....----.-- 219-227 ARINIDYS co psc Agodes oabecu soo ooo case Seas Sou S So ueeceo He 219 Spanish ‘Mackerel 3-322 5.2 seen ee eee eae pee 220 Haddock, Pollock, and other Gadidew .----.-.---.-.---- 222 (Ciba? Soe eo eke sen cons naeoco co ceoeso coKond oomoaseeosce 223 SIGDI)) tooo omeueouo cone eaneoo ss Choo accocesu uaad beso esse 223 SCH) BACB eee eee enSMEmS « Sono SaoouBonsdodeEeEEacode 223 SOMO EA AWS) SESE GoGo obo bood 5655 SasuHe coOd Saude ee eee 224 Sheepshead 5 a. 5 ssc2/s5 ct) eee eee eee eee eee 224 NOAMELOTTIN Oot. 2c) ous Sl siae geen ee ee seetere ea eens 225 Sand-dab and Four-spotted Flounder. ....--.-----.---- 227 MreyAmerican Mobster.) se caaseeee ares ce ee ene ee eee 229-238 The Transportation of Fish and Fish Eggs.-....--....--.- 239-244 Spawning Seasons of Fishes Propagated, Character of Fish Hers Period of Incubation, bC-s-52- emesis sos eee eee 245-247 Notes on the Edible Frogs of the United States and their Mriniclal Propagabion=s>.. -ss.ess-66 4s eee eee eee eee 249-261 Oysters and Methods of Oyster-Culture..........---.------ 263-338 INotessons@lam-Culture ss 22. oss foe eee eee eee 339-340 LIST OF ILLUSTRATIONS. Plate To face number. page Clackamas (Oregon) Salmon! Staion ep ater alain alole olelamial=lale ello ele l)al=lalaiel=le lal ==lal=i= le l=) l-1=)=)=|olnlaleleialelsialater 5 2. Figure of a Fish, showing the parts usually referred to in Descriptions ---....-.------.-..-.- 6 3. Oncorhynchus tschawytscha. Quinnat Salmon; Chinook Salmon; King Salmon ......-..---- 7 4. Oncorhynchus nerka. Blueback Salmon; Redfish.....-...-.-...-------.-----------2e02--ee0e 11 5. Oncorhynchuskisutch. Dog Salmon... - =... 05-2. oo owe enn ww wn ww ee wn ew nnn ws 13 Gwsalmorgarrdners. Steelheady =.= = omen aia amin == aim mlm am alain = mia lolli =m amma elm eel ale el mialel lol 13 7. Rack for stopping ascent of Salmon at Battle Creek, California..-.---..------...--.--------- 15 8. Engine-house and Hatchery at Baird; Current-wheel and Piers for holding Rack..........- 19 9. Current-wheel for pumping water at Baird, California ..-.- Fvael-l a tcleiniss siseeeein sae eiciiecisceee 21 10. Interior of Hatchery at Battle Creek, showing Salmon-basket -.-...-..----.-.--------------- 23 11. Pens for holding ripe Fish, and Stripping Platform at Battle Creek, California............... 25 iB. Staiimne Sadia, Ne WATO Spun Soceco secon senso co dunode casesccongaouNHHObSoSonbosSLDaEaOESSS 27 VOWS Of Dead ebrookinclosure tor SALMON saat cles ee aen=lniniaiel= am oie ae larelelamieineietaelaialals alae 31 14. Salmon Live-car used in transporting Fish. Live-cars en route with Fish...-..............- 33 15. Salmon Rearing-troughs, Craig Brook Station, Maine ..............-..----------------------- 43 16. Examining Fish for stripping. Stripping Female Salmon.......-..--............----------- 45 17. Packing Salmon Eggs. Picking out dead Eggs. Handling Egg-trays .............---.-.--- 51 18. Fungus on Salmon Egg. Fungus on Salmon Egg, bearing Reproductive Organs. Reproduc- Tie Orezins OF Iam INTO E DK ep s5odooSSsdobdecqecceso docu asb oa sb deHencosoondeaTosdsccssadad 63 19. Taking Spawn of Landlocked Salmon at Grand Lake Stream, Maine .............--....---.- 67 As (SHO CICRES I SENbal xO? AUHO Doon 5 coos ab donsensedeededEsodgede co cuaDoooseaDooReanoSeccaode 71 21. View of Wytheville Station, showing Breeding Ponds, with Hatchery in the paskevound: Boot 13 OP, VS ENV ALLNG? 120) 116 ee peop nc SECCOH AAS OSSOEe CoGu EO ONE rE Se POSS CEC Sen COMGRenesEALane dasrac ASSCheESEsGe 74. 23. Interior view of Wytheville Hatchery, showing men picking out dead Eggs.-.--.--.-....... 77 2st Rront Rearane-pondsab Wry thevalle! Sbabionls 2-5 s/o \smacisetan ase nie Sas “sesso celola sacle steele (eee 79 29)_ INSERT SS NDOT soso eon ocosedons ands ac docs es cocd ne noseseononcs Hasse nosocUSscons seas Sossee se 81 ZOMPSCIVEIIUUS ONTUILALUS a Lhe Brooks“ UnOUbepeeiaclne waar cena elaine seis seie nee seine ae meee ae 91 Zim ErOut He onds;“North valle; Michio anteaters ieee ea yerelaisle ce atal==isie nisin sin eisisie vie cicieieleln eine sec os seis sieicice ae 93 28. Selecting and stripping ripe Trout, Northville, Michigan ........-.......----..-------------- 95 2 niLerlOolavlews OfeNoLthivallesMabch enya a mists =m een mien leinn ieee eta eae eene ene 97 30. Removing green Eggs from Shipping-trays. Packing eyed eggs, Northville -.-.....-.....-- 101 DIEMORUSHUGMET. NAMAY CUS. lu AKO LOU is aejeme-eisiceineiee oie se eleicie sine ces eae aceon eens 103 32. Collecting lake-trout spawn on fishing steamer in Lake Michigan ......-......-....-----..-. 105 33. Coregonus clupeijormis. (Conimon Whitefish) .- =<. 2----ssece cen --5 n-ne eee ences eae So 119 Sil. SUT ONS ey Wy LU co soo ccs oose ce sasdrcocsadge esas sas SsooSoosEobsoacodooUoScoCODEoSDEBESe 122 DD VO WEO Ls banleryatorhabC Himes Went bONS Wyrm meee =m llsere eee =e em eines ete select eae 127 SORPALOSOASUDULUSS LIL. COMMONGS NAG te se se elae sala sees eee saeie cee = oe cielo eitnine enema mine cia 133 37, 38, and 39. Plates showing the development of young Shad..............----.--------eee---e- 136 40. Main deck of steamer Fish Hawk, equipped for hatching Shad ---.....-.....------..-------- 143 41. Interior of Hatchery at Battery Station, equipped with Hatching-jars.........-.-----..-...- 151 42. Battery Station Hatchery. Fish Commission car loading fish at Neosho ...-.....---..------ 158 43> Macroptenus saumovdes., uarge-mouthe Blacks Bass\-s-.--e- ne = =t so cee eon eee cine eeeee 159 44. Micropterus dolomieu. Smaill-mouth Black Bass ........--..----------------- eee cece eee eee ee 159 Aa ONLO LUN CIUMLULLONES On CLAD DIO wana aaa ea ateniseetaisiae ala wine isiee'ns sinicie sleeisinre Sosieeis seinem cee Sete 163 46. Pomoxis sparoides. Calico Bass; Strawberry Bass ..---..-----2------------- cee w een e ec eee ese 163 AT PAUIEOLODLUCES TLD CSLTUS>. INOC KS DAS St seietse saan seit nial = Sa seie eee ics oe a cine ee wa caieeGeececeeecs 163 Ase bass ange Lrout ond s at Neosho pMissOUnl ssh os= see eo ee ee sae see ee cee oo cee eee eee 167 AOS Basspeonds; at, Samy Marcos wmexagnecncmecc staan mes scc2 as ncecee see sec ce ececnc ccckecicsceec ue 173 HO MISUUILOMNUY USS ab laACk-SpoubedeLnOlbseeere eee ence setene eccrine create ane erieeeacee esceecene 179 5I. Argyrosomus artedt. Lake Herring; Cisco........------------2+e.eee--- ence sce cance ss shss 181 DUE LOMSICOMLONLAS sn COM sa nameniae amen asin ccc seine seis nace sate Hotta weet ceisisee catisear yaieeerisceuce 193 Doe SUL PINS © OGL ON VieSSe Mineman seieciaslscioece sels see mee cic eincle sss eee eee cisimomese aes secisccise 196 a MC LOMCESTOL SLAULOM Ae sie ries ke eaten el anicinis/s sien se cle sme mininaae sacle vccinnemeiews tsleisseensanemelec’ 198 Do Eoolforneraiminey brood Huish atwwWiOod S| HOl Os saree sere seis erie seineiseciee so miclsincin os - Sha 5 SoCs Soe poses Sereens. ESSSSSSSST SSS ee a ed Scale of feet. Saas Ones Wire Filter. 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 PLATE 15. (To face page 43.) Report U. S. F. C. 1897. SN IVA ‘NOILVLS YOON HIVYD ‘'ANNOYOYOVE NI SWOVYYVE GNV SONSGISSY HLIM 'SHONOML-ONINVAY NOIWTVS EES Bee GEOG: MANUAL OF FISH-CULTURE. 43 elapse between the cleanings. The wire—even galvanized—rusts out in two or three years, and lately the coarser screens have been made of slender rods of oak, which will undoubtedly prove more durable. None of the filters described will intercept the finest sediment, and the water is finally passed through a capacious wooden reservoir, 30 feet long, 8 feet wide, and 54 feet deep, before it reaches the troughs. This answers the purpose well for the amount of water supplied by the filter last described (about 500 gallons 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 in the lower part of its course many copious springs. This spring water has some advantages, but possesses the serious disadvantage of such high tem- perature in winter as to unduly hasten the development of the eggs, causing them to hatch early and necessitating shipments of eggs in 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 open waters, 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 quickly through that most difficult of all stages of growth. The aqueduct is about 1,600 feet long, with a bore 44 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 water per minute, which is sufficient for the development of 4,000,000 eggs, and possibly 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, 1895, to April 1, 1896, the mean tem- perature in the hatchery was 36.65° F. 44 REPORT OF COMMISSIONER 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 November 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 September, 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 influences 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 floor 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 wont 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, affording sufficient 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 Canadian rivers the dates are buta little earlier. Thus atthe Gaspé hatchery, in the Province of Quebec, in 1894, the work of spawning began October 10 and closed November 2. « : ; Asda cay Report U S. F. C. 1897. (To face page 45.) PLATE 16. Ripe fish. Not ripe. STRIPPING FEMALE SALMON. MANUAL OF FISH-CULTURE. 45 fish are laid for measurement. At the front is a narrow table, on which the eggs are washed; and at the rear the entire side of the room is occupied 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 pan holding about 10 quarts, which has been rinsed and emptied but not wiped out. A female salmon is dipped up from one of the floating pens and brought to the operator, who seizes her by the tail with the right hand and holds her up, head downward. If unripe, the fish 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 operation has apparently 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 the record therefore shows large numbers of salmon from 29 to 31 inches in length, weighing, including eggs, from 9 to 12 pounds, and yielding 23 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 16,000 to 20,000 eggs. As soon as the spawn 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 difficult to secure a good result if the eggs lie in too great 46 REPORT OF COMMISSIONER OF FISH AND FISHERIES. masses. The eggs are passed over to the washer, who repeats the Swaying and the shaking, and, having 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 abnormally small, and sometimes all have defects which render them incapable of fecundation. But among the thousands that have been manipulated 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 fish. 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 924 per cent down to zero. From a fish that had been dead 2 MANUAL OF FISH-CULTURE. AT hours 4,400 eggs were obtained, of which only 584 per cent were capable of fecundation. In one instance eggs taken from a dead fish and kept until the morrow before milting remained so far in normal condition that 124 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 eges 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, 874 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 experiments show that if eggs are merely covered by water, without effort to secure intermixture or the washing off of thé 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 period. 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 property 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 period. Prolonged exposure to the milt has been found to affect the health and development of the embryo unfavorably. 48 REPORT OF COMMISSIONER OF FISH AND FISHERIES. TRANSFER OF EGGS TO THE HATCHERY AND THEIR CARE. From Dead Brook 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 precautions some of the eggs are occasionally killed, though the trays are placed in pans of water and the eggs poured from the spawning-pans 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 124 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 buoyancy 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 4 inch wide and ? inch deep answers the purpose well, provided the wire be not very light. The corner pieces are 4 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 4 inch in diameter. Rusting 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-pans,” and the interior surfaces of the troughs themselves. Material subject to rust should be used only with great caution. Wire or other metallic forms galvanized with zine 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 eae so to warrant the extra expense is a qhasdan. In developing eggs, in order to economize room, the trays are piled up 10 or 20 deep in frames that contine them only at the corners and do not hinder the free passage of water horizontally through the ‘‘stack.” About 2,000 Atlantic salmon eggs are placed on a single tray, and a trough of the ordinary length, 105 feet, therefore carries 140,000 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 ina very plain trough which can, with a few minutes’ work, be transformed into a réaring-trough for young fish. For 10-tray stacks the trough is made of pine boards, 123 inches wide and 9 inches deep inside, and is set up level, with the top about 30 inches from the floor of the room. MANUAL OF FISH-CULTURE. 49 The water is fed into one end 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 an eighth of an inch above it. Fig.1. ta =e ce) Tr Ta r 7 ue fo) ip — Ww b wm Ss Ss Ss Ss a Te Ae Scale of feet. 2 2 Sere ty VICTIM LLL LL Lh hhh LL ‘4 Trough Arranged for Eggs. Fig. 1, plan. Fig. 2, longitudinal section. a, supply-trough j, down- spout. u, screen. b, screen. r, cleats. v, outlet. d, supply-pipe. s, stacks of egg-trays. w, wooden dam. J, egg-trough. t, waste-pipe. 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 offungus. It depends, to a considerable extent, on the water tempera- ture; the water at the beginning of the spawning season varies from 50° to 55° F., and maintains a mean of 43° to 45° F. during the month 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. F.C. R. 1897——4 y I IALULELELSOALESREYO ASSET, i Y 50 REPORT OF COMMISSIONER OF FISH AND FISHERIES. It is possible, by placing 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-picking 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 up 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 and 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. OMT, Wer ten y pion Th Se. PLATE 17. Report U. S. F. C. 1897. (To face page 51 ) Qs | g . ee y, HANDLING EGG-TRAYS. MANUAL OF FISH-CULTURE. ol The latter procedure 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 impregnated, 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 TRANSPORTING. 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 perish. 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 24 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 placed in the bottom of a packing-box. A little fine 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 completely envelops them. Next 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 sufficiently 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 packing. 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 will 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 much below the freezing-point. Salmon eggs packed as above commonly go a three days’ journey without completely melting the snow that was sprinkled 52 REPORT OF COMMISSIONER OF FISH AND FISHERIES. under the eggs, and on several occasions eggs of landlocked salmon have been carried across the Atlantic in prime condition, without repacking or special attention. The packing-boxes are made of thin pine or fir, 12 inches wide and 15 inches long—#-inch thick boards being used for the end pieces and 4-inch for the other parts—and hold in a single layer, without crowding, 2,500 eggs. The deepest are 34 inches deep and take four layers, or 10,000 eggs, ina box. To make upa shipment of 40,000 eggs, four boxes are piled up and secured together by tacking strips of wood against the ends, with a cover on the upper box, and this package placed in the case. Fora shipment of 80,000, two of the 40,000 packages are put side by side in a larger case, and the proportions selected for the inner boxes are such that the case required is of convenient form. Weve x Be PAC fees Fg ( 4 3 aan 0 a tone 2 = Emp . : a eee Sea Se 2, RID DLN. & SH APTI Longitudinal 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 for 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 the 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 light, and the best nonconductor known, with the possible exception of asbestos. It is used dry in the outer packing, 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. De: HATCHING. As the time for hatching draws near, the eggs are placed on trays provided with legs or some other support to keep them up from the bottom of the trough. Brass nails driven into the under sides of the tray rims are good temporary 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 another. 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 hatching 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 hatch 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 about 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 fish are liable to be drawn through the meshes. ; : THE SAC STAGE. When the shell breaks, though it has been coiled up in a space less than 4 inch in diameter, the trunk of the newly hatched salmon at once straightens out to a length of about 2 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 companions 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 fins assume form and become more effective as organs of propulsion. At last his digestive system 54 REPORT OF COMMISSIONER OF FISH AND FISHERIES. assumes its functions 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 heads 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 erevice 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 42 inches deep on the screen. RCE < SWANN Atlantic Salmon, recently hatched. 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, Huropean 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, when they are mostly liberated. To a limited extent they are kept in artificial ponds, 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 the most part. Hach 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 plays 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, compels the constant use of covers to keep out vermin; and wooden covers in pairs, running the whole length “MANUAL OF FISH-CULTURE. 55 of the trough, hinged to its sides, and, when closed, assuming the form of a roof at an angle of 45°, were finally adopted. These covers are made of thin boards, 3 inch thick, sawed in narrow pieces, which are put together so as to leave in each corner two cracks open 4 inch wide for the admission of light when the covers are closed. When open they may be fixed in an upright position, thus increasing the height of the sides and guarding against the loss of fish by jumping out. Fig. 2 Cc Ly ae El rl i ar | © ao i: ~ abe . 4 / Hed sau: [es RoE: ] VN i NPS FS FR PSS RS PAIS SSS SSeS oS RASS See SSS HSS Pees > | N ZANT Ni SZZLZZZZZZ IA ZEEE OTT MN a ia ie [=] a El aes Fig.3. c Cc 9 9) ay u | q. eee eZ ti SSS SSS —— aa Scale of feet. o = z 3 Troughs arranged for Rearing. Fig. 1, plan. Fig. 2, longitudinal section. Fig. 3, cross-section near foot of trough. Fig. 4, inlet, with rocking gate. Fig. 5, elevation of lower end. a, supply-trough. i, hollow outlet plug. b, screen. j, down-spout. c, rocking gate. k, supports. d, supply-pipe. 1, cover. ' e, water-board (to spread the water and throw it down). m, Cover open (hanging). J, fish-trough. n, cover open (upright). g, gripe, to prevent spreading of sides. p, cover closed. h, outlet screen. q, 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 14 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. 