Latin name: Salmo trutta
Brown Trout are non-migratory but are thought to be members of the same species as the migratory sea trout. It is widespread throughout the British Isles and is an indicator of relatively clean water but their populations are currently declining. In the national Species and Habitats Review 2007, Brown trout/sea trout was added to the UK list of priority species for biodiversity action. The colouration of brown trout varies depending on the prevailing conditions. For example, it is said that brown trout in acidic moorland tarns are dark-coloured, whereas brown trout in alkaline rivers in limestone country can be crimson with black spots. Furthermore, a brown trout in a deep pool can often be dark and is capable of lightening its own colouration in a matter of minutes if it moves into the clear shallows. However, generally adult fish are brownish with numerous black and rusty red spots on their upper sides. In the UK this species tends to develop to 30cm long. Brown trout are present in most rivers and streams in the Yorkshire Dales National Park. National Park staff and Dales Volunteers have assisted a PhD student who was studying brown trout populations in the Ure catchment with Durham University. The Rivers Trusts are carrying out numerous practical measures to benefit river catchments. The Yorkshire Dales Biodiversity Forum is organising a Rivers conference in November 2013 and the Catchment Sensitive Farming project also has significant benefits for river species.