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CALffORNIAl

FISH- GAME




California Fish and Game is a journal devoted to the conserva-
tion of wildlife. Its contents may be reproduced elsev/here pro-
vided credit is given the authors and the California Department
of Fish and Game.

The free mailing list is limited by budgetary considerations to
persons who can make professional use of the material and to
libraries, scientific institutions, and conservation agencies. Indi-
viduals must state their affiliation and position when submitting
their applications. Subscriptions must be renewed annually by
returning the postcard enclosed with each October issue. Sub-
scribers are asked to report changes in address without delay.

Please direct correspondence to:

LEO SHAPOVALOV, Editor
Department of Fish and Game
722 Capitol Avenue
Sacramento 14, California

Individuals and organizations who do not qualify for the free
mailing list may subscribe at a rate of $2 per year or obtain indi-
vidual issues for $0.75 per copy by placing their orders with the
Printing Division, Documents Section, Sacramento 14, California.
Money orders or checks should be made out to Printing Division,
Documents Section.



u









D



V



VOLUME 43



OCTOBER, 1957



NUMBER 4




Published Quarterly by the

CALIFORNIA DEPARTMENT OF FISH AND GAME

SACRAMENTO



STATE OF CALIFORNIA

DEPARTMENT OF FISH AND GAME



GOODWIN J. KNIGHT
Governor



FISH AND GAME COMMISSION

ANDY KELLY, President
Los Angeles

CARL F. WENTE, Commissioner WILLIAM P. ELSER, Commissioner

Son Francisco Son Diego

WELDON L. OXLEY, Commissioner T. H. RICHARDS, JR., Commissioner

Redding Sacramento



SETH GORDON
Director of Fish and Game



CALIFORNIA FISH AND GAME
Editorial Staff

LEO SHAPOVALOV, Editor-in-Chief Sacramento

JOHN E. FITCH, Editor for Marine Fisheries Terminal Island

CAROL M. FERREL, Editor for Game Sacramento

J. B. KIMSEY, Editor for Inland Fisheries Sacramento



TABLE OF CONTENTS

Page

Food Habits of the King Saliiioii. Oiicorlnjiicluis IsliatvijLscliu
(Walbaum), in the Vicinity of San Francisco, California

Terrence J. Merkd 249

The I'sc of Wii-c Vykc 'i'raps to Estimate the Kuns of Adnlt
Salmon and Steclhead in the Sacramento River

Richard J. Hollock, />. //. Frij, Jr., <ind Don A. LaFaunce 271

Fishes Collected in tlic Tropical Eastern Pacific, 11)54

Harold B. Clemens 299

Calcnhitinji' the Percenta<i-e of Kill From Sex and Age Katios

David M. Sclleck and Chester M. Hart 809
Note

Second Record of the Green Sturgeon in Southern California

Kenneth S. Norris 817

Reviews 319

Index to Volume 43 325



( 247 )



FOOD HABITS OF THE KING SALMON,

ONCORHYNCHUS TSHAWYTSCHA (WALBAUM),

IN THE VICINITY OF SAN FRANCISCO, CALIFORNIA'

TERRENCE J. MERKEL

Georgia Game and Fish Commission
Clayton, Georgia

INTRODUCTION

The king salmon, Oiicorhynchus tshaivytscha (AValbaum), is an im-
poi'taiit coiinnercial and <ranie fish native to the Pacific Coast of North
America. Its range, according to Roedel (l!*.")."^), exteiids from southern
California to Alaska, and then southward along the coast of Asia to the
Amur River and Japan. This species is known by a number of names,
including chinook salmon, quinnat salmon, spring salmon, and tyee
salmon. Like other species of Pacific salmons in the genus Oiworhyn-
chiis, king salmon are anadromous. spending part of their life in the
ocean, and entering streams to spawn. Spawning takes place in the late
summer, fall, or winter, the eggs being deposited in gravel beds. Shortly
thereafter the parents invariably die. The young emerge from the
gravel by late winter or early spring and migrate to the ocean, usually
during the first yeai- of life, although a few remain in fre>,h water until
their second year. Most king salmon mature at 3, 4, or 5 years of age.

Although much has been brought to light concerning the life of the
king salmon in fresh water, relatively little is known of its life in the
ocean.