56 REPORT 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 heads against a long feed-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 4+ inch square mesh, answers the purpose 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 the sole dependence, were it not that the labor attending their cleaning would be greater than that required by a separate filter or screen. Conduit to lower level. Scale of feet. + ipper, level ' £ Frlet q pallor SAN iS = Feed-trough, t Va Stand of Troughs for Rearing Atlantic Salmon. The system represented here by 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 supplies more water than the upper series of troughs can use, the surplus passes by way of the “overflow” directly to the catch-trough 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. 57 into conduits leading to ponds where larger fish are kept; but a stand of 100 troughs has lately been set up with the design of using all the water twice; and for many years there has 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°, 76°, 76°, 76°, 74°, 74°, 74°, 749, 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 temperature between 50° and 71° F., averaged only 56.1 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 by the former proprietor, 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 1in 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 or3 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 water, 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 in 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 be safely increased. While the greater part of the salmon reared at Craig Brook are liberated in October, when about seven months old, in 1891-92 about 16,000 were carried through the winter, most of them in tanks sunk in the ground, and nearly as many have been wintered some other 58 REPORT OF COMMISSIONER OF FISH AND FISHERIES. seasons. Fish may also be kept all winter in troughs in the open air by occasionally spreading 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 folowing manner: A large number of them are dipped 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 water 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 24 to3 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 1896 being 45.8 grains. Salmon reared in ponds have been far more thrifty, their general average in 1896 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 tosses 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 been 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 larvee, 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 steelhead trout during the season of 1896. All the fry of this species that were devoted to rearing were fed in troughs until July 22, when some of them were transferred to a pond which has an area of about 1,100 square feet and another lot was.kept ina trough. The two lots were fed exactly alike, about one-sixth of their nutriment being liv maggots, and five-sixths chopped meat, liver, and other butchers’ offal. November 7, the lot in the trough was overhauled, and the 762 survivors found to weigh 10 pounds 4 ounces, or an average of 94 grains. Three days later the pond fish were 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. Leaving out of the account the difference in depth, in the pond there were less than 7 fish to each square foot of area, while in the trough, which had an area of about 11 square feet, there were to each square foot 69 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 each. Those of the same age, reared in troughs, attained during the season only a weight of 1363 grains each. MANUAL OF FISH-CULTURE. 59: flour, and middlings. The butchers’ offal comprises livers, hearts, and lights, which are collected from the slaughter-houses twice or thrice weekly, and preserved in refrigerators until used. The flesh of old and worn-out horses has been used each year since 1892 in the same way as the butcher’s offal, with 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 production 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’ offal 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 afford 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 diffi- 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; thelarve 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. 60 REPORT OF COMMISSIONER OF FISH AND FISHERIES. When young salmon or trout first begin to feed they are quite unable to swallow full-grown maggots, and small ones are obtained for them by putting a large quantity of fly spawn with a small quantity 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. Maggots are produced and used in considerable numbers, sometimes as many as a bushelina 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 alive 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 partly overcome by putting it away in boxes, after the visits of the flies, and covering it with pulverized earth. Only flesh-eating maggots have yet been tried, and the trouble may possibly be rectified by culti- vating the larvee 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 large 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 beén occasionally gathered with nets or dredges in the lake close to the station and opened with knives and chopped. 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 slower in the 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 larvie, collected trom 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 larve (or pup) were strained out and fed to the fish. No kind of food has been MANUAL OF FISH-CULTURE. 61 more eagerly devoured, and apparently no other food has contributed more to the growth of the fish; but the time expended in collecting is out of all proportion to the quantity of food secured. Perhaps a series of breeding-tanks arranged in proximity to the fish-troughs, into which the water containing the larve might be drawn when desirable by the simple opening of a faucet, would reduce the labor involved. Middlings and flour 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 composed 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 experiments. They had been empty during the preceding winter, and in the spring were fertilized with various sorts of animal and vegetable tefuse. They were stocked with different species of crustacea native to the region, including shrimps (Gammarus) and entomostraca, of the genera Daphnia, Ceriodaphnia, Sida, Cyclops, Polyphemus, ete., 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 inducing continuous or frequent reproduction of them, and the young fish soon exhausted. the supply. 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 maggots—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 the 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. AIl meats fed directly to the fish are first passed through a chopping-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 such fish as are carried through are fed but once a day. CLEANING THE TROUGHS. 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 brush, but after the first few weeks the brush has rarely to be used 62 REPORT OF COMMISSIONER OF FISH AND FISHERIES. except to rub the debris through the 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, although 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 153 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 theroad. 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 death of many embryos, they are by no means always fatal. In 1896 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 b, 59 per cent; of lot c, 43 per cent. In the fall they were PLATE 18. (To face page 63.) Report U.S. F. C. 1897. FUNGUS ON SALMON EGG, (Enlarged 9 times.) FUNGUS ON SALMON EGG, BEARING REPRODUCTIVE ORGANS. (Enlarged 9 times.) REPRODUCTIVE ORGANS OF EGG FUNGUS. (Enlarged 150 times.) MANUAL OF FISH-CULTURE. 63 \ all weighed, and it was found that lot ¢ had made a slightly better growth than lot a. One of the most uncontrollable diseases attacks salmon fry midway in the sac stage, and finishes its work before the complete absorption of the sac. The most evident symptom is the appearance 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 have been from 1 to 9 daily, will show 17 dead on the 23d, and five days later 360 die in a single day. In 1890 this epi- demic attacked especially the fry of Atlautic salmon, destroying about a third of them; it also destroyed many landlocked salmon, and some other species 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—some 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 Saprolegnie, and probably to the genus Saprolegnia, one species of which, S. ferax, is noted as the cause of very destructive epidemics among the adult salmon of Scotch and English rivers. 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 envelcp in its threads a great many of the living eggs surrounding it. Itis by no means certain that all such growths belong to one species or even to one genus, but they are much alike in structure and growth and live upon animal and vegetable matter, either as parasites attacking living Inatter 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 consequence of neglect of the duty of picking out the dead eggs. An instance of its attacking a living egg except by reaching out from a dead oneis unknown. Fish 64 REPORT OF COMMISSIONER OF FISH AND FISHERIES. several months old are sometimes afflicted with a similar growth, which may possibly be not the original 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 fungus 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 fungus 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 cent of spring water. The fish had suffered considerably from the handling 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. Nine 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 where 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 places. 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 6 feet, so that there was practically no protection from the rays 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 compared with those now in use; they had been transported a long distance and passed three separate locks and had finally been hauled in a tub on a cart over rough ground from Alamoosook Lake to the inclosure. MANUAL OF FISH-CULTURE. 65 The conditions at Craig Pond, where some of the worst cases recov- ered, were these: An area of 231 acres; a maximum depth of 69 feet; exceedingly pure and transparent water, like that of the inclosure. At two of the other inciosures 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 depth 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 spores 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 upon and into the living tissues around it, which it seizes upon and destroys. Growing upon a dead egg, it not only ensnares the neighboring living eggs, but sometimes pierces their shelis 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 Savrolegnia 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 Saprolegnia 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 and 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 almost the last vestige of varnish. F. C.R. 18975 66 REPORT OF COMMISSIONER OF FISH AND FISHERIES. The 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, which, while 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 saltin 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-water, about 1.028 specific gravity. The fish are left 1n this 20 or 30 minutes, unless they exhibit uneasiness, and then 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 supply, 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 precautions 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 pouring 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, sandpiper, and fish- hawk, besides frogs and all large fishes. At Craig Brook the mink has caused serious loss in the ponds. As a protection some of the ponds are covered with galvanized poultry netting, and traps are kept constantly set in the avenues by which it 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 suspected 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, Report U.S. F. C. 1897. (To face page 67.) PLATE 19 ES Ee TAKING SPAWN OF LANDLOCKED SALMON AT GRAND LAKE STREAM, MAINE. THE LANDLOCKED SALMON. The landlocked salmon was formerly regarded as specifically distinet from the seagoing form, but it is now generally considered only a vari- ety. The fish found in Sebago Lake and other localities in the United States is known as Salmo salar sebago, and the Canadian form as Salmo salar ouananiche. From the fish-culturist’s point of view, however, 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 migratory instinct is at the bottom of most of the variations from the normal type of Salmo salar which the landlocked salmon exhibits. The lakes afford a far poorer feeding- ground than the sea; hence, perhaps, the diminutive size and leaner flesh of the landlocked salmon. Its lower tone of color, less permanent sexual marks, and greater liability to ovarian disease, as well as differ- ent habits of feeding, may perhaps be referable to the same general cause. There are some other peculiarities, however, 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 and more slender than the anadro- mous Salmon, but its flesh 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. 67 68 REPORT OF COMMISSIONER OF FISH AND FISHERIES. The natural range of the landlocked salmon in the United States is much restricted. Leaving out of the question the salmon formerly frequenting the rivers tributary to Lakes Ontario and Champlain, the extent of whose migration is a matter of doubt, we find them only in four limited districts, allin the State of Maine, namely, the Presumpscot River (including Sebago Lake) in Cumberland and Oxford counties, the Sebee River (a tributary of the Penobscot) in Piscataquis County, the Union River in Hancock County, and the St. Croix River in Washing- ton County. There are some minor differences between the fish of these several districts, of which, perhaps, that of size is most notable. The Sebago and Union River fish are much larger on the average than those of the Sebee and St. Croix. The Sebago salmon average at the spawn- ing season 4 or 5 pounds weight for the males and a pound less for the females, while specimens of 12 and 14 pounds weight are not rare, and there is a record of one of 174 pounds. The Union River fish are about the same size. “The St. Croix fish vary in the matter of weight in different 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. The hatching station at that place was operated continuously from 1875 to 1892. Since 1892 the station has been closed and the propagation of landlocked salmon by the United States Fish Commission has been conducted at Green Lake station. 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 Grand Lake on the Schoodice 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 a 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 summer without some provision for an artificial supply of food, which would probably invoive a great deal of expense and troubie. More- MANUAL OF FISH-CULTURE. 69 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 eatch 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 inclosure 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 spacious inclosures, 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 three 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 Salmonide. The results in the impregnation of the spawn are not so uniformly satisfactory as with sea salmon. There appears to be a greater prevalence of ovarian disease than among the migratory salmon. The occurrence of white eggs among the normally colored and healthy ones as they are yielded by the 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 95 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 unfavorable circumstance is well counterbalanced by the facilities for aeration, which are very good and very fully employed. 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, March, and some- times 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. 70 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 Grand Lake, mainly in the affluents. Great Brook, the largest tributary, is most resorted to, and on this stream is located the station of the United States Fish Commission. 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 the bed of the brook, are numerous pens of the same material 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 isthe hatchery. The hatchery is supplied with water from Rocky 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 off 14 degrees in passing down this flume; in warm weather it warms up 14 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 the Schoodic station, among the adult wild salmon caught for breeding each year are many more females than males. in 1889 the proportion was 3 females to 2 males; in 1893 it was9to4. 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 maies the same year averaged 5 pounds in weight and 22.3 inches in length; one female weighed 11 pounds 9 ounces, and measured 30 inches; another, 11 pounds 6 ounces in weight, was 304 inches in length; one male, 31 inches long, weighed 13 pounds 8 ounces. The number of eggs yielded by the females is about 4,000 each. Report U. S. F. C. 1897. (To face page 71.) PLATE 20. SALMO IRIDEUS. Rainbow Trout. Upper figure adult male, lower figure immature fish. THE RAINBOW TROUT. DESCRIPTION OF THE FISH. The body of the 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 Salino, 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- tinetly 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, with 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. Itis especially abundant in the mountain streams of California. A few specimens, however, have been taken in salt water, and it is not unlikely that some find their way through the rivers into the sea. The species is subject to considerable variation in form and color in different parts of its range, and the following varieties have received recognition by ichthyologists: The brook trout of western Oregon and Washington (Salmo tirideus 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 (Salmo trideus shasta), 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 trideus gilberti), which attains a weight of 8 pounds, and is found only in Kern River, California; the noshee or nissuee trout (Salmo irideus stonei), which inhabits the Sacramento basin, and reaches a weight of 12 pounds; the golden trout of Mount Whitney (Salmo irideus aqua-bonita), which inhabits streams on both sides of Mount Whitney, California. | 71 (2 REPORT OF COMMISSIONER OF FISH AND FISHERIES. In the extensive section of the West in which the fish abounds its name varies in different localities; ‘red sides,” ‘mountain trout,” “brook trout,” and ‘golden trout,” besides “rainbow trout,” are some of the popular appellations, while in the States east of the Mississippi River it is generally called “rainbow trout” or “California trout.” TRANSPLANTING. The rainbow trout has been successfully transplanted in many of the 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 introduced 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 py the brook trout (Salvelinus fontinalis), 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 therefore suited to many of the now depleted streams which flow from the moun- tains through the cultivated lands of the valleys. Rainbow trout differ widely from brook trout and other pugnacious fishes, in that they feed principafly upon worms, larvee, 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 abun- dant, as they will then grow more rapidly and become accustomed to life in the stream; and when worms, larve, ete., are no longer to be found, their experience and size will enable them to take a minnow or anything that may present itself in the shape of food. In the Eastern States 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 fish hatched in December and January can safely be planted in April and May. On the Pacific slope the fry may be successfully liberated at any time after the umbilical sac is absorbed. 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 Hast is probably less than a pound, but some weighing 6? pounds 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 PLATE 21. (To face page 73.) Report U. S. F. C. 1897. ns ‘GNNOYOMOVE SHL NI AYSHOLVH HLIM ‘'SGNOd ONIGSSYS ONIMOHS ‘'NOILVLS ATIASHLAM 4O Ma&IA ES ce P ee LES cn OR Se SK eS Yj peor — an PPS OT a MANUAL OF FISH-CULTURE. 