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An Overview of Pelagic Shark Fisheries in the Northeast Atlantic

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SCRS/2007/078 Collect. Vol. Sci. Pap. ICCAT, 62(5): 1483-1493 (2008) AN OVERVIEW OF PELAGIC SHARK FISHERIES IN THE NORTHEAST ATLANTIC Maurice Clarke1, Guzman Diez2, Jim Ellis3, Boris Frentzel-Beyme, Ivone Figueiredo, Kristin Helle, Graham Johnston, Mario Pinho, Bernard Seret, Helen Dobby, Nils-Roar Hariede, Henk Heessen, Dave Kulka and Charlott Stenberg SUMMARY There is a long history of exploitation of pelagic sharks by European fisheries. Fisheries for basking shark (Cetorhinus maximus) and porbeagle (Lamna nasus) were well established in northern areas (e.g. off Norway) in the early 20th century. Although targeted fisheries for basking shark have now ceased, porbeagle is still taken in locally important directed fisheries in the Celtic Sea. Tuna and billfish fisheries, which expanded in recent decades, harvest shortfin mako (Isurus oxyrinchus), blue shark (Prionace glauca), and a variety of other pelagic sharks, with some of these fisheries targeting sharks at certain times/areas. Prior to the late 1990s, most European nations reported catches as “sharks not elsewhere identified”, and only in recent years has species-specific data become available. There is currently little biological sampling of commercial pelagic shark catches by fisheries laboratories, although there are some tag and release programmes for sharks. In recent years, the ICES Working Group on Elasmobranch Fishes has begun to collate available data on landings and from other data sources, and a brief overview of progress to date is given. RÉSUMÉ Il existe un long historique d’exploitation des requins pélagiques par les pêcheries européennes. Les pêcheries de requin pèlerin (Cetorhinus maximus) et de requin-taupe commun (Lamna nasus) étaient bien établies dans les zones septentrionales (au large de la Norvège, par exemple) au début du 20ème siècle. Même si les pêcheries dirigées sur le requin pèlerin ont désormais cessé d’opérer, le requin- taupe commun est encore capturé par les pêcheries dirigées dont l’activité locale est importante dans la mer celtique. Les pêcheries de thonidés et d’istiophoridés, qui ont connu une expansion au cours de ces dernières décennies, capturent le requin taupe bleue (Isurus oxyrinchus), le requin peau bleue (Prionace glauca) et divers autres requins pélagiques, et certaines de ces pêcheries ciblent les requins à certaines époques/dans certaines zones. Avant la fin des années 1990, la plupart des nations européennes déclarent des captures comme « requins non identifiés ailleurs », et ce n’est que récemment que les données spécifiques aux espèces sont devenues disponibles. Actuellement, les laboratoires halieutiques réalisent peu d’échantillonnage biologique des prises commerciales de requins pélagiques, bien qu’il existe des programmes de marquage-récupération pour les requins. Ces dernières années, le Groupe de travail sur les poissons élasmobranches de la CIEM a commencé à rassembler les données disponibles sur les débarquements et émanant d’autres sources de données, et une brève présentation des progrès réalisés jusqu’à ce jour est fournie. RESUMEN Existe un largo historial de explotación de los tiburones pelágicos por parte de las pesquerías europeas. Las pesquerías de tiburón peregrino (Cetorhinus maximus) y marrajo sardinero (Lamna nasus) estaban bien establecidas en las zonas septentrionales (por ejemplo frente a Noruega) a comienzos del siglo XX. Aunque las pesquerías dirigidas al tiburón peregrino han cesado ya, el marrajo sardinero sigue siendo capturado en pesquerías dirigidas localmente importantes en el Mar Celta. Las pesquerías de túnidos e istiofóridos, que se ampliaron en décadas recientes, capturan marrajo dientuso (Isurus oxyrinchus), tintorera (Prionace glauca), y otros tiburones pelágicos, y algunas de estas pesquerías se dirigen a los tiburones en ciertas temporadas/zonas. Antes de finales de los 90, la mayoría de las naciones europeas 1 Marine Institute, Rinville, Oranmore, Co. Galway, Ireland. 2 Fundación AZTI, Instituto Tecnológico, Pesquero y Alimentario. Txatxarramendi ugartea z/g. 48395 Sukarrieta. Bizkaia. Basque Country (Spain). 3 Cefas Lowestoft Lab, Pakefield Road, Lowestoft, NR33 0HT, U.K. 1483 declaraba las capturas como “tiburones no identificados”, y únicamente en años recientes se ha dispuesto de datos específicos de cada especie. Actualmente existe poco muestreo biológico de las capturas comerciales de tiburones pelágicos por parte de los laboratorios pesqueros, aunque hay algunos programas de marcado y liberación para los tiburones. En años recientes, el Grupo de trabajo sobre Elasmobranquios de ICES ha empezado a recopilar los datos disponibles de los desembarques y de otras fuentes y se facilita un breve resumen del progreso alcanzado hasta la fecha. 