Estimation of genetic parameters in cultured Pacific oysters (Crassostrea gigas) grown in Tasmania, based on animal models

Abstract

Selective breeding of Pacific oysters in Tasmania is undertaken by the commercial research company — Australian Seafood Industries Pty. Ltd. (ASI). As part of their research program, we estimated the genetic parameters for several economic traits with a view to refining their ongoing breeding objectives. In 2003, strip spawning of 11 dams and 14 sires produced offspring across 19 families of which 14 were half sibs (either maternal or paternal) and 5 were full sib families. These offspring were individually tagged, placed into family mesh bags and grown out for 25 months under commercial conditions. Genetic parameters were estimated using restricted maximum likelihood methods in ASReml as applied to univariate animal models. Heritability estimates for total wet weight, length, width, depth, wetmeat weight andwet shell weight were medium to high. Overall there was no evidence for sire or dam effects. Significant positive genetic and phenotypic correlations between weight and length, width and depth were observed. Length, width and depth traits were also highly positively correlated with each other (both genetically and phenotypically). Width and depth function index traits (calculated from corresponding trait measurements) however, displayed negative genetic correlations with all other traits although phenotypic correlations were positive. While our genetic parameters will not be applicable to all Pacific oyster grow-out conditions or breeding applications, the demonstrated levels of additive genetic variation in most traits shown in this study indicate that these traits should respond well to selection employed in ASI's oyster breeding program.