13 Same State, where the water becomes moderately warm in summer and food is plentiful, they reach 12 or 13 pounds, fish of this size being from 25 to 28 inches long. In the Au Sable River, in Michigan, they attain a weight of 5 to 7 pounds. In their native streams of California they are often caught ranging from 3 to 10 pounds, but average from 1to2 pounds. The largest specimen ever produced in the ponds at Wytheville, and fed artificially, weighed 64 pounds, but many others in the same ponds weigh from 1 to 3 pounds. The average growth of the rainbow trout under favorable artificial circumstances is as follows: One year old, from 3 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, temperature of water, and extent of the range. In water at 60°, with plenty of food, fish 1 or 2 years old will double their size several times in a single season; while in water at 40°, with limited food, the growth 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° EF. in summer, and in selecting a site for a trout hatchery 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. 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 may be able to handle them without delay or inconvenience. At Wytheville they are constructed entirely of wood, about 15 by 50 feet and 3 to 33 feet deep, and shaped as shown in plate 22, and have been found very satisfactory. Excellent water circulation is obtained in all parts, and there are no corners for refuse to lodge in. The bottom of the pond 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 off 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 fish, which is very important, especially when near the spawning time. 74 REPORT OF COMMISSIONER OF FISH AND FISHERIES. A guard-rack made of thin, narrow slats is arranged on an incline of about 45°, 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, H, 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 IF), 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 approach 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 sufficient depth to bring its surface within 6 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 depth 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 apples 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 fer the support of the fish, 16 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 25, 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 estimating the capacity of \ \ Vg j sae: as aN HS Wane ea hee eS SAC boy touas ee8 i ae pe f Ue we 4 iN a Ue MANUAL OF FISH-CULTURE. 75 a pond several modifying conditions must be considered, such as the size of the fish, water supply, temperature, and shade. 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 THE 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 fish are kept confined in spring water. In the ponds at Wytheville the spawning fish may be found any time after the Ist of November; the season is well started by November 15, and generally closes about the Ist 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 nests, and may then be taken out and stripped of their spawn. To take the fish from the raceway, a square net (I, plate 22) 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 alanding-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. Bythe ‘ wet” method the eges are taken in a pan containing sufficient water to cover them and allow them to mix freely with the milt, 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 now in 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 the pan be thoroughly mixed. After the eggs and milt have had time for contact, 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 76 REPORT OF COMMISSIONER OF FISH AND FISHERIES. is poured off and clear water is put in the pan, in which the eggs 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 hatchery 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 freezing 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 fish without injury is a very delicate and exacting task, full knowledge of which can only be acquired by experience, as it is difficult to squeeze 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 same 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 easily turned over _ as itis 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. tINGH FALL Scale. ‘ Feet Section A-B: SMM LM MUM S Upper figure showing view from above. Lower left-hand figure: End view showing hatching-jar in position. Lower right-hand figure: Cross- section showing the drain-pipe and trough in center of table. WS i H ! 1 i oo Shad-hatching table. The jars are arranged on tables, as shown in the cut. From a large iron pipe, branch piping of 14 to 2 inches diameter is run over each table, where +-inch brass pet-cocks are inserted 6 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. 150 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 3.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 cup is set at the proper height to control the water level in the collector-tank. Long-handled nets of ;2,-inch mesh are required to remove egg lumps 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 — in whitefish and the shad upon a =< Vi << scale unprecedented in the his- tory of fish-culture. Millions wll fo 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 ib 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 prevents, the . spores of the fungus from ad- 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 consists of a cylindrical glass vessel, of 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 t Se @ a Automatic shad-hatching jar. Report U. S, F. €. 1897. (To face page 151.) PLATE 41. MOO OS: INTERIOR OF HATCHERY AT BATTERY STATION, EQUIPPED WITH HATCHING-JARS. MANUAL OF FISH-CULTURE. 151 the metal plate, admits the glass tube which carries off the waste 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 stuffing-boxes provided with gum-washers and binding-screws. The central or feed tube is provided with stuffing-boxes, one on the top of the disk and one on the bottom, the better to hold it to a true center. The outlet tube is provided with only one stuffing-box, and the binding- ring is beveled. In preparing the jar for work the side tube is fitted first. The 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. Serew 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 may be required. Glass | tubes can not be | procured 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 fall but a short distance, and no fish scales or other foreign matter should enter the 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. The requisite number of eggs, . 80,000 to 100,000, being in the jar, it is put in position and closed, : eare being taken that both the inlet and outlet tubes slide freely in their stuffing-boxes. If the tubes become gummed, let water trickle 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, 152 REPORT OF COMMISSIONER OF FISH AND FISHERIES. thus expelling all the air from the feed-tube; otherwise it would rise in bubbles, throwing a portion of the eggs out through the outlet-tube. With a proper quantity of semi-buoyant eggs in the jar and the water turned on and regulated, the movement of the current estab- jishes a regular boiling motion in the mass of eggs, which brings each in succession to the surface. This motion may be regulated without altering the quantity of water. By loosening the upper binding-screw of the central stuffing-box, and pushing 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 placing 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 exposed to bright sunlight, when they will hatch in five or ten minutes. If the connection of the jar must be broken, it is essential that the rubber feed-tube does not drop down and siphon the eggs from the jar. MANUAL OF FISH-CULTURE. 153 In reconnecting, the air may be expelled with the metal top screwed down in position. To effect this, draw both glass tubes up to the top 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 separation of bad from good eggs, though some days may be required to accomplish the full result. The dead 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 6 to 10 days, sometimes longer, according to temperature of water, but with high temperature they will hatch in 5 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 0.57 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 0.62 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 Ist, 4 to 44 inches; November 4th, 5 to7 inches. Some years they grow faster than others, ‘and in some streams more rapidly than in others. From the State fish- ponds at Raleigh, North Carolina, 53 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. MEASURING THE EGGS AND FRY. To estimate the number of eggs and of the young fry was for years rather a difficult matter to accomplish satisfactorily. The standard made use of at the outset was undoubtedly much too high. Thescale most used at present is a light square, made of wood, the longer leg being 15 inches and the shorter 74 inches long. The material is $ inch wide and 4inch 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 stopped at the lower end that it may displace an amount of water equal to the amount of eggs it will displace in 154 REPORT OF COMMISSIONER OF FISH AND FISHERIES. practice. Hach line on the measuring stick registers 7,000 shad eggs. The number of eggs in a liquid pint is established by actual count. Those 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 other pointing downward and touching the side of the jar. The number is indicated on the scale at the point opposite the surface of the bulk of the eggs. Searcely any semi-buoyant eggs die, under proper conditions, after hatching out has commenced, and a close approximation 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 theegg. 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 to16 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 wg ape left the egg. At about the middle of the second Application of a measur- week considerable may be seen, but the intestine ing scale toa jarofshad jg then not often very densely packed. At the eet 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 young 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 EISH-CULTURE. 155 was added to from day to day for nearly a week, when it was brought up to 1.018, or the same specific gravity as the 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 days. 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 off 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 6-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 off 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 60 per cent are held safely until about October. Rearing has been experimentally tested at Wythevilie and Neosho with good results. At Neosho on the 35d of June, 1892, 700,000 fry were received from Gloucester, N. J.; their growth was satisfactory. In preparing 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 6-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 pass 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 kept in vessels with smooth surfaces, preferably tin-lined cans. Zine 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 65°, though in rivers and ponds the fry endure a temperature of 90° F. _ As early as 1874, experiments were carried on to retard the develop ment of eggs, in order to provide a longer period between the delivery 156 REPORT OF COMMISSIONER, OF FISH AND FISHERIES. of the eggs from the parent fish and the absorption of the yolk-sae. Eggs, when transported, were placed on trays and put under melting ice, and 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 tlannel trays (ordinary air temperatures) to hatch. It would appear that 55° to 53° is the lowest temperature in which “ova will safely undergo their normal development and 9 days is the longest period of incubation attainable at that temperature—time suffi- cient, when added to the several days required for the young to absorb the yolk-sac, to ship them to Hurope, which has so far failed. One drawback is the rapid development of fungus, which grows over the eges, penetrates the membranes, and kills the ova. Retardation of the hatching of shad eggs has not been turned to practical account, buteggs can be transported hundreds of miles on trays, large numbers being moved at a relatively small expense com- pared with the same number of fry. Eggs from the Potomac River are sent to Washington, a distance of 12 miles, by steamer, and nearly a mile over cobblestone streets in Washington. Formerly they were put on the trays soon after being taken, but in April, with night air-temperature as low as 49°, and in June, with the relatively high temperature, the quality was bad; they did well between 60° and 65°, and later they were put into hatching- vessels and kept in motion 12 hours, when they became hard, and went forward in better condition. Since 1888 they have been retained in hatching-jars for 36 hours preceding transfer. They 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 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 ~ MANUAL OF FISH-CULTURE. Gon usually spread two layers deep, but can be put on morethickly. When eighteen trays are filled they are wrapped in the outer cloth, previously soaked in water, and tightly buckled together. The crate covers and tray cloths are boiled in water each time after use. ae Hach tray—14 by 19 inches area, with two layers of eggs—holds about 20,000 eggs, the contents of a full crate representing from 300,000 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. TRANSPLANTING. The propagation of shad is mainly earried on to maintain or increase the supply in rivers where the species is native, and the fry are liber- ated with that end in view; but the shad has also been planted, in some cases with great success, in waters in which it was either unknown or found in small quantities. Large numbers of fry have been liberated in- tributaries of the Gulf of Mexico, but without marked results. Between 1875 and 1892 several million fry were experimentally placed in the waters of Great Salt Lake, Utah Lake, and Bear Lake, Utah. From 1884 to 1886, 3,000,000 fry were liberated in the Colorado River at the Needles, in Arizona. It was believed that the shad would be per- manently confined to the Gulf of California by the warm water of the lower part, and would then return to the Colorado and Gila rivers to spawn. The time having gone by when the adults should return, the experiment is regarded as without result. It has been found that the shallow waters at the mouth of the Colorado River are barren of life and the conditions are unfavorable to stocking that river with shad. Remarkable success attended the stocking of waters of the Pacific Coast northward from Monterey. 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 Fish Commission made a second deposit of 35,000. Subsequent plants in the Sacramento, aggregating 609,000, were made by the United States Commission from 1876 to 1880. From these small 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 coast from southern California to southeastern Alaska. The shad rapidly made their way up the coast from San Francisco Bay. They reached Rogue River, Oregon, in 1882. In the Columbia a few were taken as early as 1876 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; and in the Stikine River, near Wrangell Island, Alaska—latitude 56° 30’—the same year. The species now is found along the entire coast from Los Angeles County, California, to Chilkat, Alaska, covering 22 degrees of latitude. Its distribution, considered from the standpoint of commer- cial importance, is from Monterey Bay to Puget Sound. 158 REPORT OF COMMISSIONER OF FISH AND FISHERIES. On the northern part of the coast the first fry were introduced in 1885, the number being 60,000. Of these, 50,000 were put in the Willa- mette River and 10,000 in the Snake River. In the following year 850,000 were introduced into the Columbia River, making a total of 910,000. The increase has been uninterrupted and rapid in California waters, and the shad is now one of the most abundant fishes of that State. As a result of the liberation of the first two consignments, consisting * of 45,000 fry, several thousand mature shad were caught in 1879, and sold in the San Francisco market. 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. Up to 1883 the increase was marvelous. Prohibitory law did not prevent their incidental capture in salmon nets, their abundance being thus indicated. The shad is most numerous on the west coast in San Francisco Bay and its tributaries. It is not common above Sacramento, owing to the low water-temperature. In the Columbia it is regularly found as far as the Cascades, about 150 miles above the mouth of the river. Contrary to their habit in eastern rivers, shad are found in the rivers tributary to San Francisco Bay and the coastal waters of that vicinity throughout the year. Report U. S. F., C. 1897. (To face page 158.) PLATE 42. BATTERY STATION HATCHERY, HAVRE DE GRACE, MARYLAND. U. S. FISH COMMISSION CAR LOADING AT NEOSHO, MISSOURI. Report U. S. F. C. 1897. (To face page 159.) \ \ He a A\ aT STH: WY a th TH ipa } AL) i! oe STH wae Th Wi Tee ANNI ! Kt NE i" ii " BEA N\ we i isl th x Sue Fae LE VE eae eras py HA is : BH gE se eile ADOC, ae oe \_I AFR ISS (=(=) Lapa PIGS eee AAR Spateesourss See PLATE 43. MICROPTERUS SALMOIDES. Large-mouth Black Bass. Report U. S. F. C. 1897. (To face page 159.) PLATE 44. MICROPTERUS DOLOMIEU. Small-mouth Black Bass. enn Se EES ey 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 sunfishes) which have come under the scope of fish-culture, namely, the large-mouth black bass (Micropterus salmoides), the small-mouth black bass (Micropterus dolomieu), the rock bass (Ambloplites rupestris), the crappie (Pomoxis annularis), and the calico bass (Poxomis sparoides). 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 physical 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 crappie 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 34 in body; eye 5to 6 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 oblique stripes across opercle and cheek; dark blotch on opercle. Small-mouth black bass: Similar in form 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 spines and 13 to 15 rays; anal with 3 spines and 12 0r13 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 bronze 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 ; . 159 160 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 24 in length; eye large, one-fourth length of head; head long, 3 in length; profile with double curve; mouth large, snout projecting. Scales on cheeks in 4 or 5 rows; scales in lateral line 36 to 48. Dorsal fin smaller than anal, with 6 spines and 15 rays, the spinous part the shorter; anal with 6 spines and 18 rays; dorsal and anal fins very high. Color silvery white or olive, with mottlings of dark green; the markings mostiy on upper part of body and tending to form narrow, irregular vertical bars; dorsal and caudal fins with dark markings; anal nearly plain. Calico bass: Similar in form to crappie, but the body shorter, back more elevated, and profile of head straighter; depth, 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 6, 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). Rock bass: Body oblong, compressed, back moderately elevated; depth 2 to 24 in length; head large, 2% in length; eye very large, 34 in head. Scales 5-39-12, in 6 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 ali 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 welchman. 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 in the mountain sections of Virginia, Tennessee, and North Carolina) trout perch, brown trout, jumper, mountain trout, together with other names of purely local use. Rock bass are variously known as red-eye, red-eye perch, afd goggle- eye, and are sometimes confounded with the warmouth (Chenobryttus gulosus), which bears some of the same common names. MANUAL OF FISH-CULTURE. 