The Assembly - Friday 22 July 2011

The content of this written ministerial statement is as received at the time from the Minister. It has not been subject to the official reporting (Hansard) process.

Carál Ní Chuilín MLA (Minister for Culture, Arts and Leisure): I am writing to update members on a reported fish kill at Loughbrickland Lake and subsequent media reports regarding the quality of the water on the lake.

Firstly, I would like to assure members that officials in my Department are working closely with the Northern Ireland Environment Agency to accurately identify what is causing this problem and to come up with solutions to alleviate the situation.

The Inland Fisheries Group in my Department has assessed the occurrence at Loughbrickland Lake as a minor fish kill. In fact, on assessing the extent of the problem, my officers found six dead fish.

My Department stocked the lake with farm-reared brown trout on 29 June and 7 July 2011. Around the 12 July there was a very rapid increase in aquatic weed growth on the lake, specifically a surface algal bloom. Summer weather conditions often give rise to periods of sudden and very rapid plant growth that thrive on the nutrient levels in the water column and lake bed. This can lead to reduced oxygen levels in the water, which can reduce chances of fish survival. This increase happened after my Department stocked the lake.

I should point out that the six dead fish recovered from the lake were Roach and not Brown Trout. Roach can be particularly susceptible to environmental stress after they have spawned.

Any reported fish kills are treated seriously by Departmental officials, who investigate the reports in conjunction with a range of agencies. A wide range of factors – both natural and man-made – can impact upon the ecosystem in a body of water.

Loughbrickland Lake, in common with many inter-drumlin lakes in the north of Ireland, reflects land use around it. The lake is now becoming eutrophic1. Invasive aquatic weed is now common to the lake and Filamentous green algae, known as blanket weed, grow on this submerged weed. This is cleared by my Department using a purpose-built weed cutting machine. The cost effectiveness of this is under review as it treats only the symptoms rather than the cause of weeds.

In conclusion, I would like to assure members that my Department has commenced another schedule of weed cutting which began on 20 July. This work will be carried out and the results assessed before further stocking of the lake continues.

My Department will continue to work closely with the NIEA and other agencies to address water quality and invasive aquatic species issues under the EC Water Framework Directive.

1
A eutrophic body of water, commonly a lake or pond, has high primary productivity due to excessive nutrients and is subject to algal blooms resulting in poor water quality.