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BIOLOGICAL INVESTIGATIONS
OF THE FISHERY RESOURCES
OF TRINITY RIVER, CALIF.

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SPECIAL SCIENTIFIC REPORT: FISHERIES No. 12

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 th«
official use of Federal, State or cooperating agencies and in
processed form for economy and to avoid delay in publication.

Washington, D* C*
February, 1950

United States Depar'bnent of the Interior
Oscar L. Chapman, Secretary
Fish and vaidlife Service
Albert M. Day, Director

Special Scientific Report - Fisheries
No. 12

BIOLOGICAL INVESTIGATIONS OF THE FISHERY RESOURCES

OF TRINITY RIVl-IR, CALIFORNIA

By

James li. Moffett and Stanford H. Smith
Fishery Research Biologists

CONIENTS

Preface Page

Introduction* ••••••••••*••...••..,••., j^

Physical characteristics of Trinity River •••• 5

Run-off and flow 5

River temperature* ••«••••••••••••••••• 9

Existing biological conditions* •••••••••• \o

Non»game fishes. •••«•••••••••••.••••• \q

Residjsnt game fishes ••••••••••••••••••. 19

Anadromous fishes* ••••••••*•••••••**•• 20

King salmon a******************** go

Commercial and sports fisheries* •••*•••• 20

Characteristics of the seasonal runs ****** 21

Spawning and development **••••.•••.* 35

Seaward migration. ...•••• . 27

Sex ratios of adults 34

Silver salmon .............. ...... 40

Steelhead trout • 40

Pacific lamprey .• 45

Salmon spawning bed surveys .. ...... 49

Nest measurements. .. ........... 49

Methods qi

Results of surveys • .............. 51

Effects of water development plans on the Trinity

River fishery and suggested means for fish protection. • . • 56

General principles of operation. ••• •••• 57

Maintenance plans for Lewis ton Deua ••••....••.• 57
Development of additional spawning

grounds in the main stream. .••.•••••••.. 57

Improvement of tributary streams. •*•• gg

Artificial propagation ** 69

Maintenance plans for Browns Creek dam •• 69

Steelhead maintenance. .•••.•••••••...•.. 70

ILLUSTRATIONS

FIGURE page

1. Chart of Trinity River Watershed 3

2. Average monthly flow of Trinity River at Lewis ton

during water years 1928-1942 7

3* Average monthly discharge of Trinity River at three

points in the drainage. Water years 1932-1939 8

4* Trinity River water temperatures recorded at
Lewiston during the period; November 1942
through July 1946 11

5« Numbers of adult king salmon passing through the

Lewiston weir in 1942, 1944, 1946 and 1946, Trinity

River 24

6* Seaward migration of young king salmon in Ti*inity

River at Lewiston. ••.•.•••• 29

?• Length-frequency distribution of male and female king

salmon from two different sections of Trinity River. • 37

8, Downstream migration of steelhead trout in Trinity

River at Lewiston* ••••••••••• •• 41

9, Average lengths of steelhead trout young taken in

fyke nets from Trinity River at Lewiston, arranged
according to brood years and time of capture* * * * * 44

10* Number of salmon nests in Trinity River between

Lewiston and North Fork as determined at two different
river flows* •*• •••••••** 5S

11* Number of salmon nests in Trinity River between Lewiston
and North Fork, as related to a constant change in
availability of gravel at various river flows* . • * • 55

12* Recommended fixed flow schedule for Trinity River at

Lewiston and its relation to the life history phenomena
of king salmon in that stream* ••**•••••*•* 59

13* The effect of a fixed flow schedule for fish at Lewiston
on the discharge of TJrinity River at various points
downstream* •••.•••••••****••*••• 61

INTRODUCTION

Demands for additional water supplies for irrigation and pro-
duction of hydroelectric power in the Central Valley and adjacent areas
in California, focused attention on the upper Trinity River drainage as
a possible source of supply. Plans to divert Trinity River water into
Sacramento Valley from that area were formulated and published in 1931
as a part of the California State Water Plan. These plans were further
studied and refined by the tJ. S. Bureau of Reclamation and U. S. Army
Corps of Engineers and by 1941, their realization seemed certain. It
was also apparent that diversion of Trinity River water would seriously
affect the fishery resources that are dependent upon the upper river^
particularly king salmon and steelhead trout. In order to determine
the magnitude and biological characteristics of these resources and to
design management plane and procedures for their protection, the U. S.
Fish and Wildlife Service conducted a comprehensive survey and study of
the entire problem. Major features of the study involved determination
of: (1) the size and composition of fish population, (2) the character-
istics of the seaward migration of young salmon and steelhead trout,
(3) the extent and utilization of spawning gravels, (4) the physical
characteristics of the drainage, (5) existing biological conditions, and
(6) possible means of controlling the fishery and its environmental factors*

Work was first started in the fall of 1942 when a temporary fish
counting weir was constructed on the Trinity River a few hundred yards
below the river bridge at Lewis ton (see map) and approximately 105 miles
upstream from the river's mouth. Studies of some of the biological and
physical conditions of the streem were also started during November of
1942. The temporary fish counting weir was replaced with a removable
structure in late 1943. Because of wartime impediments, uninterrupted
studies of the Trinity River fishery covered a period of only two years*
As a result, it is impossible to make positive and final conclusions*
This report, therefore, is an interim report with most findings and con-
clusions subject to possible revision pending further investigational
findings.

Trinity River, largest of the Klamath River tributaries, rises
in the Scott Mountains at the northern end of Trinity County, California*
It courses south and west through Trinity County, then north to its con-
fluence with the Klamath River in Humboldt County. The less canyonous
portions of the river bed abound with broad gravel riffles and provide
excellent spawning grounds for king salmon. Numerous small tributaries
and the upper part of the main stream furnish adequate spawning ground
for large numbers of anadromous and resident trout* Like many of the
rivers in the northern California, its run-off pattern consists of extremes
in flood and in drought. During STimmer, its flow is extremely low. In
winter and spring, it rages destructively when in flood and discharges
much of its annual run-off.

The Trinity and its parent stream, the Klamath, have been fish-
ing grounds for Indian tribes for ages. Well established trade routes
from the interior to the sea passed through or terminated in the Klamath
and Trinity country where a lively oooimeroe in shells and dried fish
existed* Thousands of king salmon, silver salmon, and steelhead trout
were oaught by the Indians living in Klamath and Hoopa territory (Hewes,
1942), These Indians were highly skilled in fishing. They oonstinicted
fish weirs of logs, poles, and brush across the rivers and speared or
netted the upstream migrant salmon, trout, and even lampreys, "niese weirs
remained in the streams as virtually impassable barriers \intil the first
rains of autxmm replenished river flow sufficiently to wash them away*
Year after year the weirs were installed according to strict ritual and
procedures (Snyder, 1924). In modern times, most of the fish weirs have
disappeared. One is usually built each svmaer at Hoopa on the lower
Trinity River and below it the Indians seine, spear, or operate gill nets.
Salmon and steelhead are dried, smoked, canned in the Reservation ce.nnery,
or used fresh. The Indiana practice conservation of a sorti part of the
migrating salmon are allowed to pass the weir through gates installed for
that purpose.

Trinity River has long been famous as a gold-bearing stream.
In early times, some rather large communities occupied its banks and
most of the presently existing towns are remnants of these settlements
which degenerated following exhaustion of the major placer and hard-rock
gold deposits. Extensive gravel deposits above North Fork have been
dredged for gold. Great spoil piles of barren gravel constitute the
immediate stream bank for mile upon monotonous mile. TUm original
character of the stream and its adjacent flats has been seriously altered.
Some isolated dredge operations still go on in the drainage and, at times,
the stream bears great quantities of silt in much the SEune manner as it
did for 75 years or more following the discovery of gold.

A vigorous commercial fishery on Klamath River began shortly
after gold«<iiining started. The early fishing efforts were for looal
supplies and usually concentrated on the riffles of the river and its
tributaries* Canneries began operating on the Klamath estuary prior to
1892 and reached a high state of development by 1912 (Snyder, 1931).
Over-fishing and possibly mining soon made noticeable changes in the
abundance of king salmon. Early records given by Snyder indicate a
historical peak in the Klamath River coimnercial fishery occurred in
191E when over 1,384,000 pounds of fish were packed from a catch of
approximately 141,000 salmon. Records for that year are incomplete
and conFist of estimates applied to portions of unreported packs. The
1915 pack is recorded more completely; about 1,232,229 pounds of salmon
were packed from a catch approximating 72,357 king salmon.

Essential features of the Trinity development plan consist of
an earth-fill storage dam about 352 feet high, built in the vicinity
of Fairview Ouartz Mill (see map) j a diversion dam about 110 feet high
located Just above the town of Lewiston, California^ and a series of

U. S. Rsh and Wildlife Service
Central Valley Invesiigations

TRINITY RIVER WATERSHED

Trinity and Humboldt Counties
CALIFORNIA
0 5 lOmiles

SCALE

"^/

tunnels, power plani:s, and canals leading from the diversion dam to the
Saciranonto River above Keswick Dam. A second plan contemplates con-
struction of a storage dam near Browns Creek, some 6 miles below Douglas
City* Water front this reservoir would be piimpad to the diversion tunnel
above Lewis ton. The point of diversion from the Trinity River at Lewis ton
is about 1300 feet above the Sacramento River.

Dams at the Fairview and Browns Creek sites would be high barriers
insurmountable by present type of fish ladders. Reservoirs formed by
t:ieso daas would be very long, extensive, and would cover much of the
existing spawning grounds of anadromous fishes. Ttiese fishes might be
lifted mechanically over the dans, but it is doubtful that their offspring
would pass through the reservoirs, find the river outlets, and proceed
downstream without suffering material losses. Mos-c of the water would
fiorw into the diversion tunnel and with it the majority of the young
salmon and trout produced upstream.

Alir.ost without exception. Trinity River salmon migrating above
the South Fork spawn in the 72 miles of river between the North Fork
and Ramshorn Creek. In addition to the main river, three tributaries
are used by spawning salmon. A dam at the Lewis ton site would cut off
35 miles of the main river and all of Stuart Fork, the most important
spawning tributary. The saljnon would be blocked from approximately
50 percent of their natural spawning grounds in the upper Trinity. A
dam at the Browns Creek site would cut off the remaining two spawning
tributaries and 59 miles of the main river spawning area* This dam
would eliminate seme 82 percent of the natural salmon spawning area.

Appreciation is expressed for the help given by the State of
California Division of Fish and Game and by many persons who were
connected with the work from time to time. Among these were Dr. Paul
R. Needham, who directed the project until the end of 1944, Harry A.
Hanson, George Warner, Owen Vivian, William H. Davenport, Millard
Coots, Donald Drake, S.N. MoKinsey, Norman Mattoon and many residents
of Lewiston who assisted with work on the project. Much of the infor-
mation included has been generously supplied by the U. S. Bureau of
Reclamation, U. S. Engineers, U. S. Forest Service, and the U. S.
Geological Survey. The Indian Agency at Hoopa, on the lower Trinity
River, also cooperated.

This investigation was supported by funds transferred to the Fish
and Wildlife Service by the Bureau of Reclamation. It was considered
a vital part of the pre-project engineering and exploratory work con-
ducted by the Bureau of Reclamation. Tlie study was terminated in
August 1946, when the Bureau of Reclamation ceased active work on the
Trinity River diversion project.

PHYSICAL CHA.RACTERISTICS OF TRINITY RIVER

Trinity River is approximately 159 miles long and drHins a semi-
wilderness area of approximately 2,900 square miles. It is divided
into five more or less distinct sections which have a direct bearing on
the utilisation of the stream by spawning and juvenile anadromous fishes.
The uppermost 18 miles of the river from its source to Ramshorn Creek
are precipitous (gradient 222 ft./mile), the channel is narrow, gravel
riffles are very limited, and the bottom is covered with large boulders.
The 12 miles of river between Ramshorn Creek and Trinity Center traverse
a broad valley into which many small tributary streams enter. The stream
has a gradient of 58 feet per mile and meanders through wooded and pasture
lands wherever gold dredges have left the original terrain. Its f^hannel
is broad and gravelly with large extensive riffles alternating with deep
pools. From Trinity Center to North Fork, the gradient is less s©- ere
(15 ft./mile), water volumes are greater, and very extensive riffles
characterise the channel. Most of the spawning grounds of salmon are
located in this 60-mile section of streeun. Between its North and South
Forks the river passes through a rocky canyon 40 miles in length. Water
flows are concentrated and made turbulent and exceedingly rapid by the
narrow confines which typify this canyon. Gradients are more severe
(23 ft./mile) and volumes of flow, in relation to channel capacity, are
relatively great. The Trinity between South Fork and its confluence with
Kalmath River meanders (gradient 12 ft./nile) the length of beautiful
Hoopa Valley (29 miles) and is characterized by broad gravel riffles
alternating with large, deep pools.

Run-off and Flow

The run-off ohai-acteri sties of Trinity River are cfuite similar
to those encountered in most California streams. The great bulk of the
annual run-off occurs in winter, while summer flows are quite low (Figure
2 Table 1). At Lewiston gaging station the extremes of flow between winter
and summer are represented by a high flow of 40,300 second-feet recorded
on February 28, 1940, and a low flow of 2 3 second-feet recorded on July 30,
1924 (n. S. Geological Survey data). The average annual run-off is
1,106,454 acre-feet as measured at Lewiston, and 3,811,520 acre-feet at
Hoopa, about 10 miles above the mouth.

