An investigation of the biological basis of return variability for sockeye salmon (
We tested whether variations in stock characteristics (spawner and smolt abundance) and biotic conditions (prey variability, predation, competition) during the early marine period explained variations in the return of sockeye salmon (Oncorhynchus nerka) to Great Central and Sproat lakes, adjacent lakes on the west coast of Vancouver Island. There are two freshwater age groups in each lake; fish spend 1 or 2 yrs in freshwater after hatching. We tested the influences of stock and biotic factors on the return of each of the two age groups from each of the two lakes. Results of regression analyses showed that prey biomass variability best explained the variation in return for all lake‐age groups. Euphausiid (Thysanoessa spinifera) and cladoceran (Evadne) prey biomass variability explained between 0.75 and 0.95 (adjusted R 2) of the variation in return. There appear to be instances of a mismatch between the seasonality of prey productivity and the apparent critical period of feeding for juvenile sockeye.
Document Type: Research Article
Affiliations: 1: Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada 2: Department of Statistics and Actuarial Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
Publication date: 2011-11-01