The role of predation by harp seals (Pagophilus groenlandicus) in the collapse and non-recovery of northern Gulf of St. Lawrence cod (Gadus morhua)
A statistical catch-at-age model was developed to assess the effects of predation by the northwest Atlantic harp seal population on northern Gulf of St. Lawrence cod by estimating the relative importance of different sources of mortality that affected the stock during a period of collapse and non-re...
Published in: | Marine Ecology Progress Series |
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Format: | Article in Journal/Newspaper |
Language: | English |
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2009
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Online Access: | https://ird.hal.science/ird-00549074 https://ird.hal.science/ird-00549074/document https://ird.hal.science/ird-00549074/file/Chassot20080671_cor.pdf https://doi.org/10.3354/meps07897 |
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ftunimontpellier:oai:HAL:ird-00549074v1 2023-12-17T10:30:25+01:00 The role of predation by harp seals (Pagophilus groenlandicus) in the collapse and non-recovery of northern Gulf of St. Lawrence cod (Gadus morhua) Chassot, Emmanuel Duplisea, Daniel, E. Hammill, Mike, O. Caskenette, Amanda Bousquet, Nicolas Lambert, Yvan Stenson, Garry, H. Division des Sciences Halieutiques et Aquacoles (DSHA) Fisheries and Oceans Canada (DFO) Ecosystèmes Marins Exploités (UMR EME) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM) Division of Fisheries and Oceans Canada Département de Mathématiques et Statistiques Université Laval Québec (ULaval) Division of Fisheries and Ocean Canada Northwest Atlantic Fisheries Centre (NWAFC) Species at risk funding program (SARCEP) SARCEP 2009 https://ird.hal.science/ird-00549074 https://ird.hal.science/ird-00549074/document https://ird.hal.science/ird-00549074/file/Chassot20080671_cor.pdf https://doi.org/10.3354/meps07897 en eng HAL CCSD Inter Research info:eu-repo/semantics/altIdentifier/doi/10.3354/meps07897 ird-00549074 https://ird.hal.science/ird-00549074 https://ird.hal.science/ird-00549074/document https://ird.hal.science/ird-00549074/file/Chassot20080671_cor.pdf doi:10.3354/meps07897 IRD: fdi:010048608 info:eu-repo/semantics/OpenAccess ISSN: 0171-8630 EISSN: 1616-1599 Marine Ecology Progress Series https://ird.hal.science/ird-00549074 Marine Ecology Progress Series, 2009, 379, pp.279-297. ⟨10.3354/meps07897⟩ Cod harp seal functional response model predation recovery [SDE.BE]Environmental Sciences/Biodiversity and Ecology info:eu-repo/semantics/article Journal articles 2009 ftunimontpellier https://doi.org/10.3354/meps07897 2023-11-21T23:33:55Z A statistical catch-at-age model was developed to assess the effects of predation by the northwest Atlantic harp seal population on northern Gulf of St. Lawrence cod by estimating the relative importance of different sources of mortality that affected the stock during a period of collapse and non-recovery. Cod recruitment at age 1 is modeled via a non-linear stock-recruitment relationship based on total egg production and accounts for changes in female length-at-maturity and cod condition. Natural mortality other than seal predation also depends on cod condition used as an integrative index of changes in environmental conditions. The linkage between seals and cod is modeled through a multi-age functional response that was derived from the reconstruction of the seal diet using morphometric relationships and stomach contents of more than 200 seals collected between 1998 and 2001. The model was fitted following a maximum likelihood estimation approach to a scientific survey abundance index (1984-2006). Model results show that the collapse of the northern Gulf of St. Lawrence cod stock was mainly due to the combination of high fishing mortality rates and poor environmental conditions in the early to mid-1990s contributing to the current state of recruitment overfishing. The increase in harp seal abundance during 1984-2006 was reflected by an increase in predation mortality for the young cod age-groups targeted by seals. Although current levels of predation mortality affect cod spawning biomass, the lack of recovery of the NGSL cod stock seems mainly due to the situation of very poor recruitment. Article in Journal/Newspaper Gadus morhua Harp Seal Northwest Atlantic Pagophilus groenlandicus Université de Montpellier: HAL Marine Ecology Progress Series 379 279 297 |
institution |
Open Polar |
collection |
Université de Montpellier: HAL |
op_collection_id |
ftunimontpellier |
language |
English |
topic |
Cod harp seal functional response model predation recovery [SDE.BE]Environmental Sciences/Biodiversity and Ecology |
spellingShingle |