"Bie run-off pattern of Trinity River at Lewiston varies widely from
year to year, although the seasonal wet-dry cycles occur during corre-
sponding periods each year. The voliime of annual run-off from the
drainage above Lewiston had a range of approximately 250,000 to 2,500,000
acre-feet, with a mean of 1,106,454 acre-feet, during the years 1912
through 1945,

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Figure 8. Areraga monthly dlseb&rge of Trinity River
at three points in the di*ainage, ffater
years 1932-1939,

,««

Th© general run-off pattern over the entire Trinity drainage
varies somewhat from that recorded at Lewiston. The spring run-off
peak at Burnt Ranch occurs a month earlier than the peak at Lewiston
(Figure 3) • Inflow from many small tributaries which drain an area
with little snow accumulation contributes most of the earlier run-off
at that point. River flow at Hoopa, including the inflow from New River
and the extensive South Fork drainage, reaches a spring run-off peak in
March, two months earlier than the peak at Lewiston*

River Temperatures

River temperatures at Lewiston were recorded daily from November
1942 through July 1946 (Tables 2-5 and Figure 4). Temperatures were
taken with a hand thermometer three times each day, at 8 a.m., 12 noon,
and at 5 p.m., until January 1946. Following that date, continuous
temperatures were recorded by a thermograph. During most of the year,
the river reached its maximum temperature at about 5 p.m., and its
minimum at 8 a.m.; consequently, temperatures taken by hend thermometer
at these hours closely approximate the extremes. Average daily tem-
peratures after January 1945 were computed from thermograph records
by tftking the mean of temperature readings at two-hour intervals
during a 24-hour period.

Trinity River is warmest during July and August when spring and
summer salmon are holding over in the main river. The maximum water
temperatures and dates of occurrence for years of record are as follows :
78*^., on August 13, 1943; 81**F., on July 24 and 27, 1944; and 83°F,, on
July 27, 1945» Temperature records were not complete enough in 1946 to
show the highest temperature with certainty, but a high of 80. 5*^., was
reached on July 22, 1946. The maximum temperature recorded for 1943
may not be the true peak temperature for that year, as it was taken from
partial records made during August and September. A temperature of
80*'F., or higher was recorded on 9 days during the sionmer of 1944 and
27 days during the svomner of 1945. As a result of experience gained at
Deer Creek Station on Sacramento River, California (Moffett, 1949),
80**F., is considered lethal or near lethal for king salmon. The same
species is able to survive when surface temperatures are ahove 80°F., in
Trinity River by remaining in the cooler waters of deep holes along the
river. In August 1944, water at depths over 8 feet in one of these
large holes was 7t'., cooler than surface water*

The daily temperature range is of interest when considering the
effect of majcima as lethal agents. To illustrate this range In Tt-inity
River during summer, the hourly record for July 27, 1945, is presented*

2tOO

Midnight

74.0

9:00 A. M.

71.5

5:00 P. M.

83.0

1:00

A. M.

73.5

10:00 A. M.

73.6

6:00 P. M.

82.5

2:00

Jl. H.

72.6

lliOO A. M.

75.0

7:00 P. M.

81.6

3:00

A. M.

72,0

12 :00 Noon

77.0

8:00 P. M.

80.0

4,00

A. M.

71.5

1:00 P. M.

79.0

9:00 P, M.

79.0

5:00

A. M.

71.0

2:00 P. M.

81,0

10:00 P. M.

77.5

6i00

A. M.

70.6

3:00 P. M.

82,5

11:00 P. M.

76.5

7:00

A. M.

70.0

4r00 P. M.

83.0

12:00 Mid-

8:00

A. M.

70,5

night

75.0

During 7 hours of the day, water temperatures were ahove 80°?., while
during 11 hours, temperatures were below 75*'F, Between 9 a.m. and
4 p.m., the river temperature rose 11.5 degrees, and between 6 p.m.
and midnight it fell 7.5 degrees.

On July 4, 1945, a recording thermcaneter was installed at
Junction City, some 28 miles down river from Lewiston, to determine the
warming effect of hot summer weather on the river between these two points.
The maximxan., minimum, and average daily water temperatures recorded at
this station are given in Tables 6 and 7, A maximvua temperature of
85*'F„was recorded at that station on July 27, 1945, the same day the
peak temperature of 83°F.»was recorded at Lewiston. The hottest days
of the summer were July 26 and 27, when a maximum air temperature of
108OF., was recorded at Lewiston on both days. The river temperature
reached or exceeded SO*'?., on 32 days in the suraner months at Jvinction
City. During July and August, maximum water temperatures at Junction
City were one or two degrees higher than Lewiston water temperatures
for the oorresponding day. Temperature records at Junction City during
1946 were too incomplete for analysis.

EXISTIHG BIOLOGICAL CONDITIOSS

Non-game Fishes

The Klamath black dace, Rhiniohtys os cuius klamathensis (Everaann
and Meek), and the fine-scaled Klamath River sucker, Catostomue rimi cuius
Gilbert and Snyder, are the only coarse fish taken during this study
which are known to spend their entire life cycle in the Trinity River.
Both of these species occur cOTimonly throughout the drainage.

The Klamath black ciice is the most numerous and ubiquitous species
found in the Trinity River. It inhabits all stream sections except the
headwaters of some tributaries. The d&ce is a small fish in the Trinity;
the largest individuals seldom exceed a fork-tail length of 3.1 inches
(80 millimeters). During the summer low-water period, Klamath black dace
are seen in very large numbers in pools along the river. They are almost

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18

inaotlTe dvirlng the daytime when they rest in shallow water or in rubble
on the river bottom, but they start feeding at sunset and remain active
until the next morning. There seems to be no gregarious tendency during
this active period. Observations of feeding activity indicate that dace
are omnivorous* Most feeding takes place on the algal-covered bottom,
but drifting food particles and floating insects are also taken. In
winter months, dace are seldom seen in the open, although their appearance
in fyke-net catches during this period indicates some nocturnal activity.

The Klamath black dace of Trinity River have been extensively re-
ported on by Jhingran (1948)* Much of the dace material collected during
this investigation was placed at his disposal and is incorporated in his
study.

Pine-scaled Klamath River suckers are as widely distributed in the
river as are the dace, but they are much less abundant. They are most
oonmoBly found in deeper holes along the river and in tributaries with
moderate gradients. It is common to see large schools feeding along
the bottom of pool areas any time of the year. This fish apparently
has little value in the Trinity River as a forage fish for large trout.
Tbidoubtedly, Juveniles enter the diet of native trout and steelhead,
but most small suckers are found in tributary streams where large trout
do not occur.

Resident Game Fishes

The Trinity River investigation has revealed the presence of three
resident Salmonidae: rainbow trout, Salmo gairdnerii (Richardson);
brown trout, Salmo trutta (Linnsieus) i and eastern brook trout. Salve linus
fonti nails (l(itohill)i named in order of abundance.

Rainbow trout, the only native species, are distributed in fairly
large numbers throughout the drainage, except in the upper extremities
of some tributaries. This species contributes the major portion of all
game fish taken by sportsmen. The California Division of Fish and Game
reports that approximately 7,750 anglers took an estimated 389,900 trout
from the Trinity River in 1941. No observations have been made of rainbow
trout spawning activities, but ripe males have been taken during the
steelhead spawning period (February - April) in Ruoh Creek, a tributary,
and it may be assvsaed that they spawn during that period.

Brown trout ere also generally distrtbuted but are fewer in number
flmd more conspicuously absent from the upper extremities of the river and
its tributaries than are the rainbow. There are known to be
definite spawning migrations of adult brown trout in the Trinity. From

19

Jtme 29 through August 2, 1945, 39 brown trout passed through the gates
of the Lewiston fish-counting weir* Six specimens taken for study had
an averege weight of 5.7 pounds and an average length of 23.4 inches.
Their sex products were further developed than those of steelhead, but
less than salmon taken at the same time* Less conspicuous but larger
migrations occur during November and December* Although these fish have
not been observed spawning in the Trinity River during this study, local
residents report having seen them spawning in the upper main stream amd
its tributaries from late December until early February*

Several young brown trout were usually taken in the fyke nets at
Lewiston dvu-ing the week following the first fall rain. A few young,
near or in their second year, were taken through the remainder of the
winter months. Fry of this species, that had recently left the giravel,
were taken by fyke nets on very rare occasions in March and April* It
is possible that the brown trout of Trinity River migrate to the sea as
do representatives of the same species in Europe, although no direct
evidence is yet available to demonstrate such movement* Scales from
the specimens taken at Lewiston were so resorbed that positive age and
growth determinations could not be made*

Rather limited populations of eastern brook trout occur in the
colder waters of the upper extremities of the Trinity River and its
tributaries. They are caught in fair numbers by sportsmen who frequent
the higher, primitive areas* These fish do not attain a verj' large size
in the drainage, but their gaminess and limited distribution make them
highly desirable to many sportsmen.

Anadromous Fishes

Four anadromous or sea-run fishes have been recognised in the
Trinity River during the course of this investigation* These are the
three-toothed lamprey, Entosphenus tridentatus (Gairdner)j the king
salmon, Onoorhynohus ts ohawy ts oha (Walbaum) ; the silver salmon,
Onoorhynohus kisutch (Walbaum) } and the steelhead trout, Salmo
gairdnerii (Richardson) *

King salmon

Comneroial and sports fisheries

King salmon have long been sought by Indians, comnercial fisher-
men, and sportsmen as one of the most abundant aild desirable of the
Pacific salmons* The part played by the Trinity River in supplying
the salmon fishery of California is not definitely known, but some

20

idea of its contribution oan be deduced from discussion of catch
statistics. An average annual catch of 2,286,588 pounds of salmon
has been taken commercially from waters of Humboldt and Del Norte
Counties over a period of 28 years (Table 8), These counties lie
north and south of the mouth of the Klamath River, and catches there
certainly include a major portion of the contribution of the Klamath
River. Salmon originating from other drainages appearing in these
oatohes are assumed to be compensated for by Klamath River salmon
taken north and south of these two counties. "Brinity River con-
stitutes approximately one-third of the total Klamath drainage
accessible to spawning salmon, and its contribution to the com-
mercial fishery supported by the Klamath drainage is assumed to b«
proportional to its part of the drainage area involved. Based on
these assumptions, the annual catch of salmon from Trinity River
would approximate 762,200 pounds.

An Important sports fishery materially increases the value of
the salmon production. It is difficult to even approximate the value
of these fish to the sportsmen. Businesses and people benefiting from
sport fishing are so greatly varied and widely distributed that a
summation of values is impossible. The Calif oniia Division of Fish
and Game estimates that 1,385 anglers took 11,496 salmon from the
Trinity River in 1941. Based on an average weight of 11 pounds per
salmon, this catch amounted to 126,456 pounds* The total production
of the salmon fishery resource of the Trinity River is probably 890,000
pounds per year.

Characteristios of the seasonal rims

King salmon enter the Klamath River from the ocean in two well-
defined runs, one in spring and another in fall. The spring run, once
the largest run entering the river, begins in late March, reaches a peak
in May, and diminishes to the vanishing point by the end of June. At
present, this run is very small, but Snyder (1931) cites a paper by
R. D. Hume (undated) as authority for the assertion that in 1850 and
even later the spring run was the most abundant. It was practically
extinct in 1892, and no evidence of recovery was evident when Hume
wrote his article which certainly appeared before the turn of the cen-
tury. The STsmner run usually begins to enter Klamath estuary about the
first of July. It increases gradually throughout that month, reaches
a peak in August, declines steadily through September, and practically
disappears by the beginning of winter. There appears to be little
or no segregation of this latter run into summer and fall seginents.

Adult king salmon migrate pest Lewiston enroute to their spawning
grounds in what appear to be three seasonal groups t one in spring,
one in summer, and one in fall. Each of these groups, excepting
possibly the spring run, is distinct emd divisions between them are

21

TA.BLE NO. 8
COMMERCIAL SAUiON CATCH*
DEL NORTE AND HIMBOLDT COUNnES

Year

Total
Average

Weight of catch
In poxinds

1916

1,980,953

1917

1, 521, 378

1918

1,234,653

1919

1, 458, 162

1920

1,307,568

1921

1,212,879

1922

2,006,822

1923

1,990,2 35

1924

2,193,688

1925

3,795,062

1926

2,825,650

1927

1,856,451

1928

1,211,600

1929

1,520,624

1930

2,387,507

1931

3,813,300

1932

3,047,400

1933

3,340,678

1934

2,769,304

1935

3,499,610

1936

2,347,116

1937

3,375,560

1938

1,438,2 30

1939

1,675,116

1940

3,369,492

1941

2,413,368

1942

2,255,862

1943

2,176,182

64,024,450
2,286,588

■i^i'ro* California Division of Fish and
Game published commercial catch records*

22

well defined (Figure 5 and !P5ible 9). The spring migration passes
Lewiston during June and July, the 8\anmer migration during August
and September, and the fall migration during October and November*

Counts of migrating adult salmon began early enough to include
spring-run fish in 2 of the 2 l/2 years of observations* June and
July ooiints in 1945 totaled 25 fish* The total count for the same
months, plus the first 10 days in August, amounted to 274 salmon in
1946* Ttie ran in 1946 was large enough to demonstrate trends and
limits* It began on June 28, increased rapidly to a peak on July 4,
tapei-ed off very gradually through July, and practically ceased by
the 5th of August* The spring-run segnent nearly failed in 1945*
The weir at Lewiston began operations June 6, but the first salmon
to pass it did not arrive until June 22* In the period June 28
through July 16, all but two of the 25 fish passed the weir No
other fish were counted until August 2*

Spring-rxin salmon are very delibeirate in their migratory habits*
They travel fast and do not hesitate to fight any obstacle encountered*
Their greatest movement through the counting weir took place during the
two hours following sunset, although some migration continued day and
night. They are in excellent condition, as is shown by their visceral
fat, silvery bodies, and very red flesh. In s<ane years this run is
hardly noticeable in Trinity River because of its relatively small sise
and the fact that the salmon in it rarely strike at a fisherman's lure*
Upon reaching deeper holes between Lewiston and Trinity Center, these
fish stop migrating and remain in a semi-quiescent state until they
spawn early in October.

