Dear colleagues,

My co-authors and I are please to announce the publication of our new paper titled: Foraging Behaviour and Ecology of Transient Killer Whales Within a Deep Submarine Canyon System.

McInnes, J.D., Lester, K.L., Dill, L.M., Mathieson, C.R., West-Stap, P.J., Marcos, S.L., and Trites, A.W. (2024). Foraging Behaviour and Ecology of Transient Killer Whales Within a Deep Submarine Canyon System. PLoS ONE 19(3): e0299291. https://doi.org/10.1371/journal.pone.0299291.

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0299291

Summary:

Transient killer whales have been documented hunting marine mammals across a variety of

habitats. However, relatively little has been reported about their predatory behaviours near

deep submarine canyons and oceanic environments. We used a long-term database of

sightings and encounters with these predators in and around the Monterey Submarine Canyon,

California to describe foraging behaviour, diet, seasonal occurrence, and habitat use

patterns. Transient killer whales belonging to the outer coast subpopulation were observed

within the study area 261 times from 2006–2021. Occurrences, behaviours, and group sizes

all varied seasonally, with more encounters occurring in the spring as grey whales migrated

northward from their breeding and calving lagoons in Mexico (March-May). Groups of killer

whales foraged exclusively in open water, with individuals within the groups following the

contours of the submarine canyon as they searched for prey. Focal follows revealed that

killer whales spent 51% of their time searching for prey (26% of their time along the shelfbreak

and upper slope of the canyon, and 25% in open water). The remainder of their time

was spent pursuing prey (10%), feeding (23%), travelling (9%), socializing (6%), and resting

(1%). Prey species during 87 observed predation events included California sea lions, grey

whale calves, northern elephant seals, minke whales, common dolphins, Pacific white-sided

dolphins, Dall’s porpoise, harbour porpoise, harbour seals, and sea birds. The calculated kill

rates (based on 270 hours of observing 50 predation events) were 0.26 California sea lions

per killer whale over 24 hours, 0.11 grey whale calves, and 0.15 for all remaining prey species

combined. These behavioural observations provide insights into predator-prey interactions

among apex predators over submarine canyons and deep pelagic environments.

Please feel free to email me with any questions: j.mcinnes@oceans.ubc.ca

Sincerely,

Josh D. McInnes, MSc Candidate

Marine Mammal Research Unit
Institute for the Oceans and Fisheries

Aquatic Ecosystem Research Laboratory

University of British Columbia

Vancouver, BC Canada V6T 1Z4

Research Associate | Pacific Wildlife Foundation

Port Moody, British Columbia, Canada, V3H 1V6

Centre for Wildlife Ecology

Department of Biological Sciences

8888 University Drive

Simon Fraser University, Burnaby, BC