A genetic analysis of meristic and morphometric variation in chum salmon (Oncorhynchus keta) at three different temperatures

A nested mating design was used in which 10 males were mated with 20 female chum salmon (Oncorhynchus keta), and individuals from each of the 20 families were maintained at 6, 10, and 14 °C from egg fertilization until juveniles reached a fork length of about 61 mm. Variation in 11 morphometric and 3 meristic characters was evaluated. Rearing temperature had a marked effect on juvenile morphometric variation, enough to assign correctly 91% of the juveniles reared at 14 °C, 90% of the juveniles reared at 10 °C, and 95% of the juveniles reared at 6 °C. The addition of meristic character variation increased the classification accuracy to 97, 92, and 96%, respectively. As rearing temperatures increased, the observed levels of fluctuating asymmetry for the three meristic characters increased. Morphometric characters tended to have lower heritabilities than did meristic characters. Genotype–temperature interactions generally accounted for between 10 and 30% of observed phenotypic variation for most characters.