Return of 'Tarka the otter' is welcomed

6:59am Thursday 21st June 2007

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TARKA the otter is making a steady comeback on rivers in south Wiltshire and west Hampshire, helping to give the whole of the West Country a healthy population of one of Britain's favourite mammals.

According to study just completed by the Environment Agency, the otter is making an unprecedented comeback thanks to decreasing levels of toxic substances in the environment.

Otters were once common on all UK rivers back in the 1920s but 30 years later their numbers plummeted following the introduction of organochlorine chemicals on farms.

Insecticides, including aldrin and dieldrin, proved highly toxic to animals and birds, hitting peregrine falcons, kestrels, sparrowhawks, herons and otters.

Although an effective insecticide, dieldrin remains active for up to 25 years and can be passed from animal to animal through the food chain.

Once this was realised, it was banned in 1989.

The decline of the otter continued until the 1980s and its return was hampered in many areas by competition from the aggressive mink after mink escaped - or were deliberately released - from mink farms.

Lyn Jenkins, who studied otter health in southern and south west England, told Rural View that it is encouraging to see the otter population expanding again.

"While otters continue to die on our roads and occasionally succumb to disease, our studies suggest the number of otters killed over the past 15 years has not had a significant impact on the population as a whole.

"The importance of the 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 effect of these chemicals on their physiology."

The agency relies on volunteers to help with its research and anyone finding a dead otter should call the agency on 08708 506506.