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These items were northern anchovy (29.1 percent), rockfishes (22.5
percent), euphausiids (14.9 percent), Pacific herring (12.7 percent),
squid (9.3 percent), and crab megalops (4.0 percent).

3. The composition of the food changed seasonally. The dominant food
in February and March was the Pacific herring ; in April and May,
euphausiids ; in June and July, rockfishes ; and from August to
November, northern anchovy.

4. Seasonal changes in food habits were, in some cases, related to shifts
in the locality of capture.

5. The food habits of the different sizes of king salmon utilized in this
study were found to be generally similar. King salmon were observed
to feed on fishes more than one-third their own length.

6. Maturing king salmon taken in San Francisco Bay during Septem-
ber apparently had almost ceased feeding. There was no evidence to
indicate that ocean-caught salmon approaching sexual maturity had
ceased to feed.

REFERENCES

California, Commissioners of Fisheries

1877. Salmon (Salmo quinnat) . In: Report of the Commi.ssioners of Fisheries
of the State of California for the j-ears 1S76 and 1877. p. 5-22.
Chapman, Wilbert McLeod

1936. The pilchard fishery of the state of Washington in 1936 with notes on the
food of the silver and chinook .salmon off the Washington coast. Wash.
Dept. Fish., Biol. Rept. no. 36C, 30 p.
Clothier, Charles

1950. A kev to some southern California fishes based on vertebral characters.
Calif." Div. Fish and Game, Fish Bull. 79, 83 p.

Foskett, D. R.

1951. Young salmon in the Nanaimo area. Fish. Res. Bd. Canada, Pac. Coast
Sta., Prog. Rept. 86, p. 18-19.

Fraser, C. McLean

1946. Food of fishes. Roy. Soc. Canada, Trans., ser. 3, vol. 40, sect. 5, p. 33-39.
Fry, Donald H., Jr.

1952. Cleaning losses in king and silver salmon. Calif. Fish and Game, vol.
38, no. 3, p. 425-426.



2 70 CALIFORNIA FISH AND GAME

Fry. Donald IT.. .Tr., and Eldon P. Hiishos

iir.l. The California salmon troll lishcrv. Pac. Mar. Fish. Conim., Bull. 2.
]>. 7-42.
Gilbert. Charle.s H.

101.3. The salmon of Swiftsure Bank. I'.rit. Columbia, Comm. Fish., Kept,
for ini2, p. I 14-1 IS.
lies, Kobert. and .Jack Van Hyning

15K">1. Food of the chinook and silver salmon taken off the Oregon coast. Oregon
Fish Comm. Res. Briefs, vol. 'i. no. 2, p. 32-40.
.Martin. A. C, R. II. Gensch. and C. P. Brown

1946. Alternative luctliods in upland ^'anieliird food analysis. Jour. Wild).
Mangt., vol. Id, no. 1, p. 8-12.
Milne, D. ,T.

19.5.">. Selectivity of trolling lures. Fish. Res. Bd. Canada, Pae. Coast Sta.,
Prog. Rept. 103, p. 3-.5.
Prilcliard. A. L.. and Albert L. Tester

11J44. Food of spring and coho salmon in British Columbia. Fish. Res. Bd.
Canada, Bull., 65, 23 p.
Roedel, Phil M.

19.53. Common ocean fishes of the California coast. Calif. Dept. Fish and
Game, Fish Bull. 91, 184 p.
Senter, Vance E.

1940. Observations on the food of Pacific salmon. Pac. Fisherman, vol. 38,
no. 4. p. 26.

Silliman, Ralph P.

1941. Fluctuations in the diet of the chinook and silver salmons (Oncorhynchus
tschau-ytscha and O. kisiitch) off Washington, as related to the troll catch
of salmon. Copeia, no. 2, p. 80-87.

Snyder, .T. O.

i924. Young salmon taken at sea. Calif. Fish and Game, vol. 10, no. 2, p.
62-64.
Whitney, J. Parker

1893. Salmon iu salt water. Forest and Stream, vol. 41, no. 6, p. 120-121.



THE USE OF WIRE FYKE TRAPS TO ESTIMATE THE RUNS

OF ADULT SALMON AND STEELHEAD IN

THE SACRAMENTO RIVER'

