Avoidance Responses of Salmon and Trout to Air-Supersaturated Water

Coho (Oncorhynchus kisutch), sockeye (O. nerka), and chinook (O. tschawytscha) salmon smolts, and rainbow trout (Salmo gairdneri) avoided air-supersaturated water when tested in a shallow round tank. Steelheads (S. gairdneri) did not consistently avoid the supersaturated water and died from gas bubble disease. The salmon and rainbow trout generally avoided 145 and 125% saturation but did not always avoid 115%. Territorial activity reduced avoidance by steelheads and rainbow trout.