Age: Age genetic correlations for weight of Penaeus monodon reared in broodstock tank systems

Abstract Fourth generation domesticated Penaeus monodon stocks from 21 experimental families were reared in controlled-temperature, sand-based tank systems from tagging age (approximately 16 weeks from nauplii) for 28 weeks. Weights of individual shrimp were measured at tank stocking (i.e. nominally 16 weeks) and at fixed intervals after this date, corresponding to nominal ages of 24 weeks, 32 weeks and 44 weeks. Due to low numbers at tank stocking and poor survivals, two of the families were excluded from subsequent analyses leaving 19 families for genetic evaluation. Averaged (mean ± SD) for shrimp from 19 families, weights of shrimp at week 24, which is a typical age at which shrimp would be ‘harvested’ from commercial ponds and sold at market, was 19.7 ± 7.7 g for females and 17.1 ± 5.8 g for males. At the final measure at week 44 females averaged 80.2 ± 18.8 g and males 51.8 ± 9.0 g. Growth was highly variable between families with mean observed female and male growth rates over the whole experiment of 2.17 and 1.32 g week − 1 for the lightest family and 3.20 and 2.10 g week − 1 for the heaviest family. Heritabilities for weight at weeks 24, 32 and 44 were moderate, ranging from 0.23 to 0.39. The genetic correlation between weight at weeks 16 and 24 was 0.63 ± 0.19; and correlations between week 16 and later measures were low (− 0.05–0.15). The genetic correlation between weight at weeks 24 and 32 was 0.62 ± 0.19, and the correlation between weeks 24 and 44 was low at 0.38 ± 0.26. The genetic correlation between weight at weeks 32 and 44 were high with low standard errors (0.95 ± 0.04). As a moderate correlation with week 24 weight was found at week 32, and as potential early life rearing effects likely dissipate with increasing age, our results suggest that week 32 is likely the most appropriate alternative age, of those evaluated, at which to select to increase harvest weight.