Growth and reproductive performance of triploid and diploid blacklip abalone, Haliotis rubra (Leach, 1814)

Growth and reproduction of triploid and diploid blacklip abalone Haliotis rubra (Leach, 1814) were compared in a 30-month study. Triploidy was induced by inhibition of the second polar body formation using 6-dimethylaminopurine (6-DMAP) or cytochalasin B (CB). There were no significant differences in growth and survivorship between triploid and diploid abalone. However, triploid abalone had a more elongated shell and greater foot muscles than diploid abalone. A slightly curvilinear growth in shell length was conformed to all treatments. While diploid abalone had reached sexual maturity and spawned during the study, gonadal development and gamete maturation were abnormal in triploids. Female triploids lacked an apparent gonad at the macroscopic level but microscopic examination revealed that they had a thin layer of oogonia development. In contrast, male triploids were able to form similar-sized gonads to diploids during most of the reproductive period, but with brown-yellow discolouration and stalled gametogenesis at spermatocyte formation. Sex ratio of triploid abalone did not deviate from 1:1. With the onset of sexual maturation, growth and gonadal maturation occurred concurrently in diploid abalone, and there was no indication that growth of (diploid) abalone was reduced.