REFEREVCE COPY 

Do Not Remove from the Library 

U. S. Fish and Wildlife Service 

Biological Report 82 (11.62) 'vat'0na' Wet'ands Kesearch Lenbr TR EL-82-4 

~ugust 1986 700 Cajun Dome Boulevard 

Lafayette, Louisiana 70506 

Species Profiles: Life Histories and 

Environmental Requirements of Coastal Fishes 

and Invertebrates (Pacific Northwest) 

STEELHEAD TROUT 

Coastal Ecology Group 

Fish and Wildlife Service Waterways Experiment Station 

U.S. Department of the Interior U.S. Army Corps of Engineers 
Biological Report 82 (11.62) 

TR EL-82-4 

August 1986 

Species Profiles: Life Histories and Environmental Requirements 

of Coastal Fishes and Invertebrates (Pacific Northwest) 

STEELHEAD TROUT 

Gilbert B. Pauley, Bruce M. Bortz, and Michael F. Shepard 

Washington Cooperative Fishery Research Unit 

College of Ocean and Fishery Sciences 

University of Washington 

Seattle, WA 98195 

Project Manager 

Carroll Cordes 

Project Officer 

David Moran 

National Wetlands Research Center 

U.S. Fish and Wildlife Service 

1010 Gause Boulevard 

Sl idell, LA 70458 

Performed for 

Coastal Ecology Group 

Waterways Experiment Station 

U.S. Army Corps of Engineers 

Vicksburg, MS 39180 

and 

National Wetlands Research Center 

Research and Development 

Fish and Wildlife Service 

U.S. Department of the Interior 

Washington, DC 20240 
This series may be referenced as follows: 

U.S. Fish and Wildlife Service. 1983-19 . Species profiles: life histories 

and environmental requirements of coasta fishes and invertebrates. U. S. Fish 

Wildl. Serv. Biol. Rep. 82(11). U.S. Army Corps of Engineers, TR EL-82-4. 

This profile may be cited as follows: 

Pauley, G.B., B.M. Bortz, and M.F. Shepard. 1986. Species profiles: life 

histories and environmental requirements of coastal fishes and invertebrates 

(Pacific Northwest) -- steelhead trout. U.S. Fish Wildl. Serv. Biol. Rep. 

82(11.62). U.S. Army Corps of Engineers, TR EL-82-4. 24 pp. 
PREFACE 

This species profile is one of a series on coastal aquatic organisms, 

principally fish, of sport, commercial, or ecological importance. The profiles 

are designed to provide coastal managers, engineers, and biologists with a brief 

comprehensive sketch of the biological characteristics and environmental 

requirements of the species and to describe how populations of the species may be 

expected to react to environmental changes caused by coastal development. Each 

profile has sections on taxonomy, life history, ecological role, environmental 

requirements, and economic importance, if applicable. A three-ring binder is 

used for this series so that new profiles can be added as they are prepared. 

This project is jointly planned and financed by the U.S. Army Corps of Engineers 

and the U.S. Fish and Wildlife Service. 

Suggestions or questions regarding this report should be directed to one of 

the following addresses. 

Information Transfer Specialist 

National Wetlands Research Center 

U.S. Fish and Wildlife Service 

NASA-Slidell Computer Complex 

1010 Gause Boulevard 

Slidell, LA 70458 

U.S. Army Engineer Waterways Experiment Station 

Attention: WESER-C 

Post Office Box 631 

Vicksburg, MS 39180 
CONVERSION TABLE 

mill imeters (inn) 

centimeters (on) 

meters (m) 

ki 1 ometers ( kin) 

2 

square meters (m ) 

square ki laneters ( km2) 

hectares (ha) 

liters (1) 

cubic meters (m3) 

cubic meters 

milligrams (mg) 

grams (g) kilograins (k ) 

metric tons qt) 

metric tons 

kilocalories (kcal ) 

Metric to U.S. Custanary 

& To Obtain 

inches 

inches 

feet 

mil es 

square feet 

square ,nil es 

acres 

gal 1 ons 

cubic feet 

acre-feet 

ounces 

ounces 

pounds 

pounds 

short tons 

British thenal units 

Celsius degrees 1.8("C) + 32 Fahrenheit degrees 

U.S.' Customary to Metric 

inches 

inches 

feet [ft) ~~~ 

fathoms ' 1.829 

miles (mi) 1.609 

nautical miles (mi) 1.852 

square feet (ft2) 0.0929 

acres 2 0.4047 

square miles (mi ) 2.590 

gallons (gal) 3.785 

cubic feet (ft3) 0.02831 

acre- feet 1233.0 

ounces (02) 28.35 

pounds (lb) 0.4536 

short tons (ton) 0.9072 

British thenal units (Btu) 0.2520 

Fahrenheit degrees 0.5556("F - 

mil 1 imeters 

centimeters 

meters 

meters 

kilometers 

kiloneters 

square meters 

hectares 

square kilometers 

1 i ters 

cubic meters 

cubic meters 

grains 

kilograms 

metric tons 

kilocalories 

32 Celsius degrees 
CONTENTS 

PREFACE ................................ ii i 

CONVERSIONTABLE ......................... iV 

FIGURES .................................. vi 

ACKNOWLEDGMENTS ............................ vii 

MORPHOLOGY/IDENTIFICATION AIDS ..................... 1 

REASON FOR INCLUSION IN SERIES ............... 3 

RunandStockTypes ...................... 4 

Spawning. Fecundity. and Sex Ratios .................. 5 

Hatching and Juveniles ...................... 5 

Smolts ................................. 6 

Marine Distribution and Growth ..................... 6 

HomingInstinct .......................... 9 

COMMERCIAL FISHERY ........................ 9 

SPORTFISHERY ............................. 9 

The Fishery and Its Management .................... 9 

HatcheryProgram ............................ 10 

ECOLOGICAL ROLE ............................ 13 

ENVIRONMENTAL REQUIREMENTS ........................ 14 

Water Temperature ...................... 14 

OissolvedOxygen ............................ 15 

Substrate .......................... 15 

Water Depth ............................ 16 

WaterMovement ............................ 16 

Suspended and Deposited Sediment .................. 17 

Other Environmental Factors ...................... 17 

LITERATURECITED ............................. 19 
FIGURES 

Number 

1 Steelheadtrout ............................ 1 

2 Primary distribution of winter-run steelhead in Pacific Northwest 

rivers ................................ 2 

3 Major Washington State rivers that have summer-run steelhead . 3 

4 Major Oregon State rivers that have summer-run steelhead . 4 

5 Oceanic distribution of steelhead trout of Washington, Oregon, 

and California origin. .................. 7 

6 Oceanic distribution of steelhead trout of British Columbia . . origin.. .............................. 8 

7 Saltwater locations on the outer Washington coast and the area 

around Whidbey Island where sport anglers have taken steelhead 

using modified freshwater drift gear ................ 11 

8 Numbers of steelhead caught by sport fishermen in Washington 

State for 1973-84 showing both summer-run and winter-run 

totals ................................ 12 
ACKNOWLEDGMENTS 

We are grateful to Peter Hahn and Robert Gibbons of the Washington State 

Department of Game for their review of the manuscript and valuable unpublished 

information. We also thank Vali Frank for her assistance and preparation of 

figures. 

