BirdLife International is extending its Albatros Task Force, the initiative to reduce seabird bycatch in collaboration with fishermen, to Europe. Here, the so called Seabird Task Force starts at two bycatch hotspots, Lithuania and the Spanish Mediterranean. Reasons to prioritise this latter area deserve some further explanation.
Spain has a wide diversity of seabirds, with over 40 regular species, more than 20 of them breeding, spread across three distinct geographical regions: the Macaronesia, the European Atlantic and the Mediterranean. Of these, the Mediterranean hosts smaller seabird numbers, but a relatively high diversity of species, many of them of conservation concern precisely due to their tiny populations, as well as restricted distribution ranges. Moreover, the Mediterranean region is highly populated and therefore supports high human pressure, which affects seabirds in several ways: coastal development, introduced predators, pollution, fisheries overexploitation, etc. Among these, bycatch appears to be one of the most serious threats for some species.
Of the seabirds of conservation concern, two species deserve particular attention, the Balearic shearwater Puffinus mauretanicus (Critically Endangered) and the Yelkouan shearwater P. yelkouan (Vulnerable). Both are endemic to the Mediterranean, with small global populations and sharp declining trends, that could lead to their extinction in the near future. Although they are affected by introduced predators and other threats in their colonies, the major drivers of their decline seem to occur at sea, and bycatch postulates itself as the most important of them, particularly on longlines.
Why these birds are prone to be caught in longlines? Both Balearic and Yelkouan shearwaters are often seen following fishing vessels to capture discards, and can get captured in the longline baited hooks when these are thrown overboard during the setting operations. Demersal longlines are particularly dangerous for them, as they operate over the continental shelf, where both species of shearwaters tend to forage (while pelagic longlines often operate further offshore), and use smaller hooks, as well as more suitable bait (often sardine or similar sized fish, ideal for the shearwaters). Moreover, these seabirds are highly gregarious in their foraging grounds, and can “attack” a longline by the hundreds, with the risk of “massive captures” (several tens or more).
Information supporting the idea that demersal longline is a major threat for the two small shearwaters endemic to the Mediterranean is still patchy, but increasing. Events of “mass” mortality have been reported by fishermen (up to over 200 small shearwaters in a single line), or deduced from stranded birds on the beach. Questionnaires to fishermen also point in that direction, with a described event of up to 3,900 seabirds reported!!! And observers onboard demersal longlines have reported the regular capture of the shearwaters, though effort is still limited.
The new Seabird Task Force brings the opportunity to reinforce observers’ effort in the Demersal longline fishery operating off Catalonia, NE Spain, one of the main foraging grounds for the Balearic shearwater in winter and spring (pre-breeding and breeding periods), and also the main foraging area for Yelkouan shearwaters in Spain. Other seabirds regularly captured include Scopoli’s shearwater Calonectris diomedea and Audouin’s gull Larus audouinii, both endemic to the Mediterranean. Recent observers’ work has been conducted in the region by a team from the University of Barcelona (and the Spanish Institute of Oceanography in pelagic longlines), plus questionnaires and workshops by SEO/BirdLife, but further effort is necessary to refine the existing information, most important to provide an accurate estimate of bycatch rates, given the high variability observed. During 2015, SEO/BirdLife’s observers will get onboard demersal longliners across the Catalan coast to address these issues. Later, in 2016, mitigation measures will be tested to assess their efficiency at solving the problem. The close collaboration with fishermen will be essential to achieve any success. We’ll keep you posted of future advances with the project.