Journal
DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY
Volume 56, Issue 24, Pages 2560-2569Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.dsr2.2009.03.006
Keywords
Pink salmon; Juvenile coho salmon; Harvest; Growth rate; Size; Body condition
Categories
Funding
- NOAA
- US GLOBEC Northeast Pacific program
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Coho salmon (Oncorhynchus kisutch) are a vital component in the southeast Alaska marine ecosystem and are an important regional fishery resource; consequently, understanding mechanisms affecting their year-class strength is necessary from both scientific and management perspectives. We examined correlations among juvenile coho salmon indices, associated biophysical variables, and adult coho salmon harvest data from southeast Alaska over the years 1997-2006. We found no relationship between summer indices of juvenile coho salmon growth, condition, or abundance with subsequent harvest of adult coho salmon in the region. However, using stepwise regression, we found that variation in adult coho salmon harvest was largely explained by indices of juvenile pink salmon (Oncorhynchus gorbuscha) abundance (67%) and zooplankton abundance (24%). To determine if high juvenile pink salmon abundance indicates favorable bottom-up lower trophic level environmental conditions for juvenile coho salmon, we plotted abundance of juvenile pink salmon against growth and condition of juvenile coho salmon. No change in growth or condition of juvenile coho salmon was observed in relation to the abundance index for juvenile pink salmon. Therefore, we hypothesize that coho salmon year-class strength in southeast Alaska is influenced by a top-down predator control mechanism that results from more abundant juvenile pink salmon, which serve as a predator buffer during early marine residency. Published by Elsevier Ltd.
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