161 The calico bass has received the names of strawberry bass, grass bass, bitter-head, barfish, lamplighter, goggle-eye, goggle eye perch, speckled perch, and speckled trout. The crappie is known in its native waters as crappie, new light, campbellite, sac-a-lait, bachelor, chinquapin perch, croppie, and cropet. On account of the similarity of the calico bass and crappie, anglers and fish-culturists have frequently confounded 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 ‘“‘ jumper,” which is applied in certain parts of Kentucky. That both species of the black bass are jumpers is well known to every angler, but it is better understood by those who have had occasion to collect these fishes by seining. It is almost impossible to capture them witha Seine rigged in the ordinary manner, especially when the fish have the vitality and activity which is usual when living in water of moderate temperature. Like other fishes, they lose in strength and activity when they inhabit warmer waters. 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. In seining for brood stock it is well to employ a seine about three times the depth of the water, as the bagging or bellying of a seine so rigged confuses the fish and deters them from jumping. On one occasion, when collecting black bass on the Holston River, advantage was taken of their jumping habits to effect their capture. A flatboat 12 feet wide and 50 feet long was procured and in suitable places was rapidly poled broadside from one bank to the other. As it approached the further shore the bass would leap from the stream and frequently land in the boat, the gunwale of which was cut down to within 4 inches of the water. One bass was seen to clear the entire width of the boat, making a horizontal jump of 14 feet. A marked characteristic of the rock bass is their habit of settling down in dense, compact masses, resembling a swarm of bees, which is especially true of the young in cold weather. They 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 pond- culture, and under proper conditions will repay the culturist in a large crop of young with the expenditure of very little labor and time. ‘The calico bass is a fairly game fighter, and its firm, white flesh has a fine flavor when the fish is taken from cool, pure waters; but it is a very delicate fish to artificially propagate. 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 farge numbers collected and transplanted in new waters many have flied within a few days after being deposited. The spawning and breeding habits of the calico bass and the crappie are so nearly like those of the rock bass that special remarks on the subject do not appear necessary. TO) OL IR, ileeye— ala 162 REPORT OF COMMISSIONER OF FISH AND FISHERIES. GROWTH AND WEHIGHT. There is a wide difference in the rate 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 ot the same school. The average size of adults varies in different localities, and sometimes will be found to vary from year to year in any particular locality. The variations depend upon initial vitality, upon the scarcity or abundance of food, and upon the range and space given the fish. At the age of 5 or 6 months the young bass measure from 4 to 8 inches, according to locality and surroundings, though a certain percentage of the crop will alwaysrun large. In 1892, at Neosho station, a black bass, which was positively known to be under 18 months old, weighed on the scales 1 pound 94 ounces. Large-mouth bass have been known to weigh 23 pounds. They are not infrequently taken from the San Marcos River, Texas, weighing from 12 to 15 pounds, and a 6-pound or 8-pound bass in the southern tributaries of the Mississippi and in the inland lakes of Florida excites no surprise. The small-mouth bass does not grow so large, 24 pounds probably exceeding their average size, though they occasionally reach 5 or 6 pounds. The rock-bass fry grow slowly, those 6 months old seldom averaging 2 inches in length. The adult usually weighs from 4 to 3 pound, occasionally reaching 1 pound; and examples have been reconded 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. Under like conditions of pond environment, at 6 months old the young 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 natural range of the large-mouth is from the Great Lakes and the Red River of the North to Florida, Texas, and Mexico, and west to the Dakotas, Nebraska, and Kansas. The small-mouth bass ranged formerly from Lake Champlain to Manitoba, and southward on both sides of the Alleghanies to South Carolina and Arkansas. The adaptability of these fish to extremes of temperature and their great tenacity of life under seemingly adverse conditions has rendered their distribution comparatively easy, and they have been successfully intro- duced 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 United States Fish Commission. In three years they became so numerous in Utah that 30,000 pounds were caught and marketed from one lake. nt Ne 2 x +A: en Report U. S. F. C. 1897. (To face page 163.) PLATE 45. Sue f I I I “Zane : im UM HANNS Tacs 5 > ee ve Th ti POMOXIS ANNULARIS. Crappie. Report U. S. F. C. 1897. (To face page 163.) PLATE 46. Strawberry Bass. ’ ’ POMOXIS SPAROIDES, Calico Bass Report U.S. F. C. 1897. (To face page 163.) PLATE 47. AMBLOPLITES RUPESTRIS. Rock Bass. MANUAL OF FISH-CULTURE. 163 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 Commis- sioner of Fisheries of Virginia, adult black bass were moved from the Roanoke River across the divide to the New Liver, a tributary of the Kanawha. Up to 1875 the Kanawha contained no bass, and its edible fishes consisted 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 successfully stocked with rock bass by the Virginia Fish Commission, the fish being brought from Holston River, a tributary of the Tennessee in Washington County, Virginia, in June, 1876, and deposited in the smaller tributaries of New River, in Montgomery County, Virginia, whence they have colonized the entire New River basin. Few fish thrive in water of such varying extremes of temperature as the large-mouth black bass, and, to a certain 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 fre- quently prove fatal. The small-mouth 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 under these conditions, but numbers live for months and some possibly for years. Those from hot, stagnant waters, however, have a soft, flabby flesh, and are apt to be infested with parasites; they spoil quickly and are not palatable. Bass do not voluntarily seek such unfavorable surroundings, and their presence there is attributable to accident. The bass found in the Mississippi valley under these conditions have been left by the 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 the depressions of the land. The surroundings are generally 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 1s native to certain streams on the east side of the Alleghanies. It has been successfully introduced into many new waters. In its native waters it is found in the winter months under ice, and stands a high summer temperature, 164 REPORT OF COMMISSIONER OF FISH AND FISHERIES. though not so great as the black bass. The highest temperature to which it has been subjected at Neosho is 88°. The transportation of this species would indicate that it suffers 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 of the middle South stained by decaying vegeta- tion, the rock bass thrives better in clear, pure 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 it is sometimes taken in the Great Lakes region. The calico bass is said to demand a higher temperature and clearer water than the crappie, but this is not certain. 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. They are voracious and pugnacious, and devour other fish almost indiscriminately. The food of the adults comprises crayfish, minnows, frogs, tadpoles, worms, and mussels, and the young feed on insects and other minute forms of life found in water. At times both the large-mouth and small-mouth bass refuse the most tempting bait, and at other times they bite 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 afford perhaps the highest type among fishes of parental care and watchfulness, guarding their young until after the dispersal of the school of fry; but a large part of the young, so zeal- ously protected early in the season, at a later date furnish food for adult bass, possibly their own progenitors. As with trout, bass of the same school of young vary in size, and the larger prey mercilessly upon the weaker, often attacking their own kind 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 great part of the bass caught, however, never reach 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, 1s very great. MANUAL OF FISH-CULTURE. 165 Ten years ago it was said that black bass did not exist in sufficiently large numbers to ever become a staple article of food, but they now furnish important additions to the food supply of many thousands of people. The annual sales in New York are estimated to be at least 50,000 pounds, with an average value of 10 cents per pound. Possibly because of the abundance of whitefish and lake trout, Chicago does not seem to afford as good a market for bass as other large cities. A recent estimate places the sales of all the bass handled by wholesale dealers of Chicago at 15,000 pounds, but these figures are probably too low. The Illinois fishermen ship nearly 50 tons of black bass to the markets annually, and it is a reasonable assumption that Chicago con- sumes a very large part of the production of the surrounding country. The States in which the black-bass fishery is most important are North Carolina and Ohio; in 1890, over 400,000 pounds, valued at $20,500, were caught for market in North Carolina; in Ohio, in 1894, 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 annual catch of crappie for market, according to recent statis- tics of the United States Fish Commission, is. about 850,000 pounds, having a first value of $39,000. The leading States in this fishery are Arkansas, Illinois, Minnesota, Missouri, 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 much more largely into commerce. 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-CULTURE. The artificial propagation of black bass, by taking and impregnating the eggs, has not been, up to the present time, practically successful. Unlike the shad and salmon, eggs can only be stripped from the female with great difficulty, and it has been necessary to kill the male to obtain the milt. Another obstacle is the difficulty of finding the two sexes ready to yield the eggs and milt at the same time, even when they are taken from over the: nests apparently in the act of spawning. Inter- ruption or handling seems to prevent the discharge of eggs or milt. At Neosho unsuccessful efforts were made daily for several weeks to Spawn a female black bass in which a part, at least, of the ovaries were fully developed. The fish 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 way to artificially impregnate the eggs of the bass has not yet been discovered, 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 166 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 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-culture necessary and the second render it possible. The methods hereafter described are those in use at Neosho station. ARTIFICIAL PONDS FOR REARING BASS. The size of Spawning-ponds is controlled, to a certain extent, by cir- cumstances. Small ponds which are long and narrow, with the inlet I 75 “a VY SUPERINTENDEN N FD FESIDENCE — =a SCALE OF FEET. 100 50 () 100- 200 = 300 400 . Plan of Neosho Station, showing shape and depth of ponds, with location of hatchery aud superintendent’s dwelling. at one end and the outlet at the other in the line of the longest axis, produce the best results, as the strength of the current can be better controlled, and the whole pond regulated under the scrutiny of attend- PLATE 48. (To face page 167.) ‘Report U. S. F. C. 1897. LORY) Ce ‘IUNOSSIN ‘OHSOSN LY SGNOd LNOYL ANY ssva 2. Rie LO MANUAL OF FISH-CULTURE. 167 ants from the shores. Large ponds furnish wider range, and this is desirable when fish are raised for market, but large spawning or nursery ponds are not recommended; and if the object is to produce large quantities of young for distribution in new waters small ponds are undoubtedly better. At least one-fourth of the pond should be not over 1 foot in depth, and this portion should be planted with pond-weed (Potamogeton) and water-weed -(Hlodea or 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 remainder of the pond should have a gradually sloping bottom, and consequent increase of depth to the kettle (or draw-off), where the water must be at least from 3 to 6 feet deep for the warm Southern States, and 12 to 14 feet deep for the Northern States, to provide against the danger of freezing. In the middle third of the pond water-lilies should be planted, preferably those having the largest pads, such as the Nymphea alba; these plants not only furnish the breeding fish a hiding-place from fish-hawks, but serve as sunshades during the summer. It isnot usually advisable to place large bowlders in the ponds, as they are in the way of seining or netting, and furnish an acceptable resort for crayfish. When the young, under the guidance of the parent fishes, are school- ing, they may be collected from the nests and deposited in waters to be stocked, or transferred to nursery-ponds. These ponds should be constructed to afford young bass protection from enemies and to produce the greatest quantity of insect life suited to their sustenance, and this is better accomplished 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 difference between the temperature of the shallowest part of the nursery-pond and the surface water of the other. As in all other ponds for fish propagation, the supply and discharge for each nursery-pond should be independent of any other, and the bottoms be made to slope toward the “kettle.” The young large-mouth bass is not a strong fish, 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 pile or otherwise 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 projecting above the ground. The pond should be supplied with the aquatic plants previously mentioned as desirable for the shallow parts of the spawning-pond. A plan has been suggested, which combines the features of a spawn- ing and nursery pond, by constructing one comparatively long pond, 168 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 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 4-inch wire cloth, which will confine the spawners to the deeper end of the pond, ayhills the fry, following their instinct of moving upstream, will find their way through the screen into the upper, Shallower end. This method would apparently not only save much labor in transferring the fry, but obviate the risk involved in handling them. If it is desired to hold the bass until they attain their fal growth, the fry are transferred to troughs or pools where they are reared in a purely artificial manner—that is, tamed and trained to take prepared food. For this purpose modifications in the shape and arrangement of the spawning-pond are necessary, somewhat as described above for the combination pond. The shallow part near the inlet has a long, narrow neck and the general shape, where the ground permits, follows the outline of a gourd. That part which resembles the handle is screened off from the remainder with wire netting, with a quarter-inch or less mesh. The young fry, after the dispersal of the school, seek the shal- low waters, which, warmed by the sun, at this time of year afford rich pasture of Cyclops, Daphnia, young Corixa, and other small invertebrates. Following the natural inclination of young fishes to head toward the source of the water supply, they pass through the screen and collect within the neck of the pond, where the food supply will be found to be greater than around the margin. From this part of the pond the fry have no inclination to retreat, and the parent fish can not follow and devour them. TROUGHS. The ordinary horizontal trough in general use in trout-culture is well adapted to raising young bass fry. A trough 12 to 14 feet long with 4 inches depth of water at 57°, changing 2 gallons per minute, will sup- port from 3,000 to 5,000 black-bass fry, and twice or three times as many rock bass will live comfortably under like conditions. For bass of larger size, fingerlings and upward, vats or pools answer better than troughs. The troughs can be so arranged that the water discharged from them furnishes the supply for one or more pools. The shape, size, and number of the pools must be regulated by the topography of the land, though they should not be wider than 6 feet, nor with a depth of water greater than 2 feet, and either lined with plank or built of brick or stone. Wire netting or guard-boards, projecting 1 to 14 feet above the ground, prevent the entrance of snakes and other enemies. As with all ponds, provision is made to entirely empty one pool without interfering with the water supply of another, and to have a good fall from inlet to outlet. The length of the pool must be regulated by the lay of the land, and, if long, it is advantageous to divide the pool into sections, with movable screens of wire cloth for convenience in handling several sizes of fish. MANUAL OF FISH-CULTURE. 169 The same general care and cleaning usually given to troughs con- taining trout fry is necessary in cultivating bass. . The trough is swept down twice a day and occasionally washed inside with a cloth, and the water supply, conduits, and outlets frequently 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 56° F. will thrive two months later with the temperature at 86°. However, bass grown in very high temperature are exceedingly tender, and can not be handled and transported until the approach of fall and winter has gradually reduced the temperature and so hardened them. Moreover, under such conditions they are more liable to attacks of parasites, both external and internal. While bass can live in water ranging from 33° to 98°, more moderate limits are desirable. The Cyclops and some other of the natural forms of food for young bass reproduce best at a temperature between 68° 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 off in the autumn, thus leaving the beds exposed to the combined action of sun, winds, and frost. This tends to kill out the larvee 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 crayfish holes. There is no danger of the lime injuring the fish the following vear, as lime-water is more beneficial than harmful, and the _ process purifies the pond-bed, besides killing the crayfish and the like. In addition to the yearly wintering, 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 mosses. Scraping large ponds and hauling the accumulated muck involve considerable labor and expense, possibly more than the yield of the pond warrants, and in some cases it is advis- able, once in four or five years, to lay the pond 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 pond level, and during the process should be carefully picked over, as some of the fry will be found among it. Wading into the pond 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 either end of 170 REPORT OF COMMISSIONER OF FISH AND FISHERIES the boat is a ring through which a stake is driven at the point in the pond to be worked. The vegetation is raked from the water in small lots, and. unloaded on the banks with a pitchfork. Itshould be promptly removed from the bank, as it will rot very fast and its presence is objectionable. 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 fish, sometimes working in company and sometimes sepa- rately. The nests are ordinarily built in gravel, brushed into neat circular piles 18 inches to 3 feet in diameter, and are usually found in water from 18 inches to 3 feet deep, though not infrequently in much deeper water and sometimes 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 smalJl flat heaps about 4 to 6 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; but if gravel of suitable size is to be had the bass usually select it, and no matter how dirty it may be, or how overgrown with moss and algve, they clean it with the caudal fin and tail until it is as bright as if every particle had been polished with a brush, often using the head and mouth to remove the larger stones from the nest. On the Mississippi River and in Texas, however, black bass have been observed to deposit their eggs on mud. 