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Title: Evaluating the dependence of opportunistic Yellow-legged Gulls (<i>Larus michahellis</i>) on marine habitat and fishing discards
Authors: Zorrozua, Nere; Granado, Igor; Fernandes, Jose A.; Louzao, Maite; Basterretxea, Mikel; Arizaga, Juan
Citation: IBIS, 2024, 166, 112-128
Abstract: Several bird species benefit from anthropogenic food subsidies, such as landfills and fishing discards, that are being reduced owing to introduced legislation. For instance, since 2019, Europe has passed legislation to reduce dramatically the amount of fisheries discards through the Landing Obligation (LO), which states that all fish species under Total Allowable Catch (TAC) should not be discarded at sea. This European discard ban is expected to impact some gulls, as several gull populations have been observed to be heavily reliant on this resource. In this work, GPS tracking data from adult Yellow-legged Gulls Larus michahellis and Vessel Monitoring System (VMS) data (i.e. detailed data of the spatial distribution of fishing vessels) are used to determine the utilization of the marine habitat and the level of interaction of gulls with fishing activity offshore and discards in the south-eastern part of the Bay of Biscay. We found that these gulls had a low use of the marine habitat (ca. 15\%) compared with terrestrial habitats, in contrast to the ca. 40\% of the diet of this population which comprises marine prey. Furthermore, we detected that most of the gull tracking positions at sea did not interact with the fishing vessels (an overlap of 21.5\% between gulls and VMS data). Conversely, other gull populations of the Iberian Peninsula were found to depend much more strongly on fishing activity. Therefore, the Yellow-legged Gull population of the SE Bay of Biscay did not obtain most of its fish prey from interactions with offshore fishing activity but most possibly by taking fish remains in harbours and by feeding themselves. Consequently, we expect a minimal effect of the European policies oriented to ban fishing discards offshore on this population, which would be more affected by policies directed towards the reduction of food availability in landfills or fish landing management in harbours.
Issue Date: 2024
Publisher: WILEY
Type: Article; Early Access
DOI: 10.1111/ibi.13227
ISSN: 0019-1019
E-ISSN: 1474-919X
Funder: Basque Government
Gipuzkoa Administration
European Union's Horizon 2020 research and innovation programme under the FutureMARES project [869300]
PETFISH project - Department of Economic Development and Competitiveness of the Basque Government
European Commission Data Collection Framework
IKERTALENT grant from Department of Economic Development and Infrastructures of Basque Government
Ramon y Cajal of Spanish Ministry of Economy, Industry and Competitiveness [RYC-2012-09897]
Appears in Publication types:Artículos científicos

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