River Tay - Ecology

Ecology

The river is of high biodiversity value and is a Site of Special Scientific Interest (SSSI) maintaining a flagship population of Atlantic salmon (Salmo salar), Freshwater pearl mussel (Margaritifea margaritifera) and native species such as the Eurasian otter (Lutra lutra). Freshwater pearl mussels are one of Scotland's most endangered species and the River Tay hosts two-thirds of the world's remaining stock.

The Tay is internationally renowned for its Atlantic salmon fishing and is one of the best salmon rivers in the United Kingdom, and western Europe, attracting anglers from all over the world. The largest rod caught salmon in Britain, caught on the Tay by Miss Georgina Ballantine in 1922, weighing 64 lbs, retains the British record. The river system has salmon fisheries on many of its tributaries including the Earn, Isla, Ericht, Tummel, Garry, Dochart, Lyon and Eden. Dwindling catches include a 50% reduction in 2009 so the Tay District Salmon Fisheries Board ordered a catch-and-release policy for females all season, and for males until May, beginning in the January 2010 fishing season. Research by the North Atlantic Salmon Conservation Organisation has shown that the number of salmon dying at sea has doubled or trebled over the past 20 years, possibly due to overfishing in the oceans where salmon spend two years before returning to freshwater to spawn. The widespread collapse in Atlantic salmon stocks suggests that this is not solely a local problem in the River Tay.

The first Eurasian Beaver (Castor fiber) living wild in Scotland in over 400 years was captured in the River Tay in 2007 because it may have been illegally released or not of the proper genetic stock. There is an earlier undocumented sighting of a beaver in the River Earn, a Tay tributary, in May 2001. The Tay watershed beaver may be escapees from Tayside captive beaver enclosures. The beaver became extinct in Great Britain towards the end of the 18th century, the last reference to beavers in England dating to 1789. It is estimated that at least 20, and possibly up to 100, beavers live on the Tay River, although these are targeted for trapping by the Scottish Natural Heritage . Proponents of the Tayside beavers argue that they have not been proven to be of "wrong" genetic stock and there is scientific evidence to support that they may represent a rather ideal mix of western European populations, since any single relict population in western Europe is relatively genetically depauperate. Scottish Natural Heritage did import beaver from Norway and legally released them in Knapdale in 2009. In early December 2010, the first of the wild Tayside beavers was trapped by Scottish Natural Heritage on the River Ericht in Blairgowrie, Perthshire and was held in captivity in Edinburgh Zoo. It died within a few months and Scottish Natural Heritage ended its trapping program.