The so-called summer run was much more numerous and distinct than
the spring xnin in both 1944 and 1946* Weir operation began August 4,
1944, and on that date 3 fish passed the gates* Salmon arrived at the
weir in erratic but gradually increasing nvonbers throughout the remainder
of the month* The greatest daily count was made on September 2, after
which the migration dwindled to practically nothing* The total number
of salmon involved in this run was 801* In 1945 the summer run began
passing the weir on August 16* It increased in the same erratic fashion
as did the 1944 run until the greatest daily count was made on September 4*
Unlike the 1944 migration, movement through the weir gates after the peak
day was sustained until the middle of September before a marked reduction
occurred* Migration virtually ceased by the end of September. The 1946
summer run consisted of 873 individuals*

The STxmner king salmon are slow and rather cautious In their
migratory habits* They are qfuite wary of any obstruction or disturbance,
and their greatest movement at Lewiston took place in the four hours
following sunset. Little, if any, migratory movement was observed daring
daylight houirs* Periodic fluctuations in daily counts of these fish appear
to be related to changes in water temperature* At Lewiston, there was gen-

23

50-\
0
600\

500

400-

300-

200-

I00\

1942

1944

^aoo-

a

.Ok

^ 700-
2 600^

•»

§■ 500-\

o

%

400

5 300-{

5
^

200-

100-

1945

50-

1946

rr tz 27
Jun¥

I I i I I

7 IZ 17 MZ ZT

n-

» I — I — r— ? — I I I I — r
/0 M J* jf ^10 ts zo as 30

•^ — r— I — r—i — i— r

S /O /S 20 2S ■so 4

* f4

II

July August Stpftmber October Nov.

Figure 5* Numbers of adult Mug salmon passing through the Lewiston ^
weir In 1942, 1944, 1945 and 1946, Trinity River. *

TABLE

NO. 9

KING SALMON GOUilTS

TRINITY RIVJiiR AT T.WISTON

19^2
Dct. Nov.

19UU

19U5

i<^ke

Day (

Aug.

Sept.

Oct.

Nov.

June July Aug.

Sept.

Oct.

June

July Aug.

1

5

8

Ik

11+07

2

0

1+

0

9

6

2

2

177

1

75

1

1

12

0

17

7

I

18

90

2

171

0

1

16

11

9

3

17

3

76

5

5

0

112

21

30

0

5

3

0

Uo

1

1

0

108

2

28

1

6

U

0

23

3

0

0

0

9

6

Ik

0

T

6

0

g

0

0

0

0

37

3

11

0

g

96

0

0

k

0

0

0

21

12

k

1

9

0

13

8

1

0

0

0

80

1

5

0

10

0

3

5

23

0

0

1

65

5

3

1

11

9

11

5

Ul

0

2

0

^7

12

16

12

1+

23

1

55

0

2

0

22

13

6

s

J+

k

19

91

0

0

0

2k

111+

3

1+

5

8

85

0

0

0

k

255

k

15

0

3

1

98

0

0

0

10

155

11

16

0

6

1+

151

0

1

12

0

75

6

17

0

12

2

150

0

0

8

17

173

7

18

12

2

4

359

0

0

3

9

205

k

19

3

5

9

6U1

0

0

21

7

351

0

10

20

3

6

700

0

0

35

17

478

0

12

a

6

2

385

0

0

16

k

369

0

3

22

25

1

711

2

0

6

0

3U8

0

6

23

23

2

901

0

0

0

5

33s

0

1

2^

Ik

0

1+61

0

0

3

3

37^^

0

2

25

23

U

295

0

0

0

1

M+5

0

2

26

3^^

1

399

0

0

23

9

385

0

2

27

18

k

281

0

0

56

5

755

0

3

28

22

0

259

3

0

10

7

536

2

3

29

6

13

2

166

3

0

11

1

1170

2

8

30

2

6

1

U99

3

0

6

0

1

2

31

1?

689

0

1+

7

"otals

8 187

290

511

7U71

1653

11

Ik

217

656

6612

5

250

19

Yearly

mJ\.

total

8 195

9925

7510

21k

25

orally a peaJc count two days following a low riyer temperature. Fish
of the summer migration are in fairly good condition* They have no
■visceral fat, but their flesh is qxdte red and firm. Few of these
salmon will strike a lure; however, they are quite noticeable in the
larger holes along the river between North Fork and Trinity Center.
It is possible that the summer run at Lewis ton is a late or delayed
portion of the spring run which, having stopped migrating early in the
season, is forced to move upstream to escape high sumner water tem-
peratures*

Fall-run salmon reached Lewlston about October 1 in 1944, and
once they begaa to arrive, the number counted each day increased
rapidly. After the initial surge, "waves* of migrants passed through
the counting gates until a seasonal peaJc in daily count was reached
November !• This peak accompained the first sustained rain and river
flow increase of the season. A second stona and subsequent rise in
river flow forced removal of the counting weir on November 3. The
counted portion of the fall run of 1944 amounted to 8,124 fish. The
fall ran of 1945 reached Lewis ton at about the same time in October
as did the 1944 run. It also passed through the ooimting g^tes in
successive "waves" which culminated in a peaJc daily count of the
season on October 29. This peak count also coincided with the first
sustained rainstorm of the season which continued in intensity and
forced removal of the weir on October 30. Fall-run salmon counted
in 1945 totaled 6,612 at the time operations ceased.

The fall migration is the largest 9iid most noticeable. Many of
these fish will take the fisherman's lure, and, as a result, they
support a heavy sports fishery. IBieir flesh is quite pink and readily
distinguishable frran that of the fish in the two earlier migrations,
which is almost white by the time the fall migration starts. These
salmon can also be distinguished from fish of the two previous migrations
because their gonads are not fully mature while the other fish have
begun spawning. Since these fish mature later, many of them are able to
enter smaller tributaries after the first fall freshets.

Obviously, the total annual number of adult salmon passing Lewiston
was greater than the 9,925 counted in 1944 and the 7,510 in 1945. It is
believed, however, that the number of salmon passing Lewiston was not
much greater than 120 percent of the number counted. If such is assumed
to be the case, then t\je 1944 run would have totaled about 12,000 and the
1945 run about 9,000.

Spawning and development

The first spawning activities of the spring and summer salmon are
noticeable along the river between Grass Valley Creek and Stuart Fork
during the first week of October. By the middle of that month, spawning
fish can be seen on every suitable riffle in this area, and scattered

26

spawning Ocours upriver to the East Fork and dovmstream to the North
Fork, Spawning in this stretch of the river reaches a peak during
the first two weeks of November when many of the fall-run fish are
also depositing their eggs. During the course of the investigations,
high waier flow and turbidity prohibited observation of main river
spawning after the first week of November, although spawning is known
to occur long after that date. Salmon that had recently died following
spawning, and a few living fish, have been seen as late as December 19
near Lewiston. Three freshly spent saLnon were found dead near Lewis ton
in February 1946. Salmon start to spawn in the Trinity Center area during
the first two weeks of November, and a peak in the spawning activity is
reached during the last two weeks of that month. Spawning salmon have
been observed as late as December IE near Trinity Center.

King salmon fry begin to emerge from the river gravels during
January. Iftidoubtedly, the first fry to appear are offspring of the
spring and summer adult runs which spawn some four to six weeks ahead of
the fall-run adults; however, no distinction between the hatching times
of the separate rtins can be detected from fyke-net catches after the
emergence is well underway. The movement of salmon fry from their nests
continues fr<»n January through May, as indicated by results summarized
in Table 10. The appearance of undeveloped fry serves as a rough index
to the emergence periodj however, nets placed directly downstream from
salmon nests took very few yolk sac specimens, which demonstrates that
young, not fully developed as they leave the nest, are the exception
rather than the rule.

Seaward migration

Seaward migration begins to intensify in March (Figure 6, Table 11),
usually reaches a peak in May and Jltne, continues until the first half
of July, and practically ceases by the first of August. The main
migration takes place during the spring run-off period and is only
generally influenced by fluctuations in water flows or temperatures.
Migration ceases in early sixsimer as the river becomes low and its
average temperature ranges into the seventies. The greatest numbers
of migrants for each year of observation were taken in May of 1943 and
1944, April of 1945, and June of 1946.

Figures in Table 11 do not indicate the actual size of the seaward
migration, eind, therefoire, the results obtained in one year cannot be
compared dir«ctly with those of another. Quantitative evaluation of
fyke-net catches as indices of the total nvuaber of migrants is very
difficult. Too many variables, as location of the net, stage of water
flow, current, debris, and other factors, change the fishing success
each day. The only certain value of the fyke-net records is to show
the periods of seaward migration and their relative intensity during
different seasons of the year.

27

TABLE TO. 10

DEVELQPME13T STAGE OF KIl'G SALMON CATCHES

IN THE LEWISTOIT FYKE NET

1 9

-^rr-

Yolk

1 9

U 6

Yolk

Abdomen

Total

Abdomen

Total

Peri

ods

Sac

Cfpen

Closed

Catch

Sac

Open

Closed

Catch

Feb.

5- 9

9

0

1

1

2

10-14

k

0

0

3

3

15-19
20-24

5

0

0

0

0

3

1

2

1

u

25- 1

3

0

0

2

2

May-

2- 6

29

0

1

1

2

7-11

3

2

70

75

0

3

9

12

12-16

5

19

2S

52

0

0

3

3

17-a

2

5

hs

56

0

1

3

4

22-26

0

1

39

Uo

0

0

2

2

27-31

0

0

Ul

kl

3

g

19

30

Apr.

1- 5

0

2

77

79

0

2

10

12

6-10

0

1

70

71

0

6

21

27

11-15

0

2

216

218

0

I

71

7^+

16-20

1

k

165

170

0

15

19

21-25

0

0

15

15

0

1

3S

39

26-30

0

0

g

g

0

3

67

70

May

1- 5

0

0

7

7

0

1

lOU

105

6-10

0

0

12

12

0

0

16

16

11-15

0

0

20

20

0

0

10

10

16-20

0

0

16

16

0

0

17

17

28

1942 Hatch

"I 1 1 1 1 1 1 1 1 1 1 1 1 r

I I

6\

1943 Hatch

4-

0-

I I I I I

%4A

"to-

T r

T 1 1 1 1 1 1 r

I f r

1944 Hatch

\ I I r

1 1 r

-i — ~r

Si*
O ^

1945 Hatch

c

-I 1 1 1 1 r

T=^ — I 1 I I I 1^^ r

1946 Hatch

— 1~^ I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1—

J F M A M J J A SONDJFMAM

Figure 6, Seaward migration of young king salmon in
Trinity River at Lewiston,

29

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32

Young salmon were observed from a barge anchored in the middle
of the river during a heavy migration on Jxme 24, 1946, between 8 and
9 p.m. At that time, fry in great nianbers could be seen drifting down-
stream with the current. They seemed to be evenly dispersed o\-er the
entire river with no tendency to travel in groups or schools, euid most
of them were within a few inches of the surface. Few were seen at depths
exceeding 18 inches, but all of them make some effort to stay head upstream
as they drifted with the otirront. In a 5-ininute period, 47 were counted as
they passed through an illuminated section of river 10 feet wide* Assum-
ing that the migrants were evenly distributed across the 200-foot width
of the river, they were moving past this point at the rate of 188 per
minute, or 11,280 per hour at that time.

In the warm summer months when relatively no downstream movement
is evidenced by fyke-net returns, young salmon are commonly seen at
all points along the river in the vicinity of Lewis ton* Their presence
is most conspicuous in the early morning when they can be observed Jump-
ing from the water in quiet, shallow areas along the river^s edge.
Throughout the day they apparently seek seclusion in the rooks on the
river bottom. Several hundred young salmon congregated at a small sub-
surface spring near Lewis ton on days when the water temperature rose above
75°F« Any tendency toward downstream movement in their activities is so
slight that it escapes detection. The seaward migration is resumed
immediately following the first fall rains when water temperatures approxi-
mate those recorded in April, May, and June* This migration of yoting
entenng their second year of life usually starts in October or November
and continues until March and April of the following year, as shown in
Figure 6.

The rate of growth of seaward migrant salmon is difficult to
ascertain from samples taken at a fixed location. It would be possible
only if certain population segments could be followed downstream and
sampled periodically. Sampling at a fixed location actually provides a
single set of data on a different population group each day. It is
interesting to note, however, that eis the season of downstream migra-
tion progresses, the average length of migrants taken increases uniformly
and may be indicative of the rate of growth (Table 11). Although samples
taken in February are too small for reliable statistical treataaent, salmon
of the year captured during that month in three of the four seasons were
larger than migrants caught in March of the same years. The average
length of February migrants in 1944 and 1945 was greater than similar
average lengths obtained in both March and April. This tendency is pre-
sumably indicative of the difference in time of emergence between progeny
of spring or summer-run adults and progeny of fall-run parent salmon.

