Trials with barriers to control Asian Clam

Trials have begun to examine the effectiveness of barriers to control the highly invasive Asian Clam (Corbicula fluminea) in the River Barrow.  The Asian Clam was first recorded in Ireland in April 2010, near St Mullins on the River Barrow.  Since that first sighting the clam has been recorded at multiple locations along the tidal reaches of the River Nore, the River Barrow and also the River Shannon. These three rivers are all Special Areas of Conservation (SACs) and contain a number of protected habitats and species including estuaries, three species of lamprey and the very rare Nore Pearl Mussel (Margaritifera durrowvensis).  Densities of Asian Clam can reach up to 10,000 individuals per m2 leading to river shallowing with potential implications for flooding.  At such high densities the clam will impact significantly on native aquatic invertebrate and even fish populations.  In the USA, the Asian Clam is estimated to cause $1billion of damage annually.

In a collaborative study between Inland Fisheries Ireland and Queens University Belfast, and with permission from the National Parks and Wildlife Service, plastic and jute sheeting will be used to cover porous baskets filled with river sediment and Corbicula fluminea at designated sites on the River Barrow.  A combination of the sheeting and river silt will hopefully create a localised deoxygenated environment around the clams.  Asian Clams are known to require well-oxygenated water to survive.   Having been covered for periods of 15, 30 and 45 days, the survival of the clams will be recorded and compared to nearby control sites.  Similar studies using benthic barriers made of heavy plastic matting in lakes in the USA have proven very successful.  It is hoped that this low impact method will be a success and contribute to the fight against the spread of this invasive species in Ireland.