Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.

[eng] Seabirds feeding ecology was studied at sea to assess the significance of two commercial fisheries, trawlers (demersal fishery with diurnal activity) and purse seiners (pelagic fishery with nocturnal activity), in the NW Mediterranean. Trawlers offered high amounts of discards (mostly fish of...

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Detalles Bibliográficos
Autor: Arcos Pros, José Manuel
Tipo de recurso: tesis doctoral
Estado:Versión publicada
Fecha de publicación:2001
País:España
Institución:Universidad de Barcelona
Repositorio:Dipòsit Digital de la UB
OAI Identifier:oai:diposit.ub.edu:2445/35873
Acceso en línea:https://hdl.handle.net/2445/35873
http://www.tdx.cat/TDX-0219102-114337
http://hdl.handle.net/10803/775
Access Level:acceso abierto
Palabra clave:Ocells marins
Nutrició animal
Indústria pesquera
Ecologia marina
Mediterrània (Regió)
Sea birds
Animal nutrition
Fisheries
Marine ecology
Mediterranean Region
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spelling Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.Arcos Pros, José ManuelOcells marinsNutrició animalIndústria pesqueraEcologia marinaMediterrània (Regió)Sea birdsAnimal nutritionFisheriesMarine ecologyMediterranean Region[eng] Seabirds feeding ecology was studied at sea to assess the significance of two commercial fisheries, trawlers (demersal fishery with diurnal activity) and purse seiners (pelagic fishery with nocturnal activity), in the NW Mediterranean. Trawlers offered high amounts of discards (mostly fish of small size) on a predictable basis, and consequently attracted large numbers of seabirds. At the Ebro Delta, discards provided in average 65% of the energy requirements of the seabird breeding community, being most important for large gulls and of little significance for terns. Purse seiners produced few discards, on an irregular basis, and attracted lower numbers of seabirds during discarding (after dawn). During the fishing operation, at night, only Audouin's Gulls Larus audouinii attended these vessels, capturing live fish concentrated near the sea surface, attracted by powerful lamps. During the breeding season, Audouin's Gulls preferentially attended trawlers in spite of potential competition with the more aggressive and opportunistic Yellow-legged Gulls Larus cachinnans, since the former showed to be more efficient at capturing discards and reduced competition by showing a wider range of feeding techniques. Only during trawler closures, Audouin's Gulls occurred in important numbers at purse seiners (thus acting as a secondary food resource for most individuals). During the non-breeding season Audouin's Gulls shifted to preferentially attend purse seiners, presumably because competition at trawlers strengthened at this period. The rare and threatened Balearic Shearwater Puffinus mauretanicus also made significant use of discards, which represented more than 40% of the energy requirements of the whole population during the breeding season. Seabirds feeding upon discards showed higher levels of mercury, as discards make accessible to them demersal fish that is more polluted than epipelagic fish (natural prey for most seabirds). Thus, the risks of toxicity by this metal are higher for those species capturing discards. Given the significance of commercial fisheries for seabirds in the NW Mediterranean, and considering the increasing ecosystem-based approach to fisheries management, fisheries managers should regard these birds when designing fishing policies.Universitat de BarcelonaRuiz Gabriel, XavierOro, DanielUniversitat de Barcelona. Departament de Biologia Animal2001info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://hdl.handle.net/2445/35873http://www.tdx.cat/TDX-0219102-114337http://hdl.handle.net/10803/775Tesis Doctorals - Departament - Biologia Animalreponame:Dipòsit Digital de la UBinstname:Universidad de BarcelonaInglés(c) Arcos Pros, 2001info:eu-repo/semantics/openAccessoai:diposit.ub.edu:2445/358732026-05-27T06:46:51Z
dc.title.none.fl_str_mv Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.
title Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.
spellingShingle Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.
Arcos Pros, José Manuel
Ocells marins
Nutrició animal
Indústria pesquera
Ecologia marina
Mediterrània (Regió)
Sea birds
Animal nutrition
Fisheries
