Intensive Otter, Lutra lutra, distribution surveys from 1984-1990 along rivers in the North York Moors National Park (NYMNP) and stretches of the River Derwent painted a particularly depressing picture (Woodroffe 1994). The only Otter signs consisted of occasional footprints, which suggested that the population in both the Derwent and the Esk catchments was few in number, fragmented, vulnerable and still in decline.