MFR PAPER 1189

LYLE G. GILBREATH, LARRY R. BASHAM, and EMIL SLATICK

Distribution, Age, and Size ofTagged Adult Steelhead Troutin the Snake River Drainage

ABSTRACT-Steelhead trout, Salmo gairdneri, were tagged as adults at LittleGoose Dam on the Snake ~iver during the 1972 and 1973 spawning migrations.Recovery rates of tagged fIsh from the recreational fishery upstream from LittleGoose Dam w~re 21.3 percent and 13.1 percent in 1972 and 1973, respectively.A 61 km sectIon of the lower Snake River now flooded by Lower Granite Damproduce~ 42.6 percent of the sport catch in 1972 and 37.9 percent in 1973.l~formatlOnwas also obtained on the ocean-age composition of the fish and thetlmmg of migration and size of steelhead trout recovered in four different riverareas, mcludmg the Clearwater and Salmon River systems of Idaho.

'Dart tags were size FT-2 manufactured by theFloy Tag Company. Jaw tag sizes ranged from12 to 28 and were manufactured by theNatIOnal Band Company. Reference to tradenames does .not ~ply. endorsement by theNatIOnal Marine fisheries Service, NOAA.

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object of this tagging was to determinethe distribution of these steelheadtrout in the Snake River drainage andto assess the relative contributions ofdifferent areas to the recreationalfishery, particularly the section ofriver to be inundated by Lower GraniteDam. Information on the timing ofmigration, size, and ocean-age com­position of adult steelhead trout in theSnake River was also obtained. Thisreport describes the results obtainedfrom the tag recoveries.

MATERIALS AND METHODSSteelhead trout utilized in this study

were the adults returning from smoltreleases that were marked to evaluatethe transportation experiments con­ducted in 1969-72 at Ice Harbor andLittle Goose dams by the NMFS. Thesefish had been tagged as juveniles withmagnetic wire tags (Jefferts et aI.,1963), cold branded with liquid nitro­gen (Mighell, 1969), and released nearthe point of capture (control condition)or below Bonneville Dam (test con­dition). A device to detect magnetizedwire tags on adult fish and to separatethese tagged fish from the untaggedfish (Ebel, 1974) was installed in thefish way at Little Goose Dam in 1972.

This facility operated during theadult migration seasons of 1972-73,automatically separating steelheadtrout with magnetized wire tags fromthe rest of the population ascending thefish ladder. Each migration seasoncovered portions of two calendar years.For example, steelhead trout from the1972 run were captured at Little GooseDam from the late summer of 1972through the spring of 1973. Steelheadtrout bearing wire tags were anesthe­tized, examined for cold brands,weighed, measured. and externallytagged with a dart or a jaw tag 3. Ascale sample was also taken for use inage studies.

Most tag returns were obtaineddirectly from anglers but a substantialnumber (181) were recovered at theDworshak and Pahsimeroi fish hatch­eries. A few were also incidentallyrecovered in a creel census by IdahoFish and Game Department personnel.

'Raymond. H. L. 1974. Snake River runs ofsalmon and steel head trout: trends inabundance of adults and downstream survivalof Juveniles. Northwest Fisheries CenterNatIOnal Marine Fisheries Service NOAA'Seattle. Wash. Processed rep 6 p , ,'Collins, G. B.. W. J. Ebel, G. E. M~nan, H. L.Raymond, and G. K. Tanonaka. 1975. TheSnake R,ver salmon and steelhead crisis: itsrelation to dmns and the national energy crisis.Northwest F,sheries Center, National MarineF,sheries Service. NOAA. Seattle, Wash.Processed rep., 30 p.

of seaward migrants (Raymond, 1974\and Collins et aI., 19752

). Gas bubbledisease, resulting from high concen­trations of dissolved atmospheric gas(Ebel, 1971), has been described as anadditional cause of mortality of bothjuvenile and adult migrants.

