The most comprehensive study to ever be undertaken in Europe into the health of otters has found otter populations are currently healthy and continuing to expand across England and Wales ? thanks to decreasing levels of certain pesticides.

The Environment Agency research carried out a series of studies into almost 1000 otters over 11 years, and looked into the overall health of otters, factors affecting their survival, the levels of chemicals in otters and the impacts these have on otter populations.

Scientists working on the project found that decreasing levels of certain chemicals had helped larger numbers of otters survive: ‘Otter numbers dropped significantly during the late 1950s when dieldrin and aldrin ? two intensive pesticides used in farming until the 1980s ? and it seems otters in this country are only just recovering from the effects,’ said conservation officer Lyn Jenkins, who managed the study.

‘Otters lived on all rivers in the UK in the 1920s, and now otter populations have begun to grow and expand again following the decline in numbers between the 1950s and 1980s. It’s also promising that an otter was found on the Thames last year ? not far from Tower Bridge ? and it was the first wild otter to be seen in central London for more than 100 years,’ he continued.