ABSTRACT
Although salmon supplementation and conservation programs often use hatchery fish, there is a lack of empirical knowledge about their behavior, ecology and reproductive success in the wild. We now present the results of several experiments in which we studied their behavior and ecology and quantified their reproductive success. Both wild and hatchery coho salmon were allowed to freely breed within a spawning channel in the wild. The behaviors and interactions of the fish were recorded and after all spawning had been completed we collected the alevins from the nests. Using microsatellite genetic markers, we determined the parentage, including maternity and paternity, of the fish. Several important relationships emerged, including that between male position in the mating hierarchy and paternity, between male size and reproductive success, between stock type (hatchery or wild) and paternity, and between mating partner and success. Overall, hatchery males attended fewer mating hierarchies, obtained lower paternity within a position, and made up only about a third of the male contribution to the next generation. Hatchery females were also significantly less successful than wild females. Hatchery fish were therefore relatively maladapted and decreased the wild population’s effective population size. Finally, our measures of reproductive success within hierarchies may be widely applicable to studies of salmon in the field. This research is supported by NSERC and DFO of Canada, and NINA of Norway.