Figure 1. Steel head trout. 

STEELHEAD TROUT 

Scientific name.. ..... Salmo gairdneri 

Richardson 

Preferred common name..Steelhead trout 

(Figure 1) 

Other common names ..... Coastal rainbow 

trout, silver trout, salmon trout, 

ironhead, steelie, steelhead 

Class ..................... Osteichthyes 

Order .................... Salmoniformes 

Family ...................... Salmonidae 

Geographic range: The steelhead trout 

is found from central California to 

the Bering Sea and Bristol Bay 

coastal streams of Alaska. Most 

streams in the Puget Sound region 

and many tributaries of the Columbia 

and Snake Rivers have steelhead 

populations. Major winter steelhead 

runs are found in many Pacific 

Northwest rivers (Figure 2). Figure 

3 shows the major summer-run 

steelhead rivers in Washington, 

while Figure 4 shows the major 

summer-run steel head rivers in 

Oregon. 

MORPHOLOGY/IDENTIFICATION AIDS 

Body moderately compressed; 

length to 114 cm with average length 

between 51 and 76 cm. Weight up to 

19.5 kg. Head length about 20% of 

total body length (TL). Gill rakers 

16-22 (usually 6-9 on the upper limb, 

11-13 on the lower limb). Branchiostegal rays 9-13. One dorsal fin 

with 10 to 12 fin rays; adipose fin 

fleshy with small base; caudal fin not 

forked; pectoral fins with about 15 

fin rays; pelvic fins with about 10 

fin rays; anal fin with 8-12 fin rays. 

Scales cycloid, rather small, and 

variable with different stocks. 

Pyloric caeca number between 27 and 80 

(Carl et al. 1973; Hart 1973; Scott 

and Crossman 1973). 

Lateral line is complete, 

slightly curved anteriorly, with 

100-150 pored lateral line scales. 

Color varies with habitat, size, and 

sexual condition. Marine adult 

steel head are generally metal 1 ic blue 

on the dorsal surface and silvery on 

the sides. There are black spots on 
KILOMETERS 

CALIFORNIA 

Figure 2. Primary distribution of winter-run steelhead in Pacific Northwest 

rivers. 
WASHINGTON 

Figure 3. Major Washington State rivers that have summer-run steelhead. 

the back, and on the dorsal and caudal 

fins. Spawn i ng colors are 

considerably darker with ma1 es having 

a pink or red band on the sides. 

There is no red dash under lower jaw, 

which distinguishes steel head from 

coastal cutthroat trout, -- Salmo clarki 

cl arki . 

REASON FOR INCLUSION IN SERIES 

Historical ly, steel head have been 

a valuable resource in the Pacific 

Northwest and are the major trophy 

game fish in some areas such as 

western Washington (Pautzke and Meigs 

1940). In the Columbia River Basin, 

the abundant and apparently 

inexhaustible salmon and steel head 

populations generated an intensive 

fishery. However, mainstream dams 

and reservoirs, which cause loss 

of natural habitat and increased 

mortality of smolts (fish migrating to 

the sea), contributed to the reduction 

of the Columbia River salmon and 

steelhead natural runs to seriously 

low levels (Chaney 1978; Raymond 

1979). Poor 1 oggi ng , road bui 1 di ng , and irrigation practices along with 

overgrazi ng by 1 i ves tock have a1 so 

contributed to the decl i ne of salmon 

and steelhead (Yee and Roelofs 1980; 

Pl atts 1981; Chamber1 i n 1982). 

Natural steel head runs are heavi 1 y 

supplemented by hatchery stocking in 

Washi ngton, Oregon, and Cal i forni a. 

Presently, 17 hatcheries plant steelhead smolts into the Columbia River 

system (Ayerst 1977). Steelhead were, 

and still are, an integral part of the 

economic, social, and re1 igious 1 ife 

of Indian Tribes throughout much of 

Washington, Oregon, and Idaho. Steel - 

head are one of the most highly prized 
fi WASHINGTON 

OREGON 

I 

I 

I -------- -------- ---- -- ---- ------- ---- - ------------.--------------------

Figure 4. Major Oregon State rivers that have summer-run steelhead. 

game fish in the Pacific Northwest. 

Approximately 110,000-130,000 anglers 

participate in this fishery each year 

in Washington State (Peter Hahn and 

Robert Gibbons , Washington State 

Department of Game [WDG] ; pers. 

comm. ). 

LIFE HISTORY 

Run and Stock Types 

Steelhead are sea-run (anadromous) rainbow trout (Salmo ai rdneri 

Richardson) that primarruse 9-7 coasta 

streams from Alaska to California and 

tributaries of the Columbia River 

basin. Two races, or runs, of 

steelhead exist (Smith 1960, 1968; 

Chilcote et a1 . 1980). Winter-run 

steelhead migrate to their native 

stream in the late fall and winter, 

and summer-run steelhead migrate 

upstream during the spring and summer. 

Winter-run steelhead enter their home 

stream in various stages of maturation 

and spawn within the next few months 

after entering the river, usually by 

May. Summer-run steelhead enter their 

home stream as green (immature) fish 

and do not mature and spawn until the 

following spring. Native or wild 

winter-run fish may spawn between late 
March and early May, while hatchery 

fish spawn earlier from December 

through February (Smith 1960; Sheppard 

1972; Robert Gibbons, WDG, pers. 

comm.) There is potential for summerand wi nter-run steel head spawners to 

interbreed, as well as for hatchery 

and wi 1 d group interbreeding (Chi 1 cote 

et al. 1983). Shapovalov and Taft 

(1954) noted that in some large rivers 

such as the Sacramento, Klamath, and 

Columbia, steelhead may enter from the 

ocean during most of the year. Entry 

of steelhead into streams is 

positively correlated with the 

occurrence of freshet conditions 

(Withler 1966). When adult steel head 

enter freshwater, they rarely eat any 

food and grow 1 ittle if at a1 1 at this 

time (Maher and Larkin 1954). 

Sheppard (1972) reviewed various 

stocks from different States and found 

that (1) California stocks apparently 

consist of only winter-run fish 

because of unsuitable summer stream 

conditions; (2) Washington, Oregon, 

and southern Bri ti Sh Col umbia stocks 

are a mixture of both summer and 

winter-run fish; (3) Idaho stocks are 

primarily summer-run fish that migrate 

up the Columbia and Snake Rivers; and 

(4) Alaska and northern British 

Columbia stocks are primarily 

summer-run steel head. 