Cod harp seal functional response model predation recovery [SDE.BE]Environmental Sciences/Biodiversity and Ecology Chassot, Emmanuel Duplisea, Daniel, E. Hammill, Mike, O. Caskenette, Amanda Bousquet, Nicolas Lambert, Yvan Stenson, Garry, H. The role of predation by harp seals (Pagophilus groenlandicus) in the collapse and non-recovery of northern Gulf of St. Lawrence cod (Gadus morhua) |
topic_facet |
Cod harp seal functional response model predation recovery [SDE.BE]Environmental Sciences/Biodiversity and Ecology |
description |
A statistical catch-at-age model was developed to assess the effects of predation by the northwest Atlantic harp seal population on northern Gulf of St. Lawrence cod by estimating the relative importance of different sources of mortality that affected the stock during a period of collapse and non-recovery. Cod recruitment at age 1 is modeled via a non-linear stock-recruitment relationship based on total egg production and accounts for changes in female length-at-maturity and cod condition. Natural mortality other than seal predation also depends on cod condition used as an integrative index of changes in environmental conditions. The linkage between seals and cod is modeled through a multi-age functional response that was derived from the reconstruction of the seal diet using morphometric relationships and stomach contents of more than 200 seals collected between 1998 and 2001. The model was fitted following a maximum likelihood estimation approach to a scientific survey abundance index (1984-2006). Model results show that the collapse of the northern Gulf of St. Lawrence cod stock was mainly due to the combination of high fishing mortality rates and poor environmental conditions in the early to mid-1990s contributing to the current state of recruitment overfishing. The increase in harp seal abundance during 1984-2006 was reflected by an increase in predation mortality for the young cod age-groups targeted by seals. Although current levels of predation mortality affect cod spawning biomass, the lack of recovery of the NGSL cod stock seems mainly due to the situation of very poor recruitment. |
author2 |
Division des Sciences Halieutiques et Aquacoles (DSHA) Fisheries and Oceans Canada (DFO) Ecosystèmes Marins Exploités (UMR EME) Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Montpellier (UM) Division of Fisheries and Oceans Canada Département de Mathématiques et Statistiques Université Laval Québec (ULaval) Division of Fisheries and Ocean Canada Northwest Atlantic Fisheries Centre (NWAFC) Species at risk funding program (SARCEP) SARCEP |
format |
Article in Journal/Newspaper |
author |
Chassot, Emmanuel Duplisea, Daniel, E. Hammill, Mike, O. Caskenette, Amanda Bousquet, Nicolas Lambert, Yvan Stenson, Garry, H. |
author_facet |
Chassot, Emmanuel Duplisea, Daniel, E. Hammill, Mike, O. Caskenette, Amanda Bousquet, Nicolas Lambert, Yvan Stenson, Garry, H. |
author_sort |
Chassot, Emmanuel |
title |
The role of predation by harp seals (Pagophilus groenlandicus) in the collapse and non-recovery of northern Gulf of St. Lawrence cod (Gadus morhua) |
title_short |
The role of predation by harp seals (Pagophilus groenlandicus) in the collapse and non-recovery of northern Gulf of St. Lawrence cod (Gadus morhua) |
title_full |
The role of predation by harp seals (Pagophilus groenlandicus) in the collapse and non-recovery of northern Gulf of St. Lawrence cod (Gadus morhua) |
title_fullStr |
The role of predation by harp seals (Pagophilus groenlandicus) in the collapse and non-recovery of northern Gulf of St. Lawrence cod (Gadus morhua) |
title_full_unstemmed |
The role of predation by harp seals (Pagophilus groenlandicus) in the collapse and non-recovery of northern Gulf of St. Lawrence cod (Gadus morhua) |
title_sort |
role of predation by harp seals (pagophilus groenlandicus) in the collapse and non-recovery of northern gulf of st. lawrence cod (gadus morhua) |
publisher |
HAL CCSD |
publishDate |
2009 |
url |
https://ird.hal.science/ird-00549074 https://ird.hal.science/ird-00549074/document https://ird.hal.science/ird-00549074/file/Chassot20080671_cor.pdf https://doi.org/10.3354/meps07897 |
genre |
Gadus morhua Harp Seal Northwest Atlantic Pagophilus groenlandicus |
genre_facet |
Gadus morhua Harp Seal Northwest Atlantic Pagophilus groenlandicus |
op_source |
ISSN: 0171-8630 EISSN: 1616-1599 Marine Ecology Progress Series https://ird.hal.science/ird-00549074 Marine Ecology Progress Series, 2009, 379, pp.279-297. ⟨10.3354/meps07897⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.3354/meps07897 ird-00549074 https://ird.hal.science/ird-00549074 https://ird.hal.science/ird-00549074/document https://ird.hal.science/ird-00549074/file/Chassot20080671_cor.pdf doi:10.3354/meps07897 IRD: fdi:010048608 |
op_rights |
info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.3354/meps07897 |
container_title |
Marine Ecology Progress Series |
container_volume |
379 |
container_start_page |
279 |
op_container_end_page |
297 |
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1785583389863051264 |