
Despite an increase in the area of occupancy in several parts of Europe due to
successful conservation interventions, this species is locally extinct in large
parts of central Europe. The risk of losing additional habitats, especially in
eastern Europe, is increasing. The situation in the near East and in Asia is not
well known.
Range and Population:
The Eurasian otter has the widest distribution of all otter species. Its range
covers parts of three continents: Europe, Asia and Africa. Originally the
species was widespread throughout Europe. Little is known about the original
distribution in Africa and Asia.
Habitat and Ecology:
It is known from a wide variety of aquatic habitats, including highland and
lowland lakes, rivers, streams, marshes, swamp forests and coastal areas. Otters
have been found in the brackish waters below sea level in the Netherlands, up to
1,000 m and more in the Alps or the Pyrenees, and above 3,500 m in the Himalayas
or 4,120 m in Tibet. It is very adaptable, using saltwater as well as freshwater
habitats, sewerage systems in urban areas or rivers in Asia. In most parts of
its range otter distribution is correlated with bank side vegetation. Otters in
different regions may depend upon different features of the habitat, but the
important component of otter habitat, for breeding purposes, is the presence of
holes in the river bank, cavities among tree roots, piles of rock, wood or
debris. The Eurasian otter avoids deep water. Their distribution in coastal
areas, especially the location of holts, is strongly correlated with the
presence of freshwater.
Threats:
The aquatic habitats of otters are extremely vulnerable to man-made changes.
Canalization of rivers, removal of bank side vegetation, dam construction,
draining of wetlands, aquaculture activities and associated man-made impacts on
aquatic systems are all unfavourable to otter populations. Pollution is major
threat to the otters in western and central Europe, the main pollutants posing a
danger to otters are the organochlorines dieldrin (HEOD) and DDT/DDE,
polychlorinated biphenyls (PCBs) and the heavy metal mercury. Coastal
populations are particularly vulnerable to oil spills. Acidification of rivers
and lakes results in the decline of fish biomass and reduces the food resources
of the otters. The same effects are known to result from organic pollution by
nitrate fertilisers, untreated sewage, or farm slurry. In addition, major causes
of mortality from several countries are drowning, road kills, and poaching. Fyke
nets set for eels or for fish as well as creels set for marine crustaceans have
a great attraction to otters and a high risk to those that successfully try to
enter these traps. A further potential threat is strangulation by transparent,
monofilament drift net. A potential risk comes from traps designed to kill other
species, especially underwater cages constructed to drown muskrats. Illegal
hunting is still a problem in many parts of their distribution range. In several
European countries political pressure especially by fishermen has resulted in
granting of licenses for killing otters.
Source:
IUCN Red List of Threatened Species