Several studies of the food habits of ocean-caught king salmon have
been made. Heg and Van Hyning (1951) examined the stomachs of
107 king salmon captured off the coast of Oregon and found that
herring, unidentified clupeids, anchovies, sand lance, and euphausiids
were the dominant foods. Silliman (1941) showed that specimens taken
off Washington between April and XoA-ember of 1938 had eaten mainly
sardines, herring, smelt, anchovies, rockfish, and euphausiids. Chap-
man (1936) investigated the food habits of king salmon captured off
Washington during the summer of 1936. He found that the most im-
portant foods, by weight, of 129 specimens from Swiftsure Bank, exam-
ined between July 13 and July 26, were sardines, herring, and eujjhau-
siids, in the order named. In addition. Chapman found that 105
specimens taken between Quillayute and about 15 miles south of Grays
Harbor and examined between August 16 and September 6 had eaten
mostly sardines. Pritchard and Tester (1944) studied the food of 1,383
king salmon captured in British Columbia waters over a period of

1 Submitted for publication May, 1957. This work was performed in partial fulfillment
of the requirement for a Master of Science Degree, University of California, Berke-
ley.

2—53164

( 24!) )



250 CALIFORNIA FISH AND GAME

three years, and noted 1liat iho main foods wcvo licrriiifr and sand lance;
also oaten were sai'diiies, anchovies, cai)elin. surf smelt, enlachon,
sticklebacks, whiting, tomcod, graycod, yellow shiner, sandfish, roekfish,
wolf-eel, squid, amphipods, enphansiids, pandalids, and crab larvae.
Gilbert (1918), in reference to the food of specimens taken off British
Columbia, stated that where the sand lance is plentiful in the IStraits
of -Inan de Fuca it is practically the only food eaten, but that none was
observed in the stomachs of specimens from Swiftsnre Bank, where the
dominant food was the enphausiid, Thysanoessa spinifera, followed by
smelt, herring, and other fishes. Milne (lf);")5) found that herring Avas
the dominant food of 97 king salmon captured off the southwest coast
of Vancouver Island between -lune 2!) and August 2. 1943. Fraser
(1946) observed that young specimens from British Columbia had
eaten herring, enphansiids, amphipods, cypris larvae, ostracods, small
squid, and ascidian larvae. Foskett (1951) noted that herring, crus-
taceans, mollusks, and insects were consumed by young king salmon
from Brandon Island, British Columbia. Senter (1940) reported that
king salmon from the Icy Straits region of Alaska had eaten mostly
herring, with an occasional smelt or candlefish.

No detailed study of the food habits of king salmon taken off the
coast of California has been made heretofore. California Commissioners
of Fisheries (1877) indicated that king salmon in San Francisco Bay
feed on "smelts and other small fish." Whitney (1893), referring to
the food of specimens caught in Monterey and Carmel bays, wrote, "I
have found in the stomachs a great variety of small fish, more squid
than anything else, next sardines and anchovies, with smelt, tomcod,
shad, and varieties of small rock fish." Whitney also mentioned ob-
serving salmon with their mouths open passing through large masses of
shrimps and finding their stomachs full of shrimps at times. Snyder
(1924) reported that young king salmon 71 to 129 millimeters in length,
taken at Monterey Bay, Half Moon Bay, and Lime Point, had eaten
small fish, Crustacea, annelids, small pelagic eggs, protozoa, diatoms,
and a variety of insects.

The purpose of the present study was to determine the food habits of
troll-caught king salmon from the vicinity of San Francisco.

ACKNOWLEDGMENTS

The writer wishes to extend his sincere thanks to the following per-
sons who aided in the completion of this work : Mr. Donald H. Fry, Jr.,
of the California Department of Fish and Game, and Dr. Paul R.
Xeedham of the University of California, for guidance throughout the
course of this study; JMr. Eldon P. Hughes and Mr. Howard McCully
of the California Department of Fish and Game, and Dr. A. Starker
Leopold of the University of California, for information and advice;
Dr. Cadet H. Hand and Dr. Robert L. Usinger of the University of
California for critical review of the manuscript ; Mr. Julius B. Phillips
of the California Department of Fish and Game for identification of
the rockfishes; Mr. Edward Brinton of the Scripps Institution of
Oceanography for identification of the euphausiids; Dr. Ralph I. Smith
of the University of California for identification of the polychaetes;
personnel of the Department of Ichthyology, California Academy of
Sciences, for assistance in identifying manj' of the fishes; and Mr.



KING SALMON FOOD HABITS



251



William F. Taylor and Mrs. Emily Reid for assistance with the
drawings.

Special thanks are due the San Francisco Tyee Club for financial
support of this study.

The writer is particularly indebted to the salmon party boat opera-
tors of the Berkeley Yacht Plarbor for their generous cooperation in
collecting stomachs.

METHODS AND MATERIALS

Stomachs were obtained by sampling the catch of the salmon party
boats which operate from the Berkeley Yacht Harbor on San Fran-
cisco Bay. These boats take salmon by trolling, and fish almost entirely
within an area bounded on the north by Point Reyes, on the west by
the Faralloji Islands, and on the south by Point San Pedro (Figure 1).
The king salmon is the main object of the fishery. Silver salmon {Onco-
rhyncMis kistitch), pink salmon (0. gorhuscha), and other fishes are
taken occasionally.




