Open Access Senior Thesis
Bachelor of Arts
2018 Sabrina G Wilk
The killer whales that roam the northeastern Pacific Ocean have been the objects of studies since the 1970s, making them the most well-studied population of orcas in the world. Three distinct ecotypes of killer whales (Orcinus orca), known as residents, transients, and offshores, share these waters. The ecotypes are morphologically and behaviorally distinct to the extent that some scientists consider them separate species, with residents eating salmon, transients specializing on marine mammals, and offshores preferring Pacific sleeper sharks and Pacific halibut. Resident populations have endeared themselves to the region's locals with their striking black and white markings and their tendency to frolic in waters near the shore. However, both of the two resident populations on the coast of British Columbia and Washington State are at risk, with northern residents numbering some 300 and southern residents at just 74 individuals as of December 2018. Three deaths in the span of four months in spring and summer of 2018 brought widespread attention to the southern residents' plight. Live captures of killer whales for aquaria heavily impacted the population in the 1960s and 1970s, and today they face a combination of prey shortages, pollution, and disturbance from vessel traffic. If southern resident killer whales are to persist, federal, local, and state agencies need to quickly take mitigative action.
Wilk, Sabrina, "On the Brink of Extinction: The Fate of the Pacific Northwest's Southern Resident Killer Whales" (2019). Pomona Senior Theses. 200.