Plans to repopulate Lough Conn with Arctic Char, an ancient species of fish that has been around since the Ice Age and is now almost extinct in the west of Ireland, have been abandoned due to the presence of zebra mussels.
Scientists say there is no point reintroducing char to the Mayo lake, the shoreline of which will be encrusted with reefs of zebra shells in a few years. Dr Martin McGarrigle, regional manager of the Environmental Protection Agency, said char would not be able to spawn along its shores once the mussel became established.
Lough Conn is a prime salmon and trout fishery. Arctic Char disappeared from there in the early 1990s due to nutrients pollution. It is also gone from Lough Corrib but survives, albeit in small numbers, in Lough Mask and mountain lakes such as Lough Talt near Bonniconlon and Bunnaveela in the Nephin Beg range near Keenagh, Crossmolina.
Zebra mussels filter up to a litre of water a day and consume plankton on which small fish and other aquatic life depend for survival.