Marine ecology
Mediterranean Region
title_short Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.
title_full Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.
title_fullStr Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.
title_full_unstemmed Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.
title_sort Foraging Ecology of Seabirds at Sea: Significance of Commercial Fisheries in the NW Mediterranean.
dc.creator.none.fl_str_mv Arcos Pros, José Manuel
author Arcos Pros, José Manuel
author_facet Arcos Pros, José Manuel
author_role author
dc.contributor.none.fl_str_mv Ruiz Gabriel, Xavier
Oro, Daniel
Universitat de Barcelona. Departament de Biologia Animal
dc.subject.none.fl_str_mv Ocells marins
Nutrició animal
Indústria pesquera
Ecologia marina
Mediterrània (Regió)
Sea birds
Animal nutrition
Fisheries
Marine ecology
Mediterranean Region
topic Ocells marins
Nutrició animal
Indústria pesquera
Ecologia marina
Mediterrània (Regió)
Sea birds
Animal nutrition
Fisheries
Marine ecology
Mediterranean Region
description [eng] Seabirds feeding ecology was studied at sea to assess the significance of two commercial fisheries, trawlers (demersal fishery with diurnal activity) and purse seiners (pelagic fishery with nocturnal activity), in the NW Mediterranean. Trawlers offered high amounts of discards (mostly fish of small size) on a predictable basis, and consequently attracted large numbers of seabirds. At the Ebro Delta, discards provided in average 65% of the energy requirements of the seabird breeding community, being most important for large gulls and of little significance for terns. Purse seiners produced few discards, on an irregular basis, and attracted lower numbers of seabirds during discarding (after dawn). During the fishing operation, at night, only Audouin's Gulls Larus audouinii attended these vessels, capturing live fish concentrated near the sea surface, attracted by powerful lamps. During the breeding season, Audouin's Gulls preferentially attended trawlers in spite of potential competition with the more aggressive and opportunistic Yellow-legged Gulls Larus cachinnans, since the former showed to be more efficient at capturing discards and reduced competition by showing a wider range of feeding techniques. Only during trawler closures, Audouin's Gulls occurred in important numbers at purse seiners (thus acting as a secondary food resource for most individuals). During the non-breeding season Audouin's Gulls shifted to preferentially attend purse seiners, presumably because competition at trawlers strengthened at this period. The rare and threatened Balearic Shearwater Puffinus mauretanicus also made significant use of discards, which represented more than 40% of the energy requirements of the whole population during the breeding season. Seabirds feeding upon discards showed higher levels of mercury, as discards make accessible to them demersal fish that is more polluted than epipelagic fish (natural prey for most seabirds). Thus, the risks of toxicity by this metal are higher for those species capturing discards. Given the significance of commercial fisheries for seabirds in the NW Mediterranean, and considering the increasing ecosystem-based approach to fisheries management, fisheries managers should regard these birds when designing fishing policies.
publishDate 2001
dc.date.none.fl_str_mv 2001
dc.type.none.fl_str_mv info:eu-repo/semantics/doctoralThesis
info:eu-repo/semantics/publishedVersion
format doctoralThesis
status_str publishedVersion
dc.identifier.none.fl_str_mv https://hdl.handle.net/2445/35873
http://www.tdx.cat/TDX-0219102-114337
http://hdl.handle.net/10803/775
url https://hdl.handle.net/2445/35873
http://www.tdx.cat/TDX-0219102-114337
http://hdl.handle.net/10803/775
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.rights.none.fl_str_mv (c) Arcos Pros, 2001
info:eu-repo/semantics/openAccess
rights_invalid_str_mv (c) Arcos Pros, 2001
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Universitat de Barcelona
publisher.none.fl_str_mv Universitat de Barcelona
dc.source.none.fl_str_mv Tesis Doctorals - Departament - Biologia Animal
reponame:Dipòsit Digital de la UB
instname:Universidad de Barcelona
instname_str Universidad de Barcelona
reponame_str Dipòsit Digital de la UB
collection Dipòsit Digital de la UB
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15,300719

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