Project Description

Chum salmon are the most widely distributed Pacific salmon in Alaska; however, few studies have examined their early marine life history. Further, chum salmon exhibit lower genetic divergence than other Pacific salmon, thereby reducing reliable stock delineation using standard genetic methods which have historically been used for resolving stock mixtures for salmonids. The objectives of this study were to examine the utility of using otolith elemental analysis to examine the early marine ecology of juvenile chum salmon and determine the feasibility for differentiating among and within-region variability of fish collected from the Chukchi Sea (wild origin), North Bering Sea (wild origin), and Southeastern Alaska (Icy Straight; wild versus hatchery origin). Elemental concentrations (particularly Strontium and Barium) along otolith transects provided a clear indication of the timing of ocean entry. Consistent peaks in Strontium concentration at the otolith core were indicative of maternal effects, the magnitudes of which have shown to serve as a proxy for parental female duration spent in freshwater prior to spawning. Based on the otolith element composition associated with early life history in freshwater, accuracy of discrimination from neighboring regions was relatively high (mean = 85.8%). In contrast, the ability to discriminate fish among sites within a region was relatively poor (mean = 28.7%). These results suggest regional separation among chum salmon stocks, but a mixed-stock assemblage within regions. Hierarchical cluster analysis of otolith elemental composition revealed distinct groups of individuals that were independent of location, further supporting the mixing of stocks within regions.

Project Funding

Bureau of Ocean Energy Management (BOEM)
Amount: $21,005
Start Date: 2012-05-00
End Date:2016-05-00

 

 

Research Team