MARINE DISTRIBUTION AND SIZE OF JUVENILE PACIFIC SALMON IN SOUTHEAST ALASKA AND NORTHERN BRITISH-COLUMBIA

Distribution and size during their first summer at sea were determined for juvenile salmon (Oncorhynchus spp.) caught in oceanic waters off northern British Columbia and Southeast Alaska, and in marine waters within the Alexander Archipelago of Southeast Alaska. More than 10,000 juvenile salmon were caught in 252 purse-seine sets during August 1983, July 1984, and August 1984. Distribution was patchy; juvenile salmon were highly aggregated, rather than dispersed randomly. Distribution and size of pink salmon (O. gorbuscha), sockeye salmon (O. nerka), and chum salmon (O. keta) were similar but differed from coho salmon (O. kisutch). Chinook salmon (O. tshawytscha) were excluded from most analyses because few were caught. Sizes were consistent with the concept that juvenile salmon in more northern and seaward locations had been at sea longer than those in more southern and inshore locations. Juvenile salmon migration up the Pacific coast did not peak in abundance off Southeast Alaska until August; movement from inside to outside waters was not complete by the end of August. The migration band of juvenile salmon in outside waters of Southeast Alaska extended beyond the continental shelf to at least 74 km offshore, twice the distance previously reported.