The most threatened species of fish in Co. Wicklow has now been confirmed as extinct in the county. Surveys by the Irish Char Group have confirmend that the Arctic Char (Salvelinus alpinus) is no longer to be found in the lakes of Co. Wicklow. The last recorded catch of a char was in 1988 in Lough Dan. It is believed to have also occurred in Lough Tay and the Upper Lake of Glendalough. In late 2008, a reintroduction programme was started to bring the Char back to the Upper Lake in Glendalough.
The Arctic Char has the most northerly distribution of any freshwater fish. It is a relative of the salmon, and in its northernmost range, at the edge of the arctic circle, the populations migrate to the sea. However, in Ireland the species is confined to deep, acid, mountain lakes in the West and in Wicklow, each lake having its own independent population. At least 70 Irish lakes are known to have contained Arctic Char. However in Ireland, Britain, Norway and Sweden, populations are becoming extinct. This has been due to deterioration in water quality caused by acid rain, eutrophication, afforestation and water abstraction. In at least 13 Irish lakes the Arctic Char is known to be extinct, and it is suspected to be extinct in many others. The Arctic Char is listed in the Irish Red Data Book as Vulnerable.
Salmon and Trout
The upper reaches of some of the rivers within the Park are spawning grounds for Salmon (Salmo salar) and Brown Trout (Salmo Trutta). Salmon is listed in the Red Data Book as being 'Internationally Important'. While neither species was regarded as being threatened at the time of publication, ongoing monitoring of the populations was recommended. Some streams no longer contain fish due to acidification caused by forestry.