Current address: Department of Animal Sciences, Teikyo University of Science and Technology, 2525 Yatsuzawa, Uenohara, Yamanashi 409-0193, Japan.
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INTERMINGLING OF DALLI-TYPE DALL'S PORPOISES INTO A WINTERING TRUEI-TYPE POPULATION OFF JAPAN: IMPLICATIONS FROM COLOR PATTERNS
Article first published online: 12 JUL 2006
DOI: 10.1111/j.1748-7692.2006.00077.x
Additional Information
How to Cite
Amano, M. and Hayano, A. (2007), INTERMINGLING OF DALLI-TYPE DALL'S PORPOISES INTO A WINTERING TRUEI-TYPE POPULATION OFF JAPAN: IMPLICATIONS FROM COLOR PATTERNS. Marine Mammal Science, 23: 1–14. doi: 10.1111/j.1748-7692.2006.00077.x
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Current address: Department of Animal Sciences, Teikyo University of Science and Technology, 2525 Yatsuzawa, Uenohara, Yamanashi 409-0193, Japan.
Publication History
- Issue published online: 21 DEC 2006
- Article first published online: 12 JUL 2006
- Received: 14 August 2005Accepted: 11 May 2006
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Keywords:
- Dall's porpoise;
- Phocoenoides dalli;
- migration;
- color morphs;
- subspecies;
- harpoon fishery
Abstract
There are two major color morphs, truei and dalli types, of the Dall's porpoise and the latter includes two minor morphs. A small number of dalli types are found among truei types off the Pacific coast of Japan, where truei types normally winter. Based on differences in the patch size of dalli-type porpoises taken by the harpoon fishery, we determined that those dalli types contain both minor morphs. Although the total number of both types in the sample was similar, the proportion of the two types varied seasonally. Sex ratio, body length, and maturity rate were different among the dalli and truei types. These facts strongly suggest that these dalli types were not members of the truei-type population and were actually migrants from adjacent dalli-type populations. The definition of the subspecies Phocoenoides dalli dalli and P. d. truei as polymorphic groups is not supported, although we consider that each of the three color morphs is worthy of full subspecific status.