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Eastern Pacific Gray Whales, migration patterns, photograph identification, feeding grounds


Animal Sciences | Environmental Monitoring | Marine Biology | Research Methods in Life Sciences


The Eastern Pacific population of gray whales (Eschrichtius robustus) migrates along the west coast of North America every year; this migration brings them into close contact with shipping lanes and fishing operations which present major anthropogenic (human caused) threats to gray whales. The purpose of this study is to use photo ID of the whales from their feeding and calving grounds, and their migratory corridor to study which body regions are susceptible to both natural and anthropogenic injury and examine the most common types of injury tot he whales. In order to do this, photos were collected from each location and analyzed. Study sites include Bahia Magdalena, BCS, Mexico, Flores Island, BC, Canada, and Redondo Beach and San Pedro, CA United States. Photographs were entered into catalogs for photo ID, and then analyzed to determine the body regions and injuries observed. Types of injuries included: scar, wound, rake mark (from attack by killer whale), entanglement, and fluke (injury on tail that does not fall into another category). It was found that scars, rake marks, and entanglements represented the most common types of injuries, each occurring in about 10% of the whales. Rake marks were found more often on the flukes of the whale than the body, but there was no significant difference in locations of wounds or scars when compared between the body and flukes. From examination of the results of other studies, I estimate that 3-6% of gray whales die from ship strikes. However, because the population is quite large (17,000-22,000 individuals) I conclude that anthropogenic injuries are not representing a significant source of mortality to the Easter Pacific stock of gray whales. I suspect that anthropogenic injuries are more of a threat to smaller populations of cetaceans such as the Western Pacific gray whales and North Atlantic right whale.

Department 1 Awarding Honors Status

Environmental Studies

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License