RICHARD J. HALLOCK

Inland Fisheries Branch

California Department of Fish and Game

D. H. FRY, JR.

Marine Fisheries Branch

California Department of Fish and Game

and

DON A. LaFAUNCE

Inland Fisheries Branch

California Department of Fish and Game

TABLE OF CONTENTS

Page

Introduction 272

Acknowledgments — 273

Description of the Trapping Area 274

Construction of Trap Parts 277

General Description of Traps 277

The Rings 277

Front Frame Ring Assembly 278

Patteni for Funnels and Trap Front 279

The Funnels 280

Trap Front 282

Trap Assembly Jig 282

Final Trap Assembly 282

The Door 284

Attaching the Longitudinal Stringers 285

The Bridle 285

Transporting the Traps 286

Operating the Traps 288

Placing Traps in the River 288

Adjusting the Door 288

Fishing Sites 290

Safety Cables 290

Snatch Blocks 291

Fishing Operations 291

Species of Fishes Captured 292

Steelhead Trout 292

King Salmon 294

Silver Salmon 296

Striped Bass 296

Shad 297

Other Fishes Captured 297

Summary 298

1 Submitted for publication March, 1957. This was a cooperative project carried out
with funds provided by the Marine Fisheries Branch and by Federal Aid in Wild-
life Restoration Project California F-7-R, "Sacramento-San Joaquin River Salmon
and Steelhead Study".

( 271 )



■21-2



CALIFORNIA FISH AM) (JAME



INTRODUCTION

Ono of the basic tools necosary foi- pi-opor nianajrfmr-nt of salmon
and steelhoad is a knowledge of tlic sizes of their annual spawning-
escapements or rnns. Other information. inelu<li)ig the lime lliese runs
enter different liver systems, the spawning periods, and the areas in
each stream ntilized by the fish for spawning pnrposes is also essential
to manage this resource effectively.

Such data are becoming increasingly valuabh' in i)huining for the
safety and maintenance of salmon and steelhead runs, in view of the
multitude of water development pi-ojects on our streams, both pro-
])osed and under construction.

Since 1!».SJ) the California Department of Fish and Game has made pop-
ulation estimates of fall-run king snlmon iOncorhynchus tshawytscha)
in various Saeramento-San Joaquin \'alley streams. Most of this work
has been done by the Marine Fisheries Branch. Steelhead rainbow trout
(Salmo gairdneri gairdneri) research in the Central Valley did not
become a full time program until 1!)52 and has been conducted since
then in the Sacramento River system by Dingell-Johnson Project F-7-K,
"Sacramento-San Joaquin River Salmon and Steelhead Study", under
the Inland Fisheries Branch.

Whenever possible, fish ladder counts have been used for salmon
enumeration, but there are relatively few permanent weirs or dams in
the Central Valley where complete, or even partial, counts can be
made. ]\Iost of the diversion dams are upstream from the major spaw^n-
ing areas.

During the period from 1939 through 1942, when fish ladders were
not available, the method used was to count salmon through an opening
in a weir built across the stream. This method did not prove satisfac-
tory, since the weirs washed out during high water.

In 1943, weir counts were abandoned by the Department, and a tag
and recovery method was substituted. This method of population esti-
mation requires only that a known number of salmon be tagged and
allowed to proceed upstream to spawn and die. From the ratio of tagged
to untagged carcasses on the spaAvning beds, it is possible to calculate
the size of the spawning run.

The first method of capturing salmon for this tagging employed a
temporary V-shaped webbing weir, w'hich extended across the entire
stream. The apex of the "V" was at the upstream end. An opening at
the apex allowed the fish to enter a trap, where they remained until
removed for tagging. This method proved satisfactory in use on the
American and Stanislaus rivers.

In 1950 it was decided to do some experimental fishing in the Sacra-
mento River to determine if it was practical to make a tag and recov-
ery estimate of the fall salmon run. The Sacramento carries a consid-
erable amount of traffic, including both commercial tugs and private
vessels. It is also too large to permit use of a weir of the type just de-
scribed. Obviously, another method of capturing fish had to be used.
Gill nets were first selected, principally because we had had consider-
able experience in their use. The area fished was about one and one-half
miles upstream from the mouth of the Feather River. Though showing
promise, this method was abandoned as being impractical with the man-
power available.



