Benefits, concerns, and solutions of fishing for tunas with drifting fish aggregation devices

Abstract

Drifting fish aggregating devices (dFADs) are human‐made floating objects widely used by tropical tuna purse seine (PS) fisheries to increase catch of target species. However, dFAD use has several negative impacts, including increased potential for overfishing, higher juvenile tuna catch, higher bycatch compared to other PS fishing modes, ghost‐fishing, and generation of marine litter. Based on these impacts, some stakeholders, especially environmental non‐governmental organizations and other competing fishing industries, suggest that dFADs should be completely banned. We list the pros and cons of dFAD fishing; address how to improve current management; and suggest solutions for the sustainability of dFAD fishing in the long term. A dFAD ban would lead to major changes in the availability and sourcing of tuna for human consumption and decrease the licensing revenue received by many developing states. Most importantly, we argue that tools exist today to manage for, reduce or eliminate most of the negative impacts of dFADs (e.g., bans on discards, limits on active dFADs, biodegradable non‐entangling constructions, time‐area deployment closures, recovery programs, and full data transparency, among others). Management decisions based on sound scientific reasoning are needed to address the legitimate concerns surrounding dFAD use and ensure the sustainability of both pelagic and coastal ecosystems and tropical tuna PS fisheries.

The challenge of assessing the effects of drifting fish aggregating devices on the behaviour and biology of tropical tuna

“…Considering the meeting-point hypothesis, DFADs, by increasing the density of FOBs, could provoke the dispersion of tuna, disturbing schooling behaviour and ultimately impacting their natural mortality (Figure 3, Fréon & Dagorn, 2000). It is important to note here that this potential impact on tuna natural mortality does not constitute an ecological trap: by associating with Since then, several papers reviewed existing evidence and/or proposed future research directions to address the impacts of DFADs on tropical tuna (Dagorn, Holland, et al, 2013;Davies et al, 2014;Evans et al, 2015;Fonteneau et al, 2015;Leroy et al, 2013;Pons et al, 2023;Taquet, 2013). Yet, most of these papers, except those by Taquet (2013) and Pons et al (2023), addressed these impacts at a regional scale, and all were mainly focussing on the impacts of DFADs on fishing mortality, Tuna habitat can be defined as the surface and sub-surface ocean waters, with all the abiotic (temperature, dissolved oxygen, etc.…”

“…In recent years, the increasing use of DFADs by fishers raised several questions about the sustainability of this practice. The primary concern is the increase in fishing efficiency and mortality induced by DFAD fishing (Dagorn, Holland, et al, 2013;IOTC, 2022;Pons et al, 2023). However, the increase in the number of floating objects could also induce impacts on tuna behaviour and life history parameters, which are more challenging to address.…”

Drifting Fish Aggregating Devices in the Indian Ocean: Impacts, Management, and Policy Implications

“…This movement not only makes the Somali coast a nexus of marine activity but also highlights it as a crucial epicenter for illegally discarded and systematically abandoned dFADs in the vast stretch of the IO. There is a maintained lack of accountability for ownership and responsibility to compensate for the true ecological cost of such practices, which has resulted in conflicts with conservation goals and management arrangements (Pons et al, 2023).…”

Evidence to inform spatial management of a western Pacific Ocean tuna purse seine fishery

“…Catch composition varies by purse seine set type (Dagorn et al 2013;Hall & Roman 2013;Peatman et al 2017;Pons et al, 2023). Set type was found to be an informative predictor only for silky shark catch rate, which was significantly lower in anchored FAD sets than the three other set types, and significantly higher in drifting FAD and in other associated sets (e.g., drifting logs, drifting algae, live and dead large marine organisms, marine debris such as crates, pallets and nets) than in free school sets.…”

“…Relative to free-swimming tuna schools chasing prey, sets on relatively slower-moving drifting FADs and logs catch a larger number and weight of nontarget species per set and per unit weight of target tunas (Hall & Roman 2013;Torres-Irineo et al 2014;Gaertner et al 2016;Peatman et al 2017;Lezama-Ochoa et al 2017;Pons et al, 2023). Shark catch rates, in number or weight of captures per set, are higher in drifting FAD and log sets than in free school sets (Amande et al 2008(Amande et al , 2010Clarke et al, 2011;Lopetegui-Eguren et al, 2022).…”