Spawning, Fecundity , and Sex Ratios 

Steel head spawn in cool , clear, 

we1 1 -oxygenated streams with suitable 

gravel and current velocities (Reiser 

and Bjornn 1979). After choosing the 

redd (spawning nest) site, the female 

begins digging a depression by 

repeatedly turning on her side and 

dislodging gravel with rapid lateral 

movements of the tail. Redd depth may 

vary from about 7 cm to more than 30 

cy, and the redd wi 11 occupy about 5.5 

m of stream bottom. Suitable 

spawning area consists of 1.3 cm to 

11.4 cm diameter gravel and wellaerated water having a flow of 

approximately 76.2 cm/sec. Unl i ke 

salmon, which die after spawning, some 

steelhead return from the ocean to 

their native streams several times in 

successive years to spawn. Most 

repeat spawners are female fish (Peter 

Hahn and Robert Gibbons, WDG; pers. 

comm. ). Fecundity appears to vary 

with size and geographic origin of the 

steel head (Bul kl ey 1967). According 

to Bul kley (1967), fecundity of steelhead from the Alsea River, Oregon, 

increases with size: 3,500 eggs for 

508-mm fish; 5,000 eggs for 610-mm 

fish; 8,000 eggs for 711-mm fish; and 

10,000 to 12,000 eggs for 813-mm fish. 

Alsea River steelhead produced approximately 32% fewer eggs than females 

from Trinity River, Cal ifornia, and 

51% less eggs than fish from Scott 

Creek, California, when similar-sized 

fish were compared (Bul kl ey 1967). 

Sheppard (1972) suggested that 

the sex ratio of steelhead returning 

to streams along the entire Pacific 

Coast from California to Alaska is 

1:l. This ratio is apparently the 

mean or average situation, with 

substantial variation occurring in 

individual runs in various rivers from 

year to year (Peter Hahn and Robert 

Gibbons, WDG; pers. comm. ). A1 though 

females appear to survive as repeat 

spawners considerably more often than 

males, the number of steel head that 

return as second and third time repeat 

spawners decl ines progressively, and 

only a few fourth time spawners have 

been reported (Washington 1970). The 

incidence of repeat spawners decreases 

from south to north along the Pacific 

Coast (Withler 1966). The number of 

repeat spawners a1 so varies from 

stream to stream (Withler 1966; Salo 

1974). Repeat spawners do not show 

any significant size gain (Salo 1974). 

Hatching and Juveni les 

The eggs usually hatch in 4 to 7 

weeks, and the newly hatched young 

(alevins) absorb the yo1 k and become 

free swimming in 3 to 7 days. Time of 

hatching varies with region, habitat, 
water temperature, and spawning 

season. 

As the young fish grow, move 

to deeper parts of the stream, 

and establish territories, food 

i tems change from microscopic aquatic 

organisms to larger organisms such as 

isopods, amphipods, and both aquatic 

and terrestri a1 insects (Shapoval ov 

and Taft 1954). They primarily eat 

food items associated with the stream 

bottom (Wydoski and Whitney 1979). 

Streamside vegetation and 

submerged cover in the form of rocks, 

logs, and aquatic vegetation are 

extremely important to steelhead 

during rearing, perhaps more so than 

at any other time (Narver 1976; Reiser 

and Bjornn 1979). Cover plays an 

important role in the selection of 

habitat by young steelhead. In as 

much as this cover provides food, 

temperature stabi 1 i ty, and protection 

from predators, the densities of young 

steelhead are highest in areas contai ni ng instream cover (Johnson 1985). 

The maintenance or reestablishment of 

streamside vegetation is a major part 

of successful stream management for 

steel head and other anadromous 

sal moni ds (Narver 1976; Reeves and 

Roelefs 1984; Johnson 1985). 

Smol ts 

Parr are young fish found iil 

freshwater streams before migration to 

saltwater and are characterized by 

heavy dark blotches on their sides 

cal led parr marks. Juvenile steel head 

remain in freshwater from 1 to 4 years 

before transformation to smol ts. 

Smolting is a process of morphological , behavioral, and biochemical 

changes in which bottom-dwel 1 ing parr 

transform into pelagic smol t that are 

fully capable and prepared to migrate 

to saltwater. Smol ts are characterized by a silvery color and the 

absence of parr marks. 

Wi 1 d juvenile steel head commonly 

spend 2 or 3 years in freshwater, but 

hatchery fish only 1 year. Recent 

reviews suggest that development of 

the smolt stage and seaward migration 

are initiated by various environmental 

factors including photoperiod, water 

temperature, and water chemistry 

(Folmar and Dickhoff 1980; Wedemeyer 

et al. 1980). Marine survival of 

smolts is a function of size and not 

age, with 14 to 16 cm being the 

critical minimum size at which steelhead can become smolts and subsequently survive in saltwater (Conte 

and Wagner 1965; Fessler and Wagner 

1969). 

Mari ne Di stri bution and Growth 

A rapid growth phase occurs 

after the smolts reach the ocean. 

Steelhead usually remain in the ocean 

for 2 to 3 years, and occasionally 4 

years (Shapovalov and Taft 1954). 

Many of the summer-run stocks in the 

Columbia River system spend only one 

year at sea (Peter Hahn, WDG, pers. 

comm. ). Sheppard (1972) found that 

steel head of British Columbia origin 

do not travel as far as other steelhead stocks, but, 1 i ke steel head 

originating in Washington, Oregon, 

California, and Idaho, they spend at 

least part of their ocean residency in 

the Alaskan gyre (Figures 5 and 6). 

Sheppard (1972) i ndicated that 

steelhead tagged in both the Gulf of 

Alaska and near Adak Island, Alaska, 

returned to North American coastal 

streams and that fish tagged at 

Skamani a Hatchery in Washington were 

recovered 3 years later, 45 mi south 

of Adak, Alaska. The knowledge of 

steelhead migratory patterns on the 

high seas is incomplete because the 

fish are difficult to sample since 

they do not form schools and do not 

use areas where intensive commercial 

salmon fishing occurs. Sutherl and 

(1973) indicated that the re1 ative 

abundance of steel head trout captured 

at sea was far less than that of any 

of the Pacific salmon (~ncorhynchu; 

SDD.). and that steelhead distribution 

at' ;ea appears to be influenced by 

surface water temperatures. The 
Figure 5. Hatched areas indicate oceanic distribution for steel head trout of 

Washington, Oregon, and California origin based on tagging-recapture studies from 

1956 to 1969 (after Sheppard 1972). Note that the International North Pacific 

Fish Commission abstention 1 ine, which restricts Japanese gi 11-net fishing, has 

been moved recently. 

distribution conforms closely to the 

5 OC isotherm on the north and the 

15 OC isotherm on the south. 

Steelhead age groups are designated to indicate the amount of time 

spent in freshwater and in the ocean; 

thus 2/3 refers to fish that spent 2 

years in freshwater and 3 summers or 

winters in the ocean (Maher and 

Larki n 1954). Most mature, returning 

wild adult steelhead usually fall 

into one of four major categories 

for age: 2/2, 2/3, 3/2, and 3/3. 

