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

Abstract

Coho salmon ( Oncorhynchus kisutch (Walbaum, 1792)) was first introduced into Chile from the USA in 1930 and has become an important species for aquaculture. The current Chilean coho salmon aquaculture industry is largely based on eggs imported from the Pacific Northwest. In order to reduce dependence on North America for seed and to improve genetically coho salmon stock in Chile, the Instituto de Fomento Pesquero and the University of Chile started a breeding program at the Coyhaique Hatchery, Region XI of Chile. The genetic variability in two groups of broodstock was determined by horizontal starch gel electrophoresis of allozymes. Twenty-six enzyme systems, representing 51 loci, were resolved. Seven loci were variable ( P=13.7%) and a mean heterozygosity (Hi) of 0.007 was estimated. Results indicated a reduction in polymorphism, but not in heterozygosity, with respect to information in the literature on other stocks of coho salmon. The most likely explanation for the results is the occurrence of founder effects while establishing the base population in the hatchery.