Observations of a distinctive morphotype of killer whale (Orcinus orca), type D, from subantarctic waters
- 895 Downloads
Studies have shown that killer whale (Orcinus orca) communities in high latitudes regularly comprise assemblages of sympatric ‘ecotypes’—forms that differ in morphology, behavior, and prey preferences. Although they can appear superficially similar, recent genetic evidence suggests that breeding is assortative among ecotypes within individual communities, and species-level divergences are inferred in some cases. Here, we provide information on a recently recognized ‘type D’ killer whale based on photographs of a 1955 mass stranding in New Zealand and our own six at-sea sightings since 2004. It is the most distinctive-looking form of killer whale that we know of, immediately recognizable by its extremely small white eye patch. Its geographic range appears to be circumglobal in subantarctic waters between latitudes 40°S and 60°S. School sizes are relatively large (mean 17.6; range 9–35; n = 7), and although nothing is known about the type D diet, it is suspected to include fish because groups have been photographed around longline vessels where they reportedly depredate Patagonian toothfish (Dissostichus eleginoides).
KeywordsKiller whale Orcinus orca Subantarctic Type D
We thank Paul Ensor, Nicolas Gasco, Heidi Krajewsky and Audrey Scott for assistance in the field and Anton van Helden for providing details about the 1955 stranding. The data for the 2006 sighting was collected during an International Whaling Commission minke whale assessment cruise in Antarctica; we thank IWC for permission to use the data. This manuscript benefited from the comments of John Ford and an anonymous reviewer.
- Baker AN (1983) Whales and dolphins of New Zealand and Australia. Victoria University Press, WellingtonGoogle Scholar
- Ford JKB, Ellis GM, Balcomb KC (2000) Killer whales: the natural history and genealogy of Orcinus orca in the waters of British Columbia and Washington. University of British Columbia Press and University of Washington Press, Vancouver and SeattleGoogle Scholar
- Jefferson TA, Webber MA, Pitman RL (2007) Marine mammals of the world. Academic Press, San DiegoGoogle Scholar
- Morin PA, Archer FI, Foote AD, Thomas M, Gilbert P, Allen EE, Wade P, Durban J, Parsons K, Pitman R, Li L, Bouffard P, Vilstrup J, Nielsen SA, Willerslev E, Harkins T (2010) Complete mitochondrial genome analysis of killer whales (Orcinus orca) indicates multiple species. Genome Res 20:908–916CrossRefPubMedGoogle Scholar
- Pitman RL, Ensor P (2003) Three different forms of killer whales in Antarctic waters. J Cetacean Res Manag 5:131–139Google Scholar
- Pitman RL, Fearnbach H, LeDuc R, Gilpatrick JW, Ford JKB, Ballance LT (2007) Killer whales preying on a blue whale calf on the Costa Rica Dome: genetics, morphometrics, vocalizations and composition of the group. J Cetacean Res Manag 9:151–158Google Scholar
- Roche C, Gasco N, Duhamel G, Guinet C (2007) Marine mammals and demersal long line fishery interactions in Crozet and Kerguelen exclusive economic zones: an assessment of the depredation level. CCAMLR Sci Ser 14:67–82Google Scholar
- Tixier P, Gasco N, Duhamel G, Guinet C (2010) Interactions of Patagonian toothfish fisheries with killer and sperm whales: an assessment of depredation levels and insights on possible mitigation solutions. CCAMLR Sci Ser (in press)Google Scholar