Rafts and floats along the river are checked regularly for signs of other mammals such as otter, as well as water voles, but specifically to monitor for American Mink, a species that has over the last half century or so  been responsible at least in part for a rapid decline in much water bird and small mammal life on the Meon and it is indeed a very widely present predator.  A huge effort continues to eradicate it, which has been very successful in some regions of the country.