Genetic analysis of common carp (Cyprinus carpio) strains: I: Genetic parameters and heterosis for growth traits and survival

The aim of this study was to estimate genetic parameters and heterosis for weight, length and survival traits for common carp measured at different time periods at commercial farm conditions. A diallel cross between two land race strains (Duna and Amur), and two farmed strains (Tata and Szarvas 15) was used. Five females and 10 males per strain were used to produce six families for each of the 16 cross combinations resulting in 96 families each with 20 fish. The fish were weighed at tagging (W0), and also their length were measured at first autumn (W1, L1), second spring (W2, L2), and second autumn (W3, L3). Survival was defined as survival from second spring (W2) to second autumn (W3). Heritabilities for weight and length traits were estimated using univariate models, whereas genetic correlations and heritabilities for survival were estimated using multivariate models. The difference between the strains with respect to survival was clearly significant with Duna having the highest expected survival rate (81%), followed by Amur (69%), Tata (53%) and Szarvas 15 (51%). The level of heterosis (cross vs. purebred) varied from − 14 to 29% for weight traits, from 1.7 to 8.3% for length traits, and from 8–37% for pond survival. Heritabilities were low for early weight and length traits (W0, W1, W2, L1, and L2, 0.11–0.16) but high for W3 and L3 (0.49, 0.50). For survival the heritability on the underlying scale was 0.34 ± 0.09 corresponding to a heritability of ∼ 0.2 on the observable scale. High genetic correlations (0.81–0.98) were estimated between weight and length measured at the same time (W2/L2, and W3/ L3) and between weight measured in the first autumn (W1) and second spring (W2). Genetic correlations between weight and survival were low and non-significant for W2 (0.06 ± 0.35), but high and significant for W3 (0.65 ± 0.15). The high levels of heritabilities for length and weight at harvest (W3) and the moderate heritability for survival indicate that selective breeding for these traits could be successful in common carp.