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EXPERIMENTAL FISHING

TO DETERMINE DISTRIBUTION

OF SALMON IN THE

NORTH PACIFIC OCEAN, 1955

Marine Biological Laboratory

LIBRARY

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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.

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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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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

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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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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.

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

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

26

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

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RED 318 Fish

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

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

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

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