WIRE FYKE TRAPS 273

In 1951 the Department initiated the nse of large wire-mesh traps.
These cylindrical fish traps, 10 feet in diameter and 19| feet long,
were patterned after traps formerly used by commercial fishermen in
the Sacramento River near Princeton Ferry. Snch traps had been de-
clared illegal for commercial fishing several years previonsly. After
considerable searching, an abandoned trap was fonnd in a heavily
wooded area adjacent to the Sacramento River between Princeton
Ferry and Colusa. Measurements were taken of the abandoned trap
and six new ones were constructed during the summer of 1951. These
ti-aps were first fished in the Sacramento River in the fall of 1951..
They were quite successful in taking salmon, and much to everybody's
surprise they also took large numbers of steelhead. At that time very
little was known about the migration of steelhead into the upper
Sacramento River. It was decided to take advantage of this unex-
pected opportunity and tag all trapped steelhead. The procedure for
determining the sizes of runs for both salmon and steelhead, with the
tag recovery method, is essentially the same. The principal difference
is that steelhead do not die after spawning, so the ratio of tagged to
untagged steelhead is determined by examining live fish.

Starting with the summer of 1953, seven traps have been operated
co-operatively in the Sacramento River by Uingell-Johnson Project
F-7-R and Marine Fisheries Branch personnel. Salmon data have been
analyzed by Marine Fisheries Branch personnel and the Dingell-John-
son personnel have concentrated on the steelhead data.

This report is a summary of the present methods used in constructing
the fish traps, their operation in the Sacramento River, and a general-
ized treatise on the effectiveness of these traps in capturing king
salmon, steelhead trout, silver salmon {Oncorhynchus kisutch), striped
bass (Boccus saxatilis), American shad (Alosa sapid issima), and other
species of fi.shes.

ACKNOWLEDGMENTS

Success of the trapping ))r()gi-am on the Sacramento River has been
due to the efforts of many persons in the Department of Fish and Game.
In addition, land owners in the trapping area have been most generous
ill permitting unrestricted use of their land to operate the traps, and
from time to time have helped to clear brush and trees from net fishing
sites.

We are especially indebted to the late Mr. David J. Glenn of the
Department of Fish and Game. Mr. Glenn's knowledge of the Sacra-
mento River, and of commercial fishing and fishing gear, gained through
many years of commercial fishing experience on the river, coupled with
an inherent drive to experiment with new ideas, contributed perhaps
the most to the successful development and operation of these traps.

To Mr. Taylor London, warden with the Department of Fish and
Game, we also wish to express our gratitude. It Avas largely through his
efforts that one of the old abandoned commercial fish traps was located.

To them and many others we wish to express our heartiest thanks.



<)164



274



CAI.IFOUXIA FISH AND GAME



o Nicoiaus




2 3 4 5 Miles
I I I I



LOCATION MAP



FIGURE 1. Map showing the trapping area and nearby points.



DESCRIPTION OF THE TRAPPING AREA

The trapping area starts at the downstream end of Fremont Weir
and extends downstream along the right bank of the river for a dis-
tance of about one and one-half miles. The lower end is about one-half
mile above the mouth of the Feather River. Fremont Weir is located
23 river miles upstream from the City of Sacramento. It is a flood con-
trol structure over which flood waters spill from the Sacramento River
into the Yolo Bypass.



WIRE FYKE TRAPS



275



The Sacramento River near the trapping area is about 150 feet wide
and of variable depth. In the main channel, depths of 30 and 40 feet
are common. Along the steep dirt and sand banks characteristic of this
section, water depths of 20 feet are common a few feet from shore, even
during low summer and fall flows. The river drops one foot in elevation
about every three miles. There are no gravel riffles. The first riffles of
any consequence are found just above the City of Colusa, some 70 miles
farther upstream. During summer and fall months the river flow in
this area is usually between 5,000 and 10,000 cubic feet per second.
Water velocities of 2 to 3 feet per second are encountered at the individ-
ual trapping sites, which are close to shore. Velocities in the center of
the river are higher. Figure 2 shows a general view of the Sacramento
River at the upper end of the trapping area.




FIGURE 2. The Sacramento River at the upper end of the trapping area.
Phoiograph by John E. Riggs.



During most of the year and especially during the period of steelhead
and fall-run king salmon migration, the lower Sacramento River is
heavilv laden with silt, which gives a light brown color to the water.
During summer and fall, normal turbidity is increased by returned
irrigation water, principally from rice fields between Colusa and
Knights Landing. During winter and spring, muddy water is caused
not only by silt from the main channel, but also by debris washed into
the river by rain-swollen tributaries. However, during a dry winter
the Sacramento River is comparatively clear in its lower reaches.



