Assessing the effects of increasing surface seawater temperature on black pearl production in French Polynesia: A bioeconomic simulation

Production of French Polynesia's black pearls is entirely dependent on oceanic conditions. Yet, conditions are changing due to climate change. This research evaluates the potential economic consequences of increased seawater temperature on black pearl production. A stochastic-dynamic bioeconomic simulation simulated the growth of oysters and pearl quality under current and projected seawater temperatures in 2035 in the Northern Tuamotu Archipelago. Production strategies, including grafting intensity, grafting timeframe, and overall pearl quality distribution were included in the simulation to identify production strategies which maximized net present value (NPV) over ten-years. Across all simulated management scenarios, production occurring under projected seawater temperatures resulted in an average decline of 29.1% in expected NPV. Overall, the change in expected NPV stemmed from a decline in the quantity of pearls produced, decline in the quality of pearls produced, and an increase in time between production stages. The optimal production strategy for current and projected seawater temperatures across all management scenarios was to graft a whole cohort of oysters in December with the best possible pearl quality distribution. However, with production occurring with other pearl quality distributions, optimal grafting timeframe and intensity differs between temperature regimes. Aligning production strategies with seawater temperatures can ameliorate economic losses.