Seabird mortality from longline fishing in the Mediterranean Sea and Macaronesian waters: a review and a way forward

Abstract

SUMMARY: A country-by-country review of seabird mortality from longline fishing in the Mediterranean Sea and in Macaronesian waters shows a paucity of data. Of 12 Mediterranean countries known to undertake longlining, seabird mortality is only reported for six: France, Greece, Italy, Malta, Spain and Tunisia. Seabird mortality from longlining has been reported from the Azores (Portugal) but not from the other Macaronesian Islands. Only for one country, Spain, is information on the levels of mortality available, suggesting that 4-6% of the local breeding population of Cory's shearwater Calonectris diomedea may be killed annually, a level considered unsustainable for the long-term persistence of colonies. Cory's shearwater is the most commonly affected species, although a number of Larus gull species are also being caught. There is insufficient knowledge to conclude whether any seabird species is at conservation risk within the region, but concern is expressed for Cory's shearwater. It is recommended that Mediterranean and Macaronesian countries conduct assessments of their longline fisheries and seabird mortality in terms of the Food and Agriculture Organization's International Plan of ActionSeabirds. Regional fishery organisations, such as ICCAT and GFCM, should commence the collection of seabird mortality data. A "longline action plan" for the affected seabird species should be produced.Key words: seabirds, longline fishing, conservation, Mediterranean, Macaronesia. RESUMEN: MORTALIDAD DE AVES MARINAS EN PALANGRES DEL MAR MEDITERRÁNEO E ISLAS MACARONESIAS: REVISIÓN Y PRO-PUESTAS DEFUTURO. -Este trabajo presenta una revisión de la escasa información disponible sobre mortalidad de aves marinas en las flotas palangreras del mar Mediterráneo y Macaronesia. De los 12 países mediterráneos que disponen de flota palangrera tan sólo 6 han aportado información sobre mortalidad de aves marinas: Francia, Grecia, Italia, Malta, España y Túnez. También se sabe que existe mortalidad de aves marinas en las islas Azores (Portugal) pero no en el resto de las islas de la Macaronesia. Tan sólo España dispone de información sobre niveles de mortalidad. Es posible que entre el 4-6% de la población reproductora local de pardela cenicienta Calonectris diomedea muera en el palangre anualmente, un nivel que se considera insostenible para la persistencia a largo plazo de las colonias. La pardela cenicienta es la especie más afectada, aunque también se capturan gaviotas del género Larus. Aunque no se sabe lo suficiente como para concluir si alguna especie de ave marina está amenazada localmente por el palangre, se sugiere que la pardela cenicienta sí puede estarlo. Se recomienda que los países mediterráneos y macaronésicos lleven a cabo valoraciones de sus pesquerías de palangre y de la mortalidad de aves marinas en los términos de los planes internacionales de acción de la FAO. Las organizaciones pesqueras

Does by-catch pose a threat for the conservation of seabird populations in the southern Ionian Sea (eastern Mediterranean)? A questionnaire based survey of local fisheries

“…In general, the seabird species that are more susceptible to longline by-catch are attracted to fishing vessels as a result of food provisioning via fishery discards and forage near the sea surface, scavenging and stealing bait from hooks (Montevecchi, 2002). This fact can explain the high rate of Scopoli's Shearwater mortality on longlines, which is in accordance with previous by-catch studies in the Mediterranean basin where the majority of individuals implicated in incidental by-catch belonged to this long-lived colonial pelagic species (Belda & Sánchez, 2001;Cooper et al, 2003;Sánchez & Belda, 2003;Dimech et al, 2009). In addition, incidental catches primarily occurred around sunrise and late afternoon, mainly Scopoli's Shearwaters and to a lesser extent Mediterranean Shags, which were waiting for the baited hooks to be deployed, and then attempted to eat the bait (usually sardines or squid).…”

Dual-foraging of Cory’s shearwaters in the Azores: feeding locations, behaviour at sea and implications for food provisioning of chicks

“…Cory's shearwaters are opportunistic predators (Granadeiro et al 1998b) and concern has been expressed over incidental mortality of adults in longline fisheries in the Mediterranean and Macaronesia (Cooper et al 2003, Gonzáles-Solís et al 2007. Our data suggest that breeding adults from the Azores could potentially be affected by interactions with fisheries over a much larger area of ocean than previously recognized, paralleling recent findings for the overwintering and migration periods (Gonzáles-Solís et al 2007).…”

Global seabird bycatch in longline fisheries

“…Cooper et al (2003) highlighted the lack of seabird bycatch data available for the Mediterranean. The only rigorous scientific investigations to date have come from Spanish waters in the western Mediterranean (e.g.…”