Returning hatchery adult steel head 

usually are 1/1, 1/2, or 1/3. No 

correlation exists between the 

number of years spent in freshwater 

and in saltwater. However, the 

length of residence in both freshwater and saltwater increases in 

steel head populations from south to 

north a1 ong the Pacific coast (Wi thl er 

1966). The maximum life span of 

steelhead appears to be between 8 and 

9 years (Sumner 1945; Washington 

1970). 

Length at first maturity is a 

function of the number of years spent 
Figure 6. Hatched areas indicate oceanic distribution for steel head trout of 

Bri ti sh Col umbia origin based on taggi ng-recapture studies from 1956 to 1969 

(after Sheppard 1972). 

in saltwater, according to Maher and 

Larkin (1954), with representative 

mean lengths of adult steelhead in 

British Columbia increasing with time 

spent in saltwater residence: 47.2 cm 

for 1 year, 70.1 cm for 2 years, 

81.3 cm for 3 years, and 87.9 cm for 

4 years. The more northern populations of steel head along the Pacific 

coast attain the greatest adult 

length (Wi thler 1966). Representative 

mean 1 engths of adult steel head 

after 2 years in saltwater are 58.2 cm 

for California, 66.8 cm for central 

Oregon, and 71.9 cm for southern 

British Columbia (Wi thler 1966). A 

fish that has spent 4 years in saltwater is almost twice as long as one 

that has spent only 1 year in saltwater, regardless of the number of 

years spent in freshwater. Since 

weight varies approximately as the 

cube of the length, increments in 

lengths of longer fish are associated 

with larger gains in weight (Maher and 

Larkin 1954). A rough estimate of a 

steelhead's weight can be made by 

assuming it weighs 2.3 kg at 58 cm and 
will increase by about 0.4 kg for each 

additional 2.5 cm. 

SPORT FISHERY 

The Fishery and Its Management 

Homing Instinct 

The sensitivity of the homing 

instinct in steelhead has never been 

explained, but a 1 earning process 

called imprinting is probably involved 

initially (Slatick et al. 1981). The 

homi ng instinct is particularly 

important in steel head because the 

fishery is 1 imi ted almost entirely 

to the watersheds where they return 

as adults and reproduce (Royal 1972). 

Even though a significant amount of 

other anadromous salmonid species 

stray between neighboring streams of 

adult steel head planted as smol ts 

in a particular river are usually 

avai lable for harvest in the stream 

of origin or closely neighboring 

river systems (Royal 1972). 

COMMERCIAL FISHERY 

Commercial fishing for steel head 

in the Pacific Northwest started in 

the mid-1880's. The recording of 

commercial catch statistics for 

Washington, Oregon, and Cal i fornia 

began i n 1892, when 5.3 mi 1 1 ion pounds 

of steel head were caught (Sheppard 

1972). The steel head commercial catch 

peaked in 1945 at 8.7 mi 11 ion pounds, 

with the commercial catch declining in 

subsequent years (Sheppard 1972). 

Commercial fishing for steel head in 

California ended in 1924, and is now 

restricted in Washington and Oregon to 

specific Indian tribes as guaranteed 

by particular treaty rights (Withler 

1972; Clark 1985). In British 

Columbia, steel head are incidental 

catches in commercial salmon gi 11 nets 

and totaled 20,726 fish for all the 

years between 1960-71 (W i thl er 1972). 

According to Sheppard (1972), the 

commercial catch of steelhead in 

Alaska is small: between 1942 and 

1967, the annual catch averaged 

14,671 1b in Alaska's southeast region 

and 5,230 lb in the central region. 

Steel head in Washington and 

Oregon are currently managed 

exclusively for recreational fisheries 

and tribal Indian fisheries. The 

majority of fish caught upstream in 

rivers are landed by recreational 

anglers, and most of those caught near 

the river mouth estuaries are taken by 

Indians. Steel head catch a1 locations 

are currently divided between treaty 

Indian and nontreaty fishermen 

approximately 50:50 for numbers caught 

i n Washi ngton State waters in 

accordance with the recent Federal 

Court ruling commonly known as the 

Bol dt Decision (Clark 1985). Before 

this court ruling, Sumner (1945) noted 

that Indian nets were capable of 

selecting, on the average, larger and 

probably older fish than sport anglers 

catch by hook and line. In addition 

to interacting with various Indian 

fisheries, the sport fishery must also 

interact with other types of recreation and timber management as reviewed 

by Clark et a1 . (1985). 

Since the early 19001s, particularly after World War 11, sportfishing 

for steel head has become increasingly 

popular because of advanced hatchery 

technology and widespread stocking. 

Runs of adult steelhead have been 

bui 1 t up substantial ly by planting 

hatchery fish (Larson and Ward 1954). 

Pauley (1982) reviewed the effects of 

recreational fishing on anadromous 

salmonids, incl udi ng the benefits and 

drawbacks of using hatchery salmonids 

to supplement the sport fishery. 

Since the native stock is the result 

of natural selection over centuries, 

hatchery stocks changed through 

selective breeding should not be 

expected to be as genetically robust 

as the native stocks. 

Fishing is conducted with both 

natural bait and arti f i cia1 1 ures 

(Fagerstrom 1976) even though the fish 

do not actively feed in freshwater. 
Natural baits include fish eggs, night 

crawlers, and shrimp. Popul ar 

artificial lures are spoons, spinners, 

diving plugs, flies, and brightly 

colored drift bobbers. Bait casting, 

spinning, and fly-fishing gear are all 

used by steelhead anglers. The main 

types of fishing are drift fishing and 

plunking from the river banks, and 

drift fishing and plug pulling from 

professional ly guided or privately 

owned drift and jet boats (Fagerstrom 

1976; Luch 1976). Most of the 

steelhead caught by anglers are taken 

in rivers, although there are a few 

saltwater areas where steelhead are 

consistently taken (Figure 7) usi ng 

modified drift gear (Rudnick 1981). 

Oregon and Washington have a 

compul sory punchcard system for 

anglers to record their steelhead 

catch. The information is used in 

conjunction with creel survey data 

taken along various streams to 

estimate the steelhead sport catch for 

each river and lake. In comparing 

recreational catch data from 

Washington, Oregon, Cal i fornia, 

British Columbia, and Alaska, Sheppard 

(1972) found that Washington had the 

largest annual sport catch of 

steelhead between the years 1962 and 

1970, while Oregon was second. The 

average annual catch in Washington 

between 1961 and 1981 was 38,040 

summer-run fish and 103,940 wi nter-run 

fish (Peter Hahn, WDG; pers. comm.). 

Sheppard (1972) also found that one 

out of every five anglers in 

Washington for the period from 1949 to 

1970 succeeded in catching a 

steelhead, based on punchcard returns. 

These punchcard returns are biased 

toward successful anglers, who return 

their cards at a considerably higher 

rate than do unsuccessful steelhead 

anglers (Peter Hahn, WDG; pers. 

comm. ) . 

