Description

The least social of all the otters, the Eurasian Otter is approximately 1m long, and weighing around 8kg, with males being larger and heavier than females. All four paws are webbed and the claws are well-developed as are the teeth. The whiskers are numerous and strong, and used for locating prey. The rhinarium is small, with a W-shaped upper border, and is naked. The fur is more or less dark brown on the back, shading to buff or grey on the belly and throat, with darker subspecies generally found in the north west and paler ones in the south east of the range. White otters are known, and white-spotted otters may be locally common. They mainly eat fish, especially slow-moving, nutrient dense species such as eels and butterfish, but also take water birds, crayfish and frogs. On the Shetland Islands, some otters have been known to abandon fishing in favour of rabbit hunting (Kruuk, 1995). Breeding can occur throughout the year, though locally some seasonality may be seen, correlating to prey density.

CITES Identification Sheet

Habitat

Eurasian Otters use a wide variety of aquatic habitats. They are found at sea level, and in the Himalayas, and use brackish and salt water as well as fresh water, provided fresh water is available to wash the salt from their coats. They will make use of highland and lowland rivers, streams and lakes, swamps, fens, marshes, ricefields, fjords and coastal areas. In different parts of their range, otters rely on different features of their habitat, but mostly their presence correlates with sufficient food, fresh water and bankside vegetation in which to rest and groom, along with suitable tree roots, earth, rock piles, wood and debris in which to build holts.

Distribution

This species is the most widely distributed of all the otters, ranging through Eurasia up to the Arctic Circle, from Ireland to Kamchatka, and south to North Africa, Sri Lanka and Indonesia.

Conservation Status

Red List Category Near Threatened, Decreasing
Year Assessed 2008
Assessor Roos, A.
Evaluators Hussain, S.A. (Otter Red List Authority)

The species is recovering in Western Europe (although conservation measures need to be maintained), and viable populations occur in the former USSR. However, past declines and local extinctions in the past, the sensitivity of the species to sudden changes in threat level, the lack of information about huge parts of the range and possible over-exploitation in China and Indo-China justify a precautionary Near Threatened listing.

(Source: IUCN Red List)

Current Concerns

Water pollution is the major threat to Eurasian Otters, and has caused recent local extinctions from which Western European populations are only now recovering as a result of environmental improvements and focussed conservation efforts. The main dangers are biomagnified dieldrin, DDT/DDE, PCBs and Mercury which affect otter physiology directly, and reduction of food supply due to nitrate-induced eutrophication from agricultural run-off and untreated sewage, and acidification from atmospheric pollutants. Oil spills threaten coastal populations. In parts of the range, illegal hunting is a major issue, and the rise of fish farming has led to conflict, resulting in some countries in licences to kill otters being issued by authorities. Bycatch, especially in eel fykes and crab traps, can be a significant local problem, as can accidental capture in traps and snares, and accidental killing during mink hunts. In Western Europe, road traffic accidents are becoming a major cause of mortality.

Leading Researchers

Jim Conroy, Dilian G. Georgiev, George Gorgadze, A. Kranz, Lionel Lafontaine, David MacDonald, S.M. Macdonald, C.F. Mason, Laurent Mercier, K. Roche, Jordi Ruiz-Olmo, Uolevi Skarén, Paul Yoxon

Key Publications

General

• Chanin, P.R.F. (1985). The Natural History of Otters. Croom Helm. ISBN 0 7099 3460 2
• Kruuk, H. (1995). Wild otters - Predation and populations. Oxford University Press, Oxford. ISBN 0 19 854070 1

Distribution

• Crawford, A. (2003). Fourth Otter Survey of England 2000 - 2002. Environment Agency, UK
• Conroy, J., Melisch, R. and Chanin, P. (1998). The distribution and status of the Eurasian otter (Lutra lutra) in Asia – A preliminary review. IUCN Otter Specialist Group Bulletin15(1): 15-30.

Ecology

• Beja, P.R. (1992). Effects of freshwater availability on the summer distribution of otters Lutra lutra in the southwest coast of Portugal. Ecography 15: 273-278.
• Erlinge, S. (1967a). Home Range of the Otter Lutra lutra L. in southern Sweden. Oikos 18: 186-209
• Erlinge, S. (1967b). Food Habits of the fish otter (Lutra lutra L.) in south Swedish Habitats. Viltrevy 4: 371-443
• Erlinge, S. (1968). Territoriality of the otter Lutra lutra L. Oikos 19: 81-98
• Heggberget, T. and H. Christensen. (1994). Reproductive timing in Eurasian otters on the coast of Norway. Ecography 17: 339-348.
• Heggberget, T. and K. Moseid. (1994). Prey selection in coastal Eurasian otters Lutra lutra. Ecography 17: 331-338.
  
• Kruuk, H. & Conroy, J.W.H. (1991). Mortality of Otters (Lutra lutra) in Shetland. Journal of Applied Ecology 28: 83-94
• Kruuk, H. & Moorhouse, A. (1991). The Spatial Organisation of Otters (Lutra lutra) in Shetland. Journal of Zoology, London 224: 41-57
• Kruuk, H., Conroy, J.W.H. & Moorhouse, A. (1987). Seasonal Reproduction, Mortality And Food Of Otters (Lutra lutra L.) in Shetland. Symposia of the Zoological Society of London 58: 263-278
• Kruuk, H., Kanchanasaka, B. et al (1994). Niche Separation in Three Sympatric Otters Lutra perspicillata, L. lutra and Aonyx cinerea in Huai Kha Khaeng, Thailand. Biological Conservation 69: 115-120
• Mason, C.F. and Macdonald, S.M. (1986). Otters: ecology and conservation. Cambridge University Press, Cambridge.
• Yoxon, P. (2000) Geology and Otters IUCN Otter Spec. Group Bull. 17(2): 85 - 88

Threats and Conservation

• Conroy, J. (1995). Otters and oil spills - the impacts and the effects. Cahiers d'Ethologie 15(2-4): 325-336.
• Conroy,J. W.H., Yoxon, P. and Gutleb, A. C. (2000). Proceedings of the First Otter Toxicology Conference.  IOSF, Skye, Scotland.ISBN 0-9517122-1-7
• Green, R. (1991). The impacts of hunting, poaching and accidents on otter survival and measures to protect individual animals. In: C. Reuther and R. Röchert (eds) Proceedings V. International Otter Colloquium, Hankensbüttel 1989. Habitat No.6, pp.171-190. Hankensbüttel, Germany.
• Kruuk, H. and Conroy, J.W.H. (1991). Mortality of otters (Lutra lutra) in Shetland. Journal of Applied Ecology 28: 83-94.
• Mason, C.F. (1989). Water pollution and otter distribution: a review. Lutra 32: 97-134.
• Mason, C.F. and Macdonald, S.M. (1988). Radioactivity in otter scats in Britain following the Chernobyl reactor accident. Water, Air and Soil Pollution 37:131-137.
• Skarén, U. (1988). Chlorinated hydrocarbons, PCBs and cesium isotopes in otters (Lutra lutra L.) from central Finland. Annales Zoologici Fennici 25: 271-276.
• Skarén, U. (1992). Analysis of one hundred otters killed by accidents in central Finland. IUCN Otter Specialist Group Bulletin 7: 9-12.
  

Useful Links

• International Otter Survival Fund (IOSF)
• Wildlife Institute of India, Eurasian Otter Page
• Animal Diversity Web Lutra lutra
• The Mammal Society Otter Fact Sheet
• World Association of Zoos and Aquariums (WAZA) Virtual Zoo