Assessing growth, survival, and predator management in juvenile black-lip pearl oyster (Pinctada margaritifera) farming: insights from Savusavu Bay, Fiji

Abstract

The growth, survival, and predation interactions of juvenile Pinctada margaritifera in Savusavu Bay, Fiji, with a focus on assessing the effectiveness of fish exclusion devices as a predator management tool were investigated. Results showed favorable environmental conditions for oyster growth, with an average monthly growth rate of 4.87 mm; however, maintaining high survival rates proved challenging with survival rates as low as ~ 22%, with significant variation between farm sites—Matuku farm achieved 85.4% survival over 4 months, while Vatulele farm experienced lower survival rates at 45.6%. Multiple species were found to interact with oyster lines, with species such as puffer fish (Arothron spp.), titan triggerfish (Balistoides viridescens), and golden trevally (Caranx sexfasciatus), emerging as key predators. Fish exclusion devices had limited impact on improving overall oyster survival, suggesting that other factors, including site selection, regular maintenance, and targeted predator management, should be considered. The economic feasibility of exclusion devices is promising, but a more comprehensive approach combining these devices with predator removal could enhance both sustainability and profitability. This study provides valuable insights into improving pearl oyster farming practices in Fiji, highlighting the need for future research on predator–prey dynamics and integrated management strategies to optimize survival and growth.