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 Neosho 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. Many of the wounds on the trout at spawning time are due as much to fighting as to the wear and tear of nest-building; and the bass also are hard fighters. The proximity of the nests to each other depends on the size 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 Commission, having only 108 square feet of surface and containing 30 adult fish, there were 8 nests. If the nests are placed near the banks, in water from 18 inches to 3 feet deep, the entire process of spawning and incubation is easily observed and the fry can be more conveniently secured and transferred to nursery-ponds at the proper time. 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 MANUAL OF FISH-CULTURE. 171 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 disturbances at the time of spawning which would at other times alarm them. Artificial nests for bass have been devised, which should give increased results in the number of fry saved by simplifying the trans- fer of fry to nursery ponds and eliminating the risk of handling with nets. The artificial nest is a wooden box about 20 inches square, with sides 21 inches high and slightly flaring outward. Cleats are nailed SN RRS ~ QQ ow WN Le VL DNs OG ty iy ti. > ME, Uf tig “MME, Yip /. LEE Stl Fig. Ve, Se Y Ty Ss Artificial Nest for rearing Black Bass (perspective and sectional views). on the side for convenience in handling. Coarse gravel is placed in the bottom of the box and the remaining space filled with fine gravel, flush with the top of the box. The top layer is sufficiently fine not to allow the eggs to fall through the spaces and mix with the large gravel underneath. The nest, thus completed, is placed in an excavation with the upper edge even with the bottom of the pond. A stake is driven near the nest and a board fastened to it to afford seclusion and protection from the sun and enemies. A round pottery nest, about the same size, with a rim sufficiently high to retain the gravel, is also used. Shade is 172 REPORT OF COMMISSIONER OF FISH AND FISHERIES. important, for, although bass sometimes build nests where there is no shade, in most instances they select places under overhanging grasses, lily-pads, stumps, and logs. The artificial nests should be located several weeks in advance of the expected spawning, and undue dis- turbance of the pond should be avoided. They must be examined often, and all containing young fish removed to the rearing-ponds. ~ From the time the bass commence nest-building the attendant keeps the pond and its contents under constant surveillance and maintains a close watch for fish-hawks 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. If artificial nests are used, the observations can be made more carefully, and numbers can be painted on the shade-board to designate the particular nests, and the records of hatching and spawning can be kept with greater accuracy. STOCKING THE BREEDING-PONDS. Whenever procurable, domesticated fish are to be preferred to wild fish for this purpose, as they are less liable to injury in handling and transportation. A disrupted scale, lacerated fin, or a bruise on head or body frequently causes the death of wild bass, and the conditions of their native surroundings make it 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 24 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 largé 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 thetubs. Males and females should be in equal proportion, as an excess of males is liable to prove a disturbing element at spawning time, and, later in the season, a source of loss from their 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 acse of water has been allowed, but that number might be increased. SPAWNING HABITS. When the nests 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 simultaneously void the eggs and eject the milt, the real act of spawning occupying a comparatively short time— aminute orless. The eggs, when laid, are viscid, and as soon as voided. 43 se se us, re PLATE 49. ) (To face page 173. 1897. San’ Report U. ‘SVX4L ‘SOOUVIN NVS LV SGNOd SSV@ MANUAL OF FISH-CULTURE. 173 and impregnated attach themselves to the floor of the nest. Then commences a parental watchfulness worthy of imitation on the part of some higher animals, 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, patrolling 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 killa snake three times its own length. The brightness of the nest makes the parent on guard easily distinguishable by enemies, like the fish-hawk 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 frequently 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 there are some in the brood ponds at Neosho which were adults when first taken to the station, and have been held for seven years and are still productive, though less so than formerly. Rock bass have been known to produce two separate broods within one season as far north 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 differ 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 24 pounds, a little less than 7,000 to the pound of fish; but on another occasion careful count of the mature eggs showed only 2,674 to the pound of fish. Wide discrepancies in the figures may be sometimes accounted for by different methods of count- ing, as in rejecting or counting small eggs which are commencing their maturation for the next production. The rock-bass egg is fully three times as large as that of the black bass, and the fry correspondingly large. The varying factor of initial vitality and the impossibility of equal- izing the intensity of sunlight render it impossible to determine pre- 174 REPORT OF COMMISSIONER OF FISH AND FISHERIES. cisely the period of incubation of any eggs treated in pond-culture. With some kinds, under extreme conditions of temperature and other less understood factors, wide variations are found. Bass eggs require - from 7 days to 3 weeks for hatching, but usually from 8 to 10 days— governed mostly by the temperature of the water. Eggs artificially impregnated, in an experimental way, hatch in from 70 hours to 4 days at a temperature 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 Contin of the atmosphere; “eel a fifth less time being required to absorb the sac than for hatch- ing the eggs. When the sac is absorbed, the fry rise from the nest and form a school which hovers over the meet usually from two te four 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 off intruders. When the school rises and hunger begins to be felt, the fry separate and are driven, for protection, by the parent fish into shoal water or into the thick grasses; there they are deserted, and dispersing, they seek the minute crustacea, larve, and insects. Black-bass fry do not average one-fourth of an inch in length and are almost colorless for the first three to five days, when the pigment forms along the back, making them appear quite dark when viewed from above, though Ab is difficult to distinguish the color on an indi- vidual fish hon 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 difficult of observation. FOOD OF THE YOUNG. Just how much food to give the young bass fry is as difficult to determine as with any other young fish. They are very greedy, and, if acceptable food is given them, appear 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. Bass, like the trout, are given about 14 per cent of their weight in food per day. This ratio will maintain black-bass fry in a healthy growing state, and probably less will be found to answer with rock-bass fry. Compared with other fishes reared in troughs, especially some of the trout, bass are easily managed. Healthy fry have been carried at Neosho for four months with a loss of only 2 per cent. When first brought into the troughs, they can not be induced to take the prepared food, as they are wild and must be tamed or domesticated. They are MANUAL OF FISH-CULTURE. 175 fed almost every hour in the day, though but little food is given at one time and that well scattered through the trough. The attendant should be about the trough constantly to accustom them to his pres- ence, care being taken not to alarm them. Instead of being frightened and darting to the dark corners of the trough at his approach, 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 paste. In general, bass fry under 14 or 14 inches in length are too small to take artificial food, and some die before they can be accustomed to take it. The number of young bass to be put into a pond depends upon its size and its capacity to produce food. If the nursery has been prepared in advance with aquatic plants some crustacea will be found there, and the deficiency is supplied by the introduction of snails, Gammarus, Corixa, etc. The use of beef liver as food is notadvised. Toanursery 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 percentage are to survive they must have more food than the pond can grow. Should a large part of them survive the first few weeks they can be distributed into other nurseries. At Neosho crayfish have been used for food with good results, not that they have any value over other forms of aquatic life, but because they are abundant, cost nothing, and are acceptable to the fish. Young bass can easily be fed on any kind of fish, and all that is necessary is to reduce the fish to a paste by passing it through a meat-cutting machine. Carp may be cultivated for the purpose. 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 chubs destroy the young bass, though this could be obviated by hatching the chub artificially (as can be easily done) and turning only the young chub into the pond. How- ever, the propensity to cannibalism in the bass should not be fostered, and it is better not to feed bass, old or young, on any kind of live fish. They are thus trained, while under domestication, to forego their natural inclination for fish diet. Sometimes, even with abundance of natural food, the young prey upon each other, and they should then be thinned out by transferring a part to nursery-ponds, or the entire lot removed to troughs or vats in the hope of inducing them to take the prepared or natural food. As the Summer advances the strongest fish may be observed to grow rapidly, and at the first evidence of unusual growth the fish must be sorted out and those of a certain size placed in separate ponds. The successful 176 REPORT OF COMMISSIONER OF FISH AND FISHERIES. raising of bass in ponds depends very largely on frequent and careful sorting, and a fish that persists in efforts to devour his companions should be either liberated or destroyed. TRANSFER OF FRY FROM HATCHING-PONDS. In transferring the fry to troughs or other ponds 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 6 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 an ordinary landing- net by replacing the netting with cheese-cloth. This will be useful in catching the fry that escape from the larger net. The transfer is made in tubs filled with water from the spawning-pond in order to preserve the same temperature as nearly as possible. Netting 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. The process of netting requires patience and a degree of skill which comes with practice. The operator 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 any of the fry into the tub that may stick to the cheese-cloth. The fry should never be freed from the net by the use of 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 temperature of the water in the bucket or cans is compared with that flowing through the troughs. An experienced workman can tell by the sense of touch whether there is a material difference in the temperature, and can take the steps toward equalizing it. Should there be a difference of 3° or more, it must be corrected. If a vessel is not crowded, an effective, though slow, method of equalizing the temperature 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 te 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 known among fish-culturists as ‘“‘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 MANUAL OF FISH-CULTURE. 177 top. The windowed 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 perforated window, assist in the process of tempering. The temperature being equalized, the fish are carefully ladled into troughs or pools and the various sizes sorted and separated into different troughs. 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 youngsters will be 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-off. This work is generally in June or July, when the ponds are quite warm and the temperature of the atmosphere is high, and is carried out with extreme watchfulness and care, as the midsummer drawing of a bass pond is the most delicate operation connected with their propagation in ponds. These fry need to be “tempered” and sorted in the same way as advised for other 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. SHIPPING FRY. Collecting for shipment occurs in the cool days of autumn, as experi- ence has shown that the bass can be much better and more safely transported in the spring and fall than in the summer. They can be transported more cheaply in midwinter than any other time, but when fish 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 freed from vegetation and are ready for drawing off, 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 prove a dangerous occupant the following spring when the young fry areintroduced. The same precautions should be observed in transferring fingerlings as with the very young fry. We Css 180712 Pere avs) Diy oa ele ny ey ted . a Report U. S. F. C. 1897. (To face page 179.) PLATE 5O. Ht MH riage CRIM Rt: Beaty plata NN \ S MT ng UN Ses qc \\ it ] Yo nie ari RS Mea, Mi Hy ‘ ue Ly HY yh uy / \\ \\ li RHE SALMO MYKISS. Black-spotted Trout. MISCELLANEOUS FRESH-WATER FISHES. Besides the fresh-water and anadromous 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 AND THE GRAYLING. 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 the black-spotted trout (Salmo 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 mykiss henshawi), which is extensively propagated by the California Fish Commission at hatcheries on Lake Tahoe; the Colorado River trout (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 60° 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 trout (Salmo trutta levenensis), and the European brown trout or brook trout, or Von Behr trout (Salmo Jario), 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 inponds. At Northville the spawning season of these fish is the same 179 180 REPORT OF COMMISSIONER OF FISH AND FISHERIES. as that of the brook trout. Their eggs are somewhat larger than those of the latter fish, but they are handled in the same way, the progress of incubation is similar, and the fry are fed on the same materials. Small numbers of the Huropean sea trout or salmon trout (Salmo trutta) have also been propagated at Craig Brook and other stations, and have been reared to full maturity in ponds. The fish called the Swiss lake trout, European charr, or saibling (Salvelinus alpinus), has been propagated 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. The Michigan grayling (Thymallus ontariensis) 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 game of fresh-water fishes, but is rapidly approaching extinction, owing to excessive fishing and the pollution of streams, which have not been counteracted by artificial propagation. The Montana grayling (Thymallus ontariensis montanus) inhabits a limited area in the head- waters of the Missouri River and is very abundant in some streams. The Arctic grayling (Thymallus signifer)is found from the Mackenzie River westward through Alaska and north to the Arctic Ocean. The Michigan grayling rarely weighs 14 pounds, and the average weight is only half a pound; the northern species is somewhat larger. Although thescultivation of the grayling was begun as early as 1874, it was never regularly or extensively conducted. Spawning in Michi- gan occurs in April, and the eggs are normally laid in gravel beds in clear, cold streams. The number of eggs taken from a single fish varies from 3,000 to 4,000. The same methods of culture pursued with the brook trout are applicable to the grayling. In water having a tempera- ture of 50° to 60° F., the incubation period is 14 to 20 days. THE LAKE HERRING AND OTHER WHITEFISHES. While the common whitefish is the only member of the tribe that has received much attention from fish-culturists, it is probable that several other species of whitefish 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 prognathus), the bluefin or blackfin (A. nigripinnis), the tullibee (A. tullibee), 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 whitefish, but the spawning seasons differ. The lake herring is readily distinguished from the common whitefish by its smaller size, projecting lower jaw, long and numerous gillrakers, Report U. S F.C. 1897. (To face page 181.) PLATE 51. Cisco. . , Lake Herring ARGYROSOMUS ARTEDI. MANUAL OF FISH-CULTURE. 181 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 12 to 14 inches and the average weight is under a pound, although a maximum weight of 3 or 4 pounds is attained. The fish 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 require 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 whitefish, 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 (Coregonus 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 taken and hatched in comparatively large numbers. It rarely exceeds a pound in weight, but its food qualities are good, and itis 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 heavy, adhesive, and 4 inch in diameter; the average yield per fish is 3,500, but 12,000 have been taken from a 13?-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 largest representative of the pike family. Its maximum weight is about 80 pounds and its average weight 25 or 30 pounds. 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 mouth, armed with strong, formidable teeth, its food consists chiefly of living fish, which it captures 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 182 REPORT OF COMMISSIONER OF FISH AND FISHERIES. ina year. The eggs are taken from fish caught in the lake, and are hatched in submerged boxes, provided with double wire-mesh tops and bottoms. The eggs are similar to whitefish eggs, being semibuoyant and nonadhesive. A 394-pound fish has been known to have ovaries weighing 5 pounds, and a 35-pound fish has yielded 265,000 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 97 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 practice, 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 vertical 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 found 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 efforts 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 pound. Itisa food-fish of fair quality, and.is taken for market in very large quantities 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 sum 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 impregnated, 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. 183 The fish is so abundant, however, and the supply so well maintained 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 River spawning takes place in February, March, and April. The water tem- perature 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. 14 VOMO,0 9T0 IO oO O° COP 0sca Qu of 206025090 > St Q ome Ovary of a yellow perch with nearly-ripe eggs, the forked 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 recently-laid mass of yellow-pere 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 in 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, depending on the size of the fish. One 184 REPORT OF COMMISSIONER OF FISH AND FISHERIES. fish in an aquarium at Washington deposited a string 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, in order to permit the circulation of water on the inside of the mass. The egg-string is quite light and resilient or springy, the least agita- tion of the water causing a quivering motion of the whole mass. The diameter of the egg is -4; 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 different 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 put 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 egys 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. 