The difference in average lengths of seaward migrants was i 15 mn.
(Goo9 inches) between March and May of 1943; 15 mm. (0.69 Inches) between
March and June of 1944; 15 mm. (0.59 inches) between March and June of
1945; and 16 mm. (0.63 inches) between March and July of 1946. Salmon

33

taken in Noveraber were greater in average length by 17 mm, (0.67
inches) in 1943, 22 mm, (0,83 inches) in 1944, and 30 mm, (1.18
inches) in 1945, than migrants of the same brood year netted in
Maroh. Oocasional specimens, captured by the fyke nets in March
of the year follovring their hatching, average 82 mm, (3,23 inches)
in length in 1943, 79 mm, (3,11 inches) in 1944, 75 mm. (2,95 inches)
in 1945, and 73 ram. (2.87 inches) in 1946. These lengths are probably
less than the averages which could be obtained from aeries of seunples
collected by means other than fyke netsj fish larger than 70 mm (2.76
inches) in length are able to avoid capture in most stationary fyke nets.

Sex ratios of adults

The matter of sex ratios in a given population of migjrating adult
king salmon has been the subject of considerable research effort.
Apparently, the consensus of opinion to date favors the concept of
equal numbers of males and females in the original stock with in-
equalities resulting almost entirely from the early maturation and
migration of a certain portion of the males of any given year class.
Snyder (1931, p. 103) established a sex ratio of 1 female to 1.07 males
from 9,439 salmon taken in the commercial ocean catch off Monterey,
California, during the years 1919-21. The ratio for the individual
years varied only slightly, being 1:1.10 in 1919; 1:1.02 in 1920} and
1:1.05 in 1921, From, these results, he maintains that sea fishing does
not discriminate in any great measure against either sex. It is also
fairly obvious that the sex ratio in the sea is Ijl as would be expected.
Determinations of the sex of salmon fingerlings sampled at Lewiston in-
dicate a ratio approximating equality. The sex ratio of 166 young salmon
taken during 1943 was 1 female to 1,05 males, and a sample of 116 taken
during 1945 revealed a ratio of 1:0,97, These samples were composed of
fish ranging frcwi 50 to 100 mm, (1.97-3.94 inches) in length.

Sex ratios established frcwi obsairvations on migrating adult
populations are quite certainly affected by the type of fishing which
the migration has had to pass. Gill-net fisheries are especially
selective since most of the mesh sizes are fixed by law for the
protection of the smaller sized fish in the run. Snyder (1924) re-
porting sex determinations made on a seunple of 340 king salmon taken
at Hoopa in late September 1920, found 260 males all less than 2 5 inches
long, 47 males greater tl-ian 25 inolies in length, and 33 females. These
fish were taken from Trinity River below the Indian fishing weir and
probably represented a fair cross section of the migrant population
after it had passed the gill-net fishery at the mouth of Klamath River,
The sex ratio derived from this sample is 1 female to 9.3 males.
The preponderance of males far exceeds anything observed at Lewiston

34

or Trinity Center during this study and is also an indication of
the depletion which selective fishing gear can exert on a population
despite presumably adeofuate escapement provisions made by law. In a
later study, Snyder (1931, p. 36) found that females predominated in
the gill-net oatohes at the mouth of Kalamath River. During the
years 1919-1923, inclusive, 63.2 percent of the catch consisted of
females* EQ.S records are based on oatohes from nets that allowed
the escapement of small fish, and, as he states, do not represent
a true cross section of the salmon population* Snyder points out
that a greater number of large males was taken in the fishery during
the latter part of the season^ but very seldom exceeded the nianber
of females* He also noted an increase in the size of the fish as
the fishing season progressed*

After closure of the Klamath River to commercial fishing in
1933, the migrant adult population of salmon in Trinity River must have
returned to its original composition as regards sex ratios* Results
obtained during this study would certainly be more representative than
those of Snyder* In the vicinity of Lewiston, a sample of 33 fish con-
sisted of 1 female to 1*91 males in 1942 i a sample of 90 fish consisted
of 1 female to 2,33 males in 1944; and a sample of 116 fish consisted
of 1 female to 2.66 males in 1945 (Table 12), The ratio for all years
of record at Lewiston is 1 female to 2*4 males* At Trinity Center,
some 26 miles upstream from Lewiston, a sample of 548 fish examined in
1945 consisted of 1 female to 0*85 males, almost the reverse of the
ratios found at Lewiston.

The difference in the sex ratios of fish sampled in these two areas
may be influenced to some extent by the Indian gill-net fishery at Hoopa*
The suraner and early fall runs of salmon that spawn near Lewiston must
pass nets that would take out many of the larger fish resulting in a
greater proportion of small precocious males in the upstream migration*
It has been observed on other streams, such as the Sacremento River,
that the sex ratio may change from year to year* Some investigators aver
that a preponderance of males, especially grilse, presages a large migra-
tion at maturity of the brood from irtiich the grilse were derived.

Since the spring and summer salmon tend to spawn near Lewiston, and
those migrating later utilized the area near Trinity Center, the two
areas might be considered unrelated with respect to the composition of
their spawning populations. The sex ratio of the fish spawning in one
area is not necessarily related to that of the spawning population in
the other* In order to arrive at the sex ratio of all salmon migrating
up the Trinity River above North Fork, the sex composition of both of
these populations must be considered* An average sex ratio determined
from salmon taken at the center of each area should evaluate both popu-
lations equally and should be representative for the total spawning popu-
lation* The sex ratio derived in this manner is 1 female to 1*63 males*

35

Measurements of the total length of salmon sexed in the Trtnity
Center area Indicate that females there are larger than those spawning
near Lewis ton (Table 12, Figure 7)» The mode or greatest number of
females of the same length in the Lewis ton sajnple was 29 inches and in
the Trinity Center sample it was 31 inches. In the TVinity Center area
54 percent of the females measured 31 inches or longer, and near Lewis ton
only 16 peroent were In the same category* The mean total length of
females at Trinity Center was 30*3 inches and that of females at Lewiston
was 28.9 inches* "ffne difference between these means is 1*4 inches and
tests for validity of this difference show a high degree of significance
(2*3 times the square root of the sum of the squares of the standard
errors of the means). The difference in the sise of the male fish of
the two areas is not significant* Males averaged 24*0 inches in length
at Tlrinity Center and 23*3 inches at Lewiston. Near Lewiston 59 percent
of the males were grilse, as ctwipared with 41 percent at Trinity Center*

Eggs contained in the ovaries of 70 female salmon were counted
during the course of the investigations (Table 13). Individual counts
ranged from 2,341 to 4,764 and average 3,466* The correlation between
egg content eind weight of females is not very well marked although the
two characteristics are oertainly closely related* Snyder (1931, p* 13)
reports counts frcxn salmon taken in the Klamath River that compare
favorably with these figures. He derived a mean of 3,760 eggs between
extremes of 1,718 and 4,977* These ooimts closely appi^ximate the average
number of eg^s in female king salmon from the Rogue River, which is believed
to be about 3,000, and stands In sharp contrast to the 7,000 plus eggs
carried by salmon in the Sacramento River* Part of this difference cam
be attributed to differences in average weights between females of the
two races*

The weights of king salmon in the vicinity of Lewiston were de-
termined from samples collected at the oovinting weir and along the
river at various points* Weights of salmon in the spawning area are
of little value in considering the problems of yield to commercial or
sports fisheries, but they are of biological interest* The average
weight of 70 females collected furing the 1944 and 1946 migrations was
13 pounds, while that of 61 males was 9*6 pounds* Average weights of
salmon caught by ooraiiereial natters at t he mouth of Klaaath River as
determined by Snyder (1931) were t 15*3 pounds in 1917 and 16*6 pounds
in 1919* These weights did not include many of the grilse entering the
river and may be somewhat high as averages for the entire run* If this
discrepancy is disregarded, and if the Trinity River races are similar
to all others in the Klamath drainage, then the effort expended in
migrations upstream to Lewiston requires between 4*6 and 5.r pounds of
body weight*

36

so-

40'

30-

20-

Trinify Ctnter

to-

c
o

a
o

Le wi st o n

15-

to-

5-

T

/5

Figure 7.

T ■ 1

20 25 30

Fork- fail length in inches

40

Length-frequency distribution of male and female king
salmon from two different sections of Trinity River.

Zl

TABLS NO. 12

spiMT Knra silmon - teduty piveh

Total

Lewi St on

mi'

Total

Trinity Ctr.

Length

I9U2
Female Male

I9I1U

1945

19^2-
Female

19I+5

Male

Female

Inches

Female Male

Female l-fale

Male

15

1

1

1

X6

7

2

1

10

2

17

If

3

If

11

15

10

1

3

3

7

33

19

2

12

lif

39

20

1

6

11

18

28

a

1

10

7

18

llf

22

1

7

If

12

2

8

25

1
2

If
if

2

3

2

1

u

I

6

3

3

6

I

26

2

1

1

3

1

11

8

27

2

3

3

if

6

6

11

5

28

2

5

k

5

3

12

7

16

8

29

2

6

1

7

1

15

2

Ui

6

30

1

7

3

If

i^

12

7

lf6

12

31

1

2

2

3

If

U

68

15

32

1

1

1

3

1

1

I

5

lf2

12

11

2

1

2

2

3

31

13

1

1

16

6

35

1

1

2

1

3

3

3

36

5

37

1

1

2

38

2

2

If

3

S

Ui

1

1

Not neas.

2

g

2

2

Totals

11

21

27

63

29

77

67

161

297

251

Sex ratio

1:

1.91

l»2.33

i

1J2.66

1:2.

Mo

iiOcS5

Grilse

(SU" or l€

»ss)

715^

65^

6756

59^

ifi5^

Females

(31" or over)

95^

225C

19?^

igjJ

5456

Average length

28.9'

' 23.3

1" 30.3"

2lf.O

38

TABLE HO, 13
EECUKDITY OP FEMALE KING S^JLMOW - THIKITY RIVER

1

9 ^

Total

2

1 9

1+ 5
Total

Number

length

Weight

Number

length

Weight

of eggs

(in.)

(lbs.)

of eggs

(in.)

(lbs.)

3.231

31

15

3,659
4,421

32.25

16.7

3.132

28

11

35.00

18.0

3.263

35

20

3,229

1^.00

8.6

3.»+09

26

8

3,225

29.00

11.9

3.719

33

18

3.17s

25.75

8.0

2.3^1

25

8

3.720

26.75

2.5

Mean 3,1S2

3,103

29.00

11.6

Bange 2,3Ul-3.719

^,332

34.50

19.5

3.353

31.00

13.3

1

9 4

4

2,7^3

28.00

9.5

^

2,982

32^00

13.0

Total

4,182

2S.75

10.5

Kanber

length

Weight

3,224

33.00

13.0

of eggs

(in.)

(Ibe.)

3,298

31.50

13.5

3,063

27.50

3.626

34.00

16.6

3.^92

30.25

13.5

3.462
4,409

32.00

12.3

2,965

30.00

13.0

35.00

17.3

2,862

29.50

11.0

3.1+09

33.00
34.00

i4.6

^.179

33.50

17.0

4,207

16.6

2.659

31.50

— --.

3.665

29.00

10.8

3.037
3.9^7

31. 00

11.5

2,960

26.50

7.7

31.25

13.5

3.1+91

32.50

12.0

3.222

31.00

16.0

3.105

29.50

11.4

3.1^

33.00

16.5

3,127

30.00

10.0

3.259

31.00

13.0

3.561

29.00

9.1

3.750
3.3W

29.00

13.0

3.652

29.50

9.2

27.00

11.0

3.762

33.50

11^.5

^'ft?

27.00

10.0

4,764

34.50

15.6

3.661+

30.00

11.0

3.3S1

29.00

11.5

3.505

27.00

8.5

3.505

29.00

10.3

3.052

32.00

16.0

3,997

32.00

13.0

3.249

28.00

11.0

3.1*99

29.00

11.2

3.61K)

32.50

12.0

2,961

29.00

12.0

3.^3

33.00

11.0

3.270

29.50

12.6

3,922

3»+.50

18. 0

4,0^2

33.00

15.6

3.210

25.00

18.0

Mean 3,576
Bange 2,793-^,764

^.35^

25.50
33.50

16.0

3.750

4,180

33.00

II+.5

3.233

30.50

11.0

3.015

27.00

9.0

2,357

26.00

7.S

3.15^

— -.—

}Mo

, —

Mean 3.39^

Range 2,357-4,354

39

Silver Salmon

Silver salmon enter the lower Trinity River to spawn* They are
not known to migrate above the mouth of the South Fork at the present
time, end there are no definite indications that they have ever migrated
upriver as far as Lewiston. Residents of ^yainpom on the South Fork
clearly describe a silver salmon migration to that area during one year
when unusually early fall rains occurred. Silver salmon are known
to be present in the Hoopa Valley during October.

Steelhead Trout

Steelhead trout using Trinity River spawning grounds are of little
importance to the California commercial fishery, but they are outstanding
as sports fish. Anglers seeking the thrill of catching these large gamey
fish contribute to a sitable tourist population along the river in the
fall and winter months.

In the Trinity River, yoving steelhead start to emerge from the
gravel late in April and a few begin moving downstream in May and June.
This early movement reaches a peak in June and July (Figure 8 and Table 14)
and subsides rapidly with decreasing river flow and increasing water
temperatures. In some years, many adult steelhead utilize the main
Trinity River at and above Lewiston as spawning ground. Whenever such
spawning occurs, there is a post-hatching migration downstream of very
small steelhead which are apparently not migrating seaward, but are drift-
ing downstream to satisfactory holding areas in quiet water. Generally,
tributary streams are used by the steelhead, and under such oirciaBstanoes,
the large fyke-net catches of very young fish are materially reduced*
Some downstream movement continues through the summer and generally
increases during the fall and winter. The migration is practically
complete about the time fry of the next generation are starting to leave
their nests.

