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

Fishers and scientists in the tropical Pacific, Atlantic and Indian Oceans are jointly designing biodegradable fish aggregating devices (bio-FADs) that are efficient for fishing. The tactic followed by most fishers to construct bio-FADs is to maintain the same conventional drifting FAD (dFAD) design (i.e., large, submerged net panels hanging from a floating raft) but replacing plastic ropes and netting with organic ropes and canvases. Results from these experiences show that the lifetime of bio-FADs made with conventional FAD designs is notably shorter than what fishers require, thus precluding their adoption. The short lifespan of these bio-FADs is due to the inefficient design of conventional dFADs, which results in major structural stress. Thus, to successfully replace plastic with organic materials and increase the lifespan of bio-FADs, a paradigm shift is needed. Bio-FAD structures should be re-designed to minimize structural stress in the water. The present study summarizes what we have learned from testing bio-FADs in the three tropical oceans, and it proposes a new concept in dFAD design, the jelly-FAD. Mirroring jellyfish, this new dFAD design will aim for quasi-neutral buoyancy, which should reduce (i) the structural stress of the FAD at sea and (ii) the need for additional plastic flotation. The jelly-FAD is not necessarily a fixed design; it is more of a change in the concept of conventional dFAD construction. Preliminary results show that jelly-FADs aggregate tuna as well as conventional FADs do, with lifespans greater than 6 months at sea. In addition, the jelly-FAD showed average drifting speeds similar to a conventional dFAD. To accelerate the adoption of bio-FADs worldwide, recommendations for jelly-FAD construction and tests are provided.

Automated summary

Fishers and scientists are collaborating to design biodegradable fish aggregating devices (bio-FADs) for efficient fishing in the tropical Pacific, Atlantic, and Indian Oceans. The conventional drifting FAD (dFAD) design, using organic ropes and canvases instead of plastic, has a shorter lifespan due to structural stress. To overcome this, a paradigm shift is proposed to minimize stress by redesigning bio-FAD structures, such as the jelly-FAD, which mimics the buoyancy of jellyfish. Preliminary results show that the jelly-FAD aggregates tuna and has a lifespan of over 6 months at sea, with similar drifting speeds to conventional dFADs.