Genetic differences among year classes in a hatchery population of coho salmon (Oncorhynchus kisutch (Walbaum, 1792)) in Chile

Coho salmon (Oncorhynchus kisutch (Walbaum, 1792)) was first introduced int o Chile from the USA in 1930 and has become an important species for aquacu lture. The current Chilean coho salmon aquaculture industry is largely base d on eggs imported from the Pacific Northwest. In order to reduce dependenc e on North America for seed and to improve genetically coho salmon stock in Chile, the Instituto de Fomento Pesquero and the University of Chile start ed a breeding program at the Coyhaique Hatchery, Region XI of Chile. The ge netic variability in two groups of broodstock was determined by horizontal starch gel electrophoresis of allozymes. Twenty-six enzyme systems, represe nting 51 loci, were resolved. Seven loci were variable (P = 13.7%) and a me an heterozygosity (Hi) of 0.007 was estimated. Results indicated a reductio n in polymorphism, but not in heterozygosity, with respect to information i n the literature on other stocks of coho salmon. The most likely explanatio n for the results is the occurrence of founder effects while establishing t he base population in the hatchery. (C) 1999 Elsevier Science B.V. All righ ts reserved.