Mate Choice in Coho Along the Umpqua River, Oregon USA

It has been shown that hatchery fish have lower reproductive success (RS) than wild fish when breeding in the wild and that there is a carry-over effect from hatchery bred fish to subsequent generations of wild populations. One causal mechanism that has been suggested to result in reproductive differences between wild and hatchery fish is mate choice. A pedigree study of coho from the Umpqau River in Oregon, offers a valuable opportunity to evaluate this mechanism. Mate choice can be examined in fish populations by assessing allelic variation in the Major Histocompatibility Complex (MHC) and other immune-related genes. Because immune-related genes play a significant role in combating pathogens, they are under strong selective pressure. As a result, identifying patterns of genetic variation in these genes can be used as an approach to assess mate choice. By examining pedigree data of wild and hatchery coho from the Umpqua River, patterns of allelic variation can be analyzed in immune-related genes from mated pairs and their offspring. These genetic patterns can then be assessed in terms of the reproductive success (RS) of those matings as a means of gauging fitness. The examination of mate choice in wild and hatchery coho populations will allow a better understanding of what role mate choice plays in fitness (where information on RS of respective populations is already known). This insight can then be applied in understanding hatchery and wild interactions and ultimately benefit hatchery management. Further detail on methodologies and current findings will be presented.