327 Early marine ecology of juvenile chum salmon in Kuskokwim Bay, Alaska

Here we present results on spatial and temporal patterns of estuarine distribution, diet, and condition of chum salmon juveniles in 2003 and 2004 in Kuskokwim Bay. In addition, we used spatially-explicit foraging/bioenergetic modeling to assess the growth potential of Kuskokwim Bay habitats for outmigrating juvenile chum salmon in 2004, based on an intensive field sampling program in that year. Based on zooplankton abundance, water temperatures and turbidity, we modeled growth potential for small and large juveniles outmigrating early, in the middle and towards the end of the season.

Our results provide the first data on timing of outmigration and estuarine distribution of chum salmon in relation to seasonally and spatially changing environmental conditions in Kuskokwim Bay. In addition, we determined seasonal and spatial patterns in diet and energy density of juvenile chum salmon and estimated the post-emergence age and duration of residence for chum salmon juveniles in Kuskokwim Bay.

Our results indicate that timing of outmigration may be of high importance for the condition, growth, and subsequent survival probability. Further research is needed to more closely examine the role of changing environmental conditions, on estuarine residence, condition, and growth of juvenile salmonids in Kuskokwim Bay, particularly in light of the observed changing climatic conditions in the Bering Sea.