Maturation success of pink salmon ( Oncorhynchus gorbuscha) and coho salmon ( O. kisutch) held under three salinity regimes

Adult pink salmon ( Oncorhynchus gorbuscha) and coho salmon ( Oncorhynchus kisutch) were held in freshwater, seawater (28–32%%.), and in an estuary (24–31‰ with a low-salinity surface lens) to determine the effects of salinity on survival to spawning and gamete viability. Gamete viability was determined by individual matings. Samples of blood plasma and gonadal fluids were analyzed for osmolality and potassium. Capture location of the brood fish affected time of spawning and maturation success. The low-salinity lens in the estuary eliminated or reduced the detrimental effects on final maturation of pink salmon and coho salmon in seawater. Viability of gametes from pink salmon was inversely correlated to blood plasma osmolality of males and females, osmolality and potassium concentration of ovarian fluid, and blood-plasma potassium concentration of males. Viability of gametes of coho salmon was inversely correlated with the osmolality of blood plasma, ovarian fluid, and seminal fluid.