The genetic correlation between shrimp weight at week 24 (i.e.,
the harvest age) and week 32 was moderate in our study (0.62±
0.19). While the standard errors were quite large, the magnitude of
the genetic correlation does suggest that weight-based selections at
32 weeks will produce genetic gains in harvest weights; given the
moderate heritability and high phenotypic weight variance. Notably, a
similar correlation (moderate in size with high standard errors) was
also found between weight at weeks 16 and 24. The presence of this
moderate correlation (i.e. with weight16) at week 24, yet not at the
two later ages, could be explained by either the persistence of early
life rearing effects through to week 24, or alternatively, by far less
pronounced genotype-by-age interaction between these two younger
ages. However, as mentioned previously, the relative contribution
that early life rearing effects and genotype-by-age interaction had
toward the estimated correlations cannot be determined in our study.