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Nicks and notches of the dorsal ridge: Promising mark types for the photo-identification of narwhals
Article first published online: 29 DEC 2009
© 2009 by the Society for Marine Mammalogy
Marine Mammal Science
Volume 26, Issue 3, pages 663–678, July 2010
How to Cite
Auger-Méthé, M., Marcoux, M. and Whitehead, H. (2010), Nicks and notches of the dorsal ridge: Promising mark types for the photo-identification of narwhals. Marine Mammal Science, 26: 663–678. doi: 10.1111/j.1748-7692.2009.00369.x
- Issue published online: 8 JUL 2010
- Article first published online: 29 DEC 2009
- Received: 14 May 2009Accepted: 8 November 2009
- Monodon monoceros;
- natural markings
The narwhal is a hunted species for which we have many knowledge gaps. Photo-identification, which uses photographs of natural markings to identify individuals, is widely used in cetacean studies and can address a broad range of biological questions. However, it has not been developed for narwhals. The marks used for other cetaceans are inappropriate for this species either because narwhals lack the body part on which these marks are found or because the marks are known to change with time. We investigated the marks apparent in photographs of narwhals. Nicks and notches on the dorsal ridge are the mark types most promising for photo-identification. They are found on 91%–98% of the individuals, thus allowing the identification of a large part of the population. They can be used to differentiate between individuals, in part because they are variable in their location, numbers, shape, and size. Although our results suggest that nicks and notches are relatively stable over time, rates of change should be formally measured to assess the probability of photographic matches over multiple years. However, we are confident that these marks can be used in studies spanning at least a field season.