Home  
SW Observatory Environment
SW environment information
News & Events
Search
Member area
Contacts / mailing list
Business & Economy Observatory Home Planning Public Health Skills & Learning


Last update:

12th June 2007

Quick links

State of the South West 2007

State of the Env ironment in the South West

Regional Strategy for the South West's environment

Trends in otter populations

Causes of otter declines

Otter recovery

SW otter population trends

Otter Species Action Plan objectives and targets

Local otter action

Biodiversity Action Plans

Water voles

Mammal populations

Useful websites

SW Biodiversity Implementation Plan

UKBAP

Otter species action plan

Otter environmental indicator (Environment Agency)

Otter facts and figures (Environment Agency)

Otters online - links (Environment Agency)

South West Nature Map

National Biodiversity Network

Joint Nature Conservation Council

English Nature

Environment Agency

Otters

What's new on this page...

Otter (Copyright English Nature 2004)Otters, (Lutra lutra), one of Britain's largest carnivores, are largely nocturnal mammals that live along rivers, canals, lakes and some coastal areas.

According to the Environment Agency, 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.

Otters 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.

Trends in otter population

According to the Otter Species Action Plan, 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.

Causes of otter declines

Otter populations are vulnerable to a number of issues that can result in their decline, according to the otter Species Action Plan and the Environment Agency these include:

  • 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.

Otter recovery

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

Research published by the Environment Agency in June 2007 shows that the West Country now has a healthy population of otters and numbers are continuing to grow due to decreasing levels of toxic substances in the environment.

In the most comprehensive otter survey ever undertaken by the Environment Agency, the deaths of almost 1,000 otters in England and Eales were investigated between 1992 and 2003. The results have given a unique insight into the overall health of otters, factors affecting their survival and levels of chemicals in their bodies. Research in the South West has been carried out by Vic Simpson of the Wildlife Veterinary Investigation Centre in Cornwall.

Otters were once common on all rivers in the UK in the 1920's. However, numbers crashed in the 1950's following the introduction of organochlorine chemicals (OCs) on farms where insecticides including aldrin and dieldrin proved highly toxic to animals and birds at the top of the food chain. Among those worst affected were predators such as peregrine falcon, kestrel, sparrowhawk and heron.

Studies showed these lethal chemicals could interfere with vitamin levels and cause reproductive abnormalities and other conditions including an eye disorder in otters called retinal dysplasia that made animals almost blind. Disturbingly, aldrin and dieldrin can remain in the environment for up to 25 years. Dieldrin was a very effective insecticide that remained active for a long time after application, but its use had a devastating effect on animals and it was progressively withdrawn from use from 1962.

The decline in otter numbers continued until the 1980's. Results from this latest study show they are making a good recovery and are now present on many of our rivers. Last year an otter was even found in central London - the first sighting in 100 years - although sadly it had been killed in a road accident.

The importance of this study is that while post mortems showed a decline in levels of dieldrin over time, it was the first time a link had been made between organochlorine levels in otters and the effects of these chemicals on their physiology.

Study Findings:

  • Road traffic accidents are a main cause of otter deaths. A major cause of concern is the number of breeding females killed
  • Most of the 950 otters examined during the study period (1992 - 2003) were in excellent condition. A small number, mostly orphaned or abandoned young, were suffering from infections, ill health or starvation
  • Many of the adults had serious bite wounds, almost certainly due to fighting other otters. Some young otters had been killed by dogs
  • A small number of otters had infections including tooth abscesses and lung infections

The Environment Agency relies on volunteers to help with its research into otters. Anyone finding a dead otter should call the Agency on 08708 506506.

Otter surveys

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 fourth one being carried out by the Environment Agency).

More details about the otter survey can be downloaded via the Environment Agency's website.

The, most recent, Fourth Otter Survey has 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 must reflect the growing number of otters in England’s rivers and wetlands:

Otter survey of England, 2000 to 2002 - percentage of sites where otters were found

Otter survey of England - map showing % of sites where otters were found in Englad 2000 - 2002 (click to enlarge)

Source: Environment Agency

This map and the graph below reveal that otter numbers have increase in all the English regions between 1977 and 2002. Otters are becoming more widespread throughout England, although their tends to be fewer positive signs in the South East whilst the South West remains the most important region with a consistently high number of otters.

Otter occurrence in England - 1977 to 2002

Graph showing % of survey sites with evidence of otters in the English regions 1977 - 2002 (click to enlarge)

Source: The Vincent Wildlife Trust and Environment Agency

Trends in otter population within the South West

The Fourth Otter survey of England co-ordinated by the Environment Agency between 2000 and 2002 surveyed a total of 399 sites - 83% of which showed positive signs of otters ( an increase of 24% since the last survey 1991 - 1994).

Survey sites showing positive signs of otters in South West England - 2000 - 2002

Map showing survey sites in the SW showing positive signs of otters 2000 - 2002 (click to enlarge)

Source: Environment Agency (2003)

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).

The Environment Agency also highlight real and potential problems that may affect future otter populations in the region however, a major factor of which is road kills. The Somerset and Devon border have a particularly high record of road kills and it remains an important issue for otter conservation in the region.

A summary of survey results for different catchments within the region can be found in the Fourth Otter Survey - South West region report.

Local otter action

Otter conservation and activities in your local area can be found via your local Wildlife Trust. Click on the link to the Wildlife Trust link in your area for more information:

Otter Species Action Plan objectives and targets

The Otter Species Action Plan sets out detailed objectives and targets, which include to maintain and expand existing otter populations and to, by 2010, restore breeding otters to all catchments and coastal areas where they have been recorded since 1960.

Visit the weblink to find out more about proposed actions and lead agencies.