Since 1968, the National MarineFisheries Service (NMFS) has beenconducting experiments to determinewhether transporting valuable stocksof juvenile steelhead trout and Pacificsalmon, Oncorhynchus sp., arounddams on the Snake and ColumbiaRivers could increase their survivalwithout affecting their ability to hometo parent streams (Ebel et al.. 1973;Sliitick et aI., 1975). The fish weretransported in tank trucks containingoxygenated water.

Returning adult steelhead trout fromthese studies were captured and taggedat Little Goose Dam in 1972-73. The

INTRODUCTION

In the past, the lower Snake Riversupported a high quality recreationalfishery for steelhead trout, Salmogairdneri, returning to spawninggrounds in Idaho, Oregon, and Wash­ington. Construction of dams hasnearly eliminated this fishery becausethe fishing gear now used is ineffectivein catching steelhead trout in the poolsabove dams. The recent completion ofLower Granite Dam (February 1975)has inundated a 61 km section of thelower Snake River, further reducingthe area available to the fishery.

In addition to losses to the recrea­tional fishery, dams have altered theriver environment to the detriment ofanadromous fish. Serious declines inthe escapement of adult steelheadtrout to the Snake River drainage in1973-74 have been attributed topassage problems at these dams.particularly turbine-related mortalities

LyleG. Gilbreath, LarryR. Basham,and Emil Slatick are with the North­west Fisheries Center, NationalMarine Fisheries Service, NOAA,2725 Montlake Boulevard EastSeattle, WA 98112. '

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Tag Recoveries

During tagging operations at LittleGoose Dam, 696 and 1,387 adult steel­head trout were tagged in 1972 and1973, respectively.

Tag recoveries from all sources forthe 1972-73 seasons totaled 203 and 334(29.2 and 24.1 percent), respectively.In both seasons, the ranking of areas bynumber of returns were: 1) ClearwaterRiver system, 2) Lower Granite area,3) Salmon River system, and 4) MiddleSnake River. Downriver areas pro­duced a small number of recoveriesfrom spawned-out steelhead trout re­turning to the ocean, primarily duringthe 1972 season. The majority (21.3percent in 1972) of the fish wererecovered from the fishery. The LowerGranite area was the foremost pro­ducer, with 42.6 percent of the totalrecreational catch in 1972 and 37.9percent in 1973. Recoveries from theother major areas ranged from 13.5percent in the Middle Snake River to20.2 percent in the Clearwater Riverduring 1972 and from 8.8 percent in theMiddle Snake River to 23.6 percent inthe Clearwater River during 1973 (Fig.2).

Figure 2. - Recovery (percenta!fe of total catch and numbers of fish) of marked steelhead trouttaken by recreatIOnal anglers in the different river areas, 1972-73.

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Timing of Recoveries

The recovery pattern by month forthe four major catch areas was similarin 1972 and 1973 (Fig. 3). During bothseasons, the Lower Granite and middle

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AREA RIVER SYSTEM SYSTEM RETURNS a OTHERS

Figure 1.-Map of study areas showing the Snake River and its major tributaries.

Most tag returns from the recreationalfishery were assigned to one of fourmajor river areas (Fig. 1):

1. Lower Granite area: LowerGranite Dam to the confluence ofthe Snake and Clearwater Riversat Lewiston, Idaho (about 50 km),thence upstream 10 km on theSnake River and 10 km on theClearwater River.

2. Middle Snake River: About 160km of the Snake River, from 10km above Lewiston to the HellsCanyon Dam.

3. Salmon River system: The SalmonRiver and its tributaries.

4. Clearwater River system: TheClearwater River 10 km above itsmouth and its tributaries.

The division of the river into fourmajor segments enabled us to assesscontributions to the recreationalfishery from the area to be flooded byLower Granite Dam, the mainstreamSnake River, and the Salmon andClearwater River systems.

June 1976

Adult steelhead trout with lower jaw tag and cold brand (top) and cold brand tag (bottom).

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Figure 3.-Recovery (cumulative per­centage) of marked steelhead trout takenby recreational fishers in the different riverareas by month during 1972-73.

