Zebra Mussels continue to spread

The Department of the Environment (DOE) has confirmed concern that Zebra Mussels have spread to Lough Neagh.

Zebra Mussels were first discovered in Northern Ireland in Lough Erne in 1997 and every effort has since been made to prevent their spread to other waterways.

It is well known that zebra mussels have major impacts on the ecology of lakes as they can filter as much as one litre of water per day through their gills and there are currently enough in Lough Erne to filter all the water at least once a week.

Zebra Mussels also remove large quantities of algae, zooplankton and small particles from the water, which result in a total change in the food web of the lakes they colonise.

They are a major risk to the future of some freshwater fisheries and could cause decline in income from commercial fisheries and the tourist industry associated with recreational fisheries.

Zebra mussels also are known to attach onto the shells of native swan and duck mussels preventing them from feeding, resulting in death.

Excessive weed growth resulting from increased light penetration due to zebra mussel activity is causing serious problems for boat users in Upper Lough Erne, which could have serious impacts on the tourism trade as well as having a serious economic effects at facilities that depend on water intake.

These pests attach themselves to any hard surface in the waters in which they occur, quickly spreading and covering the surface.

Preferred surfaces include stone, wood, concrete, iron/steel, aluminium, plastics and fibreglass. As a result, boats and water treatment plants can be damaged.

Bob Davidson of the Environment and Heritage Service said: "We are greatly concerned that Zebra Mussels have spread to Lough Neagh and other small lakes not connected to the navigable Shannon/Erne system. The potential impact is huge. Lough Neagh represents the last remaining viable population of the rare and endangered pollan fish species. The impact is unpredictable, as is the impact on the commercial eel fishery and sand extraction on the Lough. It is imperative that we curtail the spread now and protect other vulnerable lakes identified in the Zebra Mussel Management Strategy such as Lough Melvin, the MacNean lakes, Mill Lough and many others."

Dr Robert Rosell of the Agri-Food and Biosciences Institute added: "Lough Melvin supports a unique salmon community with 3 genetically distinct populations of trout and is regarded as the best game fishery in Northern Ireland. There is a perception that zebra mussels have improved trout fishing in Lough Erne. The increased water clarity has just improved the catchability of trout, not increased their numbers. Furthermore, it has resulted in more marginal weed growth that frustrates angling. We want anglers to work with us to prevent the spread of zebra mussels to Lough Melvin and other vulnerable lakes as they are a risk to the future of our fisheries."

(EF)