SCALE OF MILES



FIGURE 1. Map of the fishing grounds of salmon party boats which operate from ports on
San Francisco Bay. Depths are in fathoms.

The salmon are landed either dressed with head on, or in the round,
depending on whether the party boat operator cleans the fish for his
customers. Most of the stomachs used in this study were from salmon
brought ashore in the round, and then cleaned by the writer. However,
on a number of occasions the boat operators, at the writer's request,
saved the stomachs of salmon which they had cleaned for their cus-
tomers. The boat operators were asked to select the stomachs at random,
rather than to pick out only those which appeared to contain food, and
to save the entire digestive tract so that the species of salmon involved



2.l2 CALll'UKMA IlSll AAU GAME

could later be determined by a (•(niiil of tlic jiylofie caeca. Wliciicver
])()ssihle lli(^ <roiiads were also collccicd.

Each stoiiiach was ])resorv('d scpai-atdy in a 10 percent solution ol"
formalin, Avitli the coiM-<'sp<in(lin;^' jzonads and a label •^"iviiig the date
and locality of capture, lure or bait used, name of party boat, and fork
Icnyth. In oi-dci- to iiisui-e a<'curacy of the data, the locality of capture
was always obtained from the boat operator on whose vessel the salmon
was taken, rather than from the angler who caught the fish. The locality
of capture of many specimens could not be determined because the
boats often trolled for a distance of several miles, catching the fish at
various points along the way. The foi'k length of each salmon was
measured in a straight line from the tip of the snout to the center
of the fork of the tail.

A total of 1.004 king salmon stomachs was collected between October
5, 1954, and October 6, 1955, excluding the closed fishing season — No-
vember 15 to February 11. Generally stomachs were secured on at least
two days of each week during the entire collecting period. Except for
October and November of 1954, an average of approximately 20 stom-
achs was collected each week.

An idea of the distribution of the entire sample may be gained from
the fact that the salmon utilized in this study were taken on 121 days
by 25 boats, and 214 boat days were involved. These salmon ranged
from 13.50 to 41.00 inches in fork length, and averaged 24.65 inches.
Table 1 gives the distribution of the samjDle and the sizes of the salmon,
by month of capture. That the mean fork lengths of the February,
March, October, and November salmon were somewhat less than those
of specimens captured in other months was due to a change in the
State of California angling regulations. At the time this study was
initiated, in October of 1954, each angler was permitted to take one
ocean-caught salmon under the minimum size limit of 22 inches in
total length (roughly equivalent to 20.25 inches in fork length). How-
ever, on March 10, 1955, a regulation prohibiting the taking of any
ocean-caught salmon less than 22 inches in total length went into effect.

In the laboratory the contents were removed from the stomach, and
the food organisms were grouped according to the lowest category to
which they could be identified. Each group of organisms was placed on
blotting paper for one minute in order to remove excess moisture, and
the volume was determined by water displacement in a graduated cyl-
inder. Then the number of individuals in each group was determined.
The total length of any undigested fish or crustacean or the body length
of any undigested cephalopod was recorded. Items positively identified
as bait w^ere not considered in this analysis.

Partly digested fishes were often identified by vertebral characteris-
tics. In this connection, Clothier's (1950) work on the vertebral char-
acters of southern California fishes proved most useful.

Data were summarized by the aggregate volume method as described
by ]\Iartin, Oensch, and Brown (1946). The number and percentage
of stomachs in which each item occurred, and the total number of in-
dividuals of each item were calculated for the entire sample. Frequency
of occurrence was also used to compare the food habits of different sizes
of salmon.



KING SALMON FOOD HABITS



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254



CALIFORNIA FISH AND GAME




FIGURE 2. Areas in which the king salmon utilized in this study were captured, by months.
Encircled areas show approximate locations of catches; figures state numbers of salmon stomachs

examined from each orea.



KING SALMON FOOD HABITS



255



FINDINGS

Table 2 summarizes the monthly diets and the total diet of the king
salmon utilized in this study. Figure 2 pictures the areas in which
tliese king salmon were captured, by months. Figure 3 graphically
shows the percentage composition, by volume, of the whole diet. Figure
4 illustrates the monthly variation in food habits.




FIGURE 3. Percentage composition, by volume, of the food of 1,004 king salmon from the

vicinity of San Francisco.