185 THE STRIPED BASS AND THE WHITE PERCH. The striped bass, or rockfish (Roccus lineatus), ranges from New Brunswick to western Florida. It 1s especially abundant from New York to North Carolina, and is taken in large quantities for market, by means of seines, gill nets, pound nets, and lines, on the coast and in the bays, sounds, and rivers. It is one of the best food-fishes of American waters. The annual value of the catch is about $300,000. Through the efforts of the Commission, this fish 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 San 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 pounds; examples weighing 50 to 75 pounds are not uncommon; but the usual size of those taken for market is 3 to 20 pounds. 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 12 pounds, caught at the mouth of the Susquehanna River, in May, 1897, yielded 1,280,000 good eggs, and a 75-pound fish would doubtless produce 10,000,000 eggs. The commercial importance 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 occasions; 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 _ 4+of an inch in diameter, and have a very large oil-globuie. 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 number in a quart is about 24,000. The tidal apparatus, such as is used for cod and tautog eggs, is adapted to hatching the eggs of this fish. At a mean temperature of 58° F., the hatching period is about 74 hours. Lay tees ane Ire eens asl Pll iy ‘ iil Wes Ihr; Mn TAUTOGA ONITIS. Tauwtog. RIEL eSeSS MISCELLANEOUS MARINE FISHES. Tn 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 (Labride, 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 theeye. The dorsal fin is long and low, with 16 strong spines and 10 soft rays. The anal fin contains 3 spines and 8 rays. The body length is 3} or 34 times that of head and 22 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, Rhode 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. 219 220 REPORT OF COMMISSIONER OF FISH AND FISHERIES. The tautog is taken for market in considerable numbers by means of lines and traps. 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 223 pounds; such a specimen from New York, 364 inches long, is preserved in the U.S. National Museum. The annual commer- cial catch of tautog is about 1,500,000 pounds, valued at $60,000; nearly half the yield is from Massachusetts. 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 1886, In 1896, 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 stripped of a part of their eggs. The eggs taken after fish are held more than 6 hours are usually of no value, and those obtained from fish retained one night are invariably worthless. The tautog is very prolific. In 1896 a 93-pound fish yielded 1,142,600 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. 7 The eggs of the tautog are about 5 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 69° 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 4; inch. They are quite hardy and stand transpor- tation well. They are planted shortly after hatching. THE SPANISH MACKEREL. The Spanish mackerel (Scomberomorus 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 Scomberomorus found on the eastern United States coast (8. regalis, the kingfish, and S. 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 numerous rounded yellowish spots. MANUAL OF FISH-CULTURE. 2?1 This fish 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 ? pounds. Many weighing only 1 or 14 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. Theapproximate annual value of the catch at present is $130,000, which 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 Gulf States it has increased. The fish spawns throughout its entire range on the United States coast. The spawning season is quite 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 comparatively long spawning season for individual fish 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 ;4, to 31; of an inch. The artificial impregnation and hatching of Spanish mackerel eggs were first accomplished in 1880, since which 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 the steamer Fish Hawk. 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, 222 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 have 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 exelu- 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, areinjurious, but to what extent and in what way are not known. The largest number of ripe eggs thus far taken from a single specimen is 60,000, but the average is only 20,000. The Chester jar, such as is used a 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 ameaititneicne 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 GADIDE. 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 (Pollachius virens) and the haddock (Melanogrammus eglifinus). Both are important food-fishes, but much less valuable than the cod, and the collection of eggs has generally been only supplemental to cod work. The pollock is found from New Jersey northward. 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 $100,000.. The pollock is an excellent food-fish in both a fresh and a salted condition. - The eggs of the pollock have at times been PAE in large num- bers in the vicinity of Gloucester; during some seasons about 40,000,000 eggs have been taken. The eggs measure about ;4; 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. 223 with nets and lines by commercial fishermen; the average number of eggs to a fish is from 200,000 to 250,000. The period of inenbation is somewhat shorter than that of the cod, being 9 days at 43° and 6 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 $1,115,000. 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 ;4; 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 abont 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 tomeod 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 CUNNER. The eges of the cunner or chogset (Ctenolabrus 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 56° 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 34 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 (Centropristes striatus) are of the same size as scup eggs, are deposited in June, and hatch in 5 days with the water temperature 59° or 60°. The sea bass is an important food-fish, 224 REPORT OF COMMISSIONER OF FISH AND FISHERIES. found from Massachusetts 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 14 pounds. THE SQUETEAGUES. The squeteague or weakfish (Cynoscion regalis) is a prominent food- fish 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 North Carolina, Chesapeake Bay, Delaware Bay, on the New Jersey and New York coasts, and in southern New England. It varies greatly in size; the average weight is under 5 pounds, 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 60° F. hatch in 2 days. The spotted squeteague or ‘sea trout” (Cynoscion nebulosum) 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 spring and summer, the time varying with the latitude. The eggs are buoyant, =; 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 (Archosargus probatocephalus) 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 Cape 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 notregularly prosecuted. The most extensive work was conducted by the Fish Hawk 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.” The fish were then easily taken in large numbers. Seine hauls in the morning consisted only of male fish, Spawning SSS SS Se MANUAL OF FISH-CULTURE. 225 sheepshead swim in schools, and seem to prefer sandy beaches, along which they resort at a depth of 6 or 8 feet. The sheepshead egg is very small, transparent, and of less specific gravity than sea water. The diameter is =4, of an inch, and the number in a fluid ounce is about 50,000, or 1,600,000 in a quart. The eggs are satisfactorily incubated in the tidal cod-jar, about 300,000 eggs being placed in each jar. The development is very rapid, and in the warm water of the Gulf (76° 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 probably not practicable to carry on extensive sheepshead hatching north of Florida, although small quantities of eggs could doubtless be taken in North Carolina and Virginia. THE SEA HERRING. The sea herring (Clupea harengus) may be distinguished from other clupeoid fishes found in United States waters by the following char- acters: Body elongate and laterally compressed, the. depth contained 45 times in length; mouth at end of snout; lower jaw projecting, extending to beneath the middle of eye; roof of mouth 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 fins; scales thin, easily detached, posterior edges rounded, 57 in lateral series; color bluish or bluish-green above, light-silvery below. The sea herring exists in great abundance on both shores of the Atlantic Ocean north of the latitude of about 37° north. On the coast of North 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 (Clupea pallasit) 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 usual 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 in enormous quantities by cod, haddock, sharks, and many other fishes. F. C. R. 1897 —15 226 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 the spring, in April, May, and June, and the other between July and December. The spring spawning occurs entirely east of Hastport, Maine, and the fall spawning princi- pally, but not altogether, west of that place. Probably the greatest spawning-grounds south of the Gulf of St. Lawrence are at Grand Manan, where the eggs are deposited principally in July, August, and September. 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 Novem- ber 1, and south of Cape Cod from October 15 to December 1. The female herring of average size deposits between 20,000 and 47,000 eggs at a Spawning, the usual number being not far from 30,000. The eges are deposited upon the bottom, and, being covered with a glutinous material which 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 54, 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. Itis undoubtedly the most important of food-fishes, although in the United States it is exceeded in economic value by many marine and fresh-water species. Some time ago the annual yield of the world was estimated at 3,000,000,000 herring, 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 55,000,000 pounds, with a first value of $350,000, The fish is taken chiefly with seines and weirs, and about five-sevenths of the yield is obtained on the coast of Maine. The market value of the output is greatly enhanced by the salting, smoking, and canning processes to which a large part of the catch is subjected. In Maine the canning of young herring as sardines is a very important industry. Fresh herring are used chiefly for bait in the line fisheries for cod and other “ground fish.” Experiments in the artificial propagation of the herring have been conducted both in this country and in Kurope, but owing to the great abundance of the species the work has not been carried beyond this experimental stage. In the United States there has as yet been no permanent diminution of the supply that renders the cultivation of the species necessary, notwithstanding an extremely large fishery and the sacrifice of enormous quantities of very small fish. The first successful attempt to propagate this fish was in 1878, in Germany, when elaborate experiments were made. In the same year the artificial hatching of the species was accomplished by the United ~ States Fish Commission. Theeges, 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. MANUAL OF FISH-CULTURE. 227 Development takes place in water ranging in temperature between 33° and 55° F., the time of incubation varying from about 40 days at the former temperature to 11 or 12 days at the latter. Sudden and extreme variation between the temperature limits mentioned had little or no effect except to retard or accelerate the hatching in accordance with the rule just mentioned. When water of a temperature lower than 33° I’. 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. 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 maculatus) and the four-spotted flounder (Paralichthys oblongus). The eggs of both fish are buoyant, and deposited in May. Those of the former are 51, inch in diameter, and of the latter .4; inch. The period of incubation at a temperature varying from 51° to 54° IF. is about 8 days. PLATE 61. (To face page 229.) ‘Report U. S. F. C. 1897. svixapione American Lobster. HOMARUS AMERICANUS. THE AMERICAN LOBSTER. DESCRIPTION. The lobster (Homarus americanus) belongs to that group of the crus- tacea called the Decapoda, because all of its members are provided with ten feet, more or less adapted for walking. 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, ete., 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 antennz or long feelers. The Pacific Coast crayfishes have 18 gills, those east of the Rocky 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- guished from the crayfish and the common lobster by the total absence of great claws, by the greater length and stoutness of the antenne, 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 aid in tearing up the food and passing it between the lips. 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 appendages, it is assumed that it represents five fused segments. The abdomen is narrower than the cephalothorax and is composed of six separate segments movable on one another. In the female the 229 230 REPORT OF COMMISSIONER OF FISH AND FISHERIES. first five pairs of abdominal appendages, known as swimmerets, are all similar and consist of a short basal piece and two terminal pieces side by side. The appendages of the sixth segment consist of the same arrangement of parts, but the pieces are broad and paddle-like, and, with the terminal plate attached to the last segment, constitute 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 antenne; the walking legs are light blue with reddish tips and tufts of hair. Occasionally specimens 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 Newfoundland 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 the practical exter- mination of the 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 which 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, ete. Lobster eggs MANUAL OF FISH-CULTURE. 231 have been found in a lobster’s stomach, and alge sometimes serve as food. Fish is the bait most extensively employed in 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 principal phases of this subject be clearly appreciated, 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 egg-producing 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 receptacle at the base of the third pair of walking legs, and retains its vitality for along 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- hike filaments on the swimmerets. The exact method by which the fertilizing principle is conveyed to the eggs from the pouch in which it is contained is not known. The incubative period is much prolonged. After the eggs are extruded and become attached externaily, 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 independent existence immedi- ately after escaping from the egg. The lobster egg is about -; inch in diameter. When newly laid it is usually of a dark-green color, but is sometimes ligh{-grayish or yellow- ish-green. The known maximum number of eggs produced at one time by a lobster is 97,440; 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 following table illustrates, with approximate accuracy, the egg- produeing capacities of lobsters of the lengths indicated under normal conditions: Number of Length of lobster. eas laid. Siinchessacs ee deseo sneer 5, 000 OIMehEeS hee eace ne eceesesee 10, 000 DAIMNCheSee ess secsee aeseEe 20, 000 i4vin Chess.esacceescecoe cess 40, 000 16in ches! sone se sees 80, 000 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 1s 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 aninch. 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 chiefly 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 aduit in form and habits with each molt, attains a length of about 2 or3inches. At the end of the second MANUAL OF FISH-CULTURE. 233 year the length is 5 to 7 inches. By the end of 44 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 required 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 eges 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 104-inch lobster, 1? pounds; a 12-inch lobster, 3 pounds; and a 15-inch lobster, 4 to 5 pounds; 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 toa recent date, the largest lobster of authenticated weight wat about 25 pounds. In 1897, however, 3 lobsters, each weighing over 30 pounds, were taken off Sandy Hook, N.J., the weight of the largest being 33 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 New 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 definite information on this subject. In Maine, Massachusetts, New Hamp- shire, and New York the minimum limit of size of lobsters that may be sold is now 104 inches; in Rhode 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 Fish Commission on the New England coast show that the female lobster attains maturity when from 8 to 12 inches 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 per cent were under 9 inches long. On the other hand, by the time they have reached the length of 104 inches most lobsters will have produced eggs, and this should be the minimum size permitted in the markets. 234 REPORT OF COMMISSIONER OF FISH AND FISHERIES. COMMERCIAL VALUE. The lobster is the most important crustacean 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. In 1892 over 3,500 persons were engaged in this fishery in the United States: the capital invested was about $650,000, and the catch amounted to 23,725,000 pounds, valued at $1,062,000. In 1880 the yield was but little smaller (20,240,000 pounds), but the market value was much less, being only $488,000. Between 1889 and 1892 the New England lobster catch decreased over 7,000,000 pounds, or 23 per cent, while the value increased over $200,000, or 25 per cent. Fora 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 propaga- 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 many 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 propagation of the lobster. The only practical 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 inclosures. One of these parks was established in Massa- chusetts in 1872, but was afterward abandoned; another was established on the coast of Maine about 1880. It was soon demonstrated, however, that the results from inclosures of this character, so far as the rearing of the lobsters from the young were concerned, would not be sufficient to materially affect the general supply. 