1. ICES Working Group on Elasmobranch Fishes: A brief history Following marked declines in the landings of spurdog and concerns about the status of other elasmobranchs, including various skates, ICES established a Study Group on Elasmobranch Fisheries, which first met in 1989. However, the work of this Study Group was restricted by the lack of appropriate data and could not conduct assessments. In 1995, the Study Group on Elasmobranch Fish (SGEF) was re-established and reported to the Living Resources Committee (LRC) of ICES. Initial reports (ICES, 1995-2001) focused on describing the fisheries and collating landings data and biological information, and attempts to carry out analytical assessments for some of the better-known demersal species (e.g. spurdog) was still hampered by the paucity of relevant data (ICES, 1999). Members of SGEF subsequently secured EU funding for a Concerted Action entitled “Preparation of a proposal for stock assessment of some elasmobranch fish in European waters” (FAIR CT98–4156), which was followed by a successful proposal for a three-year project entitled “Development of Elasmobranch Assessments (DELASS)”. The main objective of the DELASS project was “the improvement of the scientific basis for the management of fisheries taking elasmobranch species”. The DELASS project compiled available fisheries and biological data and undertook a variety of exploratory assessments in conjunction with SGEF (ICES, 2002; Heessen, 2003). Because of the increased interest in elasmobranch fisheries at a European level, the need for ICES to provide regular advice, and the progress made under the DELASS project, SGEF changed to become the Working Group on Elasmobranch Fish (WGEF) in 2003 (ICES, 2003, 2004) and since 2005 has reported to ACFM (ICES, 2005, 2006). The ICES community has made progress in collating landings data, analysing survey data and in undertaking various exploratory assessments, primarily for demersal and deep-water elasmobranch stocks, and the recommendations from WGEF form the basis of advice that ACFM provides to the EC. There are, however, several issues that still need to be addressed if robust assessments for elasmobranchs are to be undertaken, which include improved species-specific landings data, better life-history data, and biological sampling of commercial landings. Such data requirements are especially pertinent for pelagic fisheries. In terms of pelagic sharks, the DELASS project examined blue shark Prionace glauca as one of the nine case-study species, and recent reports of WGEF (ICES, 2006) have provided the information with which ACFM provided advice for basking shark Cetorhinus maximus and porbeagle Lamna nasus. Although ICES assists in the provision of advice for fisheries operating in the NE Atlantic (Figure 1), the ICES area does not cover the northwestern Atlantic or Mediterranean Sea (even though large areas of the Mediterranean Sea are in EC waters). This is problematic for pelagic species, for which the stocks may occur throughout the North or NE Atlantic and extend into this area. To help redress this, two meetings of an elasmobranch subgroup were held by the EU’s Scientific, Technical and Economic Committee for Fisheries (STECF) to assist in the preparation of an EC Shark Action Plan. Although a considerable amount of background information for such a plan was provided, covering both the NE Atlantic and the Mediterranean (Anon., 2002, 2003), a formal Action Plan has yet to be prepared by the Commission. 2. Pelagic fisheries in the NE Atlantic and Mediterranean 2.1 Basking shark Cetorhinus maximus The basking shark fisheries that once took place in the NE Atlantic have now ceased. The main fishery was prosecuted by Norway, using harpoons, with other fisheries (e.g. off Scotland and Ireland) ceasing earlier. Although the EC used to provide Norway with a quota for livers, this practice has now been discontinued, and there have been no targeted EC fisheries for basking shark in many years, although dead by-catch is landed occasionally in some areas. Overall, catches have declined from peaks in the 1960s and 1970s and ICES (2007) considered that available landings data and anecdotal information suggested that basking sharks were depleted, and advised that no targeted fishing for the species should be permitted and that additional measures should be 1484 taken to prevent their by-catch in fisheries targeting other species. Based on this advice, Norway banned all targeted fisheries for basking sharks. WGEF has made progress in compiling landings data for this species, and in recent years there have been several studies on their movements and migrations (e.g. Southall et al., 2005) which suggest they are quite wide ranging in the NE Atlantic, which is consistent with the view of ICES that
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