Early, freshwater growth of the steelhead in Trinity River is
reflected to a certain degree by the length frequency distributions
of fish taken by fyke nets. Catches were grouped into 10-day periods,
and lengths of the fish were grouped at 3 millimeter (0.118 inch) intervals.
Idealized growth curves for each season have been fitted by inspection
on the basis of mean lengths for each period as they applied to brood
years (Figure 9) • Generally, no difficulty in separating the fish of
each brood year was experienced. Because the hatching period of the
steelhead in Tirinity River extends over about 5 months, from March
through Jtily, length frequency distributions are especially broad.
However, enough scales of young steelhead have been examined to sub-
stantiate the separations of year broods through the first 18 months

40

I

7-
6-
5-
4-
3-
2-

.^ I-

c
I

5 0-

«*>

^0

1943

T 1 1 1 1 1 1 1 1 r

1944

T 1 1 1 1 I

T I

1945

-I 1 1 1 • 1 r

Jan. Feb. Man Apr. May Jun. Jul. Aug. S*p. Ocl. Nov. Dec.

Figure 8 . Downstream migration of steelhead trout in Trinity River

at Lewi 8 ton.

41

IbJiLE NO. 11+
STKKT.KRAJ) TEOUT FYKE NET CATCHES - TfilHITY RIVER AT LEVISTON

I9I13 19^4

Total

length(mm.) JFM A MJJASONDJrMA MJJASOND

21- 25

26- 30 9 56 i

31- 35 U lU 1 1 ^

6- i+o

1- U5 2 1 111 512

U6- 50 4331 222 1 32

51-35 35521 3 10 3 11 12 1 1+

I

56-60 5 4 10 10 6 12 831+ 12 13

61- 65 6 S 21 21 16 1 1 10 5 17 1 1

66- 70 ^ 10 Ui 58 Uo 13 6 11 ii 1 1

1

11

9 56

k Ik

1

2

5

1

1

1

5

2 2

2

1

10

3 11

1

2

8

3 ^

1

2

1 10

5 17

1

13

6 11

h

1

1 8

5 19

3

2 8

3 17

2

3 7

1 10

2

U

1 2

1

1

5

6 U

3

2 1+

1 1

1

1

1 2

2

1

1

1 1

2 3

1

71- 75 4 22 38 7I+ 72 1 1 8 5 19 3 11

76- SO 7 10 38 71 78 2 8 3 17 2 1

81- 25 2 3 19 38 hS

86- 90 1 2 8 2l| 28

91- 95 1 8 12 18

96-100 1197

101-105 1 4 1

106-110 12 1 2

111-115 1

116-120 1

121-125 1 5

126-130 51 1

131-135 ^

136-lUO 1 2

1^11-11+5 15 1

1U6-150 3 1

151-155 2 1

Over 155 1 k- _JL 1

Totals 39 70 r^ ^2k 317 0 3 Uo 0 0 h 3 13 85 kz 102 29 90 13 5 0 1 8 15

Net nights

fished 22 22 22 a 13 0 2 4U 0 0 9 27 25 58 60 5^ 32 58 6o 62 60 33 ik 30
Pish/30 net

nights 53 95 265 U63 732 0 U5 27 0 0 13 3 16 ^ 21 57 27 47 7 2 0 1 17 15

■ ■»'"'' I . ■ - 1 I 1 I I II III I'll I » II

42

TABLE 110. Ik (Concluded)
STEBIflaAD TKCXrr FYEB NBT G&ICHES - TEIKITY BITER AT LEVISTOK

Total . 1 9 U 5 1 9 k S

lengthdan.) JfMAMJJASONDJJMAM J T^A

21-25 1 12 5 1

26- 30 5 12 2 208 U34 U2

31- 35 10 Ik 3^ 98 ^8

36-40 119 23 ^11 73^1

Ui- 1^5 1 7 12 11 1 1 1 3 20

1+6-50 51 9 13 11 U 1 1 2 17

51- 55 2 11 2521 k

56-60 83 12111 1

61- 65 1 9 1 1 1 1 ;5

66-70 3531112 2 h

71-75 1331 1 161

76-20 21 11 111

81- 85 1 1 1 11

86- 90 1

91- 95 13

96-100 2

101-105

106-110 2

111-115 2

116-120 11 1

121-125 2 1

126-130 1

131-135

I36-II+O

141-11+5 1

IU6-I5O

151-155 1

Over 155

Total 8 50 13 2 10 50 70 U2 0 8 9 h 0 1 1 20 2U6 5^9 I60 2

Net nights

fished 1+1 5I+ 62 39 37 29 30 28 3 13 25 31 12 21 31 30 30 29 31 9
Fish/30 net

nights 6 28 6 2 8 52 70 U5 0 18 11 k 0 1 1 20 2U6 5^8 155 7

43

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a

of life* The time of annulus formation is uniform regardless of the
time of hatching, and annuli would, therefore, appear on the scales
after 6 months to 1 year of life, depending on when the fish began inde-
pendent existence* Growth rates established in this manner are probably
low. Larger fish were usually missed by the fyke nets. Beyond the arbi-
trary limit of 80 millimeters (3.15 inches), the samples are inadequate.

The step-like character of the growth curves expresses the length
of growing seasons in Trinity River at and above Lewis ton. Apparently,
growth is quite rapid after emergence of fry from the gravels. This
acceleration slows to a virtual standstill by September, emd average
lengths are almost constant throughout the winter. Increases in length
begin in spring (March to May, depending on the year) and presumably
continue until the following September, although catches of older steel-
head are insufficient to determine the time of growth cessation in the
second year of life.

The greatest number of downstream migrating steelhead as determined
by f^e netting, move shortly before or somewhat after the end of the
first year of life. However, many migrant steelhead must be larger
than those sampled by the fyke nets, as scale studies of adults show
that many individuals remain in the stream two or three years before
reaching the ocean. It is likely that' young steelhead leave the Lewiston
area as yearlings and spend a year or more completing their migration
to the sea* Certainly the compesltion of migrants passing Lewiston is
not necessarily the same as that of migrants entering the Klamath River
or the ocean. During extended winter dry periods when the river is low
and clear, groups of several hundred steelhead trout 6 to 8 inches in
length can be seen slowly drifting downstream. The size of these fish
would indicate that they were in 'Oieir second or third year of life*
These schools migrate down the center of the river hovering close to
the bottom, thus eluding the fyke nets which, because of excessive
current in midstream, were fished near the bank.

Prior to or during the seaward movement, steelhead trout become
large enough to add materially to the fish population available to
anglers, (ihere is no size limit in California.) The magnitude of
the contribution to the sports fishery is not known, but it is etssuned
to be considerable*

Steelhead remain in the ocean from one to three years before making
their first upstream migration to spawn. Mtoy of them do not die
following spawning, but return to the ocean. Before completing their
life history, steelhead may spawn three or four times, repeating this
migratory procedure each year after maturity.

46

In 1945, the first group of steelhead migrating up the Trinity
River reached Lewis ton on June 10» This run continued until July 12
and totaled 41 fish (Table 15). A similar migration started on June 30,
1946, and continued until July 25, totaling 21 fish. These counts of
migrating fish are minimal. Many smaller steelhead in the migration
were able to pass through the pickets on the weir and were not counted*
No counts were made early in 1944, but upstream migrant steelhead were
caught by sportsmen during the first part of July. Adult steelhead
are common in the deep holes along the river below North Fork in summer*
These fish start moving upstream along with fresh run steelhead during
October. Counts of steelhead through the Lewlston weir in the first 3 daya
of November 1944 amounted to 456 fish. The weir was removed November 4*
In 1945, a run of 170 steelhead was counted in the period October 1 to
29. The counting weir was removed from the river on the latter date.
Steelhead continue their spawning migration up the Tlrinity until sometime
in March. Attempts to cotint the migrants have failed as they move during
storm periods when it is usually necessary to remove the oovinting weir.

Steelhead trout enter the larger tributaries such as North Fork,
Browns Creek, and Stuart Fork following the first fall rain. Smaller
tributaries are entered during the first rain in February after which
these streams maintain a flow sufficient to insure adequate spawning
conditions. Spawning begins in the upper IS-inity River drainage during
the last part of February and reaches a peak in the last two weeks of
March and the first two weeks of April. Some scattered spawning con-
tinues until the first week of June. All observations of spawning
activity were made in tributary streams where steelhead were confined
to small areas and could be easily seen. Host nests in tributary streams
are located in gravel pockets between large boulders. However, the few
larger riffle areas available were so heavily utilised that individual
nests could not be distinguished. Considerable spawTiing takes place
in the main Trinity during the spring run-off period when silt-laden
water obscures their activities. This main river spawning has never
been observed directly. It is evidenced by the many nests which are
exposed as waters recede following the run-off period. The idenity
of these nests was proven through recovery of dead steelhead eggs from
one nest exposed in shallow water. Usually, fry have hatched and escaped
from the gravel before such examinations can be made. Steelhead nests
in the main ri-yrer are most cosBionly found in gravel areas along the
edge of the stream and in long, comparatively shallow pools with flat
bottoms. Some of these nests are possibly those of the lamprey, whioh
spawns during the same period and under similar conditions.

Directly following spawning, adult steelhead start a return
migration to the ocean. Thia downstream movement irtiich probably starts
sometime in March continues to pass Lewlston throughout the month of
Jtme and into July. From June 6 through July 6, 1945, 195 of these
migrants were counted throvigh the gates of the Lewlston weir (ifcible 16).
The weir was not in operation in 1946 during the corresponding period,
thus only seven migrants were coxinted between June 20 and July 22, 1946*

46

TABLE NO. 15

ADULT STEELKEAD MIGEATIOITS

TEINITY RIVER AT THE LBWISTOiv ^\/ElR

1 9 U 1+
Upstream

1 9

k 5

1 9

h 6

Downstream

Upstream

Dovmstream

Upstream

Day

Migration

Nov,

Migration
June J-aly

Migral

lion

Migration
June July

June

It ton

June

July

Sept.

Oct.

July

1

95

^^

0

^^

0

0

0

_

0

•M

0

2

97

-

0

-

1

0

1

—

1

.

0

3

261;

_

0

-,

2

0

0

-

0

_

0

k

.

—

0

—

0

0

0

_

0

—

0

5

>

-

0

-

0

0

0

—

0

—

0

6

-

17

1

0

0

0

0

-

2

-

0

7

-

22

0

0

0

0

0

~

0

.

0

8

—

lU

0

0

0

0

1

—

0

—

1

9

_

11

0

0

0

0

0

-

0

—

0

10

-

0

1

0

0

0

~

0

—

0

11

-

17

0

6

0

0

1

-

0

-.

1

12

—

19

0

2

1

0

0

-

0

-

h

11

>

9

0

U

0

1

0

-

0

-

1

-

9

0

0

0

0

11

-

0

-

0

15

-

k

0

2

0

0

23

-

0

-

1

16

_

7

0

1+

0

0

1

-

0

-

0

17

-

0

0

1

0

0

u

-

0

—

1

18

-

0

0

0

0

0

2

-

0

-

0

19

-

9

0

3

0

0

1

-

0

-

3

20

—

2

0

3

0

0

0

0

0

0

0

21

«•

0

0

3

0

0

0

0

0

0

0

22

•.

0

0

0

0

0

12

0

1

0

1

11

-

3

0

0

0

0

5

0

0

0

0

-

0

0

0

0

0

17

0

0

0

1

25

-

0

0

0

0

0

9

2

0

0

k

26

-

3

0

0

0

0

2

1

0

0

0

27

-

0

0

1

0

0

1

0

0

0

0

28

-

0

0

1

0

0

6

0

0

0

0

29

-

0

0

0

0

0

73

0

0

0

0

30

-

0

0

6

0

0

0

0

3

0

31

-

-

0

-

0

-

-

-

0

-

0

Totals ^56

191+

1

37

h

1

170

3

k

3

18

Annual

tota

.Is 1+56

195

212

7

21

47

Tli« spent steelhead passing Lewlston during June and July in
their seaward migration are generally in very poor condition* Host
individuals are badly spotted with fungus growth and heavily infested
with nematode parasites* Many badly fungused individuals died and drifted
downstream against the Lewiston weir* Approximately 80 percent of these
dead steelhead were males, which indicates that they suffer the highest
mortality in spawning* A few of the spent steelhead enter the sports
fishery during May, the first month of the fishing season* Most of these
fish are taken in the Trinity Center area near the upper end of the drainage
where the flow is generally low enough to permit fishing in the main river
during the first part of the season*

Pacific Lamprey

Least Important of the anadromous fishes of the Trinity River
as a commercial or game species is the Paoifio or three ^toothed lamprey*
Hoopa Indians trap the lampreys for. food (Snyder, 1924, p. 164), but
otherwise they have no apparent economic importance*

The adult lampreys migrate up the Trinity River In small numbers
throughout the sunnier* Ocoasional migrations took place during July,
August, and September in 1944 and 1945* Migrations occurred at night
and were infrequent, lasting only one or two nights with Intervals of
several weeks between movements* Lamprey migrants were not ntxmerous emd
seldom could more than one be seen at a time* The upstream movement
seemed to be very deliberate, and there appeared to be no tendency to
pause, veer off, or delay as the migrants passed between picket openings
of the Lewiston weir and through the illuminated section of water above
the weir* Larger upstream migrations undoubtedly take place during the
winter months*

Spawning lampreys are seen In the tributaries of the Trinity
River during April and May* Lampreys presumably spawn in the main river
during these months, but their activity is obscured by rolled waters
of the spring run-off* Some lampreys are observed in nesting areas of
the main river during June, and receding water during the same month
exposes many other nests completed earlier* Lamprey nests are located
in gravel along the river bottom where the current is not excessively
swift* In tributaries, nests are most frequently located in gravel
above riffles or in riffle areas with moderate current*

Following spawning, the lampreys drift downstream and die*
Many spent lampreys were taken dtiring May and Jtine in fyke nets used
to capture seaward migrant salmon. In June and July of 1945 and 1946,
dead lampreys lodged against the pickets of the Lewiston weir eoid other
live individuals were observed feebly working their way tiirough the
pickets*

48

After hatching, the young lampreys remain in a larval stage for
a period of about four years. Larval lampreys can be found buried in
sandy areas along the Trinity River at all times of the year. The
downstream migration of lamprey ammocoetes starts during the first fall
after hatching, at which time the smallest individuals are only 16 to
20 mm. (0.63 - 0.79 inch) long. These lampreys of the first age group
are too small to be retained by the l/4-inoh mesh fyke nets used to
sample downstream migrants of this and other species. Therefore, the
downstream migration of the first age group oould only be detected by
successive poisonings of ponds along the river's edge that were overflowed
during fall floods and then isolated by receding waters. These ponds were
poisoned with rotenone preceding flood periods to be certain that they were
devoid of all fish life. Following high-water periods and isolation from
the river, they were again posioned to obtain fish that had migrated during
the flood. In poisoned ponds lampreys would emerge fron the sand, swim
aroung in frenzied distress, and usually die in shallow water where they
were easily collected. Several thousand ammocoetes representing all age
classes were colledted from each of several sand bottom ponds 20 to 40 feet
in width and length following each flood period. It is very likely that
downstream movement of ammocoete stages is a passive movement. As silt
beds in irtiich these larvae live are destroyed or moved by high water, the
relatively helpless lamprey larvae are carried to new locations downstream.

