The survival of a rare, cold-water fish, which has lived in a handful of Irish lakes since the Ice Age, is now threatened by climate change.
Warming lake temperatures across Ireland and central Europe pose a major risk to Arctic charr, a new study led by the Centre for Environmental and Freshwater Science at Dundalk Institute of Technology (DkIT), Co Louth, has found.
Closely related to our salmon and trout, charr is a secretive, ‘relict’ fish left behind after the glaciers melted at the end of the Ice Age, about 10,000 years ago. As temperatures rose, the remaining charr populations could survive only insufficiently cool, deep lakes and are usually present in mountainous areas.
Some of the last remaining Irish populations are found in Lough Bunaveela, a small lake in the Nephin Beg mountains in County Mayo, in Lough Leane, Killarney, and other Kerry lakes, and a few lakes along the west.
The species is remarkable because it is the northernmost, freshwater fish and can survive in lakes high in the Arctic circle — even living under ice for up to nine months of the year.
How it has managed to exist so far south of its native habitat is a wonder in itself.
The latest research, also involving the Marine Institute, has uncovered new evidence identifying climate change as a serious risk to diminishing charr populations in Irish lakes and other regions across Europe.
With international cooperation between climate scientists and fish biologists, researchers examined a selection of lakes across Ireland, Britain, France, and Switzerland.
The study found that winter temperatures in critical spawning areas are warming rapidly, with a likely adverse impact on charr spawning habitats. Researchers tried to determine how much additional warming might occur and what temperature risks would be posed to sensitive, developing charr eggs following spawning.
"The results are sobering. Unless greenhouse gas emissions are reduced considerably, winter warming of up to four degrees is likely to occur in these lakes in spawning habitats, rendering them highly unsuitable for the development of charr eggs,’’ says Dr Seán Kelly, of DkIT, lead author of the study.
The Irish Char (sic) Conservation Group, which has been championing the cause of this red-bellied fish for more than 20 years, says more charr populations have been lost in recent decades to pollution and development than in previous centuries.
Unfortunately, the group notes, there are few projects in European countries to protect remaining populations.