Elasmobranch bycatch distributions and mortality: insights from the European tropical tuna purse-seine fishery

Type Article
Date 2020-12
Language English
Author(s) Clavareau Lyndsay1, 7, Sabarros Philippe1, Escalle Lauriane2, Bach Pascal1, Abascal Francisco J.3, Lopez Jon4, 5, Murua Hilario4, 6, Pascual Alayon Pedro J.3, Ramos Maria Lourdes3, Ruiz Jon4, Mérigot Bastien7
Affiliation(s) 1 : MARBEC, Univ. Montpellier, CNRS, Ifremer, IRD, Ob7, Sète, France
2 : The Pacific Community SPC, B.P. D, 98848 Nouméa, Nouvelle Calédonie
3 : Instituto Español de Oceanografía, Dársena Pesquera PCL8, 38180 Santa Cruz de Tenerife, Spain
4 : AZTI Tecnalia, Herrera Kaia, Portualde z/g, 20110 Pasaia, Gipuzkoa, Spain
5 : Inter-American Tropical Tuna Commission, 8901 La Jolla Shores Drive, 92037, La Jolla, USA
6 : International Seafood Sustainability Foundation (ISSF), 1440 G Street NW, Washington, USA
7 : MARBEC, Univ. Montpellier, CNRS, Ifremer, IRD, Ob7, Sète, France
Source Global Ecology And Conservation (2351-9894) (Elsevier BV), 2020-12 , Vol. 24 , P. e01211 (12p.)
DOI 10.1016/j.gecco.2020.e01211
Keyword(s) Biodiversity, Spatio-temporal distribution, Life stage, Sex ratio, At-haulback mortality
Abstract

Despite bycatch of elasmobranch (sharks and rays) being a major concern in most fisheries worldwide, there is a lack of knowledge on their spatio-temporal species distribution, biology (life stage and sex-ratios), as well as their at-haulback mortality rate. Observer data from the French and Spanish tropical purse-seine tuna fisheries operating in the Eastern Atlantic and Western Indian Oceans between 2005 and 2017 were analysed to investigate elasmobranch bycatch. Data included 24 elasmobranchs species and distribution patterns of catch per unit of effort (CPUE) by species and sex-ratio were found to vary with life stages, areas, seasons and fishing modes. In general, higher catches were found in FAD-associated sets (>40%) than free tuna school sets (<17%) although this can vary depending on the species. For the large majority of species, a high proportion of juveniles were caught (30.7–100%), apparent at-haulback mortality rates was high (24.3–63.9%) and finally sex ratios was unbalanced (13.3–66.7% of females). Areas and seasons identified from these different components should be of interest for the monitoring and management of elasmobranch bycatches.

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Clavareau Lyndsay, Sabarros Philippe, Escalle Lauriane, Bach Pascal, Abascal Francisco J., Lopez Jon, Murua Hilario, Pascual Alayon Pedro J., Ramos Maria Lourdes, Ruiz Jon, Mérigot Bastien (2020). Elasmobranch bycatch distributions and mortality: insights from the European tropical tuna purse-seine fishery. Global Ecology And Conservation, 24, e01211 (12p.). Publisher's official version : https://doi.org/10.1016/j.gecco.2020.e01211 , Open Access version : https://archimer.ifremer.fr/doc/00642/75386/