California Sea Grant College Program

It sounds crazy, exercising fish to make them gain weight. But that is exactly what happens with juvenile California yellowtail, a once common species off California and Mexico fished heavily by the Japanese. Not surprisingly, given parallels with human health, ex- ercise also alleviates stress in fish, as measured by bloodstream levels of cortisol, the same stress hormone in humans. The findings have led a California Department of Fish and Game biologist to consider rearing juvenile endangered salmon in raceways, in the hopes of boosting their post-release survival.