Study of the coastal reef fishery pressure in a South Pacific Island (Bora-Bora, French Polynesia)

Abstract

In the context of the general overexploitation of South Pacific reef fisheries, there is a global push to precisely define fishery parameters such as fishing effort, annual landings, and exploitation levels. In Bora-Bora, several surveys were performed to define the fishing grounds and the fishing effort of the reef fishery for the first time. Maps of the fishing grounds under different fishing pressures were created for the Bora-Bora reef fishery. The average fishing effort throughout the lagoon was 40 trips week−1 km−2. Annual landings were estimated following two different methods: school participatory surveys and landing based on the catch per unit effort. These estimations were used to determine that the maximum sustainable yield of the island's fisheries was 6.5 tons km−2 year−1. the reported annual yield in 2022 was 5.35 tons km−2 year−1, under the estimated maximum sustainable yield. The level of exploitation of the fisheries was also estimated based on the catch size composition of the ten most fished species. This revealed that fishing is responsible for more than 50% of fish mortality in six of the ten studied species, and that catch length could be increased to optimize both catches and biomass. Overall, the Bora-Bora reef fishery may be experiencing growth overfishing (i.e., the catching of fish that are too small to maximise biological sustainability and economical yield), which can endanger stock recruitment in the future if no actions are taken.

Keywords

• reef fishery
• fishing effort
• exploitation rate
• length-based bayesian biomass indicator
• landing
• maximum sustainable yield