Presence of Harbour Seals ( Phoca vitulina ) May Increase Exploitable Fish Biomass in the Strait of Georgia
We tested what degree harbour seal (Phoca vitulina) populations compete with fisheries for commercially harvested species, and to what degree seal populations depend on exploited species as prey. In the Strait of Georgia (SoG), harbour seals mainly feed on fisheries target species, Pacific herring (...
Published in: | Progress in Oceanography |
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Digital Commons @ University of South Florida
2010
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Online Access: | https://digitalcommons.usf.edu/msc_facpub/1843 https://doi.org/10.1016/j.pocean.2010.09.006 |
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ftusouthflorida:oai:digitalcommons.usf.edu:msc_facpub-2843 2023-07-30T04:04:00+02:00 Presence of Harbour Seals ( Phoca vitulina ) May Increase Exploitable Fish Biomass in the Strait of Georgia Li, Lingbo Ainsworth, Cameron Pitcher, Tony 2010-01-01T08:00:00Z https://digitalcommons.usf.edu/msc_facpub/1843 https://doi.org/10.1016/j.pocean.2010.09.006 unknown Digital Commons @ University of South Florida https://digitalcommons.usf.edu/msc_facpub/1843 doi:10.1016/j.pocean.2010.09.006 https://doi.org/10.1016/j.pocean.2010.09.006 Marine Science Faculty Publications Life Sciences article 2010 ftusouthflorida https://doi.org/10.1016/j.pocean.2010.09.006 2023-07-13T21:02:23Z We tested what degree harbour seal (Phoca vitulina) populations compete with fisheries for commercially harvested species, and to what degree seal populations depend on exploited species as prey. In the Strait of Georgia (SoG), harbour seals mainly feed on fisheries target species, Pacific herring (Clupea pallasii) and Pacific hake (Merluccius productus), while herring is also a main prey of hake. Using an Ecopath model constructed based on 2005 conditions, we ran three scenarios: altering herring fishing mortality, removing seal populations and sensitivity analyses of the herring vulnerability parameter. Our results show that with more herring available, the seal population will increase greatly, but with less herring available, the seal populations in the SoG decreases gradually. Our model suggests that the total biomass of commercial fish populations in the SoG may decrease substantially with seals absent. A cull of harbour seals may not increase total fisheries catch in the SoG. Herring benefit from seal predation on herring’s largest predator, hake, so that herring may decline when seals are removed. However, this result is highly dependent on model parameterization. When juvenile herring are considered less vulnerable to hake predation (i.e., when we assume there are many refuges in which to hide), the herring population is less negatively impacted by seal removals. This indicates that survival during this crucial life-stage is important to herring abundance. The model also suggests that, with seals removed, the ecosystem would be dominated by hake. Article in Journal/Newspaper harbour seal Phoca vitulina University of South Florida St. Petersburg: Digital USFSP Hake ENVELOPE(15.612,15.612,66.797,66.797) Pacific Sog ENVELOPE(-20.972,-20.972,63.993,63.993) Progress in Oceanography 87 1-4 235 241 |
institution |
Open Polar |
collection |
University of South Florida St. Petersburg: Digital USFSP |
op_collection_id |
ftusouthflorida |
language |
unknown |
topic |
Life Sciences |
spellingShingle |
Life Sciences Li, Lingbo Ainsworth, Cameron Pitcher, Tony Presence of Harbour Seals ( Phoca vitulina ) May Increase Exploitable Fish Biomass in the Strait of Georgia |
topic_facet |
Life Sciences |
description |
We tested what degree harbour seal (Phoca vitulina) populations compete with fisheries for commercially harvested species, and to what degree seal populations depend on exploited species as prey. In the Strait of Georgia (SoG), harbour seals mainly feed on fisheries target species, Pacific herring (Clupea pallasii) and Pacific hake (Merluccius productus), while herring is also a main prey of hake. Using an Ecopath model constructed based on 2005 conditions, we ran three scenarios: altering herring fishing mortality, removing seal populations and sensitivity analyses of the herring vulnerability parameter. Our results show that with more herring available, the seal population will increase greatly, but with less herring available, the seal populations in the SoG decreases gradually. Our model suggests that the total biomass of commercial fish populations in the SoG may decrease substantially with seals absent. A cull of harbour seals may not increase total fisheries catch in the SoG. Herring benefit from seal predation on herring’s largest predator, hake, so that herring may decline when seals are removed. However, this result is highly dependent on model parameterization. When juvenile herring are considered less vulnerable to hake predation (i.e., when we assume there are many refuges in which to hide), the herring population is less negatively impacted by seal removals. This indicates that survival during this crucial life-stage is important to herring abundance. The model also suggests that, with seals removed, the ecosystem would be dominated by hake. |
format |
Article in Journal/Newspaper |
author |
Li, Lingbo Ainsworth, Cameron Pitcher, Tony |
author_facet |
Li, Lingbo Ainsworth, Cameron Pitcher, Tony |
author_sort |
Li, Lingbo |
title |
Presence of Harbour Seals ( Phoca vitulina ) May Increase Exploitable Fish Biomass in the Strait of Georgia |
title_short |
Presence of Harbour Seals ( Phoca vitulina ) May Increase Exploitable Fish Biomass in the Strait of Georgia |
title_full |
Presence of Harbour Seals ( Phoca vitulina ) May Increase Exploitable Fish Biomass in the Strait of Georgia |
title_fullStr |
Presence of Harbour Seals ( Phoca vitulina ) May Increase Exploitable Fish Biomass in the Strait of Georgia |
title_full_unstemmed |
Presence of Harbour Seals ( Phoca vitulina ) May Increase Exploitable Fish Biomass in the Strait of Georgia |
title_sort |
presence of harbour seals ( phoca vitulina ) may increase exploitable fish biomass in the strait of georgia |
publisher |
Digital Commons @ University of South Florida |
publishDate |
2010 |
url |
https://digitalcommons.usf.edu/msc_facpub/1843 https://doi.org/10.1016/j.pocean.2010.09.006 |
long_lat |
ENVELOPE(15.612,15.612,66.797,66.797) ENVELOPE(-20.972,-20.972,63.993,63.993) |
geographic |
Hake Pacific Sog |
geographic_facet |
Hake Pacific Sog |
genre |
harbour seal Phoca vitulina |
genre_facet |
harbour seal Phoca vitulina |
op_source |
Marine Science Faculty Publications |
op_relation |
https://digitalcommons.usf.edu/msc_facpub/1843 doi:10.1016/j.pocean.2010.09.006 https://doi.org/10.1016/j.pocean.2010.09.006 |
op_doi |
https://doi.org/10.1016/j.pocean.2010.09.006 |
container_title |
Progress in Oceanography |
container_volume |
87 |
container_issue |
1-4 |
container_start_page |
235 |
op_container_end_page |
241 |
_version_ |
1772815162888159232 |