During 1983-84, Washington State 

anglers harvested 37,134 summer-run 

(May-October) steel head and 68,647 

winter-run (November-Apri 1 ) steel - 

head for a total of 105,781 fish 

(Washi ngton Department of Game 1985a). 

Figure 8 depicts the number of 

steel head caught annual ly in 

Washington State by steel head anglers 

from 1973 to 1984, the period that the 

Boldt Decision had been in effect. 

The Washington State Treaty Indian 

steelhead catch in 1983-84 was 20,395 

summer-run fish and 59,826 wi nter-run 

fish for a total of 80,221 steelhead 

(Washington Department of Game 1985b). 

The increased popul ari ty of 

sportfishing and the declining qua1 i ty 

and quantity of natural habitat have 

caused all the Pacific States and 

British Columbia to closely manage 

their steel head stocks. Withler 

(1966) indicated that more females 

than males may be caught and then kept 

by anglers. Two factors are involved 

in this bias toward females in the sex 

ratio of fish kept by anglers. First, 

the frequency of repeat spawners is 

greater among female steelhead than 

among males due to increased 

post-spawni ng survival. Consequently, 

the sl ightly greater number of females 

in the population results in larger 

female catches by anglers. Second, 

males deteriorate in appearance to a 

greater extent than females as 

spawning approaches. Therefore, more 

males than females are released alive 

by anglers after being captured during 

the spawning season. Recent data from 

Washington State indicate that females 

are not more vulnerable than males to 

angling, and that the sport catch sex 

ratio is an unbiased estimate of the 

true sex ratio (Peter Hahn, WDG; pers. 

comm. ). 

Hatchery Program 

Washington, Oregon, Idaho, and 

Cal i fornia a1 1 have hatchery programs 

to supplement their natural fish runs. 

Hatcheries can be utilized to rebuild, 

improve, or even establish new runs 

of steelhead, but they should not 

be used to attempt to replace wild 

stocks of fish (Ayerst 1977). 

Washington State's steel head management program is a two-phase project: 
Strait of Juan 

Z 

4 

W 

0 

0 

0 

Y 

L 

Y 

0 

4 

P1 

WASHINGTON 

Figure 7. Saltwater locations on the outer Washington coast and the area around 

Whidbey Island where sport anglers have taken steel head using modified freshwater 

drift gear. 

(1) supplementing depleted runs and Washington (Peter Hahn, WDG, pers. 

heavily fished runs with hatchery comm. ). In 1971, Washington State had 

fish, and (2) attempting to protect 14 hatcheries and 10 semi natural 

the natural runs of steelhead already rearing ponds producing over 3 mil 1 ion 

present in various streams (Larson winter steel head smol ts; Oregon had 11 

and Ward 1954). The second phase hatcheries and few rearing ponds 

is currently the major priority in producing 1.5 mil 1 ion winter steel head 
1 SUMMERRUN a 

WINTER RUN 

120,000 

YEAR 73 74 75 76 77 78 79 80 81 82 83 

74 75 76 77 78 79 80 81 82 83 84 

Figure 8. State-wide numbers of individual steelhead caught by sportfishermen 

in Washington State for 1973-84 showing both summer-run and winter-run totals. 

smolts in 1968; California had four 

hatcheries releasing 1.88 mil 1 ion 

wi nter-run steel head smol ts in 1968; 

and Idaho released 350,000 smolts in 

1971 (Sheppard 1972). 

Hatchery steel head smol ts are 

generally 1 year old when released, 

whereas natural wild smolts are 

2 years old before they become 

smolts and migrate to the sea 

(Royal 1972). Available data 

indicate that the optimum release date 

for hatchery-reared steel head smol ts 

coincides with the peak downstream 

movement of wild steelhead smolts 

(Wagner et al. 1963), which occurs in 

late Apri 1 (Wagner 1968). 

Hatchery propagation has affected 

the length of time spent at sea and 

has altered the return migration 

pattern of adult steel head (Salo 

1974). Hatchery fish tend to return 

to the streams sooner than natural 

wild fish (Royal 1972). Evidence 

also indicates that increased plantings of hatchery fish can cause a 
corresponding decl i ne in the number 

of wild steelhead that return as 

adults (Wagner et al. 1963; Salo 

1974), even though hatchery smolts 

do not always seem to survive as 

well as wild smolts (Bjornn 1977; 

Reisenbichler and McIntrye 1977). 

This reduction in wild fish numbers is 

brought about by genetic a1 teration 

with the possible elimination of wild 

genotypes in steel head. A decline in 

the numbers of returning wild steelhead is also caused by overfishing of 

wi 1 d steel head because of increased 

fishing pressure fol lowing the stocki ng of abundant hatchery f i sh (Narver 

1976). Recent data from Washington 

rivers indicate that genetic a1 teration is a minor problem, while overfishing is a major problem (Peter Hahn 

and Robert Gibbons, WDG; pers. comm. ). 

In an attempt to solve this problem, 

Washington State currently requires 

that all native or wild fish must be 

released by anglers in most rivers. 

Returning hatchery steel head and wi ld 

steel head can be distinguished with 

near 100% accuracy by scale-pattern 

characteristics (Chapman 1958) or with 

a high degree of accuracy by examination of the dorsal fin (Pauley 1982). 

The latter method is used by sport 

fishermen to justify keeping or 

releasing their fish. Wild fish have 

dorsal fin rays that are not bent or 

crooked in any way and are generally 

more than 2.0 inches high when fully 

extended. Hatchery fish, on the other 

hand, have dorsal fin rays that are 

bent or crooked and that are usually 

less than 2.0 inches high when fully 

extended. Hatchery fish in most 

rivers in Washington State a1 so have 

cl ipped adipose fins. 

ECOLOGICAL ROLE 

A variety of predators eat 

luveni 1 e steel head: 1 arse resident 

iai nbow trout (Salmo - 

~ - 

searun cutthroat trm~almo c ar I), 

sculpins (Cottus spp. )ze=ue 

herons (Ardea herodias), mergansers 

(Mergus merganr and various 

mammals (Sheppard 1972). Johnson 

(1981) found that steelhead eggs in 

streams were subject to predation by 

both brook trout (Sal vel inus 

fontinalis) and juvenile steelhead, 

where eggs composed 20.B to 59.2% of 

the total dry weight of the diet of 

the predators examined. 

In Idaho, Bjornn (1978) found 

that steel head fry were at least as 

viable as resident rainbow trout 

fry and possibly more viable. The 

steelhead fry tended to displace 

resident rainbow trout, but did not 

appear to affect resident brook trout 

populations. Stocking hatchery rainbow trout (Salmo airdneri) into 

streams causenoca +a- i ze temporary 

displacement of juvenile steel head 

(Pol 1 ard 1978). Hatchery rainbow 

trout usually chose greater stream 

velocities and deeper water than 

steel head. Because of these 

differences, interaction between 

rainbow trout and juvenile steel head 

apparently is not great (Pollard 

1978). Hartman and Gill (1968) 

reviewed the distribution of juvenile 

steelhead and cutthroat trout in 

southeastern British Columbia. They 

reported that steelhead were found 

predominantly in 1 arge streams with 

drainage areas over 130 km2 and 

streams with steep gradients, whi 1 e 

cutthroat trout were found predominantly in small streams with drainage 

areas under 13 km2 with slightly 

sloping gradients. 

