Mystery parasite threatens otters

15th February 2007

Otter swimming Hatty Arthur

A mystery parasite, first discovered in Britain in 2005, is spreading through the otter population in Southern England. Experts at Britain’s first Wildlife Veterinary Investigation Centre fear that it could affect other animals including foxes and even dogs and cats. Vic Simpson founder of the Wildlife VIC explains:

‘The parasite is a flat worm, thought to be introduced in ornamental fish imported from Russia and Eastern Europe. Some of these fish escaped from ponds and are thriving in the Somerset Levels.  The worm is passed on when animals eat raw fish that are infected.  The worms live in the gall bladder causing liver damage and jaundice. It could kill pet cats and dogs and a range of other wildlife. The disease can - in rare cases - affect people’.

The discovery of this new threat to otters is of great concern. Otters were nearly wiped out in the late 1960s, mainly due to pollution from toxic chemicals. These are now banned and otters have been making a slow but steady recovery. In less than two years, the parasite has been identified in otters from the Somerset Levels to Exeter and Salisbury Plain.

Otter road traffic accident
P hotograph Paul Semmens

Otter corpses are collected as part of a national monitoring programme. It is essential research led by the Water for Wildlife partnership with The Wildlife Trusts, Environment Agency and Water Companies and depends on members of the public reporting them. Emma Herrera from the Environment Agency in Devon says:

‘Although it is unusual and sad to see such a magnificent animal dead, the corpse can provide valuable information about otters. It is imperative that we collect corpses for post mortem at the Wildlife VIC to determine their overall health, look for signs of disease and assess breeding condition’.

Emma adds ‘We also monitor the level of man-made chemicals that accumulate in otters as an indicator of the health of our rivers’.

The number of otter deaths has been steadily increasing in the last ten years. Kate Stokes, the otter specialist at Cornwall Wildlife Trust has been co-ordinating the collection of these corpses and explains why it’s not all bad news:

‘Although an increase in otter deaths sounds awful, it is actually a positive sign. It simply means that there are more otters out there. Cornwall and Devon have good populations of otters and correspondingly we have a high number of otter deaths. What does concern us, is that Somerset has had a dramatic increase in otter deaths in 2006 and we don’t know why – it could be related to the parasite or something else altogether.’

Kate adds a plea ‘We can’t work this mystery out if we don’t collect the corpses for post mortem at the Wildlife VIC – and for this we rely on the public telling us. So if anyone does see a dead otter, please contact your county Wildlife Trust or the Environment Agency immediately.’

As otter numbers increase, they spread out looking for new territories and have to take on new threats like roads. Otters may be forced to cross roads because the river is in flood and water flow is too strong, particularly at bridges.  The Wildlife Trust has a number of volunteers who help collect these corpses and carry out river surveys looking for otter signs. If you would like to know more about this work please contact Cornwall Wildlife Trust on 01872 273939.

BBC Spotlight’s Inside Out programme investigates the mystery parasite affecting otters tomorrow on Friday 16th February BBC1 at 7.30pm.

Other pages on this web site that may be of interest:

• Wildlife Veterinary Investigation Centre
• Otters in Cornwall

Cornwall's Nature Introduction Marine life Mammals .. Bats .. Bottlenose dolphins .. Grey seals .. Hedgehogs .. Otters .. Watervoles Wildlife gardening Invertebrates Herptofauna .. Reptiles .. Amphibians Geology Slugs and snails SEARCH . . . . . . . . .