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 quantities of lobster eggs, as well as those of other crustaceans, had been successfully hatched. In 1886 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. Irom 1887 to 1890, inclusive, the number of eggs collected was 17,821,000. From the eggs collected up to 1889 the average production of fry was about 54 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 MeDonald automatic hatching-jar. In 1889 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 fry. Work was continued at Woods Hole on about the same scale until 1894, when the collections aggregated 97,000,000 eggs. In thesame year lobster propagation was undertaken at Glouces- ter and a collection of 10,000,000 eggs was made there. During the fiscal year 1895 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 150,000,000 eggs, of which 135,000,000, 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 place in the hatching-jars during the fall and winter any lobsters having external eges that may be captured by local fisherman. The collecting-grounds extend from New London, Connecticut, to Rockland, Maine. For Woods Hole station eggs are secured from fishermen operating between New London, Connecticut, and Plymouth, Massachusetts. The most important grounds in Connecticut are in the vicinity of New London and Noank; in Massachusetts, New Bedford, 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 Grampus is used in making the collections between Portland and Rockland, the lobsters being delivered at Gloucester early in the season and later on to the steamer Fish Hawk, 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. Early 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 strip 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 urns 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 portion of the body is held firmly to prevent its closing. The lobster is then ready for stripping. A 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, where 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 eges 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 in 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 6,090 eggs. MANUAL OF FISH-CULTURE. Zor HATCHING APPARATUS AND OPERATIONS. Experiments conducted during a series of years having demonstrated that the automatic hatching-jar was the best form of apparatus 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 first 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 24 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 64° 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. "| anc Sccn See PLATE 62. ‘To face page 239) Report U. S. F. C. 1897. GSNad0 39 NVO HSI4d Y¥OS SINAWLYVdMWOD LVHL OS dA DONNH SYIVHO GNVY GS3SO19 SHLYS8 DNIMOHS Side Me ~ YVO NOILVLYOdSNVYL Baw pie dO YOINSLNI ’ - THE TRANSPORTATION OF FISH AND FISH EGGS. During the earlier years of the Commission young fish were carried by messengers in baggage cars on regular passenger trains, but as the work increased it was found that this method was inadequate and that other arrangements must be made to transport the large numbers of fish which were being hatched. Accordingly, in 1879 and 1880, experi- ments were successfully made in moving shad fry in specially 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, proper circulation of water and air in the vessels containing the fish, and sleeping and living accom- modations for the messengers attending 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 oneend 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 ear, which would accommodate two men on each side. Hach compartment 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 provided 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 car. From this the water was brought into a 6inch pipe extending all around the top of the refrigerator compartment. The pipe contained a sufficient number of pet-cocks to supply 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. While this circulating apparatus 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 AND FISHERIES. thus causing it to roll from side to side in such a manner as to make it unsafe. It was also found that while the refrigerator compartment carried the fish safely, the health of the messengers was injuriously affected 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 four transportation cars in use. While they differ somewhat in construction and arrangement, three of them are essentially alike; the fourth is simply a baggage car with living quarters and circulating apparatus. The car known as No. 2 is regarded as the best type. Its body is 52 feet 7 inches long; from buffer to buffer, 59 feet 9 inches; width, 10 feet; height, from top of rail to top of car, 14 feet 3 inches. It is equipped with 6-wheel Pull- man trucks, paper wheels, combination couplers, etc., so that it can be hauled on passenger trains. Underneath, between the trucks, are boxes for carrying provisions, tools, extra couplers, and a water-tank. Inside the car is finished in white ash, and due arrangements are made for the comfort and convenience of the crew. In one end is an office for the use of the captain, containing a sleeping-berth, desk, and toilet facilities; at the other end is the kitchen, with lockers for dishes, also the air- pump, steam-pump, and a 5-horsepower boiler for furnishing necessary power. The fish are carried in tanks or cans arranged in two refrigerator compartments on each side of the passageway. Over these compart- ments are two upper berths on each side for the accommodation of the crew, whose meals are served on a large table, placed when in use in the passageway in the center of the car. Chairs without legs are pro- vided, so that they can be placed on top of the refrigerators. The refrigerator-chambers are 26 inches high and 34 inches wide, and provided with lids; the partitions are filled with cork, which is used on account of its nonconducting properties. At one end of the chambers is an ice-box, which holds about three-fourths of a ton of ice. The transportation-tanks used in carrying yearling and adult fishes are made of heavy galvanized iron, and are 27 inches long, 27 inches wide, and 24 inches deep, holding 52 gallons each. They are heavily coated with asphalt before being used. For the transportation of fry ordinary 10-gallon iron cans, tinned, are used. These cans are 24 inches high, 12 inches in diameter on the outside, with sloping 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 simply with a dipper or bucket. The supply of water is carried in an iron pressure-tank of 500-gallon capacity, which is located in the body of the car next to the office. The water is circulated by means of a steam-pump through galvanized-iron MANUAL OF FISH-CULTURE. 241 piping, which runs from the pump 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. In order to provide sufficient air circulation, the air is driven by a pump to a 30-gallon reservoir in the top of the car over the boiler-room, from which it is taken to the transportation-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 toit through a hole .4; inchin diameter. From the pet-cock the air is carried into the tank with rubber hose and released in the water through liberators made of American linden, placed in hard- rubber holders. Before the present system of water circulation was adopted the water was taken from four 40-gallon tanks located in the bottom of the refrig- erator compartments, pumped into four 60-gallon supply-tanks, from which it flowed through the transportation-boxes and was returned thence to the lower tanks. The water supply was at first connected with a rotary hand-pump, and afterwards an arrangement was adopted to fur- nish power for the pump and an air-blower, by means of a friction wheel placed on the truck at one end of the car. This wheel was attached near one end to the top of the truck, so that it rested on the tread of the car wheel and was held there by two spiral springs. When not in use, it could be elevated above the car wheel by a lever operated from inside the car. Power was transmitted from the friction wheel by means of a countershaft and rubber belting. The friction wheel gave a great deal of trouble, however, as it was impossible to make it strong enough to stand the wear to which it was subjected. As the action of the truck springs, while the car was in motion, moved the truck frame up and down—sometimes 3 to 5 inches—the friction wheel would be jolted out of position, and so uncertain was its operation that it could not be relied upon and the pump and blower had to be worked by hand. This car is also fitted up with a hatching outfit, consisting of eight Jead-lined boxes about 6 inches high, which may be placed on top of the refrigerators and made to fit in place of the lids, which can be removed. These boxes each hold 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. Great care is taken not to make a sudden change in the F. C. R. 1897—16 242 REPORT OF COMMISSIONER OF FISH AND FISHERIES. temperature. Ifthe 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. This is done as often as is necessary to keep the water fresh. Whitefish 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 can be carried in each can. Without the circulation 20,000 are carried, and in order to aerate them itis necessary to draw off in a pail, 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 spawning-grounds where the whitefish are to be planted, by carefully lowering the cans into the water and allowing the fry to escape. 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 65°, depending on the temperature of the water in which they were hatched. These fry can not be carried successfully with the circu- lating system of water or air, and aeration, by the use of the dipper, is therefore necessary. From 20,000 to 30,000 are carried in each ean. When the water is to be changed, it is drawn off through a siphon into a pail, the head of the siphon being in a wire cage, covered with cheese-cloth to prevent the fry from escaping. After the water in the pail has been thoroughly aerated and ice added to bring the tem- perature down to what is required, itis poured back through a large funnel which reaches nearly to the bottom of the can. To prevent the force of the water from injuring the delicate fry, the lower part of the funnel for about 6 inches is made of perforated tin. When long trips are made, the sediment which collects on the bottom of the cans is removed, as soon as it is noticed, by drawing it off through a siphon into a pail. Should any fry come out with it, they are carefully returned to the can by dipping them out after the sediment has settled to the bottom of the pail. If a trip lasts five or six days, the cans are cleaned every other day by transferring the fry with a dipper from one can to the other and cleaning the empty one before the fry are returned to it. Shad fry are more tender than any other young fish moved on the cars, and the greatest care is necessary in handling them. Trout and salmon fry are carried in water at a temperature of 36° to 46°, though rainbow trout are sometimes transported in water 10° or 15° warmer. If it is necessary to reduce the temperature, ice is placed in the cans with the fish. Each can contains 5,000 trout fry, and 2,000 to 3,000 salmon fry, when the air and water circulations are used; without air circulation, 3,000 or 4,000 trout, and 1,200 to 1,500 salmon MANUAL OF FISH-CULTURE. 243 fry are auowed to each can—the number depending on the length of the trip and age of the fry. ‘These fish are moved as soon as the sacs are absorbed, or when they first begin to swim up from the bottom. If shipped before this period of life, they are liable to collect on the center of the can in the bottom and smother. If the 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 the fish do not go down when the dipper is introduced, the water is siphoned into a pail, aerated, and then poured back. Small yearling trout are sometimes carried in cans, but usually in the galvanized-iron tanks; 100 to 200 are put in each can if the air circulation is used, and the water is kept cool by introducing ice. As salmon and lake trout are more delicate than the others, the number placed in each can is reduced. When shipping adult trout but few can be taken in each tank, only from 20 to 50 if they are of large size. They are given all the air and water circulation possible and carried at a low temperature. Incessant watchfulness is necessary in moving these fish. When the fish are in distress they come to the surface of the water, and if the water is then vigorously aerated they will return to the bottom of the tank. When black bass are distributed in the fry stage they should be shipped in water from 40° to 60° F., according to the temperatureeof the water from which they are taken; but it is considered preferable to hold these fish in the ponds or feeding-troughs until they are from three to six months old, when they will have attained a length of from 14 to 3 or 4 inches, fish hatched at the same time often varying consid- erably in length. These older fish also require a temperajure of from 40° to 60°, according to circumstances, when they are transported. Young black bass are very voracious, and begin to eat each other as soon as they are confined in cans or tanks for transportation. The number of bass carried in each tank is approximately as follows: Fifty 8 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. Rock bass are commonly carried in cans, about 500 to 700 in each if the fish are about an inch long. The temperature of the water is from 40° to 60°. Codfish fry are moved in cans with water of a temperature of 33° to 38°. The trips are usually of short duration. 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 6 inches high and of a size convenient for handling. Strips of wood attached to the bottom of trays have open spaces between them to allow air circulation. About 2 inches of seaweed are spread on the bottom of the tray and the lobsters placed on it with their claws 244 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 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 refriger- ator compartments, 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 they are also daily overhauled and repacked. If the desired temperature is maintained, 50 to 60 per cent can be carried for five or six days. Lobster fry are moved in the same manner as - codfish fry. In transporting adult salt-water fishes, aS many as possible are placed in the tanks without overcrowding them. The water is kept fresh by air circulation only. Iceispacked 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 6 days or more. A large number of fish are distributed yearly by messengers, acting independently of the cars. Hach messenger is supplied with a sufficient number of 10-gallon cans, and is equipped with a dipper, a 5-gallon iron pail, a large tin funnel with a perforated bottom, a thermometer, and a piece of 32-inch rubber hose, about 4 feet long, for use as a siphon, besides a supply of ice. When it is necessary to renew the supply of water, the messenger sees that it is clean, fresh, free from lime, iron, and other 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 transporting them in cans. I SPAWNING SEASONS OF FISHES PROPAGATED, CHARACTER OF FISH EGGS, PERIOD OF INCUBATION, ETC. In 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 be 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 pelagic fishes, which come to the surface when first Aeected 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 types of hatching apparatus depend primarily on the foregoing characters of the eggs. : At the hatching stations the size of eggs is determined by placing 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 proportion 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 ‘shep GT “skep 9 ‘skep 0¢ “shep OF ‘shep GT 07 ¢ “orf 4x sep orf ‘sfep OT 10 8 ‘obe 42 Shep 19 “sep 0Z 04 01 "o8e 98 SAVp CT “o8e ye shup ar{ *oLe 9e Skep OF “og 98 SAL CZ *skEp 06 04:02 “sfvp OF *peq.1osqu Ov8-HLOA REPORT OF COMMISSIONER OF FISH AND FISHERIES. 246 gc “crrr77 skep ct | Ge | 000 ‘8r 8g 0}. gg |--7"- --- skepg | &1 000 ‘9*¢ oF ~-skep 08 0} OL [ttt cfrttt Baws vrreesrs | SUJUOULTTIOOT | F OFF ‘26 TS Sn herent sep 691 | 79 690 ‘ cFov0F | Skvp 06 09 GL | Fz €F6 ‘FT G9 07. 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"7-7" (winadqua Worpaisozys) oytd pado-[[e AK srereseressss= (O1Ds OUNDS) JNOITY IYoy WO A (po0wo2 snppbhoworyy) PoouLoy, (saguo nboynny) Soyney, serecseeserceess (O1UNIS LASUadWP) TOOSINIG SS a aa (snypaur) snoso0qz) sseq podta4g (.waup.MB owjDny) peeyjos1g SRESHOPRGOOCOR (ajpbat uowsoufig) ensvojonbs -(uinsopngau Uworvssouhy )onsvojonbs peyjodg *(sn}0) -NIDUL SNLOWOLAQULODY) JeLOyovM Ystuedg (aqnf snuazdipojayy) ysyopeds (yonsry snYyaUhy.LooUC ) TOUTVS IAATIS “(snpoydes0,nqor1d snbwmsoyory) peoysdooys AR (nunssipidns 8077) peyg =2""*-(snbuaupy vadnyQ) Surry veg torersssesos= (sn IMIAJS $9ISULAOMUAL)) BSBY COS (sngnynonur snyog) qep pueg sooseensns(saugsadnd sajydojquy) sseq yoo soress* (snaprl, OW TVG) JNOT} MOC UTE, *(pyos? -impyos, snyoufysooug) uowyes yuu seressecenessccs= (Salud SNYYINII0T) YOOTOd ss--=*-(fibuoumnbsvw snionT) osun{eysuyl NOTES ON THE EDIBLE FROGS OF THE UNITED STATES AND THEIR ARTIFICIAL PROPAGATION. BY FM. CHAMBERLAIN, Assistant, U. S. Fish Commission. 249 Ritcaows ey 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 known as the Batrachia. The batrachians are intermediate anatomically and physiologically between the fishes and the reptiles (snakes, turtles, terrapins, alligators, ete.); 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 (Urodela, containing the salamanders and newts; Proteida, the mud- puppies or water-dogs, and Trachystomata, 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 (Ranide), in the order Salientia, are the families (Bufonide and Hylide) to which the toads and tree frogs belong. The toads are very closely related to the frogs, but differ in having more terrestrial habits and, among other 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 (anide) are known. They are most numer- ous in Africa and the East Indies. The edible frogs of the United States belong to the genus Rana (Latin, a frog). Of these, Professor Cope in his Batrachia of North America (1889) lists 13 species and 6 subspecies 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 palatable. 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 the hind legs are 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 their 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 Romans. From France the use of this food passed into Germany, England, and other parts 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 New York than in any other State, but on account of their comparatively small size their value is less than in Missouri and California. The Canadian Provinee of Ontario also yields a comparatively large supply of market frogs. According to 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 River, Indiana; Oneida Lake, Seneca River, and other waters of northern New York, and the St. Francis River and the sunken lands of the Mississippi River, 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 consumption of frogs in France is much larger than elsewhere, this is not the case, and, on the authority of the Revue des Sciences Naturelles Appliquées (1889), 1t may be stated that the annual consumption of frogs in the United States is ten times that in France. MANUAL OF FISH-CULTURE. 253 hunter’s aim, and at the same time blinding or dazing the frogs. After entering on their hibernation, many are dug out of the mud, large numbers often being found together at this time. In the basin of the St. Francis River, in Missouri and Arkansas, where the business is important, frogs are captured by means of spears, with lines 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 only 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. Twomen 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 season in thisregion 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 124 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 San 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 thé supply is manifest in Lake Erie, in northern New York, and other places, and in order to meet the increasing demand hundreds of people are experimenting 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 of 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 tadpole stage, though in some species this is so rapid as to lead the casual observer to think it omitted. Upon the disappearance of frosts at the close of winter the hibernating frogs 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 @amour; in others it is continued long after the breeding season is over. During the breeding season the social instinct prevails, and species of usually solitary habits congregate in large numbers, thus becoming ready prey for the hunter, 254 REPORT OF COMMISSIONER OF FISH AND FISHERIES. The eggs are extruded by the 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) in diameter. In passing down the oviduct the egg receives a thin coating of albuminous material; this rapidly swells when the egg enters the water and forms the well-known gelatinous mass in which the frog eggs are always found imbedded. The toad’s eggs are laid in long strings and are readily distinguishable. The salamander’s eggs are also placed in the water, but the gelatinous mass is somewhat firmer and the eggs are slightly larger than the frog’s, and they are usually deposited 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 eges 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 from 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. Ina short time the mouth and anus become functional, the alimentary 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. Recent observations have shown that animal matter is preferred to vegetable; all food must be in a state of macera- tion, especial fondness for dead animals being shown. Respiration is at first carried on by means of external gills. They are soon replaced by internal structures covered by opercula. Rapidity 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 or 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 magranes, are much later in coming out. As the legs become functional the tail is absorbed and furn’shes 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. 