MEPS 420:241-252 (2010)  -  DOI:

Trawling regime influences longline seabird bycatch in the Mediterranean: new insights from a small-scale fishery

K. Laneri1,7,*,**, M. Louzao1,2,8,*,**, A. Martínez-Abraín1, J. M. Arcos3, E. J. Belda4, J. Guallart5, A. Sánchez3, M. Giménez 3, R. Maestre3,6, D. Oro1

1IMEDEA (CSIC-UIB), Miquel Marquès 21, 07190 Esporles, Mallorca, Spain
2Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo, Catedrático Rodrigo Uría s/n, 33071 Oviedo, Spain
3SEO/BirdLife, C/Múrcia 2-8, local 13, 08026 Barcelona, Spain
4Instituto de Investigación para la Gestión Integrada de Zonas Costeras, Universidad Politécnica de Valencia, Ctra. Nazaret-Oliva s/n, 46730 Gandia, València, Spain
5Laboratorio de Biología Marina, Departamento de Zoología, Universitat de València, 46100 Burjassot, València, Spain
6Institut d’Ecologia Litoral, Jacinto Benavente 21, 03560 El Campello, Alicante, Spain
7Present address: Fundació Institut Català de Ciències del Clima (IC3), Doctor Trueta 203, 08005 Barcelona, Catalonia, Spain
8Present address: Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318 Leipzig, Germany
*‑Corresponding authors. Email: , **These authors contributed equally to this work

ABSTRACT: Unintended mortality in longlines emerged in the early 1990s as one of the most important threats for pelagic seabirds worldwide. Most of the studies were focused on highly developed industrial fisheries, overlooking bycatch in small-scale artisanal fisheries. However, bycatch in small-scale fisheries might have negative effects similar to those of industrial fisheries when they overlap with hotspot areas of top predators. Moreover, different types of fishing gear coexist in the same oceanographic area, particularly in highly exploited marine ecosystems such as the western Mediterranean. We quantify for the first time the influence of trawling regime on Cory’s shearwater Calonectris diomedea bycatch in the western Mediterranean longline artisanal fishery. The availability of trawling discards has substantial influence on the foraging and breeding ecology of many seabirds, and trawling inactivity may drive shearwaters to seek alternative food resources, such as baits used in longline fishing. Based on our previous knowledge of the system, we also tested other variables affecting bycatch over 8 yr (1998 to 2005). Within this 2-fishery framework, we found that trawling regime, longline fishing time and breeding stage were key factors explaining shearwater attendance to longline vessels, but mainly trawling regime and fishing time increased the incidental capture of Cory’s shearwaters. More specifically, during the pre-breeding and chick-rearing periods, bycatch dramatically increased during sunrise sets in the absence of trawling activity. Importantly, this study indicates the need for an integrated multi-fisheries management approach for the conservation of seabirds and highlights the necessity of banning longline fishing during periods of trawling inactivity.

KEY WORDS: Small-scale fishery · Interactions between fisheries · Multi-fisheries management · Trawling inactivity · Cory’s shearwater · Mitigation measures · Western Mediterranean

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Cite this article as: Laneri K, Louzao M, Martínez-Abraín A, Arcos JM and others (2010) Trawling regime influences longline seabird bycatch in the Mediterranean: new insights from a small-scale fishery. Mar Ecol Prog Ser 420:241-252.

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