Mate Choice of Wild Spawning Coho in the Umpqua River, Oregon

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 and also among individuals of each type is mate choice. A pedigree study conducted on coho salmon from the Umpqua River, 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-relevant gene-linked markers. Because immune-relevant genes play a significant role in combating pathogens, they are under strong selective pressure. As a result, identifying patterns of genetic variation among mate pairs in these gene-linked markers can be used as an approach to assess mate choice. By examining pedigree data of wild spawning coho of hatchery and wild origin from the Umpqua River, patterns of allelic variation can be analyzed in immune-relevant gene-linked markers of mated pairs. These genetic patterns can then be assessed in terms of the reproductive success (RS) of those matings as a means of gauging fitness. Examining mate choice in wild spawning hatchery and wild coho populations will allow a better understanding of what role mate choice may contribute to an individual’s fitness.