Graduation Date

Spring 2024

Document Type



Master of Science degree with a major in Biology

Committee Chair Name

Dawn Goley

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Paul E. Bourdeau

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Ho Yi Wan

Third Committee Member Affiliation

HSU Faculty or Staff

Fourth Committee Member Name

Christine Cass

Fourth Committee Member Affiliation

HSU Faculty or Staff


Feeding ecology, Predator prey interaction, Marine mammals, Marine invertebrates, Home range

Subject Categories



As opportunistic foragers, the Eastern North Pacific population (~20,000) of gray whales (Eschrichtius robustus) feed on diverse benthic and planktonic invertebrates in northern Alaska foraging grounds before they undertake one of the largest yearly migrations of any mammal to breed in Baja California, Mexico. While most of the population travels to the summer foraging grounds in Alaska, a sub-group of whales (~230) called the Pacific Coast Feeding Group (PCFG) summer between British Columbia, Canada, and northern California. The diet of PCFG whales typically includes high-density and/or high-caloric prey items like mysids and diverse species of amphipods, yet a few studies reported from northern California show evidence of whales foraging for a different relatively low-density invertebrate prey community. I observed gray whale frequency in northern California by conducting weekly land-based and monthly boat-based surveys across four known PCFG foraging locations from May to December 2022 and April to December 2023. Further, I concurrently assessed PCFG prey quality and quantity in northern California by systematically and opportunistically (in the presence of foraging whales) collecting planktonic and benthic prey species at these four locations. I confirmed that gray whales continue to use northern California as the southern edge of their summer foraging range, and found that these whales consume relatively low quantity and quality planktonic and benthic prey, primarily made up of porcelain crab larvae and the cumacean Diastylopsis dawsoni, respectively. Future data collection is needed to determine any long-term patterns in PCFG distribution and potential changes in prey variability in northern California, especially under the threat of rapid environmental change.

Citation Style



Thesis/Project Location


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