Marena Long

Date of Award

2021

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Rycyk, Athena

Area of Concentration

Marine Biology

Abstract

The Bigg’s killer whale ecotype (Orcinus orca) is found in the coastal waters of the Northeast Pacific and is the only ecotype known to prey on other marine mammals in the Northern Hemisphere. Studies on the population of Bigg’s killer whales in the Salish Sea have been conducted, almost continuously, since 1994. However, few studies have looked at density distribution in regards to season and pinniped haul out sites. In this study, the relationship between the Bigg’s killer whale and pinnipeds was mapped according to season to determine if there are any patterns of spatial use, particularly with density. Location data provided by the Center for Whale Research were used to conduct kernel density and Getis-Ord Gi* hot spot analysis to compare distributions by season. These tests revealed a variation in hot spot locations among winter, summer, and spring, as well as among pinniped breeding, pupping, and postbreeding seasons. Kernel density indicated that Haro Strait and the upper areas of the Strait of Juan de Fuca have the most Bigg’s killer whale sightings regardless of season. Understanding seasonal spatial use of Bigg’s killer whales and how these movements affect their foraging practices can be used to better inform decisions regarding stock estimates, pinnipeds abundance, and resident killer whales’ status and habitat use in the area.

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