Special scientific report

EXPERIMENTAL FISHING

TO DETERMINE DISTRIBUTION

OF SALMON IN THE

NORTH PACIFIC OCEAN, 1955

Marine Biological Laboratory

LIBRARY

L

OCT IS 1957
WOODS HOLE, MASS.

SPECIAL SCIENTIFIC REPORT- FISHERIES No. 205

UNITED STATES DEPARTMENT OF THE INTERIOR
FISH AND WILDLIFE SERVICE

EXPLANATORY NOTE

The series embodies results of investigations, usually of restricted
scope, intended to aid or direct management or utilization practices and as
guides for administrative or legislative action. It is issued in limited quantities
for Official use of Federal, State or cooperating agencies and in processed form
for economy and to avoid delay in publication .

United States Department of the Interior, Fred A. Seaton, Secretary

Fish and Wildlife Service

EXPERIMENTAL FISHING TO DETERMINE DISTRIBUTION OF
SALMON IN THE NORTH PACIFIC OCEAN, 1955

By

Donald E. Powell
Fishery Methods and Equipment Specialist

and

Alvin E. Peterson
Fishery Research Biologist

Special Scientific Report- -Fisheries No. 205

Washington, D. C.
July 1957

ABSTRACT

Distribution of salmon on the high seas in the North Pacific Ocean
was investigated by the U.S. Fish and Wildlife Service during the summer
and early fall of 1955. Three vessels conducted extensive gill -net operations
over a 3-1/2 month period in the Gulf of Alaska and in the offshore waters
south of the Aleutian Islands and the Alaska Peninsula, with a limited amount
of fishing off the coasts of Oregon, Washington, and British Columbia. Results
showed that the several species of North American salmon and the steelhead
trout were widely distributed in the open ocean at that time of year and could
be sampled readily with surface gill nets.

Salmon were caught at all stations occupied from off northern Vancouver
Island across the Gulf of Alaska as far west as Unalaska Island. Catches farther
west and in more southerly waters revealed an apparent southern limit for high-
seas salmon at about 47° N. latitude in the area of major operation. South of
thi s line in the warmer waters albacore replaced salmon in the gill -net catches.

Length measurements of all salmon were taken aboard the vessels and
are presented graphically according to species and by mesh size.

CONTENTS

Page

Introduction 1

Description of vessels 1

Gill-n et construction and operation 1

Fishing results 10

John N . Cobb 10

Catch by species and mesh size 10

Depth of salmon 10

Vitality of gill -net -caught salmon 15

Seasonal composition of gill -net catches 15

Mitkof and Paragon 15

Catch composition 19

Water temperature 19

Length frequencies 2U

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EXPERIMENTAL FISHING TO DETERMINE DISTRIBUTION OF SALMON
IN THE NORTH PACIFIC OCEAN, 1955

INTRODUCTION

As a part of the research program re-
quested by the International North Pacific
Fisheries Commission, theU. S. Fish and
Wildlife Service undertook in the summer and
early fall of 1955 a broad study of the high -seas
distribution of salmon in the North Pacific Ocean.
Three vessels participated in this work, the
Service's own research vessel John N. Cobb and
the chartered halibut schooner-type vessels
Mitkof and Paragon.

The aims of this investigation were to
gain knowledge of the range and distribution of
salmon in the eastern and central North Pacific
Ocean and to collect samples of salmon through-
out their range for morphological and physio-
logical racial analysis . Oceanographic data
were also collected simultaneously with the fish-
ing operations for analysis by the Department
of Oceanography, University of Washington.
Ocean tagging on a minor scale was conducted
by the Cobb only, with the main tagging program
being carried out by the Fisheries Research In-
stitute, University of Washington. The ultimate
objective of all this work is to determine the ex-
tent of intermingling between Asian and North
American stocks of salmon and to separate, if
possible, the stocks of different continental
origin in the high -seas fishing areas. Results
are presented in preliminary form to make the
data available until detailed biometric analysis
now in progress, is completed.

DESCRIPTION OF VESSELS

Specifications for the exploratory fish-
ing vessel John N . Cobb, 78 net tons, are as
follows:

Length ove all 93' 5-1/4"

Length, w aterline 85' 0"

Beam over guards 25' 6-3/4"

Beam, molded 24' 6"

Depth, molded 12' 7"

Draft, molded (mean load). . 8' 6"
Draft over keel (mean load).. 9' 6"

Bunkers, Diesel fuel 12,000 gals .

