Is <scp>FAD</scp> fishing an economic trap? Effects of seasonal closures and other management measures on a purse‐seine tuna fleet

Managing populations of wild harvested species requires the ability to regularly provide accurate abundance assessments. For most marine species, changes in abundance can only be monitored indirectly, using methods reliant on harvest-based indices, with significant inherent limitations surrounding the estimation and standardization of harvest effort. Tropical tunas are some of the most exploited marine species in the world and are among several species in critical need of alternative methods for estimating abundance. Addressing this concern, we developed the Associative Behaviour-Based abundance Index (ABBI), designed to provide direct abundance estimates for animals, which exhibit an associative behaviour with aggregation sites. Its implementation in the western Indian Ocean on skipjack tuna ( Katsuwonus pelamis ), yellowfin tuna ( Thunnus albacares ) and bigeye tuna ( Thunnus obesus ), revealed similar trajectories in their relative abundance. The ABBI stands as a potentially promising alternative to enhance traditional tropical tuna stock assessments methods, as well as a new opportunity to assess the abundance of other wild species that display an associative behaviour with physical structures found in their natural environment.

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Overcapacity and dynamics of a tuna fleet facing catch limits and high efficiency: The case of the Indian Ocean tuna fishery

Tidd,

Dagorn,

Capello

et al. 2024

Preprint

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The Indian Ocean Tuna Commission (IOTC) expresses concern over the overfished state and susceptibility to the overfishing of yellowfin tuna (Thunnus albacares). Acknowledging the challenges of increased fishing effort in a profitable fishery, our study aims to understand factors influencing French purse seine fishing vessel dynamics. Our primary goal is to assess purse seine vessel utilisation with recent catch limits and compliance with the European Union Common Fisheries Policy (CFP), which mandates measures to align fishing capacity with opportunities to sustain fish stocks at maximum sustainable yield (MSY). Using Data Envelopment Analysis, we evaluate the relationship between vessel fishing capacity to catch limits and the MSY reference point for yellowfin tuna. Random Utility Models identify key drivers influencing the fleets' strategic decisions, rigorously assessed with a machine-learning algorithm. Findings indicate that the French fleet could meet catch limits with approximately 21% fewer vessels if fully utilised and 26% fewer if reduced to meet their equivalent MSY share. Key influencing factors include catch revenue, vessel age, biomass levels, and interest rates. The predictive model achieves a 93% accuracy rate, essential for effectively implementing regional conservation policies that balance economic stakes with sustainable fishing practices. Aligning capacity with fishing opportunities is crucial for the profitability and preservation of these essential tuna populations, resulting in more sustainable and economically viable fisheries.

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Is FAD fishing an economic trap? Effects of seasonal closures and other management measures on a purse‐seine tuna fleet

Cited by 3 publications

References 39 publications

When economy meets ecology, is it truly conflicted? A dashboard approach to assess the sustainability performance of European tropical tuna purse seine fisheries

When economy meets ecology, is it truly conflicted? A dashboard approach to assess the sustainability performance of European tropical tuna purse seine fisheries

Direct assessment of tropical tuna abundance from their associative behaviour around floating objects

Overcapacity and dynamics of a tuna fleet facing catch limits and high efficiency: The case of the Indian Ocean tuna fishery

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