The Spade-toothed whale (scientific name: Mesoplodon traversii) is one of 21 species of beaked whales (Hyperoodontidae or Ziphiidae), medium-sized whales with distinctive, long and narrow beaks and dorsal fins set far back on their bodies. They are marine mammals within the order of cetaceans. This rare species, known only from a very small number of specimens had been considered synonymous with Layard's beaked whale (Mesoplodon layardii) which is well known as the Strap-toothed whale.
The first speciment was a partially damaged mandible and teeth collected in 1872 from Pitt Island, Chatham Islands, New Zealand. These were examined in 1873 by James Hector. In 1874, J.E. Gray concluded that the specimen represented a new species" distinct from Layard's beaked whale. However, Hector regarded the two species as synonymous. The original and two other other specimens were subject to DNA testing beging in the late 1990's which led to the description of the Spade-toothed whale (Mesoplodon traversii) as a distinct and separate species.
Distribution and Movements
Only three specimens had been examined by 2002, from New Zealand (White Island and the Chatham Islands [Pitt Island]), and Chile (Robinson Crusoe Island in the Juan Fernandez Archipelago).
Thus, the Spade-toothed whale (Mesoplodon traversii) is probably a southern Hemisphere (possibly circum-Antarctic) species. However, it may be much more widely-distributed, and until more records are available, this will remain unknown (van Helden et al. 2002).
Threats and Conservation Status
The IUCN Red List reports:
Direct hunting has never been associated with this species. Entanglement in fishing gear, especially gillnets is probably the most significant threat.
This species, like other beaked whales, is likely to be vulnerable to loud anthropogenic sounds, such as those generated by navy sonar and seismic exploration (Cox et al. 2006).
As a species potentially limited to temperate waters, the spade-toothed whale may be vulnerable to the effects of climate change as ocean warming may result in a shift or contraction of the species range as it tracks the occurrence of its preferred water temperatures (Learmonth et al. 2006). The effect of such changes in range size or position on this species is unknown.
Evidence from stranded individuals of several similar species indicates that they have swallowed discarded plastic items, which may eventually lead to death (e.g. Scott et al. 2001); this species may also be at risk.
- "Mesoplodon traversii (Gray, 1874)". Encyclopedia of Life. Accessed 12 May 2011.
Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. 2008. Mesoplodon traversii. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4.
. Downloaded on 15 May 2011.
- Gordon, D. (Ed.) (2009). New Zealand Inventory of Biodiversity. Volume One: Kingdom Animalia. 584 pp
- IUCN (2008) Cetacean update of the 2008 IUCN Red List of Threatened Species.
- Macleod, C. D., Perrin, W. F., Pitman, R. L., Barlow, J., Balance, L., D'amico, A., Gerrodette, T., Joyce, G., Mullin, K. D., Palka, D. L. and Waring, G. T. 2006. Known and inferred distributions of beaked whale species (Ziphiidae: Cetacea). Journal of Cetacean Research and Management 7(3): 271-286.
- Mead, James G., and Robert L. Brownell, Jr. / Wilson, Don E., and DeeAnn M. Reeder, eds. 2005. Order Cetacea. Mammal Species of the World: A Taxonomic and Geographic Reference, 3rd ed., vol. 1. 723-743
- Perrin, W. (2010). Mesoplodon traversii (Gray, 1874). In: Perrin, W.F. World Cetacea Database. Accessed through: Perrin, W.F. World Cetacea Database on 2011-05-05
- Reyes, Julio C., Koen Van Waerebeek, Juan C. Cárdenas, and José L. Yáñez. 1996. Mesoplodon bahamondi sp. n. (Cetacea, Ziphiidae), a new living beaked whale from the Juan Fernández Archipelago, Chile. Boletín del Museo Nacional de Historia Natural, Chile, vol. 45. 31-44
- UNESCO-IOC Register of Marine Organisms
- van Helden, Anton L., Alan N. Baker, M. L. Dalebout, J. C. Reyes, K. Van Waerebeek, and C. S. Baker. 2002. Resurrection of Mesoplodon traversii (Gray, 1874), senior synonym of M. bahamondi Reyes, Van Waerebeek, Cárdenas and Yáñez, 1995 (Cetacea: Ziphiidae). Marine Mammal Science, vol. 18, no. 3. 609-621
- Wang, J. Y. and Yang, S. C. 2006. Unusual cetacean stranding events of Taiwan in 2004 and 2005. Journal of Cetacean Research and Management 8: 283-292.