Date of Award

Spring 6-5-2025

Document Type

Honors Project

University Scholars Director

Dr. Joshua Tom

First Advisor/Committee Member

Dr. Eric Long

Second Advisor/Committee Member

Dr. Tim Nelson

Keywords

Climate change, Eschrichtius robustus, gray whale, home ranges, spatiotemporal analysis, unusual mortality event

Abstract

Abstract: Every spring, a small subgroup of gray whales (Eschrichtius robustus), referred to as “Sounders,” migrate to northern Puget Sound (NPS), Washington State, to forage on small crustaceans, particularly during years of low prey availability in the Arctic, the primary foraging habitat for gray whales. In contrast to gray whales in other locations, Sounders primarily forage on ghost shrimp (Neotrypnea californiensis) while in NPS. These small crustaceans live in the sediment in the intertidal to shallow subtidal zones, so gray whales must wait for higher tides to feed. Gray whale abundance in NPS and time spent in the region have been increasing, especially during gray whale unusual mortality events, which are likely caused by reduced Arctic prey availability due to climate change. This study aimed to identify how gray whales in NPS are distributed between years and throughout the foraging season, and to better understand gray whale abundance in NPS relative to Eastern North Pacific (ENP) gray whale population dynamics as a whole. ArcGIS and statistical modeling were used to analyze sighting data collected by Cascadia Research Collective from 1990 to 2023 for spatial and temporal trends, specifically regarding gray whale abundance during gray whale high mortality years. I found that Sounders are significantly more likely to start coming to NPS during years of high mortality and that the abundance of gray whales in NPS is positively correlated with mortality count of the ENP gray whale population.

Comments

A project submitted in partial fulfillment of the requirements for the Bachelor of Arts degree in Honors Liberal Arts Seattle Pacific University 2025

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Copyright held by author.

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