Dear colleagues,

On behalf of my co-authors, we are pleased to share with you our recent
publication published in Aquatic Mammals:

McInnes, J.D., Trites, A.W., Mathieson, C.R., Dahlheim, M.E., Moore, J.E., Olson, P.A., and Lester, K.M. (2024). Evidence for an oceanic population of killer whales (Orcinus orca) in offshore waters of California and Oregon. Aquatic Mammals 50(2), 93-106, DOI https://doi.org/10.1578/AM.50.2.2024.93.

Summary:

In the northeastern Pacific, sightings of small numbers of killer whales (Orcinus orca) of unknown ecotype have been sporadically reported during open ocean marine mammal surveys, pelagic birding expeditions, and high seas fishing operations. However, it is unknown whether these oceanic killer whales belong to a mammal-eating ecotype of killer whale, an offshore fish-eating ecotype, or an offshore generalist type. We attempted to determine the ecotype of 49 unknown individuals observed during nine encounters from 1997 to 2021 in the deep oceanic waters far from the coastlines of California and Oregon (> 65 km) based on their foraging behaviors, prey species consumed, morphologies, and the prevalence of cookiecutter shark (Isistius sp.) bite scars. We hypothesize that these killer whales may represent a distinct oceanic subpopulation of transient killer whales or an undescribed oceanic population that feeds on marine mammals and sea turtles in the open ocean beyond the continental shelf break.

Best regards,

Josh D. McInnes, MSc Candidate