Genetic parameters for growth and survival of the base population in channel catfish(Ictalures punctatus)

Genetic parameters were estimated for growth and pond survival of channel catfish Ictalures punctatus using full-sib and half-sib families from cultured brood females collected from five different populations of the United States.The fry and juvenile were reared,tagged,and thereafter communal-reared in one pond.Variance components and genetic parameters for growth and survival were estimated using a two traits animal model and a sire-dam threshold model.The estimated breeding values of all animals were calculated using best linear unbiased prediction.The heritability estimates for harvest body weight and harvest body length in the base population were high(0.41±0.074 and 0.32±0.064,respectively)and were significantly different from zero(P<0.05).These estimates are likely biased upwards due to the common environmental effect other than additive genetic effect,although tagging body weight and tagging body length was fitted as a covariate in the mixed model to remove this effect.There was a high phenotypic and genetic correlation between harvest body weight and harvest body length(0.93 and 0.97,respectively).Heritability of pond survival was low(0.037±0.016)but still significantly different from zero(P<0.05).The correlation between family breeding values for growth(harvest body weight and harvest body length)and pond survival were low(0.065 and 0.10,respectively)and not significantly different from zero(P>0.05).Therefore,growth and survival must be included as breeding objective and simultaneously selected in the future generations by using a multiple trait selection index method.