AUG.3! SEP.30 OCT.31 N()J.30 D£C.31 JAN.JI FE8.31 MAR,31 APR.3O

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100

The ocean-age composition of steel­head trout tagged at Little Goose Damduring the 1972 season was 54 percentI-ocean, and 46 percent 2-ocean; forthe 1973 season, the composition was40 percent I-ocean, and 60 percent2-ocean. We believe the ocean-agecomposition noted in the 1973 seasonmore nearly represents the usualcomposition of Snake River steelheadtrout. The unusually large percentageof I-ocean fish in 1972 was probablydue to large numbers of smoltswire-tagged in 1971 compared to arelatively small number tagged in 1970(2-ocean returns in 1972). Age com­position among the four areas of therecreational fishery varied consider­ably with the Lower Granite areahaving the highest percentage of2-ocean fish in both 1972 and 1973. TheMiddle Snake River catches had thehighest percentage of I-ocean fish in1972; but in 1973, the Salmon Riverhad the highest percentage of I-oceanfish.

Length and Weight

Length of I-ocean steelhead troutcaptured at Little Goose Dam duringthe 1972-73 seasons ranged from 48 to75 cm (average 62 cm); weight variedfrom 0.9 to 4.5 kg and averaged 2.4 kg.Length of 2-ocean fish ranged from 59to 100 cm (average 82 cm); weightranged from 1.8 to 10.2 kg with anaverage of 5.6 kg. The five 3-ocean fishthat were recovered ranged from 83 to

trout recovered in the Lower Granitearea averaged about 4 weeks at liberty;those in the Middle Snake Riveraveraged nearly 6 weeks; and theSalmon and Clearwater River re­coveries, about 12 weeks of freedombefore capture. The first tags wererecovered in the Lower Granite andMiddle Snake River areas within 4 to 5days from time of release in 1972-73.The first recovery in the Salmon andClearwater River systems was taken in8 days in 1973; however, the averageperiod of freedom was more than 11weeks for fish caught in this area.

Ocean-Age Composition

Nearly all of the steelhead trouttagged at Little Goose Dam during the1972-73 seasons had been at sea foreither 1 or 2 years. Only a smallnumber (less than 0.5 percent of fishtagged) spent 3 years in the ocean.

Snake River recovery distributionswere nearly identical as were thedistributions from the Salmon andClearwater River systems. From 83 to95 percent of recoveries in the LowerGranite area and Middle Snake Riverareas were taken before 1 January; 48to 65 percent of those taken in theSalmon and Clearwater River systemswere recovered during the sameperiod. A substantial percentage ofrecoveries from the Salmon and Clear­water systems (35-52 percent) weretaken after 1 January, as opposed toonly 5-17 percent taken from theLower Granite and Middle Snake Riverareas. The distribution of catch by timereflects the proximity of the fishpopulations to the spawning ground asmaturation approached.

The average days of freedom for fishtaken in a given area were similar forthe 1972 and 1973 seasons. Steelhead

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Lower Granite Dam

No. of Percentage Percentagefish 1-ocean 2-ocean

Table 1.-0cean-age composition of steelhead trout recovered In the dillerent fishingareas and at the little Goose Dam adult separator during the 1972-73 seasons.

Recovery site 1972 1973 1972 1973 1972 1973

Fishing areasLower Gran ile area 62 69 47 22 53 78Middle Snake River 20 16 72 50 28 50Salmon River system 22 41 64 63 36 37Clearwater River system 30 43 63 23 37 77

Total 134 169 58 35 42 65

Liltle Goose Dam 696 1.387 54 40 46 60

June 1976

96 cm in length and weighed from 6.0to 10.4 kg.

The size of fish taken in the sportfishery was essentially the same asthat observed at Little Goose Dam. Itappeared, however, that the averagesize for a given ocean-age group waslarger in areas immediately above thedam (Le., the Lower Granite area andClearwater River) compared to upriverareas such as the Salmon River.

DISCUSSION

Steelhead trout ascending the Clear­water River are known to be predomi­nantly 2-ocean age while those as·cending the Salmon River are I-ocean'.Tag returns during this experimentfurther substantiate these findings

• Pers. commun. with Steve Pettit, Idaho Fishand Game Department. Lewiston, Idaho.