Capacity, fresh water 6,000 gals .

Cruising speed 10 knots

Maximum speed 10.8 knots

Number of bunks 14

The two chartered schooner-type vessels
were of the following specifications:

Vessel MITKOF.

.PARAGON

Total length 72 feet 90 feet

Keel length 66' 1" 80 feet

Tonnage 42 tons 64 tons

Breadth 18 ' 4" 19' 5"

Draft 9'(empty) 9'(empty)

Cruising speed 9 knots 8.5 knots

Maximum speed. ... 9.5 knots 9 knots

Engine & horsepower .Fairbanks, 200H. P. Enter-
prise, 165H.P.
Number of bunks .... 12 13

GILL NET CONSTRUCTION AND OPERATION

The John N . Cobb fished with four sizes
of nylon gill nets: 3-1/4-inch, 4-1/2-inch, 5-1/4-
inch, and 6-inch stretched mesh measure. The
nets were constructed to fish shallow (fig. 4) from
the surface to about 20 feet deep. Past experience
by the Cobb in 1953 (Schaefers and Fukuhara, 1954)
and reports from the Japanese salmon fleet
(Fukuhara, 1953) indicated that most salmon were
caught close to the surface on the high seas.

The nets were made up in 50 -fathom shack-
les, and on most sets either 20 shackles (1,000
fathoms) or 30 shackles (1,500 fathoms) were
lashed together and fished in a string. A typical
20 -shackle set was made up of two shackles of
3-1/4-inch mesh, five shackles of 4-1/2-inch
mesh, 11 shackles of 5-1/4-inch mesh and two
shackles of 6 -inch mesh, arranged randomly.
Lesser amounts of gear were used early in the
season and during poor weather on several sets.
A total of 1,018 shackles were fished during the
trip: 126 shackles of 3 -1/4 -inch mesh, 249
shackles of 4-1/2 -inch mesh, 565 shackles of
5 -1/4 -inch mesh, and 78 shackles of 6 -inch mesh.

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Double corklines, one right-hand lay
and one left-hand lay to prevent twisting, were
used on all gill nets. Each salvage mesh was
lashed tightly to one corkline with a double hitch
to minimize chafing of the salvage caused by
wave action on the open ocean. Otherwise, the
nets were hung essentially according to the con-
ventional manner used in the salmon fishery.
Details of the 5-1/4-inch nets are given in fig-
ure 4.

With the exception of three experimental
daytime sets, the nets were fished at night, be-
ing set in the evening and hauled just after day-
break . The nets were set downwind over the
stern of the boat at a speed of about 4 knots. A
lighted flagpole was tied to each end of the
string. Seven hundred feet of 4-1/4-inch cir-
cumference lubricated-core rope was attached
with a bridle to the last shackle to go overboard,
and was then made fast to the bow of the vessel
at the lee end of the nets. The vessel thus held
on to the gear all night while drifting.

Nylon rope, 15/16 -inch diameter, was
lashed along the corklines of the first eight
shackles of nets nearest the vessel to relieve
strain from the corklines while hauling. The
gear was hauled over a shark roller mounted on
the starboard rail near the bow of the John N.
Cobb. Power for hauling was transmitted
through a rubberized sheave attached to the
main anchor winch. Fish were removed on a
canvas-covered iron grating between the bow
roller and the anchor winch . Two men then
cleared the web and pulled it to the stern where
it was piled in the bin in readiness for the next
set.

Hauling time averaged about five min-
utes per shackle, increasing proportionately to
the number of fish in the net. The occasional
mackerel shark caused considerable gear dam-
age and delay in hauling. Jack mackerel were
extremely difficult to remove from the nets, but
most of the pcmfret could be shaken out with no
trouble. The nets were mended daily on the
John N. Cobb, and they were completely over-
hauled several times during the trip on brief
port calls.

The Mitkof and the Paragon fished with
four different mesh sizes of nylon gill nets,

2-1/4-inch, 3-1/4-inch, 4-1/2-inch, and 5-1/4-
inch stretched mesh measure. Construction of
the nets was the same as for the John N. Cobb,
as shown in figure 4.

