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Contrasting trends in gray seal (Halichoerus grypus) pup production throughout the increasing northwest Atlantic metapopulation |
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| Authors: | Cornelia E den Heyer W Don Bowen Julian Dale Jean-François Gosselin Michael O Hammill David W Johnston Shelley L C Lang Kimberly T Murray Garry B Stenson Stephanie A Wood |
| Institution: | 1. Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada;2. Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada
Contribution: Conceptualization, Formal analysis, Funding acquisition, ?Investigation, Methodology, Resources, Supervision, Writing - original draft, Writing - review & editing;3. Nicholas School of the Environment, Duke University Marine Laboratory, Durham, North Carolina, USA Contribution: ?Investigation, Methodology, Validation, Writing - review & editing;4. Fisheries and Oceans Canada, Maurice Lamontagne Institute, Mont-Joli, Quebec, Canada Contribution: Data curation, ?Investigation, Methodology, Supervision, Writing - original draft;5. Fisheries and Oceans Canada, Maurice Lamontagne Institute, Mont-Joli, Quebec, Canada Contribution: Conceptualization, Data curation, Formal analysis, Funding acquisition, ?Investigation, Methodology, Resources, Supervision, Validation, Writing - original draft, Writing - review & editing;6. Nicholas School of the Environment, Duke University Marine Laboratory, Durham, North Carolina, USA Contribution: ?Investigation, Methodology, Resources, Validation, Writing - review & editing;7. Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia, Canada Contribution: Data curation, Formal analysis, ?Investigation, Methodology, Resources, Validation, Visualization, Writing - original draft, Writing - review & editing;8. National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northeast Fisheries Science Center, Woods Hole, Massachusetts, USA Contribution: Conceptualization, Data curation, Funding acquisition, ?Investigation, Methodology, Resources, Supervision, Validation, Writing - original draft, Writing - review & editing;9. Fisheries and Oceans Canada, North Atlantic Fisheries Centre, St. John's, Newfoundland and Labrador, Canada Contribution: Conceptualization, Data curation, ?Investigation, Methodology, Resources, Supervision, Writing - original draft, Writing - review & editing;10. Biology Department, University of Massachusetts, Boston, Boston, Massachusetts, USA Contribution: Conceptualization, Data curation, ?Investigation, Methodology, Writing - original draft, Writing - review & editing |
| Abstract: | The northwest Atlantic subspecies of gray seal (Halicheorus grypus grypus) has been increasing for more than a half century and has reestablished breeding colonies in Canadian and US waters. In 2016, visual, oblique, and vertical large-format digital photographic surveys were conducted at all known breeding colonies in the northwest Atlantic. Total pup production in the northwest Atlantic was estimated to be 109,000 (SE = 17,500) pups. At 87,500 (SE = 15,100) pups, Sable Island accounts for 80% of total pup production. Regional differences in pup production trends are evident. Pup production in the Gulf of St. Lawrence and along the eastern shore of Nova Scotia has been relatively stable. Since 2004, the rate of increase in pup production at Sable Island has slowed to about 5%–7% per year, while the newer colonies in southwest Nova Scotia and the northeastern United States are increasing rapidly. In 2016, the Muskeget Island (MA) breeding colony produced 3,900 (SE = 200) pups, making it the third largest breeding colony in the northwest Atlantic. This southward shift in production may reflect climate-mediated changes in population growth as well as reestablishment of colonies throughout the former range associated with increased protection. |
| Keywords: | Canada gray seal Halichoerus grypus metapopulation pup production regional trends United States |