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KING SALMON FOOD HABITS



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CALIFORNIA FISH AND GAME



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KING SALMON FOOD HABITS



259



Troll-caught king salmon from the vicinity of San Francisco were
found to have eaten a variety of fishes and invertebrates. However, six
items — Pacific herring {Clupea pallasi), northern anchovy (Engraulis
morclax), rockfishes (Sebastodes spp.), euphausiids, crab megalops,
and squid — accounted for 92.5 percent of the total volume of food
consumed.

There were marked Seasonal changes in the composition of the food,
with fishes forming the bulk of the diet during all of the months cov-
ered by this investigation except April and ]\Iay, when invertebrates
predominated. This is somewhat similar to the findings of Silliman
(1941), who observed two distinct feeding phases for king and silver
salmon — a fish-eating phase and an invertel)rate-eating phase.

No single item of food was of major importance in all the monthly
samples. During February and March the most important item in the
diet was the Pacific herring. In April and May euphausiids had be-



TABLE 3

Percentage Composition, by Volume, of the Food of King Salmon Tal<en During March and April,

According to Locality of Capture



Food item



Pacific herrins

{Clupea pallasi)

Unidentified clupeids

Northern anchovy

{Engrmdis mordax)

Whitebait smelt

(Allosmerus elongatus)

Surfsmelt

{Hypotnesus pretiosus)

Unidentified osmerids ^

Pacific tomcod

{Microgadus proximus) .

Shiner seaperch

(Cymatogaster aggregata)

Unidentified embiotocids

Rockfishes

(Sebastodes spp.)

Lingcod

(Ophiodon elongatus)

Cabezon

(Scorpaenichthys marmoralus)

Irishlord

(Hemilepidotus sp.)

Unidentified cottids

Unidentified fish remains

Polychaetes

Mysids

Euphausiids

Crab megalops

Adult crab

Unidentified crustacean remains

Squid

Totals

Total volume of food in cubic centimeters
Number of stomachs



Duxbury Point-
San Francisco
Lightship region



March



57.2
1.0

19.0



6.8
0.1

3.5



0.5



0.1



1.5



10.3



100.0



April



8.9



13.9



0.4



Tr.
0.8
Tr.
Tr.
76.0

Tr.



100.0



Near
Farallon
Islands



April



32 . 6
0,1



0.7

0.7

0.2

0.2
0.1
0.3



38.9
3.0

0.2
23.0



100.0



San Fran-
cisco
Bay



-April



33.4



05.2



0.7



Tr.
0.7



100.0



1,0.56.8
68



274.1
18



1,491.1
57



29.9



2()0 rAi.iK(»i{M.\ FISH AM) <;a.\ik

eomo the main food, only to l)c replaced by rockfishes in Jiine and
July. From August to November iiortln-rn anehovies made up the bulk
of the diet.

Seasonal ehan<>es in food habits were, to soiiu^ extent, related to shifts
in the locality of capture. During' Februai-y and March, when the main
food was Pacific herriiiiz-. all of the salmon whose locality of capture
was known were caupht in tln' Diixbury Point-San Francisco Light-
ship region, largely between tin' Id- jiikI 2()-l'at lioin curves. In April
and May. when the dominaiil \'<>in\ \\;is ciipliausiids, the majority of
the salmon were captui'ed near the 1^'arallon Islands and in other
waters outside the 2()-fathom curve. However, some of the .\piil speci-
mens were from the Duxbury Point-San Francisco Lightshiy) region
and from San Francisco P>ay. When the food habits of salmon taken
in the different areas during April were compared with each other and
with the food habits of salmon known to have been captured in the
Duxbur}' Point-San Francisco Lightship region during March (Table
3), the data showed that euphausiids were important only in the diet
of specimens taken near the Farallon Islamls during April. This is
believed to indicate that the change from Pacific hei-i-ing to euphausiids
as the main item of food was related to the shift in the area of capture.
On the other haiid. the great difference l)etween the March and April
diets of salmon taken in the Duxbury Point-San Francisco Lightship
region indicates a change in food habits without a major shift in the
locality of capture.

The change from a diet in which the main food was rockfishes to one
dominated by northern anchovies also appears to be related to a shift
in the locality of capture. During June and July, when rockfishes pre-
dominated in the diet, most of the salmon were still taken near the
Farallon Islands and in other areas outside the 20-fathom curve. From
August to November, when the bulk of the diet consisted of northern
anchovies, the majority of the salmon were caught inside the 2U-fathom
curve. A few of the specimens in the July sample came from inside the
20-fathom curve, just as some of those in the August sample were from
outside the 20-fathom curve. The food habits of both the July and
August specimens were compared according to area of capture
(Table 4). The data showed that during both July and August the
northern anchovy was the chief food of salmon taken inside the
20-fathom curve, whereas rockfishes })redominated in the diet of salmon
from outside the 20-fathom curve.

Northern Anchovy


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