Heritability of juvenile growth traits in red drum ( Sciaenops ocellatus L.)

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 ( h 2 ) of a thermal growth coefficient was estimated using an animal‐additive model and a restricted maximum‐likelihood algorithm. Estimates of h 2 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 h 2 for condition coefficient ( K ) at various measurement dates averaged 0.38, suggesting a genetic component to shape in juvenile red drum.