Twelve 50 -fathom shackles of gill net
were used for each set by the Mitkof and the
Paragon, and the numbers of shackles of each
mesh size used on every set were two shackles
of 2-1/4-inch mesh, two shackles of 3-1/4-inch,
two shackles of 4- 1/2 -inch and six shackles of
5-1/4-inch mesh. A standard arrangement of
the various mesh sizes in the net was used for
all sets, with the 5-1/4-inch mesh alternating
with the smaller mesh sizes throughout the net.

In the fishing operations of both the Mitkof
and the Paragon, nylon rope, 15/ 16 -inch diameter,
was lashed along the corklines for 1/4 to 1/2 of
the net, and about 200 fathoms of manila line was
fastened to the bridle from the vessel during the
fishing. A flagpole with a light was tied to each
end of the net during fishing, and the vessel re-
mained attached to the net at all times. All sets
by the Mitkof and Paragon were overnight sets.

The same system for setting and hauling
the gill nets was used by both schooner -type
vessels. The net was set from the stern of the
vessel, paying out while the vessel proceeded
ahead at slow speed for a period of 15 to 20
minutes (fig. 8) . The net was set with the wind,
so that when it was completely out, the vessel
could remain secured to the lee end.

The net was hauled in from the starboard
side of the vessel over a roller attached to the
guard rail and over a table (where the fish were
removed) by means of a mechanically driven
"gurdy™ (fig. 9). This operation took place in the
well -deck forward of the pilot house, and from
there the net was passed along the deck to the
stern where it was re -piled in preparation for
the next set. The hauling operation required up
to two hours per set for both the Mitkof and the
Paragon .

Upon completion of hauling, measurements
and scale samples were taken from each salmon
caught (fig. 11). On all three vessels a numbered
metal strap tag was attached to the gill cover of
each salmon for identification, and the fish were
then frozen for further racial studies at the
laboratory.

Figure 5 •--Salmon were removed from the gill nets just aft of the roller
on the how of the John N. Cobb.

Figure 6. --After coming around the sheave on the anchor winch (to the
left of the photo) the gill nets were cleared on their way to the
stern of the John N. Cobb.

6

Figure 7- --The gill nets were piled in the stern "bin of the John N. Codd
in preparation for the next set.

Figure 8. — Clearing gill nets during setting from the after-deck of
the Mitkof .

Figure 9- — Hauling gill nets aboard the Mitkof.

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Figure 10. --Picking up marker buoy during hauling operations on the

Mitkof.

Figure 11. — Measuring and taking scales from salmon caught in gill nets
on the Mitkof.

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Figure 12. --Live salmon were placed in a small live "box near the bow

of the John N. Cobb, and those that survived were tagged
and released.

FISHING RESULTS
John N. Cobb

Fifty gill net stations were occupied by
the John N. Cobb from June 25 to September 13
in the offshore waters extending from off north-
ern Vancouver Island northward to southeastern
Alaska and across the Gulf of Alaska as far west
as Unalaska Island (fig. 13). Salmon were
caught in the gill nets at each station, all five
species being taken in a number of the sets .

Total gill -net catch of salmon for the 50
sets was 2,484, an average of 49 salmon per set.
Individual catches ranged from 1 to 168 salmon.
The catch included 1,248 chums, 639 pinks, 367
reds, 211 silvers, and 19 kings. Salmon-troll-
ing gear fished in the vicinity of five gill -net
stations caught 18 silvers, 3 pinks, and 1 king.
In addition to salmon, the gill nets caught 55
steelhead trout and various numbers of pomfret,
jack mackerel, dogfish, mackerel shark, and a
few ragfish and squid. Tables 1 and la present
the complete fishing log of the John N ■ Cobb, in-
cluding dates, positions, catches by species,
and other pertinent data.

Several stations in the Gulf of Alaska
were fished a second time after an interval of
about 2 months to compare catch results over a
period of time . To com pare effectiveness of
the gill nets in day and night fishing, 3 sets
were made in the daytime . The daytime sets
each caught salmon, but the catch in each in-
stance was less than the catches made in the
same place at night.

Catch by species and mesh size

Chum salmon were most abundant in the
gill -net catch of the John N. Cobb, comprising
slightly over 50 percent of the total (table 2) .
Pinks were next most abundant, at 25.7 percent.
Kings were least numerous, forming less than
1 percent of the catch. Species composition
varied with dates and areas fished, as can be
seen in the fishing log and in table 5. At no time
were any jumpers or other surface signs of
salmon seen in the offshore waters, and all gill -
net sets were made "blind" .