255 lost. As the gills are replaced by lungs during this period, 1t is essen- tial that the tadpoles have access to land or resting-places, and it is a time of peculiar difficulty in the creature’s existence. When the tail is almost fully resorbed, the purely aquatic 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 may be thrown out to quite a distance— is covered with a viscid secretion so that the frog readily captures any insects or small animals that approach it closely. Tadpoles are commonly satisfied 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 in the tadpole stage. It is generally believed that frogs live for 12, 15, or even 20 years. — During the tadpole 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 (Rana virescens). and it is in the prevention of this wholesale destruction that man mia, profitably intervene. In the adult frog stage the relenticss pursuit Dy birds and reptiles is continued until of the hundreds of cges 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 she | .d or on the bottom, and instances are recorded of their eating ..*’ , toads, and young birds, but insects and lower forms are thei « © diet. DESCRIPTIONS OF MARKETASL® PROGS OF THE UNITED STATES. The species of frogs common)y eaten are the bullfrog (Rana cates- biana), the green frog (Rana clamaia), the spring frog (Rana virescens), and the western bullfrogs (ana pretiosa and Rana aurora). The following references tc their geographical distribution and brief descriptions of their color and form have mainly been extracted from Professor Cope’s work on ‘The Batrachia of North America (Bulletin No. 34, U.S. National Murseum, 1889). 2 , 256 REPORT OF COMMISSIONER OF FISH AND FISHERIES. The most widely distributed species is the common frog, spring frog, shad frog, or leopard frog (Rana virescens). It is found from the Atlantic Coast to the Sierra Nevada Mountains, and from Lake Atha- basea, in Canada, to Guatemala, Central America, but is most abundant in the Hastern States. It reaches a length of about 34 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 distinet 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 en Frog or Spring Frog (ana 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 part of the body is yellow. The under surface is whitish or light yellow and unspotted. The leopard frog passes the tai). 2 stage the first season, and is more gregarious than the bullfrog or — een frog. These considerations are of importance from a culturist’s s amadpoint. 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, ¢!:0 legs are short, and the head is more rounded than in R. virescens. ‘he tympanum is very large, though this differs in the sexes, as a rule |»cing larger than the eye in MANUAL OF FISH-CULTURE. 257 males and smaller in females. eee RY Sr “ OS OS oe : x xyes I wy - oN 5 oR Ms ~ i * When the trunk 4 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 into 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 trunk 4 has been let down into the trench deep enough the sea level at low tide ought to be somewhat above the upper edge of the board e. The water will then, as the tide rises, flow back over the sand as far as the board 7, and will per- colate through the diaphragm into the space J, under the latter, and so find its way 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 proportion to the thickness of the stratum of sand constituting the diaphragm. After the pond has once been filled with the rise and fall of the tide in the open water the level of the latter and that 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 wl and #1 in fig. 1. Under these circumstances there will be a supply of water flowing out through the under division J of the trunk A, up through the sand and out over its surface through the outlet O under the gate G. After the ebb tide is over and flood tide begins these levels will be reversed and wi 332 REPORT OF COMMISSIONER OF FISH AND FISHERIES. in the pond will be lower than ¢l in the open water, and under those circumstances there will be an inflow of sea water into the pond through 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 support 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 be 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.* The water in the pond remained 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 pond. 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. Ryder 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 different 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 mature. It is also troublesome to free the generative gland from fragments of the liver, 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 matter, and thus interfere greatly with the life and healthy development of the embryos. By our method the objectionable features of the old plan, as stated above, are overcome. If possible select good-sized oysters; open them with the greatest possi- ble care so as not to mutilate the mantle and soft parts. Carefully insert an oyster knife between 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 the 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 fiatwise, as it is gently and firmly stroked over the generative gland and ducts to force out the generative products. To prepare the animals to take the spawn from them after opening, the following precautions 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 or so of the head or mouth end of the animal, which lies next to the hinge. Note also that 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 that of the right side of the animal. The ventral or lowermost side of the animal, anatomically speaking, is marked by the four closely corrugated gill plates or pouches, which are preceded 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 upper 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 sever the mantle of one side with a sharp penknife 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 one side of the visceral mass and the richly tinted, yellowish-white reproductive gland which constitutes its superficial portion. The opening of the gland and its superficial ramifying ducts being laid bare on -the exposed side of the animal, we are ready to press out the spawn on thatside. Before beginning this, however, it is important to observe that the principal 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 1, fig.2d). To expose the great or main generative duct it may be necessary to cut through or remove the pericardial membrane which incloses or covers the heart space on the exposed side. If the oyster issexually mature, the main duct will be observed to be distended with spawn, 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 firmly 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 the 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 pipetteful after pipetteful 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 be sucked up by the pipette and dropped into the water, the mixture of milt being first prepared, 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 practice I find that one male will supply enough milt to fertilize the eggs obtained from three or four females, and it does not matter if the operation 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. Itis 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 description 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 effectually obtaining all of the ripe eggs or milt as is possible in the process of taking the same from fishes. Ii 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, quite 90 per cent of all that are taken when the products are perfectly ripe. Itis also found that the products are not so readily removed by my process if they are 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 been 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 spot 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 generative opening on each side of the visceral mass of the oyster, and that, as we havestated, 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 asuccess. Too much milt causes the eggs OYSTERS AND METHODS OF OYSTER-CULTURE. 335 to be covered by too large a number of spermatozoa; thousands more than are required if too much is used. These superfluous spermatozoa simply become the cause of a putrescent action, which is injurious to the healthy development of the eggs. A drop of milt to 20 drops of eggs is quite sufficient. Immediately after the ova have been fertilized it is best to put them into clean sea water at once, using water of the same density as that in which theadults grew. If the attempt is made to impregnate the eggs in water much denser than that in which the adults lived, it is probable that 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 affecting 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 no practical way now known of furnishing oysters with an artificial food supply. Experiments have been made with a view to feeding the adult 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 has been prolonged beyond the early embryonic stages by feeding upon certain marine alge 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. Evenif 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, pp. 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 fiavor 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 walis 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 placing 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 16 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 harmfui 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 pollution. 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. Notwithstanding that almost every recent writer upon the subject has insisted upon 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 oceur 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 popular 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, phyco- eyanin, 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. C. R. 189722 338 REPORT OF COMMISSIONER OF FISH AND FISHERIES. TRANSPORTATICN AND LENGTH OF LIFE WHEN REMOVED FROM THE WATER. Under proper conditions the oyster will live for a long time after its removal from the water. Professor Verrill records a case in which marketablé 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 undoubtedly 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 they 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, effectually closing any small leaks, and the retained water would also be in the most favorable position te 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 i quality. As the vital activities are apparently reduced at spch 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 the 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 muddy 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 picking them up by hand or with a short rake. The long ciam or mananose (Mya arenaria) is the principal species 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 Hast, and has now become widely distributed there and an important food product. Itis 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 species which has been the object of attempted cultivation, although no doubt the quahog is equally favorabie 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, through 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, 1s liable to become suffocated 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 1s 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 1 acre or less each of the flats along the Essex River, and let them to persons desiring to plant clams for a rental of $2 per acre or lot for five years and an additional fee of 50 cents. Thus far 574 acres have been taken up and seeded with clams. Small clams are dug on the natural beds and planted on these hitherto unproductive 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 able to secure pro- tection from trespassers. But in 1891 and 1892 lots were obtained and planted. The principal difficulty encountered has been 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 aeres that were 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 about 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 per 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 clammers 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 permanently. The greater part of the land available for this purpose is covered by the deeds of people 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 progress unless checked by complications that may arise relative to the occupancy of the grounds.—Report U. S. Fish Commission, 1894, pp. 139, 140. It was hoped that these planted clams would propagate on the new beds, but the expectation has not been realized, owing, no doubt, to the unsuitableness of the bottom, a fact which would also account for the absenee of the species in the first place. The growth of the soft clam is quite rapid, and Dr. Ryder has shown that at St. Jerome Creek, Maryland, the shells reach a length of between 14 and 17 inches within several months of the time of spawning, co) Report U. S, F. C. 1897. (To face page 340.) PLATE V. \ Wun ey ae hep te WZ ZZ = FIG. 1, INNER FACE, AND FIG. 2, OUTER FACE OF SHELL OF TYPICAL AMERICAN OYSTER. From Fourth Annual Report, U. S. Geological Survey. Report U. S. F. C. 1897. (To face page 340.) PLATE VI. S= \ \\ \ \ HW yy is y Dy) is \y MN lt = js | yy / J “IU fy, Yj if, SS pate A ir ey } Sees eat “i ype S Se Z ve Fie. 1. Upper view of closed valves of Pacific oyster, Ostrea lurida. Fia. 2. Inner face of ventral valve of same specimen. Fie. 3. Outer face of ventral valve of same specimen. Report U. S. F. C. 1897. (To face page 340.) Fic. 1. Unfertilized egg shortly after mixture of spawn and milt; spermatozoa are adhering to the surface. Fic. 2. Egg after fertilization. Fig. 3. Same egg 2 minutes later. Polar body at broad end. Fic. 4. Same egg 6 minutes later. Fig. 5. About 63 hours later. Fic. 6. Another egg at about the same stage. Mass of small cells growing over large cell or mac- romere a. Fie. 7. Egg 55 minutes later. Mac- romere almost covered by small cells of ectoderm. Fie. 8. Optical section of egg 27 hours after impregnation, show- ing two large cells, derived from a in fig 6, covered by a layer of small ectodermal cells. Fie. 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 through cells of upper layer. Fig. 11. An older egg, now become flattened from above downward. Viewed in optical section. Fie. 12. Surface view of an embryo just beginning to swim. After W. K. Brooks. PLATE VII. Fig. 18. Optical section of same. Fia. 14. Surface view of same from another position. Fia. 15. Surface view of same from another position. Fie. 16. An older embryo in same position as in fig 12. Fig. 17. A still older embryo show- ing spherical ciliated digestive cavity opening by mouth, m. Fie. 18. An embryo with well-de- veloped larval shells, older than fig. 1, Plate VIII. rs, right shell; ls, leftshell; vl, velum; m, mouth. Report U. S. F. C. 1897. (To face page 340.) PLATE VIII. S) S TI ~~ KS S/i ¢ Ks Z \ i ES Si Fic. 1. View of right side of embryo about 6 days old. m, mouth; v, vent; J, right lobe of liver; vl, velum. Fig. 2. Older larva of European oyster, Ostrea lurida. L, shell; h, hinge; rs and rz, retractor muscles of the velum, vl; s, stomach; 7, intestine; am, larval adductor muscle; b, body cavity. Other letters as in the preceding. : Fie. 3. Attached spat of Ostrea virginiana. 8S, shell of spat with larval shell, LZ, at the beak or umbo; p, palps; g, gills; c, diagrammatic representation of a single row of cillia extending from the mantle border to the mouth m; r, radiating muscle fibres of mantle; ¢, rudimentary tentacles of mantle border; M, perma- nent adductor muscle; C, cloaca; ve and au, ventricle. and auricle of the heart; y, posterior extremity of the gills and junction of the mantle folds. Other figures as above. Compare this figure with PI. I, fig. 1. Fig. 1 after W. K. Brooks. Fig. 2 after Thomas H. Huxley. Fig. 3 after John A. Ryder. Report U. S. F.C. 1897. (To face page 340.) PLATE IX. SET OF OYSTERS ON RACCOON OYSTER SHELL, SHOWING CROWDING. NATURAL SIZE. Report U. S. F. C. 1897. (To face page 340.) PLATE X. OYSTER SPAT TWO OR THREE WEEKS OLD ON INSIDE OF OYSTER SHELL. NATURAL SIZE. Report U. S. F. C. 1897. (To face page 340.) . PLATE XI. OYSTER SPAT ABOUT TWO MONTHS OLD, ON A STONE. NATURAL SIZE. Report U. S. F. C. 1897. (To face page 340.) PLATE XIl. FIGS. 1, 2, AND 3, OYSTERS ONE, TWO, AND THREE YEARS OLD, RESPECTIVELY. NATURAL SIZE. Grown on hard bottom in Long Island Sound. on Ney duit Report U.S. F. C. 1897. (To face page 340 ) PLATE XIII. FIGS. 1 AND 2, OYSTERS FOUR AND FIVE YEARS OLD, RESPECTIVELY. NATURAL SIZE. Grown on hard bottom in Long Island Sound. — J ear Report U. S. F. C. 1897. (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 given, to indicate 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. 5. Navicula (Bory). 13. Coscinodiseus radiatus (E.). 20. Biddulphia sp. (Gr.). 6. N. didyma (K.). 14. Cyclotella rotula (E.). 21. Grain of pine pollen (Pinus 7. Pinnularia radiosa (?) (K.S.). 15. Synedra sp. (E.). rigida). 8. Amphora sp. (K.). 16. Diatoma sp. (De C.). 22. Foraminifera (Rotalia). 9. Pleurosigma fasciola (E.S.). 7. Cymbella sp. (Ag.). 23. Zodspore (Ulva ?). 0. P. littorale (S.). 18. Mastogloia smithii (Thw.). 24. Spicules. 1. P. strigosum (S.). 19. Triceratium alternans (Br. 2. Actinocyclus undulatus (K.). Bai.). (After Bashford Dean.) Report U. S. F,C. 1897. (To face page 349.) PLATE XV, vs , Ss Vy MI aN 3 Fie. 1. Drill, Urosalpinx cinerea. Fic. 3. Sabellaria vulgaris. Fic. 2. Mussel, Mytilus edulis. Fic. 4. Periwinkle, Fulgwr carica. PLATE XVI. (To face page 340.) Report U, S. F. C. 1897. STARFISH ATTACKING OYSTERS. [From Fifth Annual Report of Connecticut Bureau of Labor Statistics. ] WAS Shien pS 2 Be Report U. S. F. C. 1897. (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. Report U. S. F. C. 1897. (To face page 346.) FLaTe XVIII. if Dis fy f} ii ii ff MS SS WY, S= 2 ~S a, e& 2 i . “Quarter-decker,” Crepidula fornicata. . ‘*Quarter-decker,”” Crepidula plana. . “ Quarter-decker,”” Crepidula convexa. Jingle, Anomia glabra, profile view. The same, lower side. . Scallop, Pecten irradians. . Oyster attached to pebble. 5] I § - RIawrpwwe qe al aL i ra, ait, ; VIEW OF BATTE PLATE 35. —= vCOO—_ Report U. S, F, C, 1897, (To face page 340,) ils il, il (it al y IV y I (eo UTE TT UCLA LL _ = ee = ——- ——— a === == a =e = ——— WU Hat = = = = CC CTT — = | ] a= = @ ; e ) Wir \) 6) = Cones N11 (tart) | aes) 1 fiat It ri = 7 NAR dT DRS , heath ‘ll, Tr it 1 i H | I i | 5 | | Pal Ss Se I I = BS Low. : D> pi LE ZZ, TTT Ts SSS i, (ng 7 ‘ ili! eS 7 | iat) wie ) wt LAND } [a ue Viel y SPA fe | ll \) PLATE 35. 1 Oh ) <\ NE MU { it ff A = = : q oP qj alll. } / mu = ] j i) i @ an We NG i aaa fs @ fs Gmail “Way = q i Ay eh in| Hh i I iM hy eh "mh if hy i i F ANG phe ( He a IM 2 ( NG) ANE) NN = \ Z i i i a CITT TT ZS TLL Ts ——4 Ait TTT | = PZ 3 Mas i ‘ ZZ ELLA, - Sa < = Fz i SE A — -_ = mr TTT Tl TLL TUTTI 7 | Tn, OTTO ATIITUTNNTILN PR OO eee VIEW OF BATTERY FOR HATCHING WHITEFISH.