Genetic parameters of a commercial Atlantic cod (Gadus morhua) breeding program
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- Master's theses (IHA) 
Despite many quantitative genetic studies on Atlantic cod (Gadus morhua) over the last two decades, the magnitude of heritabilities and genetic correlations for some economic important traits (growth rate, carcass quality traits) as well as genotype by environment (GxE) interactions, to some extent, still remain ambiguous. Therefore, this study estimated the genetic parameter using a dataset from a commercial cod breeding program (CodFarmers AS) in Norway for 3 generations, from 2002 to 2008, to ascertain that. Univariate and bivariate models were used to obtain (co)variance components. The estimated heritabilities were from moderate to extremely high for body weight at nine rearing locations, ranging from 0.11 – 0.86. Heritabilities for harvest body weight were estimated for three generations (2002, 2005, and 2008), and were medium to high, 0.54±0.15, 0.29±0.04 and 0.22±0.04, respectively. For generation 2005, all traits other than harvest body weight were recorded, and estimates of heritability were medium for most trait (harvest body weight, gutted body weight, fillet weight, loin weight and liver weight), ranging from 0.18 to 0.28. Some traits had high heritability such as body length and gonad weight (0.43 for both), but very low heritability estimate was obtained for head weight (only 0.06). No GxE was found among different reared locations in generation of 2002 and of 2005. There were some mild GxEs found for some reared locations in generation 2008. The strong and significant genetic correlation (rg=0.99) between some traits (such as fillet weight, loin weight, gutted weight and harvest weight) indicated that they are genetically the same trait, and that estimation of genetic parameters for one trait can give good predictions for others.