Stream-dwell ing steel head trout, 

which have evolved in sympatry with 

various other species of anadromous 

sal monids , have developed mechanisms 

that parti tion the avai lab1 e habitat 

and probably promote coexistence 

(A1 lee 1981). Everest and Chapman 

(1972) found that chinook salmon 

(Oncorh nchus tschaw tscha) and 

stee _Yy_ head seareaate a9-h urina t e summer 

in two 1daho s-treams. ~6e steelhead 

occupied similar niches whether they 

were present alone or together with 

chinook salmon. Most juvenile 

steelhead preferred rubble substrates 
with water velocities less than 

15 cm/s and a depth of 0.15 m. When 

steel head grew larger, they moved to 

deeper, faster water. Hartman (1965) 

found that interaction between 

juvenile coho salmon (Oncorh + nchus 

kisutch) and juvenile stee head 

depenaed upon three factors: 

population densities in the stream, 

levels of aggressiveness, and size 

differences of the fish. Young 

steel head demonstrated more aggressive 

behavior and territorial defense in 

the riffle environment, and coho 

salmon were more strongly motivated to 

defend space in pools rather than in 

riffles. By winter, the steelhead 

attained a size range approximating 

that of the coho salmon and moved into 

the pools. However, steel head did not 

establish stable social groups in the 

pools as coho salmon did. This 

resulted in steel head and coho 

uti 1 izing the pool space differently. 

Coho salmon formed groups in open 

water above the bottom and occupied 

space beside or downstream from 

stones. Steel head scattered across 

the bottom as individuals and occupied 

space under stones. 

Juvenile steelhead tended to be 

more closely associated with the bot 

tom of streams than either coho or 

chi nook salmon (Hartman 1965; Edmunson 

et al. 1968; Bustard and Narver 1975). 

In the winter, young steel head become 

inactive and hide in any available 

cover (Bustard and Narver 1975). 

Survival of young fish as they 

migrate seaward depends somewhat upon 

size: the probability of survival is 

2.5% for 1-year-old fish, 6.0% for 

2-year-01 ds; 18% for 3-year-01 ds 

(Shapoval ov 1967). Whi 1 e at sea, 

steel head feed heavi 1 y upon juveni 1 e 

green1 i ng (Hexa rammos spp. ) , squids , and amphipods f8- Le rasseur 1966; Manzer 

1968) and travel great distances, 

primarily in the upper 12.2 m of the 

water col umn (Sheppard 1972). Marine 

mammals and fish are predators of 

steel head and salmon a1 though their 

impact is difficult to assess. 

ENVIRONMENTAL REQUIREMENTS 

Water Temperature 

Water temperature requirements of 

steelhead vary with life stage. 

A1 though no specific optimum migration 

temperatures are given for steel head, 

Reiser and Bjornn (1979) stated that 

unusual stream temperatures during 

adult upstream migration can a1 ter the 

time of migration, accelerate or 

retard maturation, and lead to 

outbreaks of disease. They suggested 

that most stocks of anadromous 

sal moni ds have evolved with specific 

temperature patterns and that 

significant abrupt deviations can 

adversely affect their survival. 

Shepard (1972) found that in small- to 

moderate-s i zed streams timi ng of the 

upstream winter migration of steel head 

was related to stream flows and 

correspondi ng low temperatures. In 

1 arger streams, the relationships were 

1 ess def i ned, but suggested that 

stocks may have evolved migration 

timing that corresponds to general ly 

sui tab1 e stream f 1 ow and temperature 

levels. 

Bell (1973) suggested that the 

spawning temperatures of steelhead 

were between 3.9 and 9.4 OC. Reiser 

and Bjornn (1979) indicated that 

salmonid spawning may cease with a 

sudden drop i n stream temperature, 

resul ti ng in decreased nest bui 1 ding 

and reduced production. A1 though 

recommended incubation temperatures 

were not specifically given for 

steel head, Rei ser and B jornn (1979) 

listed the incubation temperatures for 

all salmonid embryos as 4.0 to 14 OC. 

Embryos can develop normally at lower 

temperatures if they are sufficiently 

acclimated. 

According to Reiser and Bjornn 

(1979), water temperature during 

rearing can i nf 1 uence growth rate, 

population density, swimming ability, 

ability to capture and use food, and 

abi 1 i ty to withstand disease 

outbreaks. Bell (1973) listed the 
preferred rearing temperatures of 

steel head as 7.2 to 14.5 OC, with an 

optimum of about 10.0 OC and an upper 

lethal limit of 23.9 OC. 

Di ssol ved Oxygen 

During upstream migration, 

reduced dissolved oxygen concentrations can adversely affect swimming 

performance of migrating salmonids and 

cause avoidance reactions or cause 

migration to cease (Reiser and Bjornn 

1979). Experiments have shown that at 

temperatures of 10.0 to 20 OC, the 

maximum sustained swimming abi 1 i ties 

of juvenile and adult coho salmon were 

adversely affected when dissolved 

oxygen was reduced from ai r-saturation 

1 evel s and decreases in performance 

were observed at all temperatures when 

dissolved oxygen concentrations 

measured 6.5 to 7.0 mg/l (Davis et al. 

1963). 

Di ssol ved oxygen 1 evel s are 

critical to steel head and other 

salmonids during incubation. From 

experiments conducted by various 

authors (Alderdice et a1 . 1958; Si 1 ver 

et al. 1963; Shurnway et al. 1964) on 

coho, chum, and chinook salmon, and 

steel head, Rei ser and Bjornn (1979) 

summari zed the effects of di ssol ved 

oxygen on salmonid egg development. 

They indicated that (1) sac fry 

embryos incubated in low and 

intermediate dissolved oxygen 

concentrations were smaller and weaker 

than those reared at higher 

concentrations and may not survive as 

we1 1 ; (2) reduced oxygen concentrations led to longer incubation periods 

and smaller newly hatched fry; and (3) 

low dissolved oxygen concentrations 

may delay hatching and increase the 

incidence of anomalies in the early 

stages of development and can 

stimulate premature hatching during 

the later stages. There is a positive 

correlation between the survival of 

steel head embryos and i ntragravel 

dissolved oxygen concentrations (Cob1 e 

1961; Phi 11 ips and Campbell 1961). 

Reiser and Bjornn (1979) recommended 

that dissolved oxygen concentrations 

during incubation of anadromous 

salmonids be at or near saturation 

with temporary reductions to no lower 

than 5.0 mg/l . 

