Grey seal ( Halichoerus grypus ) from the Northwest Atlantic: female reproductive rates, age at first birth, and age of maturity in males
Mean age at first birth and reproductive rates were examined in a sample of 526 female grey seal (Halichoerus grypus) reproductive tracts collected between 1968 and 1992. Age of first birth determined from reproductive tracts with a fetus was 5.5 ± 0.12 yr (mean ± SD). No trend over time was observe...
Published in: | Canadian Journal of Fisheries and Aquatic Sciences |
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Language: | English |
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Canadian Science Publishing
1995
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Online Access: | http://dx.doi.org/10.1139/f95-864 http://www.nrcresearchpress.com/doi/pdf/10.1139/f95-864 |
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crcansciencepubl:10.1139/f95-864 2023-12-17T10:47:36+01:00 Grey seal ( Halichoerus grypus ) from the Northwest Atlantic: female reproductive rates, age at first birth, and age of maturity in males Hammill, M. O. Gosselin, J. F. 1995 http://dx.doi.org/10.1139/f95-864 http://www.nrcresearchpress.com/doi/pdf/10.1139/f95-864 en eng Canadian Science Publishing http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining Canadian Journal of Fisheries and Aquatic Sciences volume 52, issue 12, page 2757-2761 ISSN 0706-652X 1205-7533 Aquatic Science Ecology, Evolution, Behavior and Systematics journal-article 1995 crcansciencepubl https://doi.org/10.1139/f95-864 2023-11-19T13:38:23Z Mean age at first birth and reproductive rates were examined in a sample of 526 female grey seal (Halichoerus grypus) reproductive tracts collected between 1968 and 1992. Age of first birth determined from reproductive tracts with a fetus was 5.5 ± 0.12 yr (mean ± SD). No trend over time was observed in mean age at first birth or in pregnancy rates. Pregnancy rates determined from reproductive tracts containing a fetus were 0.18, 0.86, and 0.88 for animals aged 4+, 5+, and >6+ yr, respectively. Pregnancy rates calculated from the presence of a corpus luteum were 0.01, 0.45, 0.9, and 1 for ages 3+, 4+, 5+, and >6+, respectively. Mean age of sexual maturity of males was 5.6 yr as estimated from changes in testes mass in a sample of 89 seals collected during August–September 1992. A marked increase in testes mass was observed among animals aged 3+ yr. By age 7+ yr, virtually all males had attained sexual maturity. Article in Journal/Newspaper Northwest Atlantic Canadian Science Publishing (via Crossref) Canadian Journal of Fisheries and Aquatic Sciences 52 12 2757 2761 |
institution |
Open Polar |
collection |
Canadian Science Publishing (via Crossref) |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
Aquatic Science Ecology, Evolution, Behavior and Systematics |
spellingShingle |
Aquatic Science Ecology, Evolution, Behavior and Systematics Hammill, M. O. Gosselin, J. F. Grey seal ( Halichoerus grypus ) from the Northwest Atlantic: female reproductive rates, age at first birth, and age of maturity in males |
topic_facet |
Aquatic Science Ecology, Evolution, Behavior and Systematics |
description |
Mean age at first birth and reproductive rates were examined in a sample of 526 female grey seal (Halichoerus grypus) reproductive tracts collected between 1968 and 1992. Age of first birth determined from reproductive tracts with a fetus was 5.5 ± 0.12 yr (mean ± SD). No trend over time was observed in mean age at first birth or in pregnancy rates. Pregnancy rates determined from reproductive tracts containing a fetus were 0.18, 0.86, and 0.88 for animals aged 4+, 5+, and >6+ yr, respectively. Pregnancy rates calculated from the presence of a corpus luteum were 0.01, 0.45, 0.9, and 1 for ages 3+, 4+, 5+, and >6+, respectively. Mean age of sexual maturity of males was 5.6 yr as estimated from changes in testes mass in a sample of 89 seals collected during August–September 1992. A marked increase in testes mass was observed among animals aged 3+ yr. By age 7+ yr, virtually all males had attained sexual maturity. |
format |
Article in Journal/Newspaper |
author |
Hammill, M. O. Gosselin, J. F. |
author_facet |
Hammill, M. O. Gosselin, J. F. |
author_sort |
Hammill, M. O. |
title |
Grey seal ( Halichoerus grypus ) from the Northwest Atlantic: female reproductive rates, age at first birth, and age of maturity in males |
title_short |
Grey seal ( Halichoerus grypus ) from the Northwest Atlantic: female reproductive rates, age at first birth, and age of maturity in males |
title_full |
Grey seal ( Halichoerus grypus ) from the Northwest Atlantic: female reproductive rates, age at first birth, and age of maturity in males |
title_fullStr |
Grey seal ( Halichoerus grypus ) from the Northwest Atlantic: female reproductive rates, age at first birth, and age of maturity in males |
title_full_unstemmed |
Grey seal ( Halichoerus grypus ) from the Northwest Atlantic: female reproductive rates, age at first birth, and age of maturity in males |
title_sort |
grey seal ( halichoerus grypus ) from the northwest atlantic: female reproductive rates, age at first birth, and age of maturity in males |
publisher |
Canadian Science Publishing |
publishDate |
1995 |
url |
http://dx.doi.org/10.1139/f95-864 http://www.nrcresearchpress.com/doi/pdf/10.1139/f95-864 |
genre |
Northwest Atlantic |
genre_facet |
Northwest Atlantic |
op_source |
Canadian Journal of Fisheries and Aquatic Sciences volume 52, issue 12, page 2757-2761 ISSN 0706-652X 1205-7533 |
op_rights |
http://www.nrcresearchpress.com/page/about/CorporateTextAndDataMining |
op_doi |
https://doi.org/10.1139/f95-864 |
container_title |
Canadian Journal of Fisheries and Aquatic Sciences |
container_volume |
52 |
container_issue |
12 |
container_start_page |
2757 |
op_container_end_page |
2761 |
_version_ |
1785571506733973504 |