Snake River Fall Chinook Salmon Brood-Stock Program, 1981-1986 Final Report of Research.

Abstract

The objective of the Snake River Fall Chinook Salmon Brood-stock Program was to hatch eggs from upriver stocks, rear the fish to spawning maturity, and use the resulting eggs for stock restoration in the Snake River. Approximately 15,000 eyed Snake River fall chinook salmon eggs were obtained each winter in 1981, 1982, 1983, and 1984 from various Columbia River hatcheries. Fish from these eggs were reared in dechlorinated City of Seattle water at the Northwest and Alaska Fisheries Center or in constant 10.5/degree/C groundwater at the University of Washington's Big Beef Creek Research Station. Seawater tolerance trials of 0+ age (3--5 months) juveniles in all four brood stocks were strongly suggestive of the 1+ age smoltification pattern of spring chinook salmon. Attempts to transfer 0+ age fish to marine net-pens at the Manchester Marine Experimental Station were unsuccessful during the four brood years. The only Snake River fall chinook salmon that demonstrated acceptable survival after 4 months residence in seawater were fish that were transferred as 1+ age smolts. After smolts were successfully transferred to seawater, losses were minimal for several months. However, in all Snake River chinook salmon stocks, mortality due to bacterial kidney disease (BKD) and a previously undescribed ''rosette disease'' resulted in very few maturing fish at 4 or 5 years of age. 5 refs., 7 figs.