Effect of Prudhoe Bay Crude Oil on the Homing of Coho Salmon in Marine Waters

Abstract

Abstract Resource managers and the fishing industry have expressed concern that a crude-oil spill occurring in the pathway of a salmon run may destroy the ability of the maturing salmon to reach the home stream. To address this concern, groups of mature 3-year-old and precocious 2-year-old coho salmon Oncorhynchus kisutch were tagged and exposed in seawater for 1 h to sublethal concentrations of Prudhoe Bay crude oil, dispersed oil, or seawater oil dispersant alone, and then were released in seawater about 5 km from their home stream. The results show that the coho salmon's homing success and speed of return to the home stream were not affected by any of the treatments. The longevity or holding tests, in which coho salmon were held in saltwater net-pens after experimental treatments, showed that the larger 3-year-old coho salmon were more sensitive to the stress of confinement than the smaller 2-year-old fish.