Quantifying juvenile salmon prey quality and feeding

Investigators: Julie Keister (U. of Washington), Dave Beauchamp (USGS)

Variability in juvenile feeding and growth can strongly influence overall salmon marine survival, but little data exist on Puget Sound prey quality and energy composition. Two research studies are analyzing the quality of prey items for juvenile salmon in Puget Sound, and how changes in prey densities and quality impact juvenile salmon feeding responses. Fatty acid content and composition, wet and dry weight, and caloric content are being measured for key zooplankton taxa and juvenile herring to assess their food quality for juvenile salmon. Laboratory experiments determine juvenile Chinook salmon response to variable densities of crab larvae, a key prey item; these data are paired with field data on spring-summer prey densities and Chinook feeding to examine how prey changes influence growth.

In the Salish Sea, juvenile salmon eat large quantities of larval crab. Photo credit Matt Hagen.