Fyke nets retained most young lampreys measuring 90 mm. (3.54 inches)
or longer. Ammocoetes appeared in fyke-net catches throughout the year, hut
larger catches were made during and following flood periods. Eyed lampreys
are also taken in fyke nets throughout the year. The relative absence of
eyed young in samples taken by poisoning would indicate that they make a
continuous eind deliberate movement toward the ocean.

SAmON SPAWNING-BED SURVEYS

Following a preliminary survey in 1944, two surveys were conducted
during the summer of 1945 to determine as nearly as possible the spawning
capacity of the Trinity River between the proposed Lewiston dam site and
North Fork at different flows.

Nest Measurements

During the 1945 spawning period, 20 completed nests were measured
(Table 16). These measurements included the entire area of gravel
disturbed by the spawning fish. Nest digging activities are somewhat
erratic, and salmon usually disturb a margin of gravel on each side of
the nest that is not actually a part of it. "Riere is also an area at
the downstream end of the nest which is covered by loose gravel carried
down by the current during nest digging and an area at the upper end where
gravel is loosened by the fish to cover the last eggs laid. Nest measurements
shows in Table 16 may be reduced by about 45 square feet to compensate for
these unused but disturbed areas (1-foot margin on sides and lower end of
nests and 2 -foot margin at the head), making an average nest area of about
63 square feet, equal to the nest size (9» x 7») established by rough
measurements in 1944*

49

TABLE IvO. 16
tiMSUKElyiENTS OF COMPLETED ZINO SALMOIT NESTS
ON RIPFLS ABOVE LBWISTCU BRIDGE
OCTOBER 26. 19^5

Size

Area

in ft.

in sq. ft.

11 X 7

77

12 X 7

gU

13 X 7

91

lU X 6

gU

ll^ X 7

9S

1I+ X 7

98

14 X 7

9g

lU X 7

98

lU X g

112

lU X g

112

lU X g

112

15 X 7

105

15 3C 7

105

15 X 7

105

15 X g

120

15 X g

120

15 X 10

150

16 X 7

112

ig X 6

log

Ig X 10

igo

Total

2,169

Average :

Length

ih.

.5 :

ft.

Width

1^5

ft.

Area

log

M

sq. ft.

50

Mef:hod8

Individual salmon nesting sites were counted and recorded for eaoh
riffle. An area of suitable spaiming gravel, 9 by 7 feet in extent,
measured lengthwise with the current, was considered as one nesting site.
Major criteria used to define suitable nesting gravel were t (1) depth
of water (0.5 - 1.5 feet), (2) sire of gravel (1-5 inches in diameter),
(3) its location on the riffle, and (4) estimated current velocity.
Application of these criteria to Individual riffles was conditioned by
combinations of many influences. Greater water velocities enable success-
ful spawning in the areas where gravels are large. With lesser current veloci-
ties, these areas are not suitable. Under certain circumstances, water
deeper than 0«5 - 1.5 feet is certainly used. Some riffles consist of
suitable gravel, current velocities are satisfactory, and water depths
are within the range stated, but the entire riffle may be compacted and
cemented so that it cannot be used by spawning salmon. Broad standards
of estimate were set for these sui*veys. However, much of the accuracy
achieved necessarily depended on the experience and Judgment of personnel*

On riffles with scattered patches of suitable gravel between large
boulders, each individual nest site was picked out and counted. The area
of riffles with larger rocks scattered throughout suitable spawning gravel
was determined and reduced by a correction factor, the correction factor
was found by coxinting the individual nesting sites on an average cross
section of the riffle and comparing the count with the niaaber possible if
the entire riffle were suitable gravel. On riffles with greatly varying
gravel types, two or more such corrections were made as the riffle changed
in character. The areas of riffles composed entirely of suitable gravel were
divided into 9 by 7 foot sections. The number of sections was oonsidered to
be the spawning capacity.

Results of Surveys

The first 1945 spawning bed survey was started in July when the river
was flowing 350 cubic feet per second at the Lewiston gauge* The survey was
completed 10 days later when the flow at Lewiston was 250 cubic feet per
second. Slight corrections were made to compensate for variable flows so
that the entire survey would show as nearly as possible the number of ne3ts
at a flow of 300 cubic feet per second.

The second spawning bed survey was conducted during the middle of
September when the river discharge at Lewiston was 100 cubic feet per second.
Results of these surveys are presented in "Pable 17, which gives the number of
nests counted and the comparative efficiency of water and riffle usuage for
spawning at the two flows, expressed in nests per cubic foot per second per
Bile of stream.

In areas where there are broad riffles of fine gravel, the efficiency
of water and riffle usage increases with increased water flow. This la
particularly true of the stretch of river between Grass Valley Creek and
Douglas City (Figure 10) where many broad, shallow riffles are converted
to good spawning sites by increased flows* Just the opposite is true of
narrow riffles where the spawning efficienoy is reduced by increased flow*

51

TABIE HO. 17
SALMON SPAWUIITG BED SURVEYS - I9U5
TRINITY RIVER FROM LEVISTOK DO^frlSTSSAM TO ITORTH FORK

Length

of area

Number (

3f Nests

Nests/cfs/Mile

Jirea

in mi.

300 cfs

100 cfs

300 cfs

100 cfs

Lewi st on Dam -

Lewi st on

2.0

731

228

1.22

l.lU

Lewi st on -

Rush Creek

2.0

205

200

.5^

1.00

Rash Creek -

G-rass Valley Cr.

3.5

670

199

.64

.57

Crass Valley Cr. -

Lowden Dam

3.5

1,680

1+69

1.60

1.3^+

Lowden Dam -

Douglas City

7.0

2.909

856

1.38

1.22

Douglas City -

Brov;ns Creek

5.5

811

850

.56

1.54

Browns Creek -

Jiinction City

6.5

1.643

695

.ek

1.07

Junction City -

North Fork

7.0

1.2U8

U23

.59

.60

37.0

9.897

3.920

.89

1.06

TABLE NO. 18

MINIMUM AVERAGE DAILY FLOW OF TRINITY RIVER AT LEVISTON, NOVEMBER I-I5

DISTRIBUTION OF DAILY FLOW IN 50 C.F.S GROUPS

Flow 100- 150- 200- 250- 300- 350- UOO- U50- 500-
Year in c.f.s. 1U9 199 2^9 299 3U9 399 UU9 U99 5Ug

X
X

1927

234

1928

186

1929

116

X

1930

111

X

1931

138

X

1932

103

X

1933

1U7

X

1934

1+05

1935

163

1936

127

X

1937

195

1938

391^

1939

120

X

19^0

500

19U1

30U

19I+2

186

1943
19I+4

251

US2

Totals

4,162

X

X

X

X

Mean

.2iL

52

o«-.

o

^-

O

i

N^sfs p*r cubic fool p*r second ptr mift

Ltwiston
Rush en

Grass Va.ll9y
-Lowdtns

cr.

o

3

S^

3

-Browns cr.

Douglcts City

^— Juncfion City

-H*/ena

O)

I

X

T

X

I"*

Co

n

Co

Figure 10, Number of salmon nests in Trinity River between Lewiston and
Noi^ii Fork as determined at two different river flows.

53

Swifter ourrent and deeper water over gravel on this type of riffle
renders it uneui table for spawning purposes. Examples of this con-
dition can be found between Lewis ton and Rush Creek, and between
Douglas City and Browns Creek*

Expressed in terns of nests per oubic foot per second per mile
of stream, the results of the two spawning-bed surveys indicate
that »t water flows between 100 and 300 oubio feet per second, there
is a very slight decrease in water-use efficiency as flows become greater.
Since the water-use efficiency varies only slightly, there would be little
ourre in a line projected to show water-flow in relation to nesting
capacity* The change in efficiency between these two points should be
fairly constant because of tiie counteracting effects of variations in
nesting capacity with changes in river flow on the two types of riffles
(broad and narrow) already discussed*

The curve shown in Figure 11 was derived by calculating a
theoretical number of nests for each rata of water flow* In this
oaloulatlon the number of nests was obtained by multiplying the ntmiber
of miles of stream by the flow in cubic feet per second and also by
an <effioi«iey factor* This factor was oemputed by subtracting from
the observed efficiency factor at 100 cubio feet per second the decrease
in efficiency from 100 oubic feet per second to the rate of flow in
question* The calculation is algebraically expressed in the follow-
ing fomulat

H = M F

where N is the number of the nests; M, the miles of stream; F, the river
flow; E-,, the water efficiency factor at the lowest flow measure; Eg, the

water efficiency faetor at the highevt flow measured; L, the lowest flow
measured; n, the number of intervals used between the highest and lower
flow; and i, the site of the interval in cubic feet per second*

Rains of short durations and variable intensity commonly occur
during the peak of the spawning period, but temporarily increased flows
caused by these rains oannot be considered in determiidng normal spawning
flows. To elimate errors that might result from these temporary fluctua-
tions, only the minimum flows recorded at Lewiston during the peak spawn-
ing period (November 1-15) over a period of 18 years are considered
(Table 18)* The average minimum flow during this period is 233 oubio
feet per second, but since the miniumu flow is below this average in
11 of the 18 years, the meditm flow must also be less than average*
Flows above 350 cubic feet per second might be slininated as erratic
since they result from unusual weather conditions and are widely separated
in their ooourrence* The average flow wilii these years excluded is 170
o.f.s., which is again greater than the minimum flows of more than half

54

Fig\ir« 11* Nvmdber of salmc»i nssts in Trinity Hirer between
Leviston and North Fork; as related to a constant
ohange in arailability of gravel at various
river flows.

55

of the years InvolTed. The median flow, therefore, is still less,
or very near 150 cubic feet per second.

Assianing that the Trinity Rirer salmon population is at its
■aximtm density under present conditions, and assuming that spawning
space is the dvterminlng factor, then, at a median spawning flow of
150 cubic feet per second, 5,647 nests would be ooeupied in the
river between Lewlston dam site and North Fork as determined by
application of formula previously described*

EFFECTS CP HAIER DBVELOBJENT PIANS ON THE TRINITT RI7ER FISHEBT
AND SUGGESTED MEANS FOR FISHERT PROTECTION

Resident game fishes will be least affected by the dam build-
ing program on the trinity River* Movements of these fish are limited
to short niigrations up the tributaries where they spawn* This movement
will not be Interfered with by dam construction except in the ease of
the brown trout which appears to maJce extensive migrations* This
species, however, shows reBiarkable powers of adjusting itself to chang-
ing conditions and should adapt to any reasonable set of conditions
which may result from dam construction*

Steelhead trout help to maintain the heavily fished residen'^
rainbow trout population of the Trinity River* Proposed dams will
block adult steelhead and will eliminate their construction to the
sports fishery above these structures* The reservoirs formed by the
dams will support resident trout to an unknown degree^ and will tend
to offset partially the loss of the steelhead fishery now existing
above the dam sites* Adult steelhead might be lifted over the dams
so that their progeny could be added to the resident fish population*
However, this addition to the resident population would be temporary*
Losses of seaward migrants in diversion structures would very likely
result in a net loss through such a program*

The effect of the dam construction program on dace and sucker
populations cannot be stated at this time* The abundance of these
species will undoubtedly be affected. Whether they increase or de-
crease in numbers will be determined only after the stnictures are
built* If they increase or even maintain their present numbers,
they might sei^e as an important source of food for the resident
trout population*

Management plans for the anadromous species are necessarily
based on three salient features of the water development plans i
(1) It is certain that the dams would be too high for economical
or practical construction of fish ladders over Hivai (2) as much

56

as possible of the water developed by the proposed construction
program would be diverted out of the Trinity River watershed; and
(3) the location of the structures is highly important. A dam at
the Lewiston site will cut off approximately 50 percent of the river
used by king salmon for spawning and a greater percentage of the
portion used by steelhead trout. A dam at the Browns Creek site
would deprive these fish of nearly 82 percent of their spawning
grounds .

General Principles of Operation

There are several general principles of operation which are
considered essential in any of the management methods suggested.
These principles have been established fron experience with other
projects and are incorporated herein to avoid many of the troubles
encountered elsewhere.

1. The selected management procedure must be incorporated into
plans of the water development program before any construction work is
undertaken.

