Thomas E. Nickelson

Transportation stress affects performance of coho salmon, Oncorhynchus kisutch

Abstract Transportation of yearling coho salmon ( Oncorhynchus kisutch ) from their hatchery by trucking caused a marked physiological stress response, as judged by elevations in concentrations of circulating cortisol. Survivorship, as determined by recoveries of adults at sea and at the hatchery, was reduced in fish not given adequate time to recover from this transportation stress before they were released into their migratory stream. Elevated concentrations of plasma cortisol indicated reduced relative fitness of the stressed fish, as evidenced by the lower survival rates to adulthood for fish liberated while their circulating cortisol titers were still high.

Effects on Survival and Homing of Trucking Hatchery Yearling Coho Salmon to Release Sites

Abstract Effects of transporting yearling coho salmon Oncorhynchus kisutch to release sites in Oregon coastal river systems were determined by comparing survival of fish transported before release to that of fish released without being transported. Ocean catches of fish transported before release ranged from 43 to 113% of those for control fish within years. Over 4 years, ocean catches of fish trucked and returned to the hatchery for release, trucked and released upstream from the hatchery, and trucked and released in a tributary downstream from the hatchery averaged 76, 83, and 84% of ocean catches of untrucked fish. For yearling coho salmon trucked to another Oregon coastal river system for release, fish acclimated at the release site for 6 weeks before release showed consistently higher survival than groups released immediately upon arrival at the release site. Almost all returning adult fish released as yearlings at a site 23 km upstream from the rearing hatchery returned to the rearing site, whereas ...