ESTIMATION OF PHENOTYPIC AND GENETIC CORRELATION FOR BODY MEASUREMENT TRAITS IN A SELECTIVE BREEDING POPULATION OF RAINBOW TROUT(ONCORHYNCHUS MYKISS)

The second generation(G2) of a rainbow trout selective strain population was used as the experimental population.This strain was being selectively bred in the Heilongjiang River Fishery Research Institute(HRFRI),the Chinese Academy of Fishery Sciences(CAFS).Single-trait animal model was used to estimate the heritability of eight body measurement traits,including head length,body length,body height,body thickness,caudal peduncle length,caudal peduncle height,and the distance from dorsal fin to the snout and dorsal fin base length.The results show that the heritabilities of these measurement traits ranged from 0.131 to 0.313,mainly at middle or low level.The heritability of dorsal fin base length was the lowest one at 0.131 ± 0.039,and that of body height the highest at 0.313 ± 0.086.The genetic correlations between each pair of the above traits were estimated by using two-trait animal model,and phenotypic correlations between each pair of these traits were estimated by using Pearson correlation method.The results show that the genetic correlations ranged from 0.065 to 0.866,and the phenotypic correlations from 0.016 to 0.815.In addition,we found that the phenotypic correlation between body thickness and caudal peduncle length was the lowest,with a value of only 0.016,and did not reach significant level(P0.05).However,the genetic correlation between them was 0.247,which is significant(P0.05) as indicated in likelihood ratio test(LRT) statistics.The phenotypic correlation between body thickness and the dorsal fin base length was 0.647,reaching a significant level(P0.05) by t-test,but the genetic correlation between them was only 0.305,which is not significant(P0.05) indicated in LRT statistics.Therefore,not all of these body measurement traits were in similar levels of phenotype and genetic correlation in this experimental population.Mistakes may occur when only phenotypic or genetic correlation is considered in a design of a breeding program.The results could provide useful knowledge for selective breeding in body measurement traits of rainbow trout(Oncorhynchus mykiss).