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WIRE FYKE TRAPS 277

CONSTRUCTiON OF TRAP PARTS

General Description of Traps

The traps are essentially large cylinders, 10 feet in diameter and
19^ feet in length (Fignre 3). They are open at one end and contain
two funnels, which act as a one-way passage for fish into a pot or im-
ponnding area. The traps are always fished with the back or open end
downstream.- The two fnnnels face the same way, with the small open-
ings upstream, and a fish must swim through both to enter the pot.
The funnels and the exterior of the trap are covered with wire mesh
netting. Captured fish are removed with a dip net through a door Avhich
opens into the pot.

The trap frame consists of five rings made of three-quarter-inch pipe.
The rings are held rigidly in place by six 2 by 4 inch wooden stringers
which extend the length of the trap. Two different sizes of wire netting
are employed in the trap construction. One-inch mesh, 18-gauge stucco
wire is used to cover the pot of the trap, which includes the front
funnel. The remainder of the trap, including the back funnel, is covered
with 2 by 3 inch mesh, 15-gauge salmon trap Avire. When the coarser
mesh was used to cover the impounding area there were too many casu-
alties due to gilling, particularly among the steelhead. All pipe, wire
netting, and other wires used are galvanized.

A completed trap weighs between 500 and 600 pounds and contains
approximately $100 worth of materials. With experienced personnel, it
takes a two-man team about 16 hours to construct a trap, starting with
prefabricated rings and the necessary materials and tools.

The Rings

The frame rings are 10 feet in diameter and approximately 31^ feet
in circumference. A convenient method of construction is to use stand-
ard 21-foot lengths of pipe. Each ring then consists of one and one-half
lengths of pipe welded together. As an alternative to welding, a short
length of three-cpiarter-inch diameter iron rod, bent to the proper
radius, may be inserted into the ends of the pipes and the joint then
secured with two or more quarter-inch diameter rivets on each side of
the joint. In event of damage to a trap, a riveted ring can more easily
he taken apart and reshaped. The original frame rings were shaped
with a pipe bending jig at the Department's Elk Grove Fish Screen
Shop. Since that time all new rings have been constructed b}' a com-
mercial firm.

The small funnel rings, which are attached to the small end of the
funnels, are made of three-eighths-inch diameter pipe. They are bent
by hand and checked against a pattern. The ring for the back funnel
opening has a diameter of 42 inches, while the front funnel has a 20-
inch diameter.

2 Throughout this report, "upstream", "forward", and "front" mean toward, or nearest
to, the closed end of the trap ; and "downstream", "rear", and "back" mean toward,
or nearest to, the open end.



278



CALIFORNIA FISH AND (iA^^IE



Front Frame Ring Assembly
The t^vo frunl Iramc rin^s arc assfiiihlcd as a niiit by weldiiifr four
pieces of three-quarter-iiieli pipe betAveeii them. Two of these 54-iiich
loug pipe stringers are wekled to the rings 48 inches apart, to form a
48-inch high door opening for removing fish. Tlic otlier two pipe
stringers are wekled between tlie rings oi)])()site the door opening, to
provide additional support (Figure 4). The door opening is completed
by welding a 48-inch long section of pipe between the two stringers,
parallel to. and 10 inches from, tlie niistream frame ring. The latter
section of pipe is bent to conform with the shape of the frame rings.
This provides a door opening 44 inches wide and 48 inches high. By
having the front edge of the door opening 10 inches back from the
upstream ring, an area is jjiovided for overlapping and securing the
netting covering the end of ihc iraji Tm tlint covcriiiL' tlie sides.




jjWi



■sr.-mBZ^^-.-wi



FIGURE 4. The front frame ring assembly with the wire mesh
front in place, but not yet secured. Photograph by Don A.

LaFaunce.



WIRE FYKE TRAPS



279



Pattern for Funnels and Trap Front

When cutting the wire netting to cover the funnels and front end
of the trap, a great deal of time can be saved if a pattern is first marked
on the ground or the floor. Satisfactory patterns for 10-foot diameter
traps are shown in Figure 5. When used on a working surface the pat-
terns are superimposed for convenience as shown in Figure 6.




FIGURE 5. Pattern for funnels (A) and trap front (B).



The funnels are made as cones. The tip of the cone is cut off wlien
the small funnel ring is attached. To lay out the funnel pattern, start
at a focal point near the center of the pattern area and describe an
arc, using a seven-foot radius. The radius of the pattern arc coincides
with the length of the sides of the cone or funnel, assuming that the
funnel is projected to an apex. The length of the arc described is 32
feet. The circumference of the trap frame ring to which the base of
the funnel will be attached is 31 1 feet. The additional six inches are
to allow for overlapping the meshes at the center seam.

