• heritability;
  • growth rate;
  • red drum;
  • microsatellites


Heritability of juvenile growth rate was estimated for red drum (Sciaenops ocellatus), an economically important sciaenid fish in the southern USA. Thirty-eight families were generated via ‘natural’ spawning of multiple sets of five breeders (three dams × two sires) in individual brood tanks. Offspring were individually tagged with Passive Integrated Transponder (PIT) tags and mixed for grow-out in replicate ‘common-garden’ tanks. Juvenile growth was followed from 166.4±18.6 to 254.0±27.0 mm (total length). Offspring were assigned a posteriori to individual brood fish (dam and sire) based on genotypes at nuclear-encoded microsatellites. Heritability (h2) of a thermal growth coefficient was estimated using an animal-additive model and a restricted maximum-likelihood algorithm. Estimates of h2 were 0.33±0.08 and 0.31±0.08 for thermal growth coefficient based on length and weight respectively. These results indicate a significant genetic component in juvenile growth rate in red drum. Estimates of h2 for condition coefficient (K) at various measurement dates averaged 0.38, suggesting a genetic component to shape in juvenile red drum.