Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals ( Phoca vitulina), on Sable Island
Abstract Annual censuses of the number of harbour seal Phoca vitulina pups born on Sable Island Canada showed an increasing trend during the 1980s, but a rapid decline through the 1990s from 625 pups in 1989 to only 32 by 1997. Weekly surveys of the North Beach of the island during the 1991–98 breed...
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crwiley:10.1017/s0952836903004047 2024-06-02T08:07:48+00:00 Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals ( Phoca vitulina), on Sable Island Don Bowen, W. Ellis, Sara L. Iverson, Sara J. Boness, Daryl J. 2003 http://dx.doi.org/10.1017/s0952836903004047 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1017%2FS0952836903004047 https://onlinelibrary.wiley.com/doi/pdf/10.1017/S0952836903004047 https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1017/S0952836903004047 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Zoology volume 261, issue 2, page 155-163 ISSN 0952-8369 1469-7998 journal-article 2003 crwiley https://doi.org/10.1017/s0952836903004047 2024-05-03T11:55:33Z Abstract Annual censuses of the number of harbour seal Phoca vitulina pups born on Sable Island Canada showed an increasing trend during the 1980s, but a rapid decline through the 1990s from 625 pups in 1989 to only 32 by 1997. Weekly surveys of the North Beach of the island during the 1991–98 breeding seasons showed that the number of adults and juveniles also declined during the 1990s. Despite the dramatic demographic changes, maternal postpartum mass, pup birth mass, relative birth mass, lactation duration, pup weaning mass and relative weaning mass showed no significant trends during 1987–96. However, two traits did change. The age structure of parturient females increased significantly, indicating reduced recruitment to the breeding population. Mean birth date increased by 7 days during the early 1990s, suggesting nutritional stress of females and later implantation dates. This nutritional stress may in turn have been caused by increased competition from the rapidly increasing grey seal population on Sable Island. Although minimum estimates of shark‐inflicted mortality can account for much of the decline, evidence suggests that food shortage arising from interspecific competition may have also played a role in causing the decline of the population through effects on fecundity and juvenile survival. Article in Journal/Newspaper harbour seal Phoca vitulina Wiley Online Library Canada North Beach ENVELOPE(-131.924,-131.924,54.042,54.042) Journal of Zoology 261 2 155 163 |
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Open Polar |
collection |
Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract Annual censuses of the number of harbour seal Phoca vitulina pups born on Sable Island Canada showed an increasing trend during the 1980s, but a rapid decline through the 1990s from 625 pups in 1989 to only 32 by 1997. Weekly surveys of the North Beach of the island during the 1991–98 breeding seasons showed that the number of adults and juveniles also declined during the 1990s. Despite the dramatic demographic changes, maternal postpartum mass, pup birth mass, relative birth mass, lactation duration, pup weaning mass and relative weaning mass showed no significant trends during 1987–96. However, two traits did change. The age structure of parturient females increased significantly, indicating reduced recruitment to the breeding population. Mean birth date increased by 7 days during the early 1990s, suggesting nutritional stress of females and later implantation dates. This nutritional stress may in turn have been caused by increased competition from the rapidly increasing grey seal population on Sable Island. Although minimum estimates of shark‐inflicted mortality can account for much of the decline, evidence suggests that food shortage arising from interspecific competition may have also played a role in causing the decline of the population through effects on fecundity and juvenile survival. |
format |
Article in Journal/Newspaper |
author |
Don Bowen, W. Ellis, Sara L. Iverson, Sara J. Boness, Daryl J. |
spellingShingle |
Don Bowen, W. Ellis, Sara L. Iverson, Sara J. Boness, Daryl J. Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals ( Phoca vitulina), on Sable Island |
author_facet |
Don Bowen, W. Ellis, Sara L. Iverson, Sara J. Boness, Daryl J. |
author_sort |
Don Bowen, W. |
title |
Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals ( Phoca vitulina), on Sable Island |
title_short |
Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals ( Phoca vitulina), on Sable Island |
title_full |
Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals ( Phoca vitulina), on Sable Island |
title_fullStr |
Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals ( Phoca vitulina), on Sable Island |
title_full_unstemmed |
Maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals ( Phoca vitulina), on Sable Island |
title_sort |
maternal and newborn life‐history traits during periods of contrasting population trends: implications for explaining the decline of harbour seals ( phoca vitulina), on sable island |
publisher |
Wiley |
publishDate |
2003 |
url |
http://dx.doi.org/10.1017/s0952836903004047 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1017%2FS0952836903004047 https://onlinelibrary.wiley.com/doi/pdf/10.1017/S0952836903004047 https://zslpublications.onlinelibrary.wiley.com/doi/pdf/10.1017/S0952836903004047 |
long_lat |
ENVELOPE(-131.924,-131.924,54.042,54.042) |
geographic |
Canada North Beach |
geographic_facet |
Canada North Beach |
genre |
harbour seal Phoca vitulina |
genre_facet |
harbour seal Phoca vitulina |
op_source |
Journal of Zoology volume 261, issue 2, page 155-163 ISSN 0952-8369 1469-7998 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1017/s0952836903004047 |
container_title |
Journal of Zoology |
container_volume |
261 |
container_issue |
2 |
container_start_page |
155 |
op_container_end_page |
163 |
_version_ |
1800752926874927104 |