Cobia aquaculture began in Australia in 2007; however, expansion of commercial production has been limited, due in part to low and inconsistent supply of seed stock for on-growing. This study aimed to address the constraints of reproductive performance of cobia in captive conditions and investigate strategies to improve the efficiencies of broodstock management in commercial and research facilities. In a study evaluating the growth of three cohorts of captive reared cobia, to determine the existence and extent of sexually dimorphic growth, intersex development in cobia was identified and recorded for the first time. There was no sexually dimorphic growth in the first two cohorts of fish. In contrast, females from third cohort were significantly larger than males once mean body weight exceeded 2 kg. It is proposed that the observed variations in growth and gonad malformations observed in cohorts 1 and 2 were the result of exposure to endocrine disruptors, the type and source of which remains unknown.
Submitted in the fulfilment of the requirements of the degree of Doctor of Philosophy, University of the Sunshine Coast, 2016.