Written question asked by David Simpson (Democratic Unionist Party) on Wednesday, 25 October 2006, in the House of Commons. It was due for an answer on Monday, 30 October 2006. It was answered by David Cairns (Labour) on Tuesday, 31 October 2006 on behalf of the Northern Ireland Office.

Zebra Mussels

Question: To ask the Secretary of State for Northern Ireland pursuant to the answer of 24 October 2006, Official Report, column 1787W, on zebra mussels, what assessment he has made of the impact of zebra mussels on the Lough Neagh ecology; and what the projected impact is for each of the next three years.

Answer: The zebra mussel population in Lough Neagh has not yet reached the point where we would expect to see ecological impacts and it is too early to judge what the impact may be over the next three years.The colonisation of Lough Erne was rapid reaching maximum population levels within four years. It is not possible at this stage to predict exactly how quickly the colonisation in Lough Neagh will progress but it may be slower than in Lough Erne. Lough Neagh has a lower proportion of hard grounds such as rock and gravel, which are the areas initially favoured by zebra mussels, and more of the less suitable sand and mud which may remain zebra mussel free for longer.As population levels of zebra mussels increase the nature of the lake bottom will change and their filter feeding activity will reduce the amount of algae in the lake increasing water clarity. This will have as yet uncertain implications for fish, birds, water abstraction, navigation and other interests. The Inter-Departmental Zebra Mussel Control Group will continue to work closely with the Lough Neagh Advisory Committee in relation to monitoring the spread of mussels, advising on mitigation measures and keeping the public aware of the issues.

Secondary information