Abstract
Recent interest in developing aquaculture of the endemic New Zealand yellowbelly flounder (YBF) has highlighted the need to develop captive breeding technology for this species. A pilot investigation of induced reproduction was conducted, where twenty-seven female and twelve male wild-caught sexually mature fish were placed into indoor tanks and administered either a sham (saline) or gonadotropin releasing hormone analogue (GnRHa) treatment (50 µg kg-1 or 100 µg kg-1 bw). Ovulation only occurred in GnRHa treated fish. The total number of ovulated fish was low, but the majority of fish treated with 50 µg/kg-1 of GnRHa progressed either into, or through, final oocyte maturation (FOM) to produce hydrated oocytes. Fertilisation rates in excess of 80% were achieved in fish from both the 50 and 100 µg/kg-1 GnRHa treatments, indicating that high quality gametes can be achieved using hormone induced reproduction. In contrast, control fish appeared to arrest oocyte development at FOM suggesting that reproductive dysfunction may occur in wild caught broodstock. With further refinement, induced spawning using GnRHa should be a viable methodology to enhance the hatchery production of YBF.