DAO 122:171-183 (2017)  -  DOI: https://doi.org/10.3354/dao03080

Causes of mortality of harbor porpoises Phocoena phocoena along the Atlantic and Pacific coasts of Canada

Heather Fenton1,6, Pierre-Yves Daoust1,*, María J. Forzán1, Raphaël V. Vanderstichel2, John K. B. Ford3, Lisa Spaven3, Stéphane Lair4, Stephen Raverty5

1Canadian Wildlife Health Cooperative, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE C1A 4P3, Canada
2Canadian Wildlife Health Cooperative, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown PE, C1A 4P3, Canada
3Pacific Biological Station, Fisheries and Oceans Canada, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada
4Réseau canadien pour la santé de la faune, Faculté de médecine vétérinaire, Université de Montréal, 3200 rue Sicotte, Saint-Hyacinthe, QC J2S 2M2, Canada
5Canadian Wildlife Health Cooperative, Animal Health Branch, British Columbia Ministry of Agriculture, Animal Health Centre, 1767 Angus Campbell Road, Abbotsford, BC V3G 2M3, Canada
6Present address: Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Wildlife Health Building, 589 D. W. Brooks Drive, Athens, GA 30602, USA
*Corresponding author:

ABSTRACT: There is increasing public interest in the overall health of the marine environment. Harbor porpoises Phocoena phocoena have a coastal distribution, and stranded animals function as sentinels for population and ecosystem health. The goal of this retrospective study was to join datasets from the western Atlantic and eastern Pacific coasts of Canada to investigate causes of morbidity and mortality in this species. A total of 241 necropsy records were reviewed including 147 (61%) from the Pacific region and 94 (39%) from the Atlantic region from 1988 to 2011. A cause of death could be determined with confidence in 118 (49%) of these cases. Of these 118 cases, the leading cause of mortality for both regions, together and separately, was infectious disease. In the Pacific region, this was followed by traumatic and anthropogenic causes, whereas in the Atlantic region, it was followed by emaciation/starvation, mortality of dependent calves, and anthropogenic causes. Pathogens of potential zoonotic significance or indicative of environmental contamination, e.g. Salmonella sp. and Cryptococcus gattii, were identified. Numerous parasitic species were observed within the lungs, liver, stomach, middle ear, and subcutaneous tissues, although they were usually interpreted as incidental findings. Anthropogenic causes may be underrepresented as they are notoriously difficult to diagnose with certainty, thereby making up a proportion of the ‘unknown causes of death’ (51%) category. Improved standardization of data collection and documentation is required to better understand harbor porpoise and ecosystem health.


KEY WORDS: Harbor porpoise · Phocoena phocoena · Cetacean · Stranding · Mortality · Disease · North America · Canada


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Cite this article as: Fenton H, Daoust PY, Forzán MJ, Vanderstichel RV and others (2017) Causes of mortality of harbor porpoises Phocoena phocoena along the Atlantic and Pacific coasts of Canada. Dis Aquat Org 122:171-183. https://doi.org/10.3354/dao03080

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