Quantifying the increase in fishing efficiency due to the use of drifting FADs equipped with echosounders in tropical tuna purse seine fisheries

Wain Gwenaëlle, Guery Loreleï, Kaplan David Michael, Gaertner Daniel. 2021. Quantifying the increase in fishing efficiency due to the use of drifting FADs equipped with echosounders in tropical tuna purse seine fisheries. ICES Journal of Marine Science, 78 (1) : 235-245.

https://doi.org/10.1093/icesjms/fsaa216

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Quartile : Q1, Sujet : FISHERIES / Quartile : Q1, Sujet : MARINE & FRESHWATER BIOLOGY / Quartile : Q1, Sujet : OCEANOGRAPHY

Résumé : Numerous pelagic species are known to associate with floating objects (FOBs), including tropical tunas. Purse seiners use this behaviour to facilitate the capture of tropical tunas by deploying artificial drifting fish aggregating devices (dFADs). One major recent change has been the integration of echosounders in satellite-tracked GPS buoys attached to FOBs, allowing fishers to remotely estimate fishable biomass. Understanding the effects of this new technology on catch of the three main tuna species (yellowfin tuna, Thunnus albacares; bigeye tuna, Thunnus obesus; and skipjack tuna, Katsuwonus pelamis) is important to accurately correct for this change in catch-per-unit-effort (CPUE) indices used for stock assessments. We analysed catch data from the French purse seine fleet for the period 2010–2017 in the Indian Ocean to assess the impact of this fleet's switch to echosounder buoys around 2012. Results indicate that echosounders do not increase the probability a set will be succesful, but they have a positive effect on catch per set, with catches on average increasing by ≈2−2.5 tonnes per set (⁠≈10%⁠) when made on the vessel's own dFADs equipped with an echosounder buoy. Increases were due to a decrease in sets below ≈25 tonnes and an increase in those greater than ≈25 tonnes, with a non-linear transition around this threshold. This increase explains the considerable investment of purse seiners in echosounder buoys, but also raises concerns about bias in stock size estimates based on CPUE if we do not correct for this fishing efficiency increase.

Mots-clés Agrovoc : pêches, méthode de pêche, rendement, augmentation de rendement, efficacité, échosondage, Katsuwonus pelamis, Thunnus albacares, Thunnus obesus

Mots-clés géographiques Agrovoc : océan Indien

Mots-clés libres : Catch per unit effort, Hyperstability, Indian Ocean, Standardization, Fisheries

Classification Agris : M11 - Production de la pêche
M01 - Pêche et aquaculture - Considérations générales

Champ stratégique Cirad : CTS 1 (2019-) - Biodiversité

Agences de financement européennes : European Commission

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