Feeding, Growth, and Productivity of Northwest Atlantic Harp Seals ( Pagophilus groenlandicus)
The food of harp seals inhabiting the northwest Atlantic consists chiefly of pelagic fish, especially capelin, Mallotus villosus, and pelagic and benthic Crustacea (Euphausiacea, Mysidacea, Amphipoda, Decapoda), with smaller quantities of benthic fish. Feeding has been observed to take place on indi...
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Canadian Science Publishing
1973
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crcansciencepubl:10.1139/f73-003 2024-05-19T07:46:13+00:00 Feeding, Growth, and Productivity of Northwest Atlantic Harp Seals ( Pagophilus groenlandicus) Sergeant, D. E. 1973 http://dx.doi.org/10.1139/f73-003 http://www.nrcresearchpress.com/doi/pdf/10.1139/f73-003 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Journal of the Fisheries Research Board of Canada volume 30, issue 1, page 17-29 ISSN 0015-296X journal-article 1973 crcansciencepubl https://doi.org/10.1139/f73-003 2024-04-25T06:52:01Z The food of harp seals inhabiting the northwest Atlantic consists chiefly of pelagic fish, especially capelin, Mallotus villosus, and pelagic and benthic Crustacea (Euphausiacea, Mysidacea, Amphipoda, Decapoda), with smaller quantities of benthic fish. Feeding has been observed to take place on individual items by suction, and small fish are taken tail first. Feeding is intensive in winter and (by deduction) in summer, less intensive during spring and autumn migration, and in spring during whelping and moult. A weight loss in spring due chiefly to loss in thickness of subcutaneous fat (blubber) is most intensive in adult females as a result of lactation. This loss is made up slowly in summer. The preparturient females are partly segregated in midwinter on what may be the best feeding grounds. During lactation, and immediately following it when they are again segregated from other age-sex groups, adult females tend to feed on decapod Crustacea. In spring, the only time when all age classes are in the same geographic area, there is a stratification of feeding by size of organism and by depth, from chiefly Euphausiacea taken in surface waters by the weaned young, through capelin taken probably at intermediate depths by the immature animals, to herring, cod, and other groundfish taken by the moulting adults to depths of perhaps 150–200 m. Social feeding begins at about 1 year of age with the change from Crustacea to pelagic fish. From knowledge of the rate of feeding, body weights, and reproductive rates, the ecological efficiency of harp seals (i.e. weight of annual increment of population/weight of annual food eaten) is calculated at 0.005, a low figure. Annual weights of food items eaten by the northwest Atlantic population of harp seals are roughly estimated as: all organisms, 2 × 10 6 metric tons; capelin, 0.5 × 10 6 tons; and herring, 2 × 10 4 tons. Predation by harp seals on capelin stocks off eastern Canada occurs only during the winter months when pack ice is present as a resting substrate, the same ... Article in Journal/Newspaper Northwest Atlantic Pagophilus groenlandicus Canadian Science Publishing Journal of the Fisheries Research Board of Canada 30 1 17 29 |
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Open Polar |
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Canadian Science Publishing |
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crcansciencepubl |
language |
English |
description |
The food of harp seals inhabiting the northwest Atlantic consists chiefly of pelagic fish, especially capelin, Mallotus villosus, and pelagic and benthic Crustacea (Euphausiacea, Mysidacea, Amphipoda, Decapoda), with smaller quantities of benthic fish. Feeding has been observed to take place on individual items by suction, and small fish are taken tail first. Feeding is intensive in winter and (by deduction) in summer, less intensive during spring and autumn migration, and in spring during whelping and moult. A weight loss in spring due chiefly to loss in thickness of subcutaneous fat (blubber) is most intensive in adult females as a result of lactation. This loss is made up slowly in summer. The preparturient females are partly segregated in midwinter on what may be the best feeding grounds. During lactation, and immediately following it when they are again segregated from other age-sex groups, adult females tend to feed on decapod Crustacea. In spring, the only time when all age classes are in the same geographic area, there is a stratification of feeding by size of organism and by depth, from chiefly Euphausiacea taken in surface waters by the weaned young, through capelin taken probably at intermediate depths by the immature animals, to herring, cod, and other groundfish taken by the moulting adults to depths of perhaps 150–200 m. Social feeding begins at about 1 year of age with the change from Crustacea to pelagic fish. From knowledge of the rate of feeding, body weights, and reproductive rates, the ecological efficiency of harp seals (i.e. weight of annual increment of population/weight of annual food eaten) is calculated at 0.005, a low figure. Annual weights of food items eaten by the northwest Atlantic population of harp seals are roughly estimated as: all organisms, 2 × 10 6 metric tons; capelin, 0.5 × 10 6 tons; and herring, 2 × 10 4 tons. Predation by harp seals on capelin stocks off eastern Canada occurs only during the winter months when pack ice is present as a resting substrate, the same ... |
format |
Article in Journal/Newspaper |
author |
Sergeant, D. E. |
spellingShingle |
Sergeant, D. E. Feeding, Growth, and Productivity of Northwest Atlantic Harp Seals ( Pagophilus groenlandicus) |
author_facet |
Sergeant, D. E. |
author_sort |
Sergeant, D. E. |
title |
Feeding, Growth, and Productivity of Northwest Atlantic Harp Seals ( Pagophilus groenlandicus) |
title_short |
Feeding, Growth, and Productivity of Northwest Atlantic Harp Seals ( Pagophilus groenlandicus) |
title_full |
Feeding, Growth, and Productivity of Northwest Atlantic Harp Seals ( Pagophilus groenlandicus) |
title_fullStr |
Feeding, Growth, and Productivity of Northwest Atlantic Harp Seals ( Pagophilus groenlandicus) |
title_full_unstemmed |
Feeding, Growth, and Productivity of Northwest Atlantic Harp Seals ( Pagophilus groenlandicus) |
title_sort |
feeding, growth, and productivity of northwest atlantic harp seals ( pagophilus groenlandicus) |
publisher |
Canadian Science Publishing |
publishDate |
1973 |
url |
http://dx.doi.org/10.1139/f73-003 http://www.nrcresearchpress.com/doi/pdf/10.1139/f73-003 |
genre |
Northwest Atlantic Pagophilus groenlandicus |
genre_facet |
Northwest Atlantic Pagophilus groenlandicus |
op_source |
Journal of the Fisheries Research Board of Canada volume 30, issue 1, page 17-29 ISSN 0015-296X |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/f73-003 |
container_title |
Journal of the Fisheries Research Board of Canada |
container_volume |
30 |
container_issue |
1 |
container_start_page |
17 |
op_container_end_page |
29 |
_version_ |
1799486360486150144 |