Heritability, genetic correlations and genotype by environment interactions in productive traits of the Caribbean scallop, Argopecten nucleus (Mollusca: Bivalvia)

Argopecten nucleus is a hermaphroditic scallop native to the Caribbean Sea, whose aquaculture production currently relies on hatchery-produced seed. Although this species exhibits a relatively fast growth, its survival, fecundity and commercial size are lower than those of other economically important pectinids. To assess the feasibility to improve productive traits in this species through selective breeding, heritabilities (h2) and genetic correlations (rG) for survival, fecundity and growth were estimated. The existence of genotype by environment interactions (GEI) associated with the culture depth, i.e. location of culture systems in the water column, ware also examined. Fifty sexually mature individuals were individually spawned, collecting female and male gametes separately. The sperm of one “male” was used to fertilize the eggs of four female individuals randomly chosen from the base population, generating 10 half sibling families and 40 full sibling families, in a nested experimental design. Shell length, height, and width, and total wet weight, were measured in 3.5 (juveniles) and nine (adults) months old progenies. Additionally, at 9 months the adductor muscle and remaining soft tissues wet weight were separately measured, and fecundity and survival recorded. The components of the phenotypic variance and heritabilities were estimated using an animal model. Most of the traits exhibited medium to high heritability (h2 ≥ 0.26), with the exception of shell width in juveniles and survival (h2 ≤ 0.18). h2 estimations were generally higher in juveniles than in adults and h2 for fecundity was not significantly different from zero. The growth related traits exhibit significant positive genetic correlations (rG ≥ 0.69), but were not genetically correlated with fecundity or survival. Interestingly, GEI in relation to culture depth were statistically significant. Results suggest a high potential response to direct and indirect selection, indicating that productive traits can be improved through selective breeding. The differential relative performance of different genotypes at different depths will be an important consideration to take into account in designing selective breeding plans for this species.