Dear Colleagues,

On behalf of my coauthors, I’m pleased to share our new publication on the 
movements and dive behavior of Eastern Tropical Pacific killer whales in 
Pacific Mexico: https://onlinelibrary.wiley.com/doi/10.1111/mms.70133

Stewart, J. D., R. L. Pitman,  P. Martinez-Loustalot, N. Ransome, T.R. Azizeh, 
H. Rosales-Nanduca, I.A. Fonseca-Ponce, A.A. Zavala-Jimenez, J. Urban R., 2026. 
“Shelf Life: Nearshore Movements, Dive Behavior, and Ecotype Status of 
Satellite-Tagged Killer Whales in Pacific Mexico.” Marine Mammal Science 
https://doi.org/10.1111/mms.70133.

Abstract:
Relatively little is known about the ranging patterns, diving behavior, or prey 
preferences of killer whales (Orcinus orca) in tropical latitudes. However, 
they are suspected to be prey-generalists rather than the prey-specialists that 
are typically found in high latitudes. In February 2025, we satellite-tagged 
three killer whales from a pod of seven in Bahía de Banderas, Mexico. The tags 
transmitted for 8–41 days. The tagged whales traveled a total of 4002 km along 
a narrow, 1000 km stretch of coastline. While tagged, they remained within 50 
km of shore 92.5% of the time and in water < 500 m deep 69% of the time, but 
ranged up to 87 km offshore, to water deeper than 1000 m. Dives were slightly 
deeper during the day (mean dive depth 44 m) than at night (34.5 m), and they 
dived deeper (max 528 m) in deeper water. The group was observed 
attacking/consuming marine mammals, including a humpback whale (Megaptera 
novaeangliae) calf, a dwarf sperm whale (Kogia sima), common bottlenose 
(Tursiops truncatus) and spinner (Stenella longirostris) dolphins, and 
attacking/harassing two species of sea turtles. These data provide the first 
high-resolution records of movements and dive behavior of killer whales in the 
Eastern Tropical Pacific and support the existence of a unique ecotype in the 
region.



Joshua Stewart, Ph.D.

Pronouns: He/Him

Assistant Professor, Marine Mammal Institute

Oregon State University, Hatfield Marine Science Center



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