North Pacific Anadromous Fish Commission

Technical Report 15

Table of Contents

Spatial and Temporal Trends in Juvenile Sockeye Salmon Diets across Oceanographic Regimes on the Coast of British Columbia

Authors:
Samantha E. James, Evgeny A. Pakhomov, and Brian P.V. Hunt

Abstract Excerpt:
The Fraser River watershed is one of the world’s largest sockeye salmon (Oncorhynchus nerka) producers. However, productivity in several populations has declined since the early 1990’s (Peterman and Dorner 2011). It is believed that bottom-up environmental conditions and trophic interactions during the juvenile salmon early marine migration are contributing factors (Beamish and Mahnken 2001; Aydin et al. 2005; Ware and Thomson 2005; Farley and Trudel 2009). The phenology of bottom-up oceanographic processes and of the juvenile salmon outmigration are intrinsically linked (Chittenden et al. 2010; Malick et al. 2015). Indeed, the timing and size of the spring phytoplankton bloom has been demonstrated to be significantly correlated with salmon productivity (Malick et al. 2015). Furthermore, marine survival has been found to be higher when the juvenile marine outmigration overlaps with periods of high prey abundance (Chittenden et al. 2010). Long term changes to zooplankton assemblages in the Strait of Georgia have been observed (Johannessen and Macdonald 2009; Li et al. 2013), potentially impacting both the quality and quantity of prey along the juvenile salmon migratory route. Changes in the prey community may therefore explain the variability of sockeye salmon survival and returns to the Fraser River in British Columbia in recent years.

*This is the first paragraph of an extended abstract. Download the full abstract below.

DOI:
https://doi.org/10.23849/npafctr15/85.89.

Citation

James, S.E., E.A. Pakhomov, and B.P.V. Hunt.  2019.  Spatial and temporal trends in juvenile sockeye salmon diets across oceanographic regimes on the coast of British Columbia.  N. Pac. Anadr. Fish Comm. Tech. Rep. 15: 85–89.  https://doi.org/10.23849/npafctr15/85.89.