The Asian clam (Corbicula fluminea) is a most unwelcome recent addition to the fauna of Irish rivers and lakes. This bivalve mollusc is regarded as one of the most notorious aquatic invasive species in the world. The Asian clam was first recorded in Ireland in the River Barrow near St Mullin’s in April 2010. Subsequent studies conducted by Inland Fisheries Ireland (IFI) under the EU Life+ funded CAISIE (Control of Aquatic Invasive Species and Restoration of Natural Communities in Ireland) project have revealed that it is firmly established in the lower Barrow attaining staggering densities of up to 10,000 clams per square metre. Considering that each clam can produce up to 70,000 juveniles each year, the potential for the enormous expansion of this population is apparent. In late 2010 and in 2011 populations of the Asian clam were recorded in the River Nore downstream of Inistioge and in the River Shannon at Banagher and Carrick-on-Shannon and in Lough Derg.
The inadvertent introduction and transfer of the invasive Asian clam to uninfested waterways represent a major threat to Ireland’s habitats, native species and internationally renowned fisheries. The ecology of invaded watercourses can become dramatically altered and may become unsuitable for water-based amenity and recreational pursuits. At present, as water temperatures are increasing in our rivers and lakes Asian clam populations are reproducing releasing vast quantities of planktonic juveniles into the water. The microscopic juvenile clams subsequently settle out of the water column attaching to underwater surfaces using sticky threads. In order to limit the further spread of this highly invasive species IFI is urging all water users, particularly anglers and boaters, to implement strict biosecurity measures including disinfecting all equipment that has been exposed to or used in waterways when moving from one area to another.
Dr Joe Caffrey, Senior Scientist with IFI and Project Leader of the EU funded Life+ CAISIE project, stated that “It is imperative that every effort is made to limit the expansion and spread of this highly adept invasive species outside of its current range. Before and after use in waterways, boats, angling gear and related equipment should be thoroughly inspected for Asian clams with any found removed and disposed of in a biosecure manner. Additionally, all such equipment should be cleaned and disinfected with reference to the invasive species biosecurity guidelines produced by IFI.”
Further information on these biosecurity guidelines produced for anglers, boaters and scuba divers and on invasive species generally is available on the CAISIE (www.caisie.ie) and IFI websites (www.fisheriesireland.ie). Any new sightings of the Asian clam should be reported to IFI. Inland Fisheries Ireland appreciates the cooperation and goodwill of stakeholders and the public in adhering to these biosecurity measures as they are essential if we are to effectively halt the spread of harmful pathogens and invasive species.