|Scientific Name:||Mesoplodon bidens|
|Species Authority:||(Sowerby, 1804)|
|Red List Category & Criteria:||Data Deficient ver 3.1|
|Assessor/s:||Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L.|
|Reviewer/s:||Hammond, P.S. & Perrin, W.F. (Cetacean Red List Authority)|
There is no information on global abundance or trends in abundance for this species. It is not believed to be uncommon but it is potentially vulnerable to low-level threats and a 30% global reduction over three generations cannot be ruled out (criterion A).
|Range Description:||Sowerby's beaked whales are known almost exclusively from the colder waters of the North Atlantic, from at least Massachusetts, USA to Labrador, Canada in the west, and from Iceland to Norway in the east (Mead 1989; MacLeod et al. 2006). This is the most northerly distributed of the Atlantic species of Mesoplodon, with most records north of 30°N. There are a number of strandings or sightings considered to be extralimital in the Mediterranean Sea, and from the Gulf of Mexico side of Florida.|
Native:Belgium; Canada; Denmark; France; Germany; Gibraltar; Iceland; Ireland; Netherlands; Norway; Portugal; Spain; Sweden; United Kingdom; United States
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – northeast; Atlantic – northwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Very little is known of the population biology of this species. It is one of the most commonly seen mesoplodonts in some parts of its range.|
|Habitat and Ecology:||
As with other members of the genus, these whales occur almost exclusively in deep waters past the continental shelf edge. Although it is one of the most commonly stranded Mesoplodon species, there have been few sightings at sea, and it is poorly known. De Buffrénil (1995) mentioned that two sightings were north of Scotland and west of the Orkney Islands, in waters several 100 m deep. Hooker and Baird (1999) observed groups of Sowerby's Beaked Whales in the Gully, a submarine canyon off eastern Canada, on four occasions. Sightings were in water depths of between 550 m and 1,500 m.
Ostrom et al. (1993) evaluated the diet of Sowerby's beaked whales, based on isotopic comparisons among northwestern Atlantic cetaceans. They feed on squid and fish, including Atlantic cod (Gadus morhua).
There is little specific information on the status or threats to whales of this species (Reeves et al. 2003). However, some are known to have been incidentally killed by whalers in Newfoundland, Iceland, and in the Barents Sea. A few entanglements in fishing gear (e.g., driftnets) have been documented. Waring et al. (2001) reported that for 1989-1998 observed bycatch in pelagic drift gillnets along the US East Coast amounted to 24 Sowerby's beaked whales. These were caught exclusively in the area from Georges Canyon to Hydrographers Canyon, along the continental shelf break and continental slope during July-October. This fishery has now been closed.
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).
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.
Predicted impacts of global climate change on the marine environment may affect this species of whale, although the nature of impacts is unclear (Learmonth et al. 2006).
|Conservation Actions:||The species is listed in Appendix II of CITES. Research is needed to determine the impacts of potential threatening processes on this species.|
Balcomb, K. C. and Claridge, D. E. 2001. A mass stranding of cetaceans caused by naval sonar in the Bahamas. Bahamas Journal of Science 8(2): 2-12.
Barlow, J. 1999. Trackline detection probability for long-diving whales. In: G. W. Garner, S. C. Amstrup, J. L. Laake, B. J. F. Manley, L. L. McDonald and D. G. Robertson (eds), Marine mammal survey and assessment methods, pp. 209-221. Balkema Press, Netherlands.
Cox, T. M., Ragen, T. J., Read, A. J., Vos, E., Baird, R. W., Balcomb, K., Barlow, J., Caldwell, J., Cranford, T., Crum, L., D'Amico, A., D'Spain, A., Fernández, J., Finneran, J., Gentry, R., Gerth, W., Gulland, F., Hildebrand, J., Houser, D., Hullar, T., Jepson, P. D., Ketten, D., Macleod, C. D., Miller, P., Moore, S., Mountain, D., Palka, D., Ponganis, P., Rommel, S., Rowles, T., Taylor, B., Tyack, P., Wartzok, D., Gisiner, R., Mead, J. and Benner, L. 2006. Understanding the impacts of anthropogenic sound on beaked whales. Journal of Cetacean Research and Management 7(3): 177-187.
de Buffrenil, V., 1995. Mesoplodon bidens - Sowerby-zweizahnwal. In: D. Robinueau, R. Duguy and M. Klima (eds), Handbuch der Saugetiere Europas, pp. 545-560. Aua-Verlag, Wiesbaden, Germany.
Fernández, A., Edwards, J. F., Rodriguez, F., Espinosa, A., De Los Monteros, Herraez, P., Castro, P., Jaber, J. R., Martin, V. and Arebelo, M. 2005. "Gas and fat embolic syndrome" involving a mass stranding of beaked whales (family Ziphiidae) exposed to anthropogenic sonar signals. Veterinary Pathology 42: 446-457.
Gomercic, H., Gomercic, M. D., Gomericic, T., Lucic, H., Dalebout, M., Galov, A., Skrtic, D., Curkovic, S., Vukovic, S. and Huber, D. 2006. Biological aspects of Cuvier's beaked whale (Ziphius cavirostris) recorded in the Croatian part of the Adriatic Sea. European Journal of Wildlife Research 52(3): 182-187.
Hooker, S. K. and Baird, R. W. 1999. Observations of Sowerby's beaked whales, Mesoplodon bidens, in the Gully, Nova Scotia. Canadian Field-Naturalist 113: 273-277.
Jepson, P. D., Arebelo, M., Deaville, R., Patterson, I. A. P., Castro, P., Baker, J. R., Degollada, E., Ross, H. M., Herraez, P., Pocknell, A. M., Rodriguez, F., Howie, F. E., Espinosa, A., Reid, R. J., Jaber, J. R., Martin, V., Cunningham, A. A. and Fernandez, A. 2003. Gas-bubble lesions in stranded cetaceans. Nature 425: 575-576.
Learmonth, J. A., Macleod, C. D., Santos, M. B., Pierce, G. J., Crick, H. Q. P. and Robinson, R. A. 2006. Potential effects of climate change on marine mammals. Oceanography and Marine Biology: An Annual Review 44: 431-464.
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.
Malakoff, D. 2002. Suit ties whale deaths to research cruise. Science 298: 722-723.
Mead, J. G. 1989. Beaked whales of the genus Mesoplodon. In: S. H. Ridgway and R. Harrison (eds), Handbook of marine mammals, Vol. 4: River dolphins and the larger toothed whales, pp. 349-430. Academic Press.
Ostrom, P. H., Lien, J. and Macko, . A. 1993. Evaluation of the diet of Sowerby's beaked whale, Mesoplodon bidens, based on isotopic comparisons among northwestern Atlantic cetaceans. Canadian Journal of Zoology 71: 858-861.
Reeves, R. R., Smith, B. D., Crespo, E. A. and Notarbartolo di Sciara, G. 2003. Dolphins, Whales and Porpoises: 2002-2010 Conservation Action Plan for the World's Cetaceans. IUCN/SSC Cetacean Specialist Group, Gland, Switzerland and Cambridge, UK.
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.
Waring, G. T., Hamazaki, T., Sheehan, D., Wood, G. and Baker, S. 2001. Characterization of beaked whale (Ziphiidae) and sperm whale (Physeter macrocephalus) summer habitat in shelf-edge and deeper waters off the northeast US. Marine Mammal Science 17(4): 703-717.
|Citation:||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 bidens. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 10 December 2013.|
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