2. All fish should be allowed to pass upriver until the summer
before the dams first act as barriers. By this time facilities for the
conduct of any maintenance program adopted should be installed and operable.

3. Possible sources of stream pollution resulting froai construction
or its processes must be eliminated.

4. Releases at the dams should be made from the lowest possible
level so that a minimum number of resident fish in the reservoirs will
be drawn through turbines or turned into diversions. Releases at low
levels in the dam will insure a supply of cold water to the stream
below.

Maintenance Plans for Lewiston Dam

Three methods of maintaining the salmon blocked by the Lewiston
Dam might be considered. First, additional spawning area might be
developed by increasing the river flow above normal during the
spawning period. Second, suitable tributary streams might be developed
into spawning areas. Third, fish hatcheries could be constructed. A
satisfactory management plan may be found in one or a combination of
these methods.

Development of Additional Spawning Grounds in the Main Stream

A plan for developing additional spavming areas by increasing the
river flow is believed to be the least expensive, easiest to operate
and least likely to prove unsatisfactory after it is placed into opera-
tion. The spawning bed surveys of 1945 showed conclusively that the
spawning capacity varied directly with the river flow.

57

This method of increasing the spawning capacity of the river
might be carried out in three general types of operation:

1* A minimum flow sufficient to accommodate the maximum
population could be maintained throughout the year* — ^A ml nimum
flow would call for the least administration, supervision,
construction, and maintenance of fish retaining and counting
structures. This method would be least hazardous for spawning
fish, as it would guarantee adequate water at all times. The
minimxfltt flow required would be 300 cubic feet per second. To
maintain such a flow, 217,200 acre-feet of water would be needed
and most of this water would be derived from storage. When
spawning, egg incubation and migration were not in progress, some
of this water would not be necessary and its flow downstream might
be construed as wastage. This plan has the greatest biological possi-
bilities, but due to its relatively large water demand, it will probably
be the least desirable to the constructing agency.

2* A fixed flow schedule could be established to accommodate
the salmon life history and what is presumed to be the maximum spawning
migration.— A fixed flow schedule would prescribe water releases througji-
out the year designed to accommodate the life history phenomena of the
salmon as known at the present time (Figure 12). This schedule would
not vary from year to year, but would remain the same regardless of
the numbers of spawning salmon. It would require a minimum of admin-
istration and construction. Some maintenance and operation of fish
retaining and counting structures would be necessary.

A fixed spawning flow of 300 cubic feet per second during November
would make available the estimated 9,897 salmon nesting sites between
Lewiston dam site and North Fork (Table 19). Approximately 5,600 of
these nesting areas are normally occupied, and the additional 4,300
spawning areas available could accommodate 11,200 spawning salmon,
using the established sex ratio of 1 female to 1.63 males. Adequate
spawning area for the greatest number of salmon actually counted at
Lewiston during 1944 and 1945 would result from this flow. However,
observations in the fall of 1946 when no count was made, definitely
indicate that a g reater population of spawning salmon was present and
may have been crowded under the conditions of this plan. The amount
of crowding on spawning beds which can occur without reducing repro-
ductive efficiency has not been determined, but certainly scsne could
ooour* Furthermore, it is almost certain that the spawning capacities
fixed by survey are conservative.

Populations of spawning salmon are known to vary in number over
very wide limits. Studies in California's Central Valley and elsewhere
demonstrate variations between years and between cycles which exceed
500 percent. The provision of a slight margin is available nesting

58

•1

tpoo-

^

Recommended flow schedule

100-

Spawning above North Fork

c
o
.{:

o

^

\t
*>

o

"b

c
o

-8

w
o

o

d

<

VI

a

O

■t

C
%

•S

Q:

T T

T r

T r

Emergence of fry from gravel

-i 1 r

-I r

Seaward migration

Jan. Feb.
Figure 12.

1 r

Mar. Apr. May Jan. Jul. Aug. Sep. Oct. Nov. Dec.
Reooaranended fixed flow schedule for Trinity River at Lowiston
and its relation to the life history phenomena of king salmon
in that stream. 59

TABLE NO. 19
TUSD SPAWNING FLOV SCHEDULE AS MEASURED AT LEVISTON GAGE

C.f. 8,

Acre- feet

Number

Acre-feet

Month

at Levi st on

per day

of days

per month

January

200

396.7

"IT

12,298

Tebrxiary

200

396.7

28

11,108

March

200

396.7

31

12.298

i^rii

150

297.5

30

8.926

May

150

297.5

31

9.223

June

150

297.5

30

8,926

Jtily

100

198.3

31

.6,149

August

100

198.3

31

6,1^9

September

100

198.3

30

5,951

October 1--15

100

198.3

15

2.975

16-31

200

396.7

16

6.3^^7

November

300

595-0

30

17. 852

December

200

396.7

31

Total

12,298
120.500

TABLE NO. 20
AVEHASE MONTHLY TLOWS IN TEINITY BITES
OOTOEER 1931 TO SEPTEMBER 1939

Lewi St on

Present

Burnt Ranch

Less
Lewiston Proposed

Present

Hoopa

Less
Lewi St on

Month

Present

Proposed*

i'r.oposed

(Slows expressed in (

:ubic feet

per secont

i)

Oct.

181.8

151.6

301.0

119.2

270.8

532.8

351.0

502.6

Nov.

71^.3

300.0

1256.9

5^2,6

842.6

2526.4

1812.1

2112.1

Dec.

897.6

200.0

1658.6

761.0

961.0

4010.6

3113.0

3313.0
5447.2

Jan,

980.1

200.0

2267.6

1287.5

1487.5

6227.3

52^7.2

Iteb.

1U63.I

200.0

2929.7

1466.6

1666.6

D25.9

5862.8

60^2. S

Mar.

2515.0
3li72.5

200.0

U762.O

2247.0

2447.0

10980.0

8465.0

8665.0

Apr.

150.0

5567.8

2095.3

2245.3

10364.8

6892.3

7042O

May

355^.4

150,0

5137.4

1583.0

1733.0

7970.3

4415.9

4565.9

June

1868.5

150.0

2825.6

957.1

1107.1

4198.5

2330.0

2480.0

July

^38.3

100.0

777.0

338.7

438.7

1275.4

837.1

937.1

Avig,

1U2.1

100.0

2U6.0

103.9

203.9

462.5

320.4

420.4

Sept,

108.5

lOCoO

168.6

60.1

160.1

- „ 221^2__

?21.?

•Probable releases at Lewiston for fish needs^

60

Uncontrolled flow
average for wafer-years
1932- 1939

1 1 -1 1 1 1 1

Oct. Nov. Dee. Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep.
Pigiire 13. The effect of a fixed flow schedule for fish at Lewiston
on the discharge of Trinity River at various points

downstream*

61

areas over the number necessary to aocommodate salmon ooxmted at
Lewiston in 1944 is not adequate. It will not cover the probable
maximum number of salmon which will return to the Trinity River
in some years. A fixed release schedule for salmon has the added
disadvantage of rigidity. It cannot bo quickly or effectively
changed when greater or lesser amounts of water and spawning
grounds are needed for the proper safeguarding of spawning stock*

A fixed flow schedule such as the one proposed in Figure 12
requires a release of 120,500 acre-feet of water as measured at the
Lewiston Bridge, "ftie peak flow of 300 cubic feet per second would be
maintained only during the period of heaviest spawning. After spawning
is completed, the flow could be reduced to 200 cubic feet per second.
Such a flow will cover all gravel in which eggs have been deposited.
This flow should be maintained vintil the end of March when all but a
very few of the young salmon have left their nests. The river flow
should be not less than 150 cubic feet per second during April, May,
and June, to adequately provide for steelhead spawning and hatching.
The flotr should not be less than 100 cubic feet per second from July
1 to October 15. The svmuner flow schedule (April through October 15)
should insure the seaward migration of young salmon during April, May,
and June, and the upstream adult migration from the end of June until
the flow is increased to 200 cubic feet per second during the last 16
days of October to provide for the spring and summer runs that normally
start spawning at that time.

The effect of this flow schedule on average river discharges below
Lewiston is shown in Figure 13 and Table 20. The comparison presimes
total diversion or storage of all other flow at Lewiston. The main
river flows during summer are relatively unaffected. Flows during
the steelhead spawning season are considerably reduced between Lewiston
and Burnt Ranch and may make the river bed more suitable for the spawning
of this species.

Fish-tight counting structures should be built near the Union HLll
Pipe Crossing two miles below the Lowden dam site, and at a site to be
selected between Douglas City and the mouth of Browns Creek. These
barriers would divide the spawning grounds into throe areas of nearly
equal capacity and prevent a congestion of spawning fish in any one
area. A trap and sturdier fish barrier should be installed at or near
the present Lewiston weir to be used if it becomes necessary to transfer
fish. Tlie Lewiston barrier should be maintained as a means of preventing
\indesirable concentrations of fish immediately below the proposed Lewiston
dam where practically no spawning grounds exist. It may be desirable,
after further study, to locate tho Levdston barrier above the mouth of
Deadwood Creek to allow use of this small stream by steelhead trout.

62

Fish barriers should consist of oonorete dams 10 to 15 feet
high, with long, shallow aprons. They should be equipped with high
standard fish ladders adapted for ease in counting the fish passing
over them. "Phe ladders should also be fitted with effective closing
devices. The barriers should be strong enough to withstand floods
which might be anticipated following construction of the dams and should
be located where spawning areas are restricted and where a minimum of
gravel will be inundated by their forebays.

3. The flow could be regulated to produce only the ario\mt of
spawning area needed each year, depending on the number of migran'ts. —
Regulation of the flow to approximate the needs of migratory fishes
on an annual basis would require reservoir operation similar to that
in type 2, but with variable spawning flows. Regulation of the spawning
flow each year to meet needs of the particular salmon population would
be more expensive to operate than other plans. It would call for the
construction of an additional fish block and counting structure near
the North Fork of Trinity River that would of necessity be sufficiently
massive to withstand any floods that might occur*

fhe plan for eaoh year would be based on counts by resident
biologists of migrating salmon and stealhead made as they passed
North Fork, which is prestnnably far enough downstream to allow flow
schedule determination prior to the aottial need* This system could
be hazardous for the salmon, as their migration past North Fork may
not be completed before the peak spawning period starts below Lewis ton.
Lake segments of the runs may not find sufficient gravel for their needs.
Flow changes should be made at weekly intervals starting October 15, and
the revisions should be determined by the cumulative counts obtained at
the oo\inting station near North Fork. The flow would be increased in
accordance with the need for additional nesting capacity between Lewiston
dam and North Fork as determined from Table 21* This plan would utilize
both water flow and spawning areas most effectively*

Probable water requirements for this plan, had it been in operation
during 1944 and 1945, are given in Table 22, Ihe peak spawning period
would have required a release of 280 cubic feet per second in 1944, and
250 in 1945* These flows are conservative as they only provide additional
spawning area for the number of salmon acttially counted at Lewiston, and
do not provide for salmon passing Lewiston before and after the counting
period* The spawning flows given in Table 22 were determined by adding
the number of nests needed for counted fish to the number of nests
•normally occupied in the spawning area (5,647)* The spawning population
passing Lewiston required 3,774 nests in 1944, and 2,856 in 1945, The
flow producing the total number of nests was chosen to the nearest 10
cubic feet per second from Table 21*

63

TABLE NO. 21
Kim SALMON SPAWNING IIEST5. TRINXTY RIVER

—— ' lllll^ I II I lllllllll I -■■■■ I I — ^-»»p-m.t--i-«»— m' i u,j 14

Lewiston C-am Site Lewiston Dam Site Srass valloy Crcsk

to North Fork to Orass Ve.lloy Oreek to North Fork

Flow NoBts/c.f.So Number Nests/cf.s. Number Noata/c.f.s. Numlisr

e.f.Bt per Mile of Neets per Mile of Nests per Mile of Hosts

J 3 K B N S l!^

50 i.ioii^ 2,038 .8666 32^ i.i6n i,72U

60 1.0930 2,U26 .86oif 387 i.^522 2»039

70 1.0846 2,809 .85if3 Uks 1.1432 2J61

80 1.0762 3,186 .8^82 507 i.13^2 2.677

90 1.0679 3.556 .81^21 56s 1.1252 2,987

100 (J,) 1.0595 (El) 3,920 ,8360 (%) 627 1.1163 <%) 3.293

no 1.0511 4,278 .8299 685 1.1073 3.553

120 1.0426 4,629 .8238 7^1 1.038^ 3.8gS

130 1.03U3 4,975 .8176 797 1.0894 4, lis

140 1.0259 5.314 .8116 852 1,0804 4,4^2

150 1.0175 5.647 .8054 906 l„07l4 4,7Uj.

160 1.0091 5*974 ,7993 959 1.0624 5,015

170 1,0007 6,294 .7952 1.011 1.0535 5,283

ISO ,9923 6,609 .7871 1,063 l«0445 5,546

190 ,9839 6,917 .7810 1,113 1.0355 5,804

200 .9755 7,219 .7749 1,162 1.0266 6,057

210 .9671 7.514 .7687 1.211 1.0176 6.304

220 .9588 7,805 .7627 1,258 1.0086 6,546

230 .9504 8,088 .7566 1,305 .9996 6,782

240 .9420 8,365 .7504 I.351 ,9907 7,Ol4

250 .9336 8,636 ,7443 1,396 .9817 7,240

260 .9252 5,900 .7382 1,439 ,9727 7.461

270 ,9168 9.159 .7321 1,483 .9638 7,677

280 .9084 9,4ii .7260 1,525 ,9548 7.887

290 .9000 9^657 .7199 1.566 .9458 8,091

300 (P2) .8916 (B2) 9o897 .713s (Eg) 1,606 ,9368 (B2) 8,291

310 .88^2 10,130 .7077 1.645 ,9279 8,4g6

320 .8748 10,358 o70l6 1,684 .9189 8,674

330 .8654 10,579 .6954 1.721 .9099 8,858

340 .8581 I0e795 .6893 1,758 .9009 9.036

350 .8450 10,9^3 .6832 1.793 .8920 9.210

Ej^ or E2 - N ♦ M 2 ■ Efficiency Rating.

