Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8248
Title: Multi-population analysis of Puget Sound steelhead survival and migration behavior
Author: M. E. Moore, B. A. Berejikian, Fred A. Goetz, Andrew G. Berger, Sayre S. Hodgson, E. J. Connor, T. P. Quinn
Publication Year: 2015
Journal: Marine Ecology Progress Series
Keywords: steelhead,smolts,telemetry,migration,survival,
Abstract:

Until recently, research on mortality of anadromous fishes in the marine environment was largely limited to estimates of total mortality and association with aspects of the group, or the environment. Miniaturization of sonic transmitters now allows estimates of survival in discrete marine habitats, yielding important information on species of conservation concern. Telemetry studies of steelhead (Oncorhynchus mykiss) smolts in Puget Sound, Washington, U.S.A. indicated that approximately 80% of fish entering marine waters did not survive to the Pacific Ocean. This level of early marine mortality may limit recovery of threatened Puget Sound steelhead. The present study re-examined data from previous research and incorporated data from additional Puget Sound populations tagged during the same time period (2006-2009) for a comprehensive analysis of steelhead early marine survival. We used mark-recapture models to examine the effects of several factors on survival of smolts, and to identify areas of Puget Sound where mortality rates were highest. Wild smolts had higher survival probabilities in general than hatchery smolts, though there were exceptions, and wild smolts migrating in early April and late May had a higher probability of survival than those released in early and mid-May. Steelhead smolts suffered greater instantaneous mortality rates in the central region of Puget Sound and from the north end of Hood Canal through Admiralty Inlet than in other monitored migration segments. With this information we can begin to identify specific locations associated with high rates of mortality and the mechanisms responsible.

Description:

 This study compiles acoustic telemetry data from several hatchery and wild Puget Sound steelhead populations during outmigration years 2006-2009. Mark recapture models are used to estimate survival from release to the Strait of Juan de Fuca and through discrete segments along the migration path, and to investigate factors affecting survival. Travel times and travel rates of migration through Puget Sound are also presented and compared between Puget Sound regions.

Theme: Recovery and rebuilding of marine and coastal species
Foci: Characterize the population biology of species, and develop and improve methods for predicting the status of populations.