The Jelly-FAD: A paradigm shift in the design of biodegradable Fish Aggregating Devices

Lessons learnt from the first large-scale biodegradable FAD research experiment to mitigate drifting FADs impacts on the ecosystem

“…However, once plastic is replaced by weaker organic materials, the tension and structural stress suffered by conventional design make the bioFADs deteriorate before the time required by fishers to operate with them. Despite this limitation and lessons learned, which will inform future developments and trials on biodegradable FADs such as the ones currently being conducted in other oceans [39], this project showed that bioFAD prototypes tested significantly contribute to the reduction of the synthetic material in FAD constructions. Moreover, the willingness of the fleet to use the cotton ropes in the tail of commercial FADs and the incorporation of this material by some companies demonstrates the utility of this large-scale trial to mitigate the potential contribution of lost and abandoned FADs to marine litter, reducing consequently impacts on the ecosystem, which is the objective promoted by IOTC Res.…”

“…For example, bioFAD Prototype A1, which is the FAD design most use and preferred by the fleet, reduces 81 % the synthetic material on the bioFAD construction and the use of plastic fraction is around 14 % of its total weight (only the floats to ensure buoyancy and the twine to tie the raft). Moreover, in addition to significantly increasing the use of biodegradable materials, bioFADs reduce the total material weight used in FAD construction, which is also important as the impact of FADs are considered to be proportional to its size [39]. For example, bioFAD prototypes A1, A2 and B2, in comparison to their equivalent NEFADs, required less material (in kg) for their construction, with a reduction of 44 %, 50 % and 11 % of material used, respectively.…”

“…This result was also expected as the fishers and scientists have reported since the beginning of the fishery that large tuna aggregations could be found in small natural logs and other objects, provided that those floating objects were drifting in productive areas. This is an important result itself, indicating that tunas do not differentiate between natural and synthetic materials and/or floating objects structure and design, however, this does not overcome the logistical necessity for the bioFADs to last for a long enough time (e.g., one year) and drift slowly, as required by fishers, to increase the chances of an object to aggregate fish in productive areas without drifting outside the fishing grounds [39].…”

“…Although the lifespan of the different bioFAD types showed a maximum lifespan longer than 1 year, which is the FAD time required by fishers for commercial fishing, this analysis did not consider the degradation process of the FAD's components. The observed degradation of, particularly, the cotton canvas (i.e., used in the raft) and, to a lesser extent, cotton ropes (i.e., for the construction of the tail) suggest that biodegradable materials using conventional FAD designs were not strong enough to withstand the tension suffered by oceanographic currents to remain at sea the required time for fishing [39]. This is an important lesson learned and future trials should consider the effect of construction designs (i.e., distribution of elements in the surface and submerged FAD parts) on the durability of the biodegradable material tested.…”

“…1), shows that bioFADs works well and reduce the amount of material in its construction, however, it seems that the lifetime of those bioFADs is shorter than that required by fishers. This is mainly due to the structural stress suffered by conventional FAD structure designs, which are subject to different directional forces between superficial and subsurface currents [39]. Strong synthetic plastic materials allow conventional FADs to persist without breaking despite the tension and structural stress suffered in the different layers of the water column.…”