Spatiotemporal variation in pup abundance and preweaning survival of harbour seals ( Phoca vitulina ) in the St. Lawrence Estuary, Canada

Marine mammal populations worldwide greatly benefitted from conservation measures put in place since the 1970s following overexploitation, and many pinniped populations have recovered. However, threats due to bycatch, interspecific interactions or climate change remain, and detailed knowledge on vit...

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Bibliographic Details
Published in:Canadian Journal of Zoology
Main Authors: Renaud, Limoilou-Amélie, Pigeon, Gabriel, Van de Walle, Joanie, Bordeleau, Xavier, Hammill, Mike O., Pelletier, Fanie
Format: Article in Journal/Newspaper
Language:English
Published: Canadian Science Publishing 2023
Subjects:
Animal Science and Zoology
Ecology, Evolution, Behavior and Systematics
Canada
harbour seal
Phoca vitulina
Online Access:http://dx.doi.org/10.1139/cjz-2023-0005
https://cdnsciencepub.com/doi/full-xml/10.1139/cjz-2023-0005
https://cdnsciencepub.com/doi/pdf/10.1139/cjz-2023-0005
Description
Summary:Marine mammal populations worldwide greatly benefitted from conservation measures put in place since the 1970s following overexploitation, and many pinniped populations have recovered. However, threats due to bycatch, interspecific interactions or climate change remain, and detailed knowledge on vital rates, population dynamics, and their responses to environmental changes is essential for efficient management and conservation of wild populations. In this study, we quantified pup abundance and survival of individually marked harbour seal ( Phoca vitulina Linnaeus, 1758) pups during the preweaning period at Bic Island and Métis sites in the St. Lawrence Estuary from 1998 to 2019. We used mark-recapture models to evaluate competing hypotheses regarding variation in daily preweaning survival rates and capture probability during the pups’ first 30 days of life. Pup abundance increased from 76 [95% CI: 59, 101] to 323 [95% CI: 233, 338] in the past two decades at Bic Island and from 66 [95% CI: 47, 91] to 285 [95% CI: 204, 318] at Métis. Preweaning survival was generally higher at Bic (0.73 [95% CI: 0.58, 0.82]) than at Métis (0.68 [95% CI: 0.52, 0.79]). We hypothesize that differences between habitats and human disturbance contribute to lower preweaning survival at Métis, but behavioural studies are needed to understand the impacts of disturbance on mother–pup interactions during the nursing period.

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