Table 2 also shows the catch by species
for each of the four sizes of gill nets. The 4-1/2-

inch mesh was most effective, catching 3.31
salmon per shackle. Next most effective mesh
size was 5-1/4-inch, with an average catch of
2.45 per shackle. The 3-1/4-inch nets were
least effective, 1.2 salmon per shackle, while
the 6 -inch nets were slightly higher at 1.58 sal-
mon per shackle. Average catch for the 1,018
fifty-fathom shackles fished was 2.44 salmon
per shackle.

Each of the net sizes was selective to a
degree in sizes of fish caught (fig. 16). This
selection also affected the catch of some species
for each mesh size. For instance, more reds
and chums were taken in the smaller 3-1/4-inch
nets than any of the other species, because small,
immature individuals were more abundant in
these two species than the others. Chums oc-
curred most often in the 4- 1/2 -inch and 5-1/4-
inch mesh. No small, immature pinks were
caught. The number of kings taken was too small
for significant comparison.

Depth of Salmon

A record was kept of the depth in the net
at which the salmon were enmeshed (table 3).
From these observations it is apparent that the
salmon spend much of their time in the offshore
waters very near the surface.

The nets were constructed to fish from
the surface to a depth of approximately 20 feet.
For purposes of recording depth of the salmon,
the nets were arbitrarily divided into three parts,
and the position of each salmon caught was re-
corded as in the "upper", "middle", or "lower"
third of the net. In recording these data the
observer merely made a quick judgment of the
position of each fish as the net came near the
vessel, as it approached the roller, or as the fish
were being removed. Thus, there is some chance
for error on those fish which were near the border
lines of "upper", "middle", or "lower".

Table 3 shows that over half (53 percent)
of the salmon caught by the John N. Cobb were
recorded in the upper one -third of the nets, or
within 7 feet of the surface. In the lower one-
third there was a higher percentage of Kings and
reds than of the other 3 species, and conversely,
kings and reds had lower percentages than the
others in the upper part of the nets. The apparent

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Figure 13. — Area covered by the three salmon-research vessels, showing fishing stations, numbered chronologically, and catch distribution.

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13

Table 3. — Depth at which salmon entered the gill nets, John N. Cobb

Species
of

Number

of
salmon ,
observed-/

Number and percent in each portion of net

salmon

Upper l/3 meshes

Middle 1/3 meshes

Lower 1/3 meshes

King

19

Number
8

Percent
1x2

Number

5

Percent
26

Number
6

Percent
32

Red

318

126

hO

70

22

122

38

Silver

193

113

59

30

15

50

26

Pink

596

3U8

58

126

21

122

21

Chum

1189

632

53

262

22

295

25

Totals

2315

1227

53

U93

21

595

26

1/ For various reasons, the above data were not recorded for I69 salmon in
the total catch of 2,1*8U.

Table U- — Vitality of gill-net -caught salmon and number tagged,
John N. Cobb

Species

of
salmon

Numbers
observed 1/

Dead

Alive

Tagged £/

19

Number

i5

Percent

Number

Percent
21

Number
3

Percent

King

79

h

16

Red

367

211

57

156

1x3

72

20

Silver

205

156

76

1x9

2\x

36

18

Pink

635

507

80

128

20

66

10

Chum

12U3

1010

81

233

19

13li

11

Totals

2U69

1899

77

570

23

311

13

1/ Vitality of 15 salmon in the total catch was not recorded.

2/ Only those live salmon which remained active in a live box for several
minutes after capture were tagged . Many died shortly after being removed
from the net. In addition to the 72 red salmon tagged, an additional h5
live reds, which could have been tagged, were saved for blood samples.

14

small advantage of the lower one -third over
the middle one -third of the nets could be due to
observational error and probably should not be
considered significant.

Vitality of gill -net caught salmon

Most of the salmon caught in the gill
nets were dead when landed. Condition of the
fish was directly related to the state of the sea.
In rough weather many salmon had most of
their scales removed by the chafing action of
the nets, and the increased strain on the gear
caused the nylon meshes to grip the fish more
tightly, resulting in cuts and abrasions of the
skin and flesh and often making it necessary to
cut the mesh in order to release the fish with-
out further damage.

