Reproductive performance and mature gonad morphology of triploid and diploid B lack T iger shrimp ( P enaeus monodon ) siblings

Sibling harvest age B lack T iger shrimp triploids and diploids of both sexes were reared to reproductive maturity, crossed with wild caught females and males, conditioned for spawning and a comprehensive reproductive performance trial was undertaken. Ovarian development, spawning frequency, fecundity, hatch rate, gonad morphology, male reproductive tracts and thelycum impregnation rates of the wild female × triploid male cross were assessed. After ablation, ovarian development and cycling between wild G 0 diploid and G 1 diploids was not significantly different, whereas G 1 triploids failed to show any signs of ovarian development and cycling, thus resulting in no G 1 triploid female spawnings. There were 10 G 0 diploid female × G 0 diploid male first‐spawnings and 9 G 0 diploid female × G 1 diploid male first‐spawnings, all of which produced viable nauplii. In comparison, there were 7 G 0 diploid female × G 1 triploid male first‐spawnings, none of which produced viable nauplii. The 26 wild G 0 diploid female spawnings had more eggs than the 1 G 1 diploid female spawning. Gonad morphology and male reproductive tract assessments showed impaired reproductive development in triploid gonadal tissues of both sexes (compared with sibling diploids and wild shrimp) to a point where complete maturation had not occurred. The thelycum of 16 wild G 0 diploid females crossed with G 1 triploid males had no visible spermatophore present, suggesting that G 1 triploid males are incapable of developing viable spermatophores and mating with females. This study demonstrates that the triploid females and males are incapable of producing viable gametes and are thus reproductively sterile.