Otters

• Numbers of otters have increased significantly over the last 25 years, especially in the South West.

Otters are good indicators of overall river quality because they require clean rivers with an abundant, varied supply of food and plenty of bankside vegetation offering secluded sites for their holts.

They are strictly protected by the Wildlife and Countryside Act (1981) and cannot be killed, kept or sold, except under licence. They are also protected under CITES, the Bern Convention and the Habitats Directive. There is a UK Species Action Plan for otters.

Otter populations experienced significant declines between the 1950s and 1970s, due to the use of organo-chlorine pesticides, effectively being lost from the Midlands and South-Eastern counties by the 1980s.

Otter populations are vulnerable to a number of issues that can result in their decline, including:

• Poor water quality and pollution of watercourses, especially by PCBs.
• Insufficient prey (fish) due to poor water quality.
• Habitat degradation, including lack of bankside habitat needed for breeding and resting.
• Incidental mortality, primarily by road deaths and drowning in eel traps.
• Development along waterways and in floodplains.
• Disturbance from increasing recreation along waterways.

According to the Environment Agency, otter populations have increased significantly since the 1980s, primarily due to:

• The ban on the use of organo-chlorine pesticides
• The legal protection of otters
• More holistic river management
• A move towards more environmentally-friendly farming practices
• Wetland creation schemes and investment by water companues to prevent pollution

Numbers of otters have increased significantly over the last 25 years, especially in the South West. This recovery appears to be related to the legal protection of otters, habitat restoration and controls on the use of organochlorine pesticides, which are persistent in the environment. Otters are still absent or sparse in many areas and require the provision of improved habitat for breeding and resting.

As otters are largely nocturnal and are rarely spotted in the wild, surveying numbers can be difficult. However, surveys are conducted by detecting their presence through looking for spraints (faeces) and footprints. There have been a number of national otter surveys since 1977 (the first taking place between 1977 to 1979, the second 1984 to 1986, the third 1991 to 1994 and the fourth 2000 to 2002.

The, most recent, Fourth Otter Survey identified that otters now occur almost everywhere in England and are present in 34% of sites surveyed in 2000 - 2002 (compared with 5.8% of sites in 1977 - 1979 - a massive 527% increase). This increase reflects the growing number of otters in England’s rivers and wetlands.

In the South West, a total of 399 sites were surveyed - 83% of which showed positive signs of otters ( an increase of 24% since the last survey 1991 - 1994). 

Devon and Cornwall are particularly important counties in terms of having the highest populations of otters in the region, with a 17% increase in positive signs between 1991 / 1994 and 2000 / 2002/. There has also been a 26% increase in sites with positive signs of in the northern parts of the region since the 1991 - 1994 survey - showing otters to be spreading eastward through the region.

The Environment Agency attributes the increasing population in the region to :

• Very high water quality.
• Low disturbance - being the most rural of the English regions, the South West has a relatively low population (although otters do appear to be more tolerant of cities than was previously thought and there have been sightings of the animals in built up areas such as Bristol)
• Extensive semi-natural habitat providing cover along river banks.
• Numerous wetlands in the headwaters of many streams.
• Predominantly sheep and cattle farming rather than arable.
• Good food supply (course fish, eels and salmonids).

• Environment Agency otter occurrence

• Otter Species Action Plan