Dissolved oxygen concentrations 

are also important during the rearing 

phase. Reiser and Bjornn (1979) 

summarized di ssol ved oxygen cri teria developed by Davis (1975) for 

salmonids, which indicated that freshwater salmonid populations function 

without impai rment at di ssol ved oxygen 

concentrations of 7.8 mg/l ; exhibit 

initial distress symptoms at 6.0 mg/l; 

and are adversely affected at 4.3 

mg/l. Reiser and Bjornn (1979) 

indicated that freshwater salmonid 

populations can function without 

impairment when dissolved oxygen is at 

the following saturation levels 

(dependent on temperature): 76% at 0 

to 15 OC; 85% at 20 OC; and 93% at 

25 OC. Initial distress symptoms 

appear with saturation 1 eve1 s of 57% 

at 0 to 10 OC; 59% at 15 OC; 65% at 

20 OC; and 72% at 25 OC. Fish populations are adversely affected with 

saturation levels of 38% at 0 to 

10 OC; 42% at 15 OC; 46% at 20 OC; and 

51% at 25 OC. Low dissolved oxygen 

levels can affect the rate of 

metabol i sm, swi mmi ng speed, growth 

rate, food consumption rate, efficiency of food utilization, behavior, 

and ultimately the survival of 

anadromous sal moni ds. 

Supersaturation of atmospheric 

gases has caused problems to various 

salmonids as discussed by Ebel and 

Raymond (1976) and Weitkamp and Katz 

(1980). Serious hi stopathological 

problems associated with gas-bubbl e 

di sease have been noted i n f i ngerl i ng 

salmonids under conditions of supersaturation (Paul ey and Nakatani 1967). 

Substrate 

The composition of the stream 

substrate is particularly important to 

steelhead as well as to other 

salmonids during spawning, incubation, 
and rearing. The preferred size of 

gravel substrate varies with the 

different sizes and species of 

salmonids (Rei ser and Bjornn 1979). 

The acceptable gravel substrate has a 

wide range of sizes for steelhead as 

indicated by several authors. The 

gravel composition on steel head 

spawning areas ranges from 1.0 to 

10.0 cm according to Hunter (1973). 

Bell (1973) states that since stream 

bed composition is a result of slope 

and quantity of flow, the substrate 

composition of the spawning bed for 

salmon and trout may vary from 2.0 to 

10.0 cm. Reiser and Bjornn (1979) 

indicated suitable substrate for 

spawning was 1.3 to 11.7 cm in 

diameter. 

Reiser and Bjornn (1979) indicated that spawning bed materials can 

i nf 1 uence the development and emergence of salmonid fry. In general, 

high substrate permeabi 1 ity is 

essential for good salmonid production. Excessive sand and silt in the 

gravel hinders successful fry emergence. Bjornn (1969) and McCuddin 

(1977) demonstrated that when sediments less than 6.4 mm in diameter 

constituted at least 20% to 25% of the 

substrate, both survival and emergence 

of chinook salmon and steel head 

embryos were reduced. Gravel mixtures 

containing high percentages of fine 

sediments caused decreased embryo 

survival, smaller steel head fry, 

and emergence before yolk-sac absorption was complete (Tappel and Bjornn 

1983). 

During the rearing phase, the 

substrate composition probably affects 

salmonid production mostly by regulating the production of invertebrates, a 

valuable food source. Reiser and 

Bjornn (1979) indicated that the 

highest production of invertebrates is 

in habitats with gravel- and rubblesized material s and that invertebrate 

production decreases proportionately 

as the size of the substrate particles 

decreases. In a1 1 cases, the composition of the stream substrate was a 

function of water velocity, with the 

size of the material increasing with 

water velocity. Reiser and Bjornn 

(1979) developed overall criteria for 

optimum salmonid food production in 

streams: water velocity, 0.5 to 1.1 

m/s; depth, 0.5 to 0.9 m; substrate 

composition, largely coarse gravel 

from 3.2 to 7.6 cm in diameter, and 

rubble from 7.6 to 30.4 cm in 

diameter. 

Water Depth 

Insufficient water depth can be a 

barrier to the upstream migration of 

steel head and other anadromous 

salmonids. The minimum depth required 

for the successful upstream migration 

of adult steelhead is 18 cm (Thompson 

1972). Waterfall s , however, can be 

obstacles even when the water depth 

below the falls exceeds 18 cm. Reiser 

and Bjornn (1979) indicated that 

spawning steel head preferred water 

depths of 24 cm or more. 

As with substrate size, the depth 

of water required by rearing salmonids 

may be most closely associated with 

food production. Literature reviewed 

by Reiser and Rjornn (1979) suggested 

that the most productive areas in 

terms of aquatic insect production are 

shallow areas typical of riffles. 

Hooper (1973) found that when 

substrates and velocities were 

sui tabl e, the highest invertebrate 

production was associated with stream 

depths between 15 and 91 cm. 

Water Movement 

Sui tab1 e stream velocities 

(stream flows) are important during 

migration upstream, spawning, incubation, and rearing of steelhead. The 

maximum water velocity that allows 

successful upstream migration of 

steel head is 2.4 m/s (Thompson 1972). 

Any section of a stream can become an 

obstacle, regard1 ess of depth, when 

stream velocities exceed the swimming 

speeds of steelhead. Minimum and 

maximum acceptable stream flows for 
migration of adult steelhead can be 

calculated for specific stream 

sections using methods outlined in 

Thompson (1972). 

The preferred water velocity for 

spawni ng steel head ranges between 40 

and 91 cm/s (Smith 1973). Total 

streamflow, a function of velocity and 

depth, regulates the amount of spawning area available (Reiser and Bjornn 

1979). Reiser and Bjornn (1979) cited 

several authors (Sams and Pearson 

1963; Thompson 1972; Col 1 i ngs 1972, 

1974; Waters 1976; Stalnaker and 

Arnett 1976) who provided detailed 

descriptions of spawning flow 

method01 ogy. 

During the incubation stage, the 

velocity of water moving through the 

interstitial spaces in the gravel may 

be the single most important factor in 

the embryos' i ntragravel environment , since it determines the amount of 

dissolved oxygen supplied and the rate 

at which metabolic waste products are 

removed (Reiser and Bjornn 1979). 

Phillips and Campbell (1961) found 

that the survival of steelhead and 

coho salmon eggs was high when 

apparent intragravel velocities were 

greater than 20 cm/h. Coble (1961) 

a1 so demonstrated higher survival of 

salmon embryos with higher apparent 

velocities, between 5 cm/h and 100 

cm/h. 

Reiser and Bjornn (1979) stated 

that most recommended stream flows for 

salmonid rearing habitat have been 

based on food production, cover, and 

microhabitat needs of the fish, rather 

than the direct re1 ationships between 

fish production and stream flow. They 

1 i sted the fol 1 owing recommendations 

for stream flow and stream 

characteristics developed by Thompson 

(1972) for salmonid rearing habitat: 

depth of 0.46 to 0.91 m over riffles 

for optimum food production; 

riff1 e/pool ratio near 1: 1; 

approximately 60% of riffle area 

covered by water; riffle water 

velocities of 31 to 46 cm/s; pool 

water velocities of 9 to 24 cm/s; and 

some type of stream cover available as 

shelter for fish. 

