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Genetic stock identification (GSI) is used extensively in fisheries applications and otolith isotopic composition ( 87 Sr/ 86 Sr) can be used to identify provenance in freshwater and anadromous species; however, each approach has inherent limitations. The potential to combine these methodologies to improve discrimination among populations has yet to be realized. In this study, GSI was combined with information from otolith 87 Sr/ 86 Sr and artificial tags (Coded Wire Tags, CWTs) to: (1) determine the stock composition of a Chinook salmon ocean terminal area fishery conducted near the mouth of the Elk River in southern Oregon, U.S.A. and resolve intractable discrimination between hatchery and naturally spawned fish; and (2) evaluate the efficacy of a spatial management boundary designed to maximize collection of Elk River hatchery fish and minimize collection of naturally spawned fish from the adjacent Sixes River. A test fishery was established within two experimental areas: (1) a traditionally open, southern fishing area (SFA); and (2) a traditionally closed, northern fishing area (NFA). There were four potential sources of Chinook salmon within each area. GSI, otolith 87 Sr/ 86 Sr, and CWT data were used in a hierarchical manner to estimate the proportions of fish within each fishing area that were: (1) from outside of the Elk and Sixes Rivers (mean = 0.118 and 0.074 for the SFA and NFA, respectively); (2) produced at the Elk River hatchery (0.377 and 0.372); (3) naturally spawned in the Sixes River (0.254 and 0.278); and (4) naturally spawned in the Elk River (0.251 and 0.277). As stock composition was similar in the two areas, the spatial boundary appears to be an ineffective conservation tool. The combination of genetic and ecological markers can improve mixture estimates and generate information at scales more relevant to conservation and management efforts.

Pacific ocean perch, Sebastes alutus, stocks in the northeastern Pacific Ocean off the coasts of Oregon, Washington, and British Columbia experienced severe damage from overexploitation in the mid-1960's. Catch limits were imposed during 1978. Fishermen questioned the need for these limitations on the basis of lack of precision in biomass estimates provided by research surveys and because of the recruitment of a relatively strong 1970 year class. To respond to these concerns and to provide an updated biomass estimate with better precision than for previous estimates, a trawl survey was conducted between 22 March and 2 May 1979. The survey was designed and conducted jointly by the Northwest and Alaska Fisheries Center of the National Marine Fisheries Service, the Washington Department of Fisheries, and the Oregon Department of Fish and Wildlife with the primary objective of obtaining information needed for improved management of this species. The objective was attained through stratification of th...

Plasma corticoid concentrations in juvenile chinook salmon (Oncorhynchus tshawytscha) netted and confined in a small live-cage rose from approximately 100 ng/ml to about 500 ng/ml in 24 h, then fell to 250 ng/ml at 48 h. In juvenile chinook salmon dip netted into a bucket containing aerated water and sampled serially at 90-s intervals, plasma corticoids increased from < 10 ng/ml to approximately 100 ng/ml in 20 min. In juvenile cutthroat trout (Salmo clarki clarki) acclimated to 13 C and subjected to a rapid increase in water temperature to 26 C, plasma corticoid concentration increased from about 20 ng/ml to 70 ng/ml in 25 min and remained elevated for more than 3 h. Juvenile cutthroat trout acclimated to diurnal temperature cycles (13–23 C) had no substantial changes in plasma corticoid concentration throughout the cycles. Juvenile cutthroat trout acclimated to 23 C had the same initial corticoid concentration as cutthroat trout acclimated to 9 C. When both groups were subjected to identical ne...