Testing biodegradable materials and prototypes for the tropical tuna FAD fishery: progress report and staff’s recommendations

Purse-seine effort on the fish-aggregating device (FAD) fishery in the EPO has steadily increased since the early 1990s due to its efficiency in capturing tropical tunas that aggregate under FADs. As with most fishing methods, FADs may also have negative effects on associated species and ecosystems through entanglement of vulnerable species (e.g., sea turtles), accumulation of marine debris and pollution, and stranding events in vulnerable habitats (e.g., coastal nursery areas). To address these potential effects, the IATTC staff was required to present scientific recommendations that would help with transitioning from traditional to biodegradable FADs, which are expected to reduce those impacts. The European Union granted the IATTC funds for a two-phase project involving experiments with biodegradable nonentangling FADs in a controlled environment (Phase 1) and under real- time at-sea fishing conditions (Phase 2). During Phase 1, the selection of biodegradable materials to be used in the construction of three different prototypes for Phase 2 was determined. The work plan for Phase 2 included several activities, such as the design of prototypes for non-entangling and biodegradable materials (NEDs), the identification of collaborators and participants, the construction of the NEDs, the development and agreement of an experimental design, the monitoring and tracking of the experimental FADs, as well as the data collection and analyses. A total of 715 NEDs (114 prototype 1; 392 prototype 2; 209 prototype 3) were deployed along with their corresponding paired controls for a total of 1,420 experimental FADs. Similar values in catch per set were observed between NEDs and paired controls (NEDs = 34.0 mt/set, paired control FADs = 31.2 mt/set; Table 1). The submerged rope of prototype 1 was in poor condition, but the rest of materials appeared to be in good condition after a minimum of two months at sea. Prototype 2 was in good condition after at least two months of soak time. The NED design of prototype 3 was the least durable, and therefore some modifications were made in collaboration with the fleet to improve durability. The staff’s conclusions, recommendations, future actions, and lessons learnt from positively engaging with the industry and fishers are also described.