False killer whales (Pseudorca crassidens) around the main Hawaiian Islands: Long-term site fidelity, inter-island movements, and association patterns |
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Authors: | Robin W.,Baird Antoinette M.,Gorgone &dagger Daniel J.,McSweeney &Dagger Daniel L.,Webster &Dagger Dan R.,Salden § Mark H.,Deakos ¶ Allan D.,Ligon Gregory S.,Schorr # Jay,Barlow Sabre D.,Mahaffy &dagger &dagger |
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Affiliation: | Cascadia Research Collective, 218½West 4th Avenue, Olympia, Washington 98501, U.S.A. E-mail:; NOAA Southeast Fisheries Science Center, 101 Pivers Island Road, Beaufort, North Carolina 28516, U.S.A.; Wild Whale Research Foundation, P. O. Box 139, Holualoa, Hawai'i 96725, U.S.A.; Hawai'i Whale Research Foundation, 52 Cheshire Drive, Maryville, Illinois 62062-1931, U.S.A.; The Hawai'i Association for Marine Education and Research, Inc., PMB #175, 5095 Napilihau Street 109B, Lahaina, Hawai'i 96761, U.S.A.; Hawaiian Islands Humpback Whale National Marine Sanctuary, 726 South Kihei Road, Kihei, Hawai'i 96753, U.S.A.; Cascadia Research Collective, 218½West 4th Avenue, Olympia, Washington 98501, U.S.A.; NOAA Southwest Fisheries Science Center, 8604 La Jolla Shores Drive, La Jolla, California 92037, U.S.A.; Cascadia Research Collective, 218½West 4th Avenue, Olympia, Washington 98501,U.S.A. and Wild Whale Research Foundation, Box 139, Holualoa, Hawai'i 96725, U.S.A. |
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Abstract: | Despite their world-wide distribution throughout the tropics and subtropics, false killer whales ( Pseudorca crassidens ) are one of the lesser-known large odontocetes. Genetic evidence indicates a demographically isolated population around the main Hawaiian Islands. We examine site fidelity, movements and association patterns in this population using data from directed surveys and opportunistic photographs from 1986 to 2007. This species was only infrequently encountered, and while found in depths from 38 to 4,331 m, sighting rates were greatest in depths >3,000 m. We photo-identified 152 distinctive individuals. Resighting rates were high, with an average of 76.8% of distinctive individuals within groups documented on more than one occasion. Most (86.6%) were linked by association into a single social network; only one large group (16 distinctive individuals), documented the farthest offshore (42–70 km), did not link by association to that large network, and may be part of an offshore population. Individual movements of up to 283 km were documented, with a large proportion of individuals moving among islands. Individuals were resighted up to 20.1 yr after first being documented, showing long-term fidelity to the islands. Repeated associations among individuals were documented for up to 15 yr, and association analyses indicate preferred associations and strong bonds among individuals. |
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Keywords: | false killer whale Pseudorca crassidens site fidelity social organization Hawai'i movements |
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