Seasonal Habitat Use and Early Marine Ecology of Juvenile Pacific Salmon in Southeastern Alaska

Habitat use and early marine ecology of juvenile (age-.O) Pacific salmon (Oncorhynchus spp.) were studied monthly at inshore, strait, and coastal habitats along a seaward migration corridor in southeastern Alaska from May through October 1997-99. A total of 31 ,853 fish from 40 taxa were captured with 283 surface trawl hauls; juvenile salmon made up 61 % of the total catch. Predation on juvenile salmon was observed in 4 of 19 fish species examined, and occurred in 33 (5%) of the 661 predators examined. Juvenile salmon catches typically peaked in June and July and in strait habitats, where two Alaska hatchery chum salmon (0. ketal stocks made up > 50% of the chum salmon sampled. Of the juvenile chinook salmon (0. tshawytscha) and coho salmon (0. kisutch) stocks of known origin, marine migration rates averaged 1 and 3 km/d for Alaska stocks and 19 and 29 km/d for Columbia River Basin stocks. Our results imply that seasonal habitat use patterns of juvenile salmon are related to favorable temperatures and zooplankton abundance and are also linked to species and stock of salmon. Long-term ecological monitoring of key juvenile salmon stocks is needed over varying environmental conditions to understand relationships among habitat use, marine growth, yearclass strength, and ocean carrying capacity.