From table 4 it may be seen that 77 per-
cent of the salmon caught by the John N . Cobb
were dead when landed. The percentage of
reds alive was about twice that for any other
species (43 percent as compared to the average
of 23 percent). The reason for this apparent
greater tenacity of life of the red salmon was
not clear. They may struggle less in the nets;
this was indicated by the observation that the
reds in general were less de-scaled than the
other species. Swimming habits might be
responsible, if, for some reason, the reds
entered the nets more often in the early morn-
ing just before the gear was hauled.

Of the total 23 percent of live gill -net -
caught salmon 13 percent, or 311 fish, were
tagged and released after being held for a while
in a live box. Many others died shortly after
being removed from the net. In addition to the
72 red salmon tagged, 45 live reds which could
have been tagged were saved for blood samples.
Seventeen silvers and two pinks caught trolling
were tagged and released. The small number
of tag returns from the gill -net -caught fish (3
returns reported to March 1956) is insufficient
for any good indication of the number of tagged
fish which survived.

Seasonal composition of gill -net catches

Table 5 presents information on the com-
position of the John N. Cobb's salmon catches

during the several months of operation. The
fishing effort was concentrated during July and
August, and these two months produced the bulk
of the catch. During July the catch per shackle
was greatest. It should be remembered that the
vessel moved over a wide area and that the
species composition was undoubtedly affected
by area fished in addition to time of fishing.

Reds were dominant in the small catch
made during June, composing 53 percent of the
total. Pinks and chums increased in July and
August, and by September chums made up 95
percent of the catch. In July and early August
when the catch of red salmon was highest, the
fishing was mainly in the western Gulf and south
of the Alaska Peninsula out to Dutch Harbor.
The large catches of pinks and chums in late
August and September were made in the eastern
half of the Gulf of Alaska .

Three positions were fished a second
time after a 2-month interval with identical
amounts of gill nets. These stations were in the
eastern Gulf of Alaska, on a line between Cape
Spencer and Kodiak . They were fished first in
early July (sets 9-11) and again in early Septem-
ber (sets 44-46), with good catches each time.
Red and pink salmon, which were caught in fair
numbers at each of these stations in July, dis-
appeared entirely from the catches made in
September. Almost the entire catch at all three
stations in September was chum salmon. At two
of the three stations the chum catch was greater
in September than in July .

Mitkof and Paragon

The Mitkof and Paragon operated mainly
in the offshore waters south of the Aleutian Is-
lands and Alaska Peninsula, with 26 gill -net
stations by the Mitkof and 26 stations by the
Paragon being completed, as shown in figure 1 3
and tables 6 and 7. The westernmost stations
south of the outer Aleutian Island chain between
175° E. longitude and 175° W. longitude were
fished by the Paragon, with one additional station
being taken on the homeward trip to Seattle at
station number 37 south of the central Gulf of
Alaska. The Mitkof series of stations, east of,
but overlapping, the rectangular fishing area of
the Paragon, ranged from 175° W. longitude to

15

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south of the western Gulf of Alaska, with 4 ad-
ditional stations being fished along the 48° N.
latitude line on the homeward journey. The
fishing period for these two vessels extended
from August 11, 1955 to October 5, 1955.

Catch composition

The total salmon catch for the 11 sta-
tions where salmon were caught by the Mitkof
was 232, an average of 21 salmon per set for
12 shackles of gill net. Individual catches
ranged from 3 to 57 salmon. The seasonal
catches by species were 122 reds, 94 chums, 13
silvers and 3 kings. No pinics were taken. Five
steelhead were caught. The complete fishing
log of the Mitkof showing the catches of salmon
and other species of fish as well as other perti-
nent data is given in table 6.

The total salmon catch by the Paragon
for the 14 stations where salmon were netted
was 558, an average of 40 salmon per set. The
catch per set ranged from 2 to 127 salmon. In
all, 76 reds, 470 chums, 1 silver and 11 kings
were taken. As with the Mitkof, no pinks were
caught. Three steelhead were taken. The com-
plete fishing log for the Paragon is given in
table 7.

