GENETIC-PARAMETERS OF SIZE PRE-SMOLTIFICATION AND POST-SMOLTIFICATION IN COHO SALMON (ONCORHYNCHUS-KISUTCH)

Size and growth rate are important traits for cultured salmonids in both farming and enhancement operations. This study investigated the heritabilities and the genetic correlations for size pre- and post-smoltification and the genetic effects on specific growth rate in two different year class populations of coho salmon (Oncorhynchus kisutch) from the University of Washington stock. One population was transferred to saltwater at smoltification, while the other was maintained in freshwater. Estimates of heritability for size parameters were moderate to high pre-smoltification (0.5 to 0.7), and lower in post-smoltification samples (0.2 to 0.5), particularly for the population moved to saltwater. The effect of maternal egg size on growth was significant in both populations through smoltification. The genetic correlations between size in pre- and post-smoltification samples were much higher for the population reared in freshwater.