El = Efficiency Sating at low flow.

Eg = Efficiency Re.ting at high flow.

n a Number of intervsils between E^ & E2.

i = Size of interval in c.f. s.
N-EXFXM i«= How

Pi = Flow at Bi in c.f. 9.

N = Number of nests.

M -= Miles of river.

64

TABLE HO. 22
PHCBABLE WATSR KSQUIEEMEKTS FOR A CaTTROLLED SPA'iVl^ING liOW

l<^k 19^+5

Probable

11 II. ~£S

Maximum

Flow at

Lewi St on How at

Lewi 9 ton

Flow at

Lewlston

Month

C.F.S.

A.F. C.F.S.

A.F.

C.F.S.

A.F

January

1S7

ll,l+9S 167

10,261+

213

13,971

Fetruary

137

10,386 167

9,275

213

11,830

March

1S7

ii.Ugg 167

10,26»+

213

13.971

April

150

8,926 150

8,926

150

g.926

May

150

9.223 150

9.223

150

9.223

June

150

8,926 150

S,926

150

8.926

July

100

6,1^9 100

6,iU9

100

6,lU9

August

100

6,1^9 100

6,1^9

100

6,lU9

September

100

5.951 100

5.951

100

5.951

Octoter I-I5

100

2,975 100

2.975

100

2.975

16-31

1S7

5.935 167

5.300

213

6,760

November

2S0

16,661 250

lU,g76

320

19,042

December

187

ll.Ugs 167

10,264

213

l?.971

Totals

115.775

108,5^2

127,^

TABLE NO. 23

ESTIMATED BUN- OFF

ON PORTION OF TRIlIITy RIVER DRAINAGE

FOR SALMON FISHERY S*
Average inflow Lew

rUDIES

te

Lston dam si

to Lowden dam site

1917 to igUo,

Month

inclusive

Acrs Feet

C.F.S.

January

3,^30

56

February

5,870

106

March

7,500

122

April

10,010

168

May

10,120

165

June

H.750

80

July

1,220

20

August

U30

7

September 370

6

October

620

10

November

2,;6o
3,i^0

Ho

December

56

U. S. Bureau of Reclamation data.

I

65

The estimated 1946 requirement of 128,000 acre-feet of water
for this plan (Table 22) Ib the amount needed for 15,000 salmon which
are believed to have passed Lewiston in 1946* The 1946 estimate was
established from observations of concentration on spawning beds during
that year compared with observed oonoentrations in 1944 and 1945 when
actual counts were made.

Because of the unreliability in flow of tributary streams immediately
below Lewiston, required stream flows should be measured at Lewiston dam.
As shown in Table 2 3, there is very little water entering the river be-
tween Lewiston and Lowden during the salmon nesting season (October-
December). This early fall inflow is supplied almost entirely by
periodic rains, and in dry years it would be negligible in its effect
on salmon spawning conditions. It is, therefore, necessary to request
a quantity of resex-voir water for fishery management equal to the amounts
required by the plans discussed herein, to be certain of producing proper
spawning conditions each year.

The studies that preceded the formulation of these management plans
were made during a period when no mining silt was introduced into the
river in the major areas involved. These plans, if they are to be
sticoessful, can be placed in operation only under similar conditions.
If a heavy load of mining silt were allowed to enter these crowded
spawning areas, the fishery might be seriously threatened. Regulated
flows are far below those normally encountered following salmon spawn-
ing under natural conditions; thus silt could settle out rapidly, impact
the gravel, and suffocate eggs and yotuig fish* Therefore, stringent
measures must be taken so that no mining silt will be introduced into
the river during the salmon and steelhead spawning ajad hatching periods
(October 1 through July 15).

IJaprovement of tributary streams

Four streams tributary to the Trinity River below the Lewiston
dam site might be developed for salmon and steelhead spawning. These
are Rush Creek, Browns Creek, the South Fork of the Trinity River, and
Hay Fork, a tributary to South Fork. Rush Creek and Browns Creek are
available for salmon spawning only after rains increase their flows,
and the South Fork has spring and fall migrations of salmon each year.
No salmon spawn in upper Hay Fork.

Eaoh of these streams has been studies to determine the extent
to which it might be developed for salmon spawning. Information obtained
is not complete, but enough data have been gathered to show relative
possibilities. It has not been possible to make spawning bed surveys
of these streams during optimum flow conditions. Surveys have been con-
ducted, however, to determine the general stream types, and nest covuits

66

f

have been made on Ruah Creek and Parts of the South Fork at lower than
optimtim flows. With this information, the approximate nesting capacities
of the tributaries at their optimvun flows have been estimated. Using
the nests per cubic foot per second per mile factors, established for
portions of the Trinity River at the 100 cubic feet per second flow,
nesting capacities were computed for comparable portions of the tribu-
taries at their optimum flows (Table 24). Normal spawning flows for
these streams were set up by evaluating statements made by people living
along the streams and comparing this infonmation with the few flow
records that are available*

Improvement of these streams could probably make an additional
3,565 nests available for 9,376 spawning salmon. In order to make these
nests available, additional water development on each stream is necessary*
Rather large storage dams should be built in the upper portions of each
stream drainage to provide a constant and adequate minimum flow during
the entire year. Greater flows would be necessary when spawning occurs.
It would be desirable to remove several obstructions which are barriers
to fish migration during low water periods. Natural barriers obstruct
fish movements into Hay Fork Valley. Artifical dams and diversions
block from access miles of spawning area in Browns and Rush Creeks when
water flows are low.

Two methods of developing salmon runs in these streams, after
improvement, are possibles (1) Salmon could be trapped at Lewiston or
at other locations above the mouth of South Fork and hauled to the
streams J (2) small runs now entering the streams or present in the main
Ti*inity off their mouths could be left to take over the new spawning
areas and develop natural runs to offset losses of salmon blocked by
the Lewiston dam. Experience would dictate the latter course of action,
although it may be very slow and gradual in developing. Transferring
adult salmon is a costly process, not only in money, but also in fish.
It is generally better to encourage a native seed stock to increase in
abundance than to introduce a foreign race which may or may not adapt
to the new situation. This attitude is especially applicable to the
South Fork of Trinity River and its major tributary. Hay Fork. Some
main stream salmon probably could be diverted into South Fork, Browns
Creek and Rush Creek by constructing barriers on the main Trinity
immediately above their respective mouths, but such construction would
be costly and might result in serious disruption of the normal habits
of the entire anadromous fish population. There are no means available
whereby fish headed for the area above Lewiston can be segregated from
those using the river below that point.

Fterhaps the most serious obstacle in any plan to transfer salmon
from one place to another in the Trinity River drainage is the almost
utter lack of good roads. Tank trucks suitable for hauling adult salmon
are very heavy and would operate in months when roads are wet and slippery.
It is doubtful that any transfer program could be successful without major
road construction and bridge strengthening projects preceding the actual
truck operation.

67

TABLE ITO. 24
MINIMUM HiOWS HSQ]JIEED
FOR DEVSLCPIiMT OF SPAWNI1I5 ASMS
IN TEIBUTARIES

Tributary Nov. -April April May June July- Sept. Oct.

Location

South Fork
Trinity River:
at Forest Glen 100

at Hyanpom 200

Hay Fork 100

Browns Creek 65

Rush Creek U5

100 SO 65

50

100 100 100 100

100 60 20 10

1+0 30 20 10

35 25 15

50 SI3 TIS R7E HM

(Forest Glen)

150 S26 T3N RGB HM
(Hyampom)

70 S2 T30N Rlltf MDM
(East Fork)

50 SI 9 T31N R9W MDM
(East Fork)

UO S23 T3UN RgV MDM
(Below China Gulch)

SALMON SPAWNING CAPACITIES OF TRIBUTARIES

Water

flow

Number

of Nests

Possible
Nests

Increase

Tributary

Present

Increased

Present

Increased

Salmon

South Fork

100

cfs

200

cfe

l.Ulg

2,1+32

l,0l4

2,667

Hay Fork

20

100

0

1.300

1,300

3 Ms

Browns Creek

20

65

370

1,200

830

2.183

Hush Creek

15

^5

211

632

1+21
3.565

1.107

9.376

68

Transfer of Trinity River salmon from the main stream to
improved tributaries would not save any significant quantities of
water for the project. Minimum flows ranging between 100 and 200
cubic feet per second would have to be released from the Lewiston
dam to satisfy water users, to maintain the resident fish population
in the river below, and to provide adequate spawning grounds for the
salmon and steelhead populations which use the mainstream below
Lewiston*

Artificial propagation

A third method of aocomraodating the salmon normally passing
above the Lewiston dam site to spawn is artifioal propagation. As
yet, hatcheries have not proved themselves capable of maintaining
large runs of king salmon. Therefore, this method cannot be recommended
for the Trinity River at this time.

Adequate sources of water suited to hatchery operation are very
scarce in the Trinity drainage below Lewiston. Many stream flows are
cold enough, but they are insufficient in volume to supply a hatchery
large enough to accommodate present runs of fish. Plenty of water of
fair quality could be obtained from the reservoirs to be built* How-
ever, such an arrangement would require that a hatchery be located
near the Lewiston dam site. The hatchery would need approximately 50
cubic feet per second of water for operation* In addition, sufficient
water would have to be released to the river to bring salmon and
steelhead to the hatchery* Quantities of water involved in this
latter operation would exceed 100 cubic feet per second. Very little
water would be saved to the project through artificial propagation*

Maintenance Plans for Browns Creek Dam

The construction of a dam at the Browns Creek site would out
off approximately 82 percent of the part of Trinity River used by
salmon for spawning. Optimum development below Browns Creek could
produce only 1,800 additional nests in the main river* Development
of the South Fork and Hay Fork, which are the only suitable spawning
tributaries below this dam site, would produce 2,300 additional salmon
nests* Together, these additional nests in the river, and tributaries
would provide for only 10,700 of a possible 21,000 Vsalmon that would
normally spawn above the dam* The only method known that would take care
of the remaining salmon that could neither spawn in the river nor in the
tributaries would be to construct a 30-^illion egg hatchery utilising
water fro* the reservoir. Such a plan could not be reoaranended because
of the very questionable outoone.

l/__ Determined by estimating the natural salmon population between Browns
" Creek and Lewiston, using the number of nests at the normal spawning

flow (150 c.f.s.) in that area, and adding the maximum number of

salmon counted at Lewiston.

69

Steelhead Malntenanoe

Maintenanoe of the steelhead trout population would not
present the serious problems inherent in the perpetuation of salmon
if a dam is constmioted at the Lewiston site. These fish are believed
to spawn voluntarily in the lower reaches of tjie river during low
water years and their nests are made during the spring run-off period*
Muoh steelhead spawning takes plaoe in tributaries in the main river
below Lewis ton which are all carrying ample water to produce adequate
available gravel during the steelhead spawning period*

TO accommodate steelhead spawning in the river, a flow of 150 o.f .0.
would be required during the steelhead spawning period. This flow is
included in all flow schedules for salmon spawning that are suggested in
this report. The inflow from tributaries in the upper portion of the
spawning area below the Lewis ton dam (T&ble 23) will make additional
spawning area avail&ble in the main river for steelhead blocked by the
dam. Tributary inflow peaks during the steelhead spawning season and
should be fairly reliable from year to year. These tributaries are, at
present, under-populated with spawning steelhead. If mining silt can be
excluded from tributaries during the spawning and incubation period
(February 15 through June 15), they would be better suited to accommodate
part of the steelhead held back by the Lewis ton dam. Uajor steelhead
spawning tributaries below Lewiston dam site are Rush Creek, Grass Valley
Creek, Indian Creek, Redding Creek, Browns Creek, Canyon Creek, and the
North Fork of the Trinity, including its East Fork.

Browns Creek dam would present a major problem in connection
with steelhead spawning. Only two of the major spawning tributaries
are below this dam, thvts an unknown number of these fish would have to
be diverted into the South Fork, or removed into a hatchery, or both.
Neither possibility would seem feasible when it is considered that
streams and hatchery facilities would have to be developed to a maximum
for the salmon alone, and a project including steelhead salvage would
involve operations of unprecedented proportions.

70

LI OEM TORE CITED
HE7iES, GORDON W.

1942. Econonio and geographical relations of aboriginal fishing
in northern California. Calif. Fish and Game, Vol, 28,
No. 2, pp. 103-110,

JHINGRAN, VISHKA G.

1948. A contribution to the biology of the Klamath Black Dace,
Rhiniohthys os cuius klamathensis (Evormann and Meek) ,
Doctorate thesis unpublished, Stanford University Library,
Stanford, California,

MOFFETT, JAMES V.

1949. The first four years of king salmon maintenance below
Shasta Dam, Sacramento River, California, Calif.
Fish and Game, Vol, 35, No, 2, pp. 77-102.

SNYDER, JOHN 0.

1924. Indian methods of fishing on Trinity River and sane notes
on the salmon of that stream. Calif. Fish and Game,
Vol. 10, No, 4, pp. 163-172.

1931« Salmon of the Klamath River, California. Calif. Div, of
Fish and Game, Fish Bulletin, No, 54, 129 pp.

1^1 730M3

1

p. '! lllllllllllll'*'

5 WHSE 00982