Sir: Your suggestion that otters were brought to the verge of extinction by hunting in the 1960s and 1970s is incorrect ("Otters are lured back to Thames after 20 years", 24 March). It was otter hunters who raised the alarm about the fall in numbers, now known to be a result of organochloride pesticides. It was the same hunters who, wishing to protect the otter, turned their attentions to mink. Animal rights activists continue to illegally release this pest, to the detriment of wildlife.
High Wycombe, Buckinghamshire