WRITTEN QUESTION P-1620/03
by Patricia McKenna (Verts/ALE)
to the Commission

Subject: Extinction of artic char in Lough Conn, Ireland

A gill net survey by the Irish Central Fisheries Board in 1978 and 1984 on Lough Conn, County Mayo, Ireland, showed a good stock of arctic char in the lake. Later surveys in 1994, 1998 and in 2001 recorded no char and now this unique fish is deemed to be extinct in that lake. This extinction has been attributed by scientists to the excessive enrichment of the lake. Although the nutrient dynamics are complex in the lake, excessive algal accumulations, including blue-green algae, on the char spawning beds in autumn and early winter in the early 1990s are believed to be the cause.(These still occur, particularly on mild winter days with a gentle breeze.) These beds were covered by what can only be described as a thick jelly (made up of almost pure cultures of anabaena which is known to become toxic under certain circumstances) of silt, and it is accepted that char avoid silt and only spawn on clean gravel. The causes for extinction of char in Ireland are varied, however experts believe that the case for Lough Conn relates directly to the increased nutrient loading, particularly phosphorous in the lake.

Mid lake sampling (OECD classification) by statutory agencies, although useful to classify lakes, does not necessarily reflect conditions along the lake margins, for example accumulation of algae (measured chlorophyll) along the margins of a lake during the critical period for arctic char. Recently the brown trout stocks of that lake have also crashed, again this is attributed to the consequences of nutrient enrichment (e.g. expanding cyprinid communities).

Although advances are being made to control human sewage sources, nutrient enrichment from the other sectors continues to increase significantly.

Does the Commission agree that the continued enrichment of the lake is essentially a failure by the Irish authorities to control and limit phosphorous inputs to Lough Conn and is therefore in breach of the Dangerous Substances Directive?

Does the Commission agree that lakes with sensitive species like the arctic char require special measures to protect them from the effects of nutrient enrichment, including phosphorous loading?

Should Ireland not restore the lake to conditions favourable for the native arctic char and the brown trout, i.e., radically reduce the inflow of nutrients?

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