Chum salmon and red salmon formed the
bulk of the salmon catches by the Mitkof and
Paragon, as is demonstrated in tables 8 and 9.
The Mitkof caught 52.6 percent reds, 40.5 per-
cent chums, 5 .6 percent silvers, 1.3 percent
kings and no pinks. The Paragon caught 84.2
percent chums, 13.6 percent reds, 2 percent
kings, 0.2 percent silvers and no pinks.

Tables 10 and 11 show the salmon catch
by species for each of the mesh sizes fished
both in total numbers and on a catch -per -shack-
le basis. The 4-1/2 -inch mesh was the most
effective on the Mitkof, taking 3.32 salmon per
shackle. On the Paragon the two most effective
nets were the 4- 1/2 -inch mesh (4.21 salmon
per shackle) and the 5-1/4-inch mesh (4.28 sal-
mon per shackle). In the catch of all three
vessels the 4-1/2-inch mesh was the most ef-
fective for taking salmon.

Water temperature

Whereas the John N . Cobb fished through-
out the Gulf of Alaska in waters where salmon
were present at every station, the Mitkof and
Paragon deliberately fished in more southerly
waters in and out of the warm Japanese current
to determine the southern range of the salmon.
Hence, salmon were taken only on the more
northerly stations by the latter two vessels.

On the more southerly stations, while
salmon were not present, numbers of albacore
were taken. A total of 210 albacore at 15 sta-
tions between 45° N. latitude and 48° N. latitude
were taken by the two vessels. Also, blue
sharks were usually caught along with albacore.

The relation of surface water tempera-
ture to numbers of salmon and albacore caught
by the two vessels is demonstrated in figure 14.
The extreme range of water temperatures where
salmon were caught was from 48.4° F. to 56.8°
F. On the other hand, water temperatures
ranged from 53.6° F. to 63.7° F. where alba-
core were taken. Salmon and albacore were
taken in the same net haul only once --at station
26 of the Paragon. The general trend shown in
figure 14 is U-shaped, with the greater catches
of salmon occurring in the colder waters, small
catches or no catches of salmon and albacore at
intermediate temperatures, and the greater
catches of albacore in the warmer waters.

The surface water temperatures at the
50 John N ■ Cobb fishing stations ranged from
48.3° F. to 54.0° F. with salmon taken at all
stations and no albacore taken at any station.

A series of sets (stations 12-14) by the
Paragon along the 175° E. longitude line made
between August 24 and August 26, 1955 was re-
peated in mid-September (stations 26-28) when
the water temperature had cooled 4.7° F. to 4.9°
F. at each station. On the initial run no salmon
were taken, but on the later run salmon were
caught at all three stations. This phenomenon
indicates that the salmon tend to increase their
geographic range in a southerly direction as the
warm Japanese current is restricted southward.

After the main fishing cruises of the
Mitkof and Paragon were completed, a short ad-
ditional cruise was made south along the North

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20

Table 8. — Composition of salmon gill-net catches
(total for 11 sets), Mitkof

Species

Number caught

Percent of total catch

King

3

1.3

Red

122

52.6

Silver l/

13

5.6

Pink

0

0.0

Chum

9k

ho. 5

Totals

232

100.0

1/ All but one of the 13 silvers were caught station h6
off Cape Flattery.

Table 9. — Composition of salmon gill-net catches
(total for lh setsjt, Paragon

Species

Number caught

Percent of total catch

King

11

2.0

Red

76

13.6

Silver

1

.2

Pink

0

0.0

Chum

h70

8h.2

Totals

558

100.0

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American coastline by the Mitkof. No salmon
were caught at three stations off Cape Bianco,
Oregon, and 2 silvers and 1 king were taken at
two stations off the mouth of the Columbia
River.

LENGTH FREQUENCIES

In figure 16 the fork lengths of 1,052
salmon (all species) caught by the John N . Cobb
are shown in frequency distributions according
to mesh size. Similarly the length frequencies
of all salmon caught by the Mitkof and Paragon
are graphed in figures 17 and 18, respectively.

The various mesh sizes were selective
for particular size ranges of salmon, but con-
siderable overlapping of the size distribution of
salmon occurred in the catches of the different
nets. The sizes of fish taken by each mesh
were in part dependent on the sizes of fish avail-
able to the nets, and the length frequencies
which are shown represent size selectivity over
a wide range of area and time .

