Assessing spatio-temporal patterns of drifting fish aggregating devices (dFADs) entering the EEZ of French Polynesia

The use of drifting Fish Aggregating Devices (dFADs) by purse seine fleets has continuously increase in the last few decades. These devices allow a very effective exploitation of large pelagic fishes (tuna and related species) but drastically increase their stock vulnerability. They also represent a threat for some protected species since this fishing technique induces a lot of bycatch. Although purse seine fishing and the use of drifting FADs are prohibited in its Economic Exclusive Zone(EEZ), French Polynesia is harmed by the large influx of these devices. Indeed, these floating objects also represent a threat for shipping and a major source of pollution since they inevitably end their drift, either on the bottom of the oceans or beached on the coasts. The growing complaints from local populations led us to investigate the origin and trajectories of these devices. In this work, we propose to characterize and quantify its massive influx crossing the EEZ of French Polynesia. Unfortunately, the positions of these dFADs are not communicated by the international fishing fleet. Therefore, we used a modeling approach based on theLagrangian tool Ariane to investigate the main trajectories of these dFADs. Using both modeled and remote sensed currents, we revealed areas with high probability of dFADs accumulation and islands with high beaching rates. Several parameters are also determined such as the drifting time and the entry point in the EEZ. These results will help to better understand the growing ecological threat induced by these devices on French Polynesia.