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ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 4:247-256 (2008) - DOI: https://doi.org/10.3354/esr00078 Geographic variation in killer whale attacks on humpback whales in the North Pacific: implications for predation pressure Gretchen H. Steiger1,*, John Calambokidis1, Janice M. Straley2, Louis M. Herman3, Salvatore Cerchio4,17, Dan R. Salden5, Jorge Urbán-R.6, Jeff K. Jacobsen7, Olga von Ziegesar8,18, Kenneth C. Balcomb9, Christine M. Gabriele10, Marilyn E. Dahlheim11, Senzo Uchida12, John K. B. Ford13, Paloma Ladrón de Guevara-P.14,19, Manami Yamaguchi15, Jay Barlow16 1Cascadia Research Collective, 2181Ú2 West Fourth Avenue, Olympia, Washington 98501, USA 2University of Alaska Southeast, 1332 Seward Avenue, Sitka, Alaska 99835, USA 3Kewalo Basin Marine Mammal Laboratory, University of Hawaii and the Dolphin Institute, 420 Ward Avenue, Honolulu, Hawaii 96814, USA 4Moss Landing Marine Laboratories, PO Box 450, Moss Landing, California 95039, USA 5Hawaii Whale Research Foundation, 52 Cheshire Drive, Maryville, Illinois 62026, USA 6Departamento de Biología Marina, Universidad Autónoma de Baja California Sur, Ap. Post 19-B, La Paz, BCS 23081, Mexico 7Humboldt State University, Department of Biological Sciences, Arcata, California 95521, USA 8North Gulf Oceanic Society, PO Box 15244, Homer, Alaska 99603, USA 9Center for Whale Research, 1359 Smugglers Cove Road, Friday Harbor, Washington 98250, USA 10Glacier Bay National Park, PO Box 140, Gustavus, Alaska 99826, USA 11National Marine Mammal Laboratory, NOAA, 7600 Sand Point Way NE, Seattle, Washington 98115, USA 12Okinawa Churaumi Aquarium, Motobu-cho, Okinawa-ken 905-0206, Japan 13Pacific Biological Station, Nanaimo, British Columbia V9T 6N7, Canada 14Facultad de Ciencias, Universidad Nacional Autónoma de México, Ap. Post 70-572, México DF 04510, Mexico 15Ogasawara Marine Center, Byobudani, Chichijima, Ogasawara-mura, Tokyo 100-2101, Japan 16Southwest Fisheries Science Center, 8604 La Jolla Shores Dr., La Jolla, California 92037, USA 17Present address: Wildlife Conservation Society, American Museum of Natural History, Central Park West, New York, New York 10024, USA 18Present address: Eye of the Whale, PO Box 15191, Homer, Alaska 99603, USA 19Present address: Instituto Nacional de Ecología c/o CICESE Km 107 Carr. Tijuana-Ensenada, Ensenada, BC 22860, Mexico *Email: gsteiger@cascadiaresearch.org ABSTRACT: We examined the incidence of rake mark scars from killer whales Orcinus orca on the flukes of humpback whales Megaptera novaeangliae throughout the North Pacific to assess geographic variation in predation pressure. We used 3650 identification photographs from 16 wintering or feeding areas collected during 1990 to 1993 to determine conservative estimates in the percentage of whales with rake mark scarring. Dramatic differences were seen in the incidence of rake marks among regions, with highest rates on wintering grounds off Mexico (26 vs. 14% at others) and feeding areas off California (20 vs. 6% at others), 2 areas between which humpback whales migrate. Although attacks are rarely witnessed, the prevalence of scars demonstrates that a substantial portion of animals are attacked, particularly those that migrate between California and Mexico. Our data also suggest that most attacks occur at or near the wintering grounds in the eastern North Pacific. The prevalence of attacks indicates that killer whale predation has the potential to be a major cause of mortality and a driving force in migratory behavior; however, the location of the attacks is inconsistent with the hypothesis that animals migrate to tropical waters to avoid predation. Our conclusion is that, at least in recent decades, attacks are made primarily on calves at the wintering grounds; this contradicts the hypothesis that killer whales historically preyed heavily on large whales in high-latitude feeding areas in the North Pacific. KEY WORDS: Killer whale · Predation · Humpback whale · Rake marks · Fluke scarring · North Pacific Full text in pdf format PreviousNextCite this article as: Steiger GH, Calambokidis J, Straley JM, Herman LM and others (2008) Geographic variation in killer whale attacks on humpback whales in the North Pacific: implications for predation pressure. Endang Species Res 4:247-256. https://doi.org/10.3354/esr00078Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 4, No. 3. Online publication date: March 13, 2008 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2008 Inter-Research.