Distribution and Abundance of Pacific Harbor Seals (Phoca vitulina richardii) in Oregon, May 2024, Science Bulletin 2024-13

Identification Information

Citation

Originator: Wright, Bryan E. and S. D. Riemer

Publish Date: December 19, 2024

Online Link: None

BPA Project #:

Contact Information

Agency: Oregon Department of Fish and Wildlife

Name: Bryan Wright

Job Position: Biometrician, Marine Mammal Program

Telephone: 541-760-9543

E-Mail Address: Bryan.E.Wright@odfw.oregon.gov

Description

Abstract: The Marine Mammal Program of the Oregon Department of Fish and Wildlife conducted a statewide aerial photographic survey for Pacific harbor seals (Phoca vitulina richardii) during May 2024. A total of 8,946 seals (of which 20.5% were pups) were counted from a subset of nearly 2,000 images at 54 haulout locations. Two estuaries accounted for just over half of the total: the Columbia River (39%) and the Alsea River (12%). The estimated total population size of harbor seals in Oregon, after adjusting for the probability of hauling out, was 13,700 seals (95% confidence interval [CI]: 12,000-15,600, rounded to nearest hundred). This represents an approximately 36% increase (1.4% annual growth rate) since 2002. While notable, the increase in the statewide total does not necessarily reflect trends at more meaningful spatial scales, such as within a particular estuary or at the stock-level (which includes coastal Washington). Future work will include trend analyses at these scales (local and stock), as well as creation of a publicly available digital atlas containing current and historic survey data. In addition, triennial statewide aerial surveys (next scheduled for 2027) will be supplemented with more frequent monitoring of select locations using shore-, vessel-, and/or drone-based observation platforms.

Purpose:

Time Period of Content: May 2024

Geographic Extent: Oregon coast and associated estuaries

Status: Final

Use Constraints:

Format: pdf

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