(Table 1). There is obviously somevariation in the ocean-age compositionof steelhead trout ascending the SnakeRiver from year to year. It is ouropinion, however, that the percentageof I-ocean fish we reported for 1972was unusually high for all areasbecause only a small number of smoltswere marked in 1970 (the 2-ocean yearclass). Steelhead trout recovered fromthe Clearwater River and the LowerGranite area were of the same generalage (mostly 2-ocean), suggesting thatthe Lower Granite area was a majorholding area for those fish destined forthe Clearwater River.

A major part of the Lower Granitearea is an interstate fishing area; thatis, it is readily accessible and legallyfished by residents of both Washingtonand Idaho. Fishery managementproblems may emerge with the virtual

removal of this section of river fromthe fishery. For example, it nowappears that Washington anglers willnot be successful (Tri-State Steel­headers Inc., 1970) in catching highly­prized Clearwater River-bound steel­head trout as in the past, because the

entire Snake River downstream fromthe Clearwater River is now a reser­voir. Assuming that fish populations

are restored to pre-I973 levels, moresteel head trout will be available toanglers in both Clearwater and SalmonRiver drainages in Idaho. Managementprograms in these areas (especially theClearwater River) may have to bemodified to adjust for increased fishingpressure if the Lower Granite fisheryshifts to the Clearwater River.

Tag loss from the rigors sustained bythe fish during migration and thenonresponse of anglers catching taggedfish are factors affecting observedrecovery rates. Butler (1962) stressednonresponse, concluding that anglerinterest and recovery efforts by the

tagging agency were of primary im­portance. Creel census effort in thisstudy was not a factor because themajority of tags were returned volun­tarily. Lacking estimates of tag lossand the factor of nonresponse in ourstudies, the recovery rates reportedshould be considered minimal.

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ACKNOWLEDGMENTS

The authors wish to thank thefisheries biologists and hatchery per­sonnel from the Idaho Fish and GameDepartment and the Bureau of SportFisheries and Wildlife. who assisted inrecovering tags at hatcheries and inthe fishery. We are especially gratefulto the many anglers who returned tagsand provided us with essential data forthis study.

LITERATURE CITED

Butler. R. L. 1962. Recognition and return oftrout taRs by California anglers. Calif. FishGame 48:5-18.

Ebel, W. J. 1971. Dissolved nitrogen concen­trations in the Columbia and Snake Rivers in1970 and their effect on chinook salmon andsteel head trout. U. S. Dep. Commer.,NOAA Tech. Rep. NMFS SSRF-646, 7 p.

---;_.,----.;.1974. Marking fishes and inverte­brates. III. Coded wire tags useful in auto­matic recovery of chinook salmon and steel­head trout. Mar. Fish. Rev. 36{7l:10-13.

Ebel, W. J., D. L. Park, and R. C. Johnsen.1973. Effects of transportation on survivaland homing of Snake River chinook salmon

and steelhead trout. Fish. Bull., U. S.71 :549-563.

Jefferts, K. B., P. K. Bergman, and H. F.Fiscus. 1963. A coded wire identificationsystem for macro-organisms. Nature (Lond.)198:460-462.

Mighell, J. L. 1969. Rapid cold-branding ofsalmon and trout with liquid nitrogen. J.Fish. Res. Board Can. 26:2765-2769.

Slatick, E., D. L. Park, and W. J. Ebel. 1975.Further studies regarding effects of trans·portation on survival and homing of SnakeRiver chinook salmon and steelliead trout.Fish. Bull., U. S. 73:925-931.

Tri-State Steelheaders, Inc. 1970. Steelheadfishing method study: Lake Sacajawea,WashIngton. Tri-State Steel headers, Inc.,Walla Walla, Wash., 57 p.

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MFR Paper 1189. From Marine Fisheries Review, Vol. 38, No.6, June1976. Copies 01 this paper, in limited numbers are available Irom 0825,Technical Inlormation Division, Environmental Science InlormationCenter, NOAA, WaShington, DC 20235. Copies 01 Marine FisheriesReview are available Irom the Superintendent 01 Documents, U.S.Government Printing Office, Washington, DC 20402 lor $1.10 each.

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