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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

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Alex Tidd at Institute of Research for Development
Alex Tidd
Laurent Dagorn at Institute of Research for Development
Laurent Dagorn
Manuela Capello at Institute of Research for Development
Manuela Capello
Patrice Guillotreau at Institute of Research for Development
Patrice Guillotreau
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Abstract and Figures

The Indian Ocean Tuna Commission 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, 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. 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. 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. Graphical abstract
Box and whisker plot of capacity characteristics A length overall (m), B gross tonnage (gt), C age (years) of the IO PS fleet versus the French PS—the horizontal bar at the 50th percentile, the top of the box at the 75th percentile, and the base of the box at the 25th percentile. Whiskers represent the range of data, and the black dots represent the outliers
Box and whisker plot of capacity characteristics A length overall (m), B gross tonnage (gt), C age (years) of the IO PS fleet versus the French PS—the horizontal bar at the 50th percentile, the top of the box at the 75th percentile, and the base of the box at the 25th percentile. Whiskers represent the range of data, and the black dots represent the outliers
… 
A Box and whisker plot of the results of the DEA analysis—the horizontal bar at the 50th percentile, the top of the box at the 75th percentile, and the box base at the 25th percentile: UCU = Unbiased capacity utilisation; CU = Capacity utilisation; TE = Technical efficiency. Whiskers represent the range of data, and the black dots represent the outliers. B Representation of the French-flagged fleet size in the IO and the choices of entry, exit, or stay in the fishery
A Box and whisker plot of the results of the DEA analysis—the horizontal bar at the 50th percentile, the top of the box at the 75th percentile, and the box base at the 25th percentile: UCU = Unbiased capacity utilisation; CU = Capacity utilisation; TE = Technical efficiency. Whiskers represent the range of data, and the black dots represent the outliers. B Representation of the French-flagged fleet size in the IO and the choices of entry, exit, or stay in the fishery
… 
Each facet represents a year from when yellowfin was deemed overfished and subject to overfishing: A 2013, B 2014, C 2015, D 2016, E 2017, F 2018, G 2019. The points represent the cumulative catch of yellowfin (black spheres) and skipjack (white spheres) by vessel (the point) ranked from 1 (most efficient) to the total number of vessels in those years. The orange horizontal line is the yellowfin catch limit of 29,501 tonnes (E–G) (target, 2017 onwards), and the orange vertical line is the theoretical number of vessels to achieve the catch limit. The green dashed lines would represent the estimated theoretical catch share (23,943 tonnes) and the optimal number of vessels if vessels were to fish at MSY
Each facet represents a year from when yellowfin was deemed overfished and subject to overfishing: A 2013, B 2014, C 2015, D 2016, E 2017, F 2018, G 2019. The points represent the cumulative catch of yellowfin (black spheres) and skipjack (white spheres) by vessel (the point) ranked from 1 (most efficient) to the total number of vessels in those years. The orange horizontal line is the yellowfin catch limit of 29,501 tonnes (E–G) (target, 2017 onwards), and the orange vertical line is the theoretical number of vessels to achieve the catch limit. The green dashed lines would represent the estimated theoretical catch share (23,943 tonnes) and the optimal number of vessels if vessels were to fish at MSY
… 
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Vol.: (0123456789)
Rev Fish Biol Fisheries (2025) 35:619–631
https://doi.org/10.1007/s11160-025-09925-y
ORIGINAL RESEARCH
Overcapacity anddynamics ofatuna fleet facing catch
limits andhigh efficiency: thecase oftheIndian Ocean tuna
fishery
AlexTidd · LaurentDagorn ·
ManuelaCapello · PatriceGuillotreau
Received: 4 June 2024 / Accepted: 28 January 2025 / Published online: 7 February 2025
© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025
Abstract The Indian Ocean Tuna Commission
expresses concern over the overfished state and sus-
ceptibility to the overfishing of yellowfin tuna (Thun-
nus 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, which mandates
measures to align fishing capacity with opportunities
to sustain fish stocks at maximum sustainable yield
(MSY). Using Data Envelopment Analysis, we evalu-
ate the relationship between vessel fishing capacity to
catch limits and the MSY reference point for yellow-
fin tuna. Findings indicate that the French fleet could
meet catch limits with approximately 21% fewer ves-
sels if fully utilised and 26% fewer if reduced to meet
their equivalent MSY share. 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.
A.Tidd(*)· L.Dagorn· M.Capello· P.Guillotreau
CNRS, Ifremer, IRD, MARBEC, Univ Montpellier, Sète,
France
e-mail: alex.tidd@ird.fr
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
ResearchGate has not been able to resolve any citations for this publication.
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