Document Detail

Recent salmon declines: a result of lost feeding opportunities due to bad timing?
MedLine Citation:
PMID:  20805978     Owner:  NLM     Status:  MEDLINE    
As the timing of spring productivity blooms in near-shore areas advances due to warming trends in global climate, the selection pressures on out-migrating salmon smolts are shifting. Species and stocks that leave natal streams earlier may be favoured over later-migrating fish. The low post-release survival of hatchery fish during recent years may be in part due to static release times that do not take the timing of plankton blooms into account. This study examined the effects of release time on the migratory behaviour and survival of wild and hatchery-reared coho salmon (Oncorhynchus kisutch) using acoustic and coded-wire telemetry. Plankton monitoring and near-shore seining were also conducted to determine which habitat and food sources were favoured. Acoustic tags (n = 140) and coded-wire tags (n = 266,692) were implanted into coho salmon smolts at the Seymour and Quinsam Rivers, in British Columbia, Canada. Differences between wild and hatchery fish, and early and late releases were examined during the entire lifecycle. Physiological sampling was also carried out on 30 fish from each release group. The smolt-to-adult survival of coho salmon released during periods of high marine productivity was 1.5- to 3-fold greater than those released both before and after, and the fish's degree of smoltification affected their downstream migration time and duration of stay in the estuary. Therefore, hatchery managers should consider having smolts fully developed and ready for release during the peak of the near-shore plankton blooms. Monitoring chlorophyll a levels and water temperature early in the spring could provide a forecast of the timing of these blooms, giving hatcheries time to adjust their release schedule.
Cedar M Chittenden; Jenny L A Jensen; David Ewart; Shannon Anderson; Shannon Balfry; Elan Downey; Alexandra Eaves; Sonja Saksida; Brian Smith; Stephen Vincent; David Welch; R Scott McKinley
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-08-27
Journal Detail:
Title:  PloS one     Volume:  5     ISSN:  1932-6203     ISO Abbreviation:  PLoS ONE     Publication Date:  2010  
Date Detail:
Created Date:  2010-08-31     Completed Date:  2010-11-04     Revised Date:  2013-05-28    
Medline Journal Info:
Nlm Unique ID:  101285081     Medline TA:  PLoS One     Country:  United States    
Other Details:
Languages:  eng     Pagination:  e12423     Citation Subset:  IM    
Department of Arctic and Marine Biology, University of Tromsø, Tromsø, Norway.
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MeSH Terms
Animal Feed*
Animal Migration
Fisheries / statistics & numerical data*
Gastrointestinal Contents
Oceans and Seas
Population Dynamics
Survival Rate
Time Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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