Widespread in the mid-1950s, by 1976 otters were rarely seen in Essex. So great was concern that legal protection was granted in England and Wales in 1978. However, when the National Otter Survey first came to Essex in 1986, the otter was already extinct in the county.
The otter population crashed due to accumulated pollutants in waterways. These built up in the fish on which otters fed, leading to infertility in otters which subsequently caused rapid declines. Until the bans on organo-chlorines and lead in petrol, rivers were unable to support thriving otter populations.
The first record of otters returning was in 1991, when signs of the mammals were found at three sites on the Stour and Colne rivers – presumably an animal travelling from the re-introduction sites in Suffolk. In 1996 the University of Essex conducted the first annual Essex Otter Survey, finding otter signs in several north Essex rivers. Essex Wildlife Trust took over in 2003 and the yearly surveys continued to track otters as they gradually spread through the county, moving south, catchment by catchment. Finally, last year an otter was observed on the Thames at West Canvey – the final part of Essex to be colonised.
Darren Tansley, River Catchment Coordinator at Essex Wildlife Trust says, “The otter has been part of the fossil records of the British Isles for a staggering half a million years, so it is startling to realise it was driven to near extinction in East Anglia in just three decades.
“It has been fantastic to see a clear trend in the return of the otter over the past 25 years. The significance of this natural movement is clear: without good habitat, relatively unpolluted water and an adequate population of fish in our watercourses, this expansion of the species would not have been possible. This is not only good news for otters, but for all species that rely on clean water for their survival.”
Help on the 25th Essex Otter Survey
Essex Wildlife Trust is leading on the final Essex Otter Survey, where up until June 2020 they aim to revisit every one of the 256 Essex Otter Survey sites, a feat in which they require help from dedicated volunteers.
The Trust is offering free training days to give people the skills to look for otter signs on their local river or stream and input into this anniversary survey.
Darren continues, “this survey is incredibly exciting, not only is it our final survey but we’re expecting it to reveal otter records from all corners of our county. We’re very thankful to have the help of our dedicated river wardens on this survey but by giving members of the public the chance to take part as well we’re hoping more people will recognise otter signs and celebrate the return of this species on our waterways.”
For details on how to take part in the final annual Essex Otter Survey contact riverw@essexwt.org.uk