GENETIC CHANGES IN THE GROWTH OF COHO SALMON (ONCORHYNCHUS-KISUTCH) IN MARINE NET-PENS, PRODUCED BY 10 YEARS OF SELECTION

A 10-year selection and breeding program with coho salmon was conducted to improve traits of primary importance to the saltwater net-pen industry. After four generations, this program has produced two pedigreed lines (maturing in odd- and even-years) which have shown a greater than 60% improvement in weight. Heritabilities (h2) for weight after 8 months of rearing in marine net-pens, as determined by ANOVA, remained high, even in later generations (h2≈0.20). Realized heritabilities for this trait in the odd- and even-year broodstocks were exceptionally high, 1.22±0.32 and 0.81±0.30, respectively. The discrepancies between realized h2 and h2 derived from familial relationships suggest that significant "domestication" selection is being exerted by the production system. The results indicate that a long-term selection program on coho salmon could produce large improvements in performance without dramatically reducing genetic variation. © 1990.