Eurasian Otter : Conservation
What went wrong?
The plight of the British otter was recognised in the early 60s, but it wasn't until the late 70s that the chief cause was discovered. Pesticides, such as dieldrin and aldrin, were first used in 1955 in agriculture and other industries - these chemicals are very persistent and had already been recognised as the cause of huge declines in the population of peregrine falcons, sparrowhawks and other predators. The pesticides entered the river systems and the food chain - micro-organisms, fish and finally otters, with every step increasing the concentration of the chemicals.
From 1962 the chemicals were phased out, but while some species recovered quickly, otter numbers did not - and continued to fall into the 80s. This was probably due mainly to habitat destruction and road deaths. Acting on populations fragmented by the sudden decimation in the 50s and 60s, the loss of just a handful of otters in one area can make an entire population unviable and spell the end.
And now for the good news
Otter numbers are recovering all around Britain - populations are growing again in the few areas where they had remained and have expanded from those areas into the rest of the country. This is almost entirely due to conservation efforts, slowing down and reversing the destruction of suitable otter habitat and reintroductions from captive breeding programs.
Releasing captive-bred otters is seen by many as a last resort. The argument runs that where there is no suitable habitat for them they will not survive after release and where there is suitable habitat, natural populations should be able to expand into the area. However, reintroducing animals into a fragmented and fragile population may add just enough impetus for it to stabalise and expand, rather than die out. This is what the Otter Trust accomplished in Norfolk, where the otter population may have been as low as twenty animals at the beginning of the 1980s. The Otter Trust has now finished its captive breeding program entirely, great news because it means it is no longer needed.