Coypu discovered in Irish rivers: Sadly, this pest must be eradicated

LORD POWERSCOURT introduced Japanese Sika deer — just one stag and three hinds — to Ireland in 1860, for “ornamental purposes”. 

Half a century later, in 1911, grey squirrels from England — six pairs only — were released at Castle Forbes, in Longford, for “aesthetic reasons”. The deer have spread across the island and have interbred with red deer, diminishing the genetic integrity of our magnificent native deer. The grey squirrel has largely displaced the native red squirrel, which is just a memory in former strongholds. The negative impact of just 16 animals was unforeseen and, even at this remove, unimaginable.

Zebra mussels, a native of the Caspian and Black Seas, reached Ireland through ballast water dumped in the Shannon Estuary in the 1990s. The female mussel can produce up to one million eggs each year. Zebra mussels remove a great proportion of the plankton on which juvenile fish rely, so the mussels have an unwelcome impact on threatened fish stocks.