Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation

Detalhes bibliográficos
Autor(a) principal: Dellinger, Thomas
Data de Publicação: 1999
Outros Autores: Trillmich, Fritz
Tipo de documento: Artigo
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10400.13/3423
Resumo: Analysis of fish otoliths in scats and vomits of Galápagos fur seals (Arctocephalus galapagoensis) and Galápagos sea lions (Zalophus californianus wollebaeki) was used to determine the numerical composition of the diets for the post-El Niño year 1983, the cold seasons in 1984 and 1985, and the warm season in 1986. Between 84 and 99% of all otoliths in fur seal scats were from myctophids and bathylagids. The fur seals’ diet included 26 species. Only 3 species contributed more than 1% of otoliths. No seasonal differences in diet were found. Sea lion samples contained a mean of 14 otoliths. Sardines (Sardinops sagax) contributed 75–85% of otoliths. Sea lions preyed on 24 species, but only 3 surpassed 1% abundance. Seasonality was not reflected in the sea lions’ diet. After the 1982–1983 El Niño, the diets of both species deviated from those in all other years of the study. Food-niche overlap between the two sympatric species was almost non-existent. This is hard to understand, based on our knowledge of the diving capabilities of the two species, but reflects the fact that Galápagos fur seals are nighttime foragers and sea lions are daytime foragers.
id RCAP_d92a769cfa75f2f409ba33754f9b72a0
oai_identifier_str oai:digituma.uma.pt:10400.13/3423
network_acronym_str RCAP
network_name_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository_id_str 7160
spelling Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separationGalápagos fur sealsGalápagos sea lionsFish preyDietsSeasonal difference.Faculdade de Ciências da VidaAnalysis of fish otoliths in scats and vomits of Galápagos fur seals (Arctocephalus galapagoensis) and Galápagos sea lions (Zalophus californianus wollebaeki) was used to determine the numerical composition of the diets for the post-El Niño year 1983, the cold seasons in 1984 and 1985, and the warm season in 1986. Between 84 and 99% of all otoliths in fur seal scats were from myctophids and bathylagids. The fur seals’ diet included 26 species. Only 3 species contributed more than 1% of otoliths. No seasonal differences in diet were found. Sea lion samples contained a mean of 14 otoliths. Sardines (Sardinops sagax) contributed 75–85% of otoliths. Sea lions preyed on 24 species, but only 3 surpassed 1% abundance. Seasonality was not reflected in the sea lions’ diet. After the 1982–1983 El Niño, the diets of both species deviated from those in all other years of the study. Food-niche overlap between the two sympatric species was almost non-existent. This is hard to understand, based on our knowledge of the diving capabilities of the two species, but reflects the fact that Galápagos fur seals are nighttime foragers and sea lions are daytime foragers.La composition numérique des poissons dans le régime alimentaire a été déterminée par analyse des otolithes contenus dans les fèces et les régurgitations des Otaries de Galápagos (Arctocephalus galapagoensis) et des Lions de mer de Galápagos (Zalophus californianus wollebacki) au cours de l’année post-El Niño, 1983, au cours des saisons froides 1984 et 1985, et au cours de la saison chaude 1986. De 84 à 99% de tous les otolithes contenus dans les fèces des otaries étaient des otolithes de myctophidés et les bathylagidés. Le régime alimentaire des otaries contenait 26 espèces dont seulement trois ont fourni plus de 1% des otolithes. Le régime ne subissait pas de variations saisonnières. Les échantillons provenant des lions de mer contenaient en moyenne 14 otolithes. De 75 à 85% des otolithes étaient des otolithes de Sardines (Sardinops sagax). Les lions de mer se sont nourris de 24 espèces, mais seulement trois d’entre elles ont fourni plus de 1% des otolithes. Il n’y avait pas de variation saisonnière dans le régime alimentaire des lions de mer. Après El Niño, en 1982–83, le régime alimentaire s’est avéré différent de ce qu’il a été au cours de toutes les autres années. Les régimes alimentaires des deux espèces ne se chevauchaient presque pas, ce qui est étonnant si l’on tient compte de leur capacité de plongée, mais qui s’explique si l’on tient compte des habitudes alimentaires nocturnes des otaries et des habitudes alimentaires diurnes des lions de mer.NRC Research PressDigitUMaDellinger, ThomasTrillmich, Fritz2021-05-21T15:14:49Z1999-01-01T00:00:00Z1999-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10400.13/3423engDellinger, T., & Trillmich, F. (1999). Fish prey of the sympatric Galapagos fur seals and sea lions: seasonal variation and niche separation. Canadian Journal of Zoology, 77(8), 1204-1216.10.1139/z99-095info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2022-09-05T12:56:23Zoai:digituma.uma.pt:10400.13/3423Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T15:06:28.646350Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation
title Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation
spellingShingle Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation
Dellinger, Thomas
Galápagos fur seals
Galápagos sea lions
Fish prey
Diets
Seasonal difference
.
Faculdade de Ciências da Vida
title_short Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation
title_full Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation
title_fullStr Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation
title_full_unstemmed Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation
title_sort Fish prey of the sympatric Galápagos fur seals and sea lions: seasonal variation and niche separation
author Dellinger, Thomas
author_facet Dellinger, Thomas
Trillmich, Fritz
author_role author
author2 Trillmich, Fritz
author2_role author
dc.contributor.none.fl_str_mv DigitUMa
dc.contributor.author.fl_str_mv Dellinger, Thomas
Trillmich, Fritz
dc.subject.por.fl_str_mv Galápagos fur seals
Galápagos sea lions
Fish prey
Diets
Seasonal difference
.
Faculdade de Ciências da Vida
topic Galápagos fur seals
Galápagos sea lions
Fish prey
Diets
Seasonal difference
.
Faculdade de Ciências da Vida
description Analysis of fish otoliths in scats and vomits of Galápagos fur seals (Arctocephalus galapagoensis) and Galápagos sea lions (Zalophus californianus wollebaeki) was used to determine the numerical composition of the diets for the post-El Niño year 1983, the cold seasons in 1984 and 1985, and the warm season in 1986. Between 84 and 99% of all otoliths in fur seal scats were from myctophids and bathylagids. The fur seals’ diet included 26 species. Only 3 species contributed more than 1% of otoliths. No seasonal differences in diet were found. Sea lion samples contained a mean of 14 otoliths. Sardines (Sardinops sagax) contributed 75–85% of otoliths. Sea lions preyed on 24 species, but only 3 surpassed 1% abundance. Seasonality was not reflected in the sea lions’ diet. After the 1982–1983 El Niño, the diets of both species deviated from those in all other years of the study. Food-niche overlap between the two sympatric species was almost non-existent. This is hard to understand, based on our knowledge of the diving capabilities of the two species, but reflects the fact that Galápagos fur seals are nighttime foragers and sea lions are daytime foragers.
publishDate 1999
dc.date.none.fl_str_mv 1999-01-01T00:00:00Z
1999-01-01T00:00:00Z
2021-05-21T15:14:49Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/article
format article
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10400.13/3423
url http://hdl.handle.net/10400.13/3423
dc.language.iso.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv Dellinger, T., & Trillmich, F. (1999). Fish prey of the sympatric Galapagos fur seals and sea lions: seasonal variation and niche separation. Canadian Journal of Zoology, 77(8), 1204-1216.
10.1139/z99-095
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv NRC Research Press
publisher.none.fl_str_mv NRC Research Press
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron:RCAAP
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron_str RCAAP
institution RCAAP
reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
repository.mail.fl_str_mv
_version_ 1799129935412985856