BIDIRECTIONAL MASS SELECTION FOR BODY SHAPE IN COMMON CARP

Bidirectional mass selection for the ratio of height/length generated a response in both directions. Estimates of realized heritability were 0.47 +/- 0.06 and 0.33 +/- 0.10 for up and down selection respectively and 0.42 +/- 0.03 for the divergence. This means that body shape of common carp can be changed fairly rapidly by mass selection. Presumably, differences in body shape among different genetic groups of common carp are due to different intensities and number of generations of mass selection for this trait practised in the past. The traditional belief that body shape and growth rate are correlated was not confirmed in this study. The down selection line, possessing the lowest ratio of height/length, showed the fastest growth rate. At face value this implies a negative correlated response of growth to selection for height/length. We suggest treating this finding with some reservation, since growth did not differ significantly among our test lines. These results may be applied to aquaculture by selecting for an increasing ratio of height/length only if high backed fish have some advantage in their own right such as a higher price or improved market acceptance.