Suspended and Deposited Sediment 

During adult upstream migration, 

salmonids may cease movement when 

silt load exceeds 4,000 mg/l (Bell 

1973). A thermal barrier may develop 

as a result of the increased absorption of radiation in turbid waters 

(Rei ser and Bjornn 1979). Excessive 

amounts of sand and silt in the gravel 

may also inhibit salmonid fry emergence from the gravel (Reiser and 

Bjornn 1979). Fish subjected to 

continuous clay turbidi ties of 

approximately 50 nephel ometric 

turbidity units (NTV) grew less well 

than those 1 iving in clear water, and 

more of them emigrated from the test 

channel s containing turbid water 

(Sigl er et a1 . 1984). 

During rearing , suspended and 

deposited fine sediment can directly 

affect salmonids by abrading and 

clogging gills, and indirectly by 

causing reduced feedi ng , avoidance 

reactions, destruction of food 

supplies, reduced survival of eggs or 

a1 evi ns , and changed rearing habitat 

(Reiser and Bjornn 1979). Bell (1973) 

indicated that si 1 t 1 oads averaging 

less than 25 mg/l permit good 

freshwater fisheries. 

Other Environmental Factors 

Partial or complete barriers such 

as waterfall s , debris jams, excessive 

velocities (Reiser and Bjornn 1979), 

high temperatures, high turbidity 

(Bell 1973), and dams can impede or 

prevent the upstream migration of 

adult steelhead and, in some cases, 

the outmigration of juvenile fish 

(Northwest Power Pl anni ng Counci 1 

1985). 

The amount, type, and location of 

cover is important during the adult 

freshwater phase and the rearing phase 

of steelhead. Reiser and Bjornn 
(1979) stated that cover is essential 

to adult steelhead due to the 

protracted periods they spend in 

freshwater before they spawn. They 

suggested that the proximity of cover 

may be important in the selection of 

spawning sites. They listed cover 

types as overhanging vegetation, 

undercut banks, submerged vegetation, 

submerged objects such as logs and 

rocks, and floating debris. Cover may 

be most important during the rearing 

phase; it provides shaded areas, 

reduces predation, and general ly 

a1 lows increased salmonid production (Reiser and Bjornn 1979). 

Riparian vegetation, in addition 

to providing cover, provides habitat 

for terrestrial insects that fall 

into the stream and become food for 

juveni le salmonids, and provides 

plant materials that become food 

of aquatic invertebrates (Rei ser 

and Bjornn 1979). Some 1 imited 

success has been accomplished in 

enhancing stream habitat for 

anadromous sal moni ds (Reeves and 

Roe 1 of s 1982). 

The Northwest Power Planning 

Council (1985) has recently reviewed 

the impact of hydroelectric facil ities 

on anadromous salmon and steelhead. 

The outmigration time of juveni 1 es is 

delayed as is the upstream migration 

of adults. The reservoirs created 

behind the facilities have inundated 

important spawning areas. The greater 

surface area of these impounded waters 

causes abnormal i ncreases in river 

water temperatures. Other operational 

impacts on salmon and steelhead 

include turbine mortal i ties of 

juveniles, gas supersaturation of the 

water that can result in gas-bubble 

disease, stunning of outmigrants 

making them more susceptible to 

predators, and regulated stream flow 

f 1 uctuations that cause stranding and 

mortality of fish. 
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2823-2841. 

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Station, Port1 and, Oreg. 
12. Sponsorins Organiz~tion Name end Address 

National Wetlands Research Center U.S. Army Corps of Engineers 13. TYD- of ~eport h Period Covered 

Fish and Wildlife Service Waterways Experiment Station 

U.S. Dep. of the Interior P.O. Box 631 

Washington, DC 20240 Vicksburg, MS 39180 

15. Supplamantarl Notes 

*U.S. Army Corps of Engineers Report No. TR EL-82-4 

16. Abstna (Limit: 200 words) 

REPORT DOCUMENTATION 

PAGE 

Species profiles are literature summaries of the range, life history, and environmental 

requirements of coastal aquatic species. They are designed to assist in environmental 

impact assessment. The steelhead is an anadromous form of the rainbow trout Salmo 

airdneri found from central California to Alaska. The commercial fishery in the Pacific 

Borthwest is restricted to specific Indian tribes. Washington and Oregon support an 

important recreational fishery. In Washington and Oregon, two runs of steelhead exist. 

Winter-run steelhead enter their native streams in late fall and winter, and usually 

spawn by the following May. Summer-run steelhead return to their home streams in spring 

and summer, and usually spawn in the following spring. California stocks apparently 

consist only of winter-run fish. Female steel head bury their eggs in gravel in streams 

after spawning. Proper temp~rature and dissolved oxygen levels are necessary for 

incubation of eggs and rearing in streams. Adequate particle size of stream gravel and 

adequate stream velocity are essential for incubation. 

REwm 2. 

Biological Report 82(11.62)* 

17. Document Analpis a. Oescnpton 

Competition Trout Depth Life cycles 

Growth Fisheries Sediments Animal migrations 

Oxygen Salinity Feeding habits 

Streams Temperature Suspended sediments 

3. Recipient's Accession NO. 

4. Titla end Subtitla 

Species Profiles: Life Histories and Environmental 

Requirements of Coastal Fishes and Invertebrates (Pacific 

Northwest)--Steelhead Trout 

7. Authoris) 

Gilbert Pauley, Bruce Bortz, and Michael Shepard 

9. Performins Omaniretion Name end Addresm 

b. IdantlfienlOven.Ended Terms 

5 Report oat. 

August 1986 

6. 

8. Petformins Orpenization Rept. NO. 

10. PmiacllTesklWork Unit No. 

Steel head trout 

Spawning 

Salmo gairdneri 

Predators 

c. COSATI FieldlGroup 

18. Availablllty Statement 1 19. ~ccuraty lass (~hls ~emrt) 1 21. No. of PalIes 

Unclassified 

Unl imi ted +-+- 20. security CI~SS (This Page) 

Unclassified 

(Sw ANSI-239.18) OPTIONAL FORM 272 

(Formerly NTIS-35) 

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DEPARTMENT OF THE IWTERIOR 

U.S. FISH AND WllDLlA SERVICE 

As the Nation's principal conservation agency. the Department of the Interior has responsibility for most of our .nationally owned public lands and natural resources. This includes 

fostering the wisest use of our land and water resourcm, protecting our fish and wildlife, 

preserving thsenvironmental and cultural values of our national parks and historical places, 

and providing for the enjoyment of life through outdoor recreation. The Department assesses our energy and mineral resources and works to assure that their development is in 

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