Evaluating the dependence of opportunistic Yellow-legged Gulls (Larus michahellis) on marine habitat and fishing discards
Several bird species benefit from anthropogenic food subsidies, such as landfills and fish-ing discards, that are being reduced owing to introduced legislation. For instance, since2019, Europe has passed legislation to reduce dramatically the amount of fisheries dis-cards through the Landing Obligation...
| Authors: | , , , , , |
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| Format: | article |
| Publication Date: | 2024 |
| Country: | España |
| Institution: | Universidad del País Vasco |
| Repository: | Addi. Archivo Digital para la Docencia y la Investigación |
| OAI Identifier: | oai:addi.ehu.eus:10810/71236 |
| Online Access: | http://hdl.handle.net/10810/71236 |
| Access Level: | Open access |
| Keyword: | EU policies fishing vessels foraging activity GPS habitat use VMS |
| Summary: | Several bird species benefit from anthropogenic food subsidies, such as landfills and fish-ing discards, that are being reduced owing to introduced legislation. For instance, since2019, Europe has passed legislation to reduce dramatically the amount of fisheries dis-cards through the Landing Obligation (LO), which states that all fish species under TotalAllowable Catch (TAC) should not be discarded at sea. This European discard ban isexpected to impact some gulls, as several gull populations have been observed to beheavily 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. detaileddata of the spatial distribution of fishing vessels) are used to determine the utilization ofthe marine habitat and the level of interaction of gulls with fishing activity offshore anddiscards in the south-eastern part of the Bay of Biscay. We found that these gulls had alow use of the marine habitat (ca. 15%) compared with terrestrial habitats, in contrast tothe 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 fish-ing vessels (an overlap of 21.5% between gulls and VMS data). Conversely, other gullpopulations of the Iberian Peninsula were found to depend much more strongly on fish-ing activity. Therefore, the Yellow-legged Gull population of the SE Bay of Biscay didnot obtain most of its fish prey from interactions with offshore fishing activity but mostpossibly by taking fish remains in harbours and by feeding themselves. Consequently, weexpect a minimal effect of the European policies oriented to ban fishing discards offshoreon this population, which would be more affected by policies directed towards thereduction of food availability in landfills or fish landing management in harbours. |
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