In figure 19 the fork lengths of all sal-
mon caught by the Cobb during the entire season
segregated according to species are shown.
Likewise, the seasonal length frequencies of
each species of salmon taken by the Mitkof and
Paragon are given in figures 20 and 21, respec-
tively.

These length -frequency data along with
age readings from the scales and with the size
and development of the ovaries and testes are
being analyzed for a later report. The complete
morphological and physiological racial analyses
of the ocean catches of the three research ves-
sels will aid in evaluating the extent of inter-
mingling of North American and Asian stocks of
salmon.

LITERATURE CITED

Fukuhara, Francis M.

1953. Japanese 1952 North Pacific salmon-
fishing expedition. Dept. of the
Interior, Fish and Wildlife Service,
Commercial Fisheries Review,
vol. 15, no. 2, 1953, 17 pp., 7 figs.

Schaefers, Edward A., and Francis M. Fukuhara

1954. Offshore salmon explorations adja-
cent to the Aleutian Islands, June-
July 1953. Dept. of the Interior,
Fish and Wildlife Service, Commer-
cial Fisheries Review, Sep. No.
371, vol. 16, no. 5, May 1954,

20 pp . , 16 figs . , 5 tables .

Figure 15. --This group of red salmon illustrates the size range of
fish taken in one gill-net set by the John N. Cobb.

2k

INT.-DUP. SEC. WASH.. D.C. 2 ; li 7 1

20
10

■•»

6-inch Mesh

33 Shackles
44 Fish

0
60
50

f\

5^-inch Mesh

311 Shackles
705 Fish

40
30

JVPn

M

^ 20

«*-
o

* 10

w

ja

E n

n " «

Lnn

3 °

30
20

_i

r~—

42-inch Mesh

118 Shackles
251 Fish

10

„rJ

U\,

0
10

^^

3^-inch Mesh

60 Shackles
52 Fish

-a . n — .

31

40

50

60

70

80

Fork Length in cms.

Figure l6 .- -Length frequency distribution of 1,052 salmon (combined
species) taken by each mesh size, John N. Cobb.

25

20

10

CA

V)
w
0>

E
z

0
I0r

10 ■

_□_

JO-

5^-inch Mesh
60 Shackles
99 Fish

J^.

4 2-inch Mesh

20 Shackles
68 Fish

0«7
31

O — ex

Wv-^nrn

3-4-inch Mesh
18 Shackles
52 Fish

40

50

60

— i—
70

— r
80

Fork Length in cms.

Figure IT- — Length frequency distribution of salmon (combined species)
taken by each mesh size, Mitkof .

26

50

Jl

5^--inch Mesh

40
30

/

\

84 Shackles
358 Fish

20

of Fish
o o

J

J

^H i i l 1 i — i r-i

4g-inch Mesh

£ 20

JO

-

16 Shackles
n 117 Fish

1 l0

Atp*.

0
10

0
10

0^

n n

r^ U ^„

3^-inch Mesh
_ 20 Shackles

2^-inch Mesh
4 Shackles
6 Fish

>l 40

50 60 70 80

Fo

rk

Length

in cms.

Figure 18. — Length frequency distribution of salmon (combined species)
taken by each mesh size, Paragon.

27

</>

(A

w
V

.O

CHUM
1200 Fish

PINK
612 Fish

SILVER
223 Fish

RED
318 Fish

KING
20 Fish

excajJ t^-* . n n

50 60

Fork Length in cms.

r
70

~80~

90

Figure 19- — Length frequency distribution of each species of salmon,
John N. Cobb.

28

20

10

0

(A

(A

0)

E 10

0
10

Oh

u^\

CHUM
87 Fish

„^P^

31

50

SILVER
I Fish

RED
1 14 Fish

KING
2 Fish

40 50 60

Fork Length in cms.

— r
70

Figure 20. — Length frequency distribution of each species of salmon,
Mitkof (catch at station k6, off Cape Flattery, is not
included) .

29

60 -
50 ■
40
30 \
20

<A

01

iiof

0
10

0
10

31

J-L

/

CHUM
468 Fish

X

-Z

IbzL

SILVER
I Fish

^H^^n-

RED
76 Fish

— i —
40

-i —
50

KING
II Fish

r~i HI n n .n r~i n.

60

70

- r
80

Fork Length in cms.

Figure 21. — Length frequency distribution of each species of salmon,
Paragon .

30

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