Next, draw radial lines between the focal point and the ends of the
arc, completing the pattern. It was found to be more practical not to
lay out, as part of the pattern, lines indicating material to be cut away
from the apex of the cone, to install the small funnel rings. This
material is cut away later, when the funnel rings are attached. For con-
venience, a center line may be drawn on the platform first. A center
line is an aid in laying out the netting to cover the pattern. A common
center line and focal point are also desirable when funnel patterns for
more than one diameter of trap or funnel height are to be drawn on the
same platform.

The trap front is a complete cone. A satisfactory pattern can be
made using a 6-foot radius and a 35-foot arc. The base of a trap front
cut on this pattern will fit snugly on a 10-foot diameter ring, five and
one-half feet from the apex, measured along the sides of the funnel,
and Avill also leave six inches of netting for overlapping the barrel of
the trap. The trap front will ha^-e a height of about two feet, measured
vertically from the base to the apex.



2Sn C'ALTPORXIA nsil AXI> CAME

The Funnels

ilatcrial required for the t'l-out funnel is as follows:

1. one JU-foot diiunetcr ring of ij-iuch pipe;

2. one 20-ineh diameter ring of |-inoh pipe ;

;>. one-inc-li niesli, IS-gauge stucco netting (72 inches wide if jiossiide) ;
4. IG-gauge galvanized Avire for lacing.

Material required foi- the back funnel is as follows:

1. one 10-foot ring of J-iuch pipe ;

2. one 42-incli ring of |-inch pipe ;

o. G-foot wide 2-inch by 3-inch mesh, lo-gauge salmon trap netting;
4. 16-gauge galvanized wire for lacing.

To assemble a funnel, unroll the netting witli one edge along the
center line of the pattern. Weight it down with bricks, rocks, etc., and
cut around the are of the pattern. By cutting the netting an inch or
two wider than the pattern a better fit can often be obtained on the
frame ring, especially if the ring is not perfectly round, lloll more
netting out on the other side of the center line, weight it down, and
again cut around pattern. When the netting is cut, the pieces are laeed
together at the selvage edges Avith Xo. 16 galvanized wire. Figure 6
shows a funnel being cut and laced. The two netting edges formed by
the radial pattern lines are not joined until after the material has
been fitted on the frame ring. An additional small piece of netting is
required at each side to cover the funnel pattern. Wlierever possible,
it is best to lace selvage edges together, since they are stronger than
cut edges. Otherwise, it would be theoretically possible to construct
the funnel out of three pieces instead of four, since the netting is six
feet wide.

After the netting has been cut and laced, it is suspended by the
apes, so that the base of the funnel is several inches olf the platform.
A 10-foot frame ring is then fitted to the inside of the base of the
funnel, as shown in Figure 6B. The wire mesh is tied to the frame
ring at about 30-ineh intervals with temporary ties of No. 16 wire. Any
irregularities in the funnel can then be corrected by slightly shifting
the ring on the netting. The lapped portion of the center seam, formed
by the tw^o radial edges of the pattern, is secured by twasting the cut
ends of the wires into the adjacent meshes. All of the wire ends must
point tOAvard the inside or center of the funnel, to eliminate any sharp
projections in the pot of the trap, upon which the confined fish might
cut themselves.

The small funnel ring is attached by setting the funnel on its base
and putting the small ring over the apex, as shown in Figures bC and
6D. A man can then crawl underneath the funnel, cut off the apex, al-
lowing a sufficient overlap, bend the wire over the ring, and twist the
cut edges through the adjacent mesh.

Figure 6 shows the construction of a front funnel made with li-
iucli mesh netting." The same pattern and procedure are used for the
back funnel, except that it is made with 2 by 3 inch mesh netting.



'■^ These photographs were taken before the mesh size was changed to one-inch mesh.
The same construction procedure is followed, however, regardless of mesh size.



WIRE FYKE TRAPS



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282 cAUKoiixiA FISH AXi) r;A>rK

Trap Front

The trap front forms tlic forward wall of the fish inipouiiding area.
In addition to the front fraino riii^' assembly, a supply of one-inch
mesh Avire netting is reqnired. It is constructed in llie form of a cone,
with the apex pointing upstream. This shape helps to shunt floating
debris around tlie trap, and increases the volume of the impounding
area.

Figure 5A show8 a pattern for the trap front. The same general
procedure is followed for cutting out and assembling the front as is
used for the finiin'ls. After the netting has been cut to fit the pattern
and laced, it is suspended by the aj)ex, and the frame ring assembly


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