Abstract

The Highseas Salmon program of Fisheries and Oceans Canada conducted a survey of Pacific salmon in the Gulf of Alaska from June 20-July 5, 2007 on the CCGS W. E. Ricker. The objectives of the survey were to (1) evaluate the distribution and ecology of juvenile Pacific salmon (Oncorhynchus spp.) during their first year in the ocean, (2) describe the ambient oceanographic conditions, and (3) quantify the biomass of zooplankton. Fish, oceanographic, and zooplankton sampling was conducted at stations ranging from the west coast of Vancouver Island to Baranof Island off Southeast Alaska (56.3° N).

A total of 5820 Pacific salmon were caught on this summer survey. Of these, 53 were juvenile pink salmon (O. gorbuscha), 2413 were juvenile chum salmon (O. keta), 1093 were juvenile sockeye salmon (O. nerka) and 795 were juvenile coho salmon (O. kisutch) in their first summer (age X.0) in the ocean and 196 were juvenile chinook salmon (O. tshawytscha) under 300 mm in fork length. Juvenile pink catches were very low which may be consistent with low Fraser River smolt output in odd years, or perhaps the survey was too early to intercept the out-migration of smolts into Queen Charlotte Sound and Hecate Strait. Juvenile chum, sockeye, coho and chinook were caught on the shelf throughout the range of the survey. Juvenile coho were also caught on 4 tows at relatively very high rates in Quatsino Channel and Neroutsos Channel on the west coast of Vancouver Island. These juvenile coho were considerably smaller that those on the shelf, and is possible they had not yet reached some critical size that might trigger an exodus.

On this survey, 40 juvenile chinook with CWT’s were recovered that originated from the Columbia-Snake River watershed, 16 juvenile coho with CWT’s were recovered that originated from Oregon, Washington, British Columbia, and Southeast Alaska, and one juvenile sockeye with a CWT was recovered in Dixon Entrance that originated from Red Lake in the Snake River watershed in Idaho. The CWT recovery patterns revealed that a significant proportion of juvenile chinook from the Columbia-Snake River, and juvenile coho from coastal Oregon, Washington, and British Columbia stocks undertake a rapid northward migration to Southeast Alaska along the shelf in their first year at sea, and that the juvenile chinook migration stream bifurcates around the Queen Charlotte Islands.