Threatened Irish Freshwater Fishes

Abstract

F. Igoe e-mnail: igoeashrfb.com), Irish Char Conservation Group, 1i Poddle Green, Kimmage, Dublin 12. Some 17,000 years ago, as the last Ice Age finally retreated from Ireland (Bowen et al. 2002), freshwater fish species first reached the country's newly forming loughs and rivers, following cordors of saline waters or travelling directly by sea. For millennia these native fish species, the oldest of Ireland's surviving animal species, were the sole fish species in the country's freshwaters. The formation of the Irish sea between Britain and Ireland acted as barrier to fish species with more sedentary habits and lower salinity tolerance, prematurely severing their natural colonisation pathways (Charlesworth 1930), and it was not until sometime during the miiddle of the last millennium that these non-native species were introduced to Ireland by Homo sapiens (McCormick 1999). Much of this early postglacial fauna, which still persists in many Irish loughs, must have been prevalent throughout north-westem Europe immediately after the last Ice Age (Ferguson 1986) before more warm water species moved in from the south and east. These com munities pretty much reflect the Irish freshwater fish fauna first encountered by our early ancestors dunrng the Megalithic penrod. As such, these native freshwater fish species are highly significant, not just for Ireland, but also for much of western Europe, where in many such communities have been lost or altered. The Inrsh environment has changed since these early times, as humans made their mark on the landscape and waterscape. These changes have accelerated during the last few decades (Stapleton et al. 2000). A decline in water quality in many areas, the impacts of introduced non-native fish species, alteration to habitats, and changes in a range of land-use practices have modified and changed the complexion and composition of our freshwater fish fauna. However, even today, much of the country holds aboriginal postglacial fish com munities, particularly in mountain loughs and loughs in the south-west and north-west, reflecting the early period before the arrival of humans. Whether we value our native fish communities from a heritage, cultural, recreational or economical perspective, one thing is clear: currently we are losing discrete populations of some species (e.g. Arctic char) and, if we are not careful, we will lose actual species and/or unique genetic vanants soon, and by default lose a precious link to our past. From a conservation perspective some of these fish species are important internationally and in a European context. The importance of other fish species should be considered in the national context. In fact some of our native fish species (e.g. pollan, Killarney shad, ferox, gillaroo and sonaghen trout) are among the most unique components of the entire Irish fauna, not just the fish fauna. Consider the following: