ABSTRACT:
One captive broodstock strategy being used in the management of Pacific salmon involves capturing juveniles, rearing them to maturity in captivity, and releasing them to spawn naturally with returning wild adults; however, captively-reared fish typically do not exhibit many of the physical characteristics of sexually mature adults. Since salmon compete for mates in a courtship ritual, it is not clear whether such fish would successfully mate with wild fish. In one experiment, captively-reared adult coho salmon were placed in experimental channels with an equal number of wild-caught adults. The fish were allowed to court and spawn undisturbed. Microsatellite genotyping of the resulting progeny was used to evaluate reproductive success of the two groups. We were able to assign over 98% of the progeny examined to single pair matings. The variance in reproductive success among individuals was quite high. Because all potentially spawning parents were known and their number was limited (20 per channel), the number of loci needed to determine individual pedigrees was minimal (from 3-5); however, we also genotyped additional individuals from the adult source populations and performed simulations to examine how many loci might be necessary to perform such an analysis with a larger population.