
Prey-Related Suffocation in Harbor Porpoises
- Behavior
- Foraging
Abstract
Harbor porpoise (Phocoena phocoena) diets are predominantly comprised of small fish species (<30 cm) and squid. However, predation on larger species (up to 63 cm) occurs, raising the question of increased risk of asphyxiation associated with this behavior. Literature was reviewed and stranding data from 1983 to 2020 from the U.S. West Coast (including California, Oregon and Washington) were searched for cases of prey-related asphyxiation of harbor porpoises and analyzed in relation to age, sex, reproductive status and prey species. Twenty-nine cases were documented. Twenty-seven cases involved large prey; non-native American shad caused the asphyxiation in 87% of the cases where the prey species was identified. The majority (92%) of harbor porpoises were females, and at least 83.3% were pregnant or recently post-partum. Reproductively active females may be more likely to attempt potentially risky behavior in order to compensate for their increased energetic needs. Increasing numbers of non-native American shad may pose a unique danger in this region for harbor porpoises not adapted to deal with the challenges of that prey. This may be a cause for concern, as there is likely an interaction between location, age and reproductive status on the diet composition and foraging strategies of harbor porpoises.
Elliser, C.R., Calambokidis, J., D’Alessandro, D.N., Duffield, D.A., Huggins, J.L., Rice, J., Szczepaniak, I. and Webber, M., 2020, September. Prey-Related Asphyxiation in Harbor Porpoises (Phocoena phocoena) along the US West Coast: Importance of American Shad (Alosa sapidissima) on Adult Female Harbor Porpoise Mortality. In Oceans (Vol. 1, No. 3, pp. 94-113). Multidisciplinary Digital Publishing Institute.
foraging
Marc Webber
Related Publications
{"image":"\/Animals\/Patients\/Harbor seals\/hs-by-bill-hunnewell-c-the-marine-mammal-center.jpg","alt":"harbor seal in a life preserver enrichment item","title":"Enrichment as a Tool for Rehabilitating Harbor Seals","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/enrichment-as-a-tool-for-rehabilitating-harbor-seals","label":"Research Paper"}

{"image":"\/Animals\/Wild\/Humpback whale\/cropped-images\/humpback-whale-breach-golden-gate-by-pilar-rodriguez-c-the-marine-mammal-center-noaa-permit-26532-647-0-1710-1336-1702426697.jpg","alt":"humpback whale breaches with Golden Gate Bridge in the background","title":"New Urban Habitat for Endangered Humpback Whales: San Francisco Bay","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/new-urban-habitat-for-endangered-humpback-whales-san-francisco-bay","label":"Research Paper"}

{"image":"\/Animals\/Wild\/Gray whale\/cropped-images\/gray-whale-baleen-shutterstock-526-1-3317-2591-1604510915.jpg","alt":"gray whale with mouth open above water","title":"Fish Feeding and Rapid Foraging Behavior Switching by Gray Whales (Eschrichtius robustus) in California","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/fish-feeding-and-rapid-foraging-behavior-switching-by-gray-whales-eschrichtius-robustus-in-california","label":"Research Paper"}

Fish Feeding and Rapid Foraging Behavior Switching by Gray Whales (Eschrichtius robustus) in California
Read More{"image":"\/Animals\/Wild\/Other species\/cropped-images\/bearded-seal-shutterstock-622-6-4852-3789-1717182444.jpg","alt":"bearded seal on ice","title":"Comparative Muscle Physiology of Ringed, Bearded, and Spotted Seals from the Bering and Chukchi Seas","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/comparative-muscle-physiology-of-ringed-bearded-and-spotted-seals-from-the-bering-and-chukchi-seas","label":"Research Paper"}

Comparative Muscle Physiology of Ringed, Bearded, and Spotted Seals from the Bering and Chukchi Seas
Read MoreRecent News
{"image":"\/Animals\/Patients\/Harbor seals\/cropped-images\/hs-group-with-hats-photo-by-bill-hunnewell-c-the-marine-mammal-center-34-0-1270-992-1750873865.jpg","alt":"Four harbor seals with small ID tags on their heads swim in a rehabilitation pool.","title":"How Our Patients are Named and Identified","link_url":"https:\/\/www.marinemammalcenter.org\/news\/how-our-patients-are-named-and-identified","label":"Patient Update","date":"2025-06-26 02:00:00"}

{"image":"\/Animals\/Wild\/Gray whale\/cropped-images\/gray-whale-oreo-by-josie-slaathaug-c-the-marine-mammal-center-108-0-1270-992-1750880575.jpg","alt":"Gray whale fluke above the water","title":"Los Angeles Times: The numbers of gray whales migrating along the California coast continue to plummet","link_url":"https:\/\/www.marinemammalcenter.org\/news\/los-angeles-times-the-numbers-of-gray-whales-migrating-along-the-california-coast-continue-to-plummet","label":"In the News","date":"2025-06-25 02:00:00"}

Los Angeles Times: The numbers of gray whales migrating along the California coast continue to plummet
June 25, 2025
Read More{"image":"\/Animals\/Wild\/Harbor seal\/cropped-images\/harbor-seal-pup-photo-by-Ruvim-Miksanskiy-251-0-1270-992-1750880392.jpg","alt":"Harbor seal pup resting on the beach","title":"ABC7 San Francisco: Animal trauma could be linked to bad human behavior, Bay Area marine mammal experts say","link_url":"https:\/\/www.marinemammalcenter.org\/news\/abc7-san-francisco-animal-trauma-could-be-linked-to-bad-human-behavior-bay-area-marine-mammal-experts-say","label":"In the News","date":"2025-06-24 02:00:00"}

ABC7 San Francisco: Animal trauma could be linked to bad human behavior, Bay Area marine mammal experts say
June 24, 2025
Read More{"image":"\/People\/Action\/Response\/cropped-images\/mbo-crew-es-rope-rescue-photo-by-lesley-simms-c-the-marine-mammal-center-2-0-0-1270-992-1749571082.jpg","alt":"MBO crew carrying a crate up a cliff","title":"The Marine Mammal Center reports high levels of marine mammal disturbance in Central and Northern California for third year in a row","link_url":"https:\/\/www.marinemammalcenter.org\/news\/the-marine-mammal-center-reports-high-levels-of-marine-mammal-disturbance-in-central-and-northern-california-for-third-year-in-a-row","label":"Press Release","date":"2025-06-10 02:00:00"}

The Marine Mammal Center reports high levels of marine mammal disturbance in Central and Northern California for third year in a row
June 10, 2025
Read More