In 1889 a party of English pike anglers arrived in Ireland and they brought their own live baits with them. At the end of their trip they tipped their surplus baits into the River Blackwater thus introducing two new species to the country — the roach and the dace.
I’ve searched hard but I can’t find the original reference on which this story is based or any more detail about it. For instance I don’t know where the incident happened — and the Munster Blackwater is a long river. I do have my suspicions though.
To transport live fish from England to Ireland in the days before battery-powered aerators would have required fast and efficient transport. In 1889 there was a rapid rail link from England, via Rosslare, to Cappoquin.
The station operated from 1878 to 1967 and the old rail bridge is still a dominant feature in the town. The river is tidal at Cappoquin but pike are tolerant of slightly brackish water and the area would have been suitable for pike live-baiting — which is illegal today but was popular in the 19th century.
For about 60 years both species were confined to the Blackwater and its catchment. Then the roach escaped. They are a popular species with coarse anglers and were illicitly transferred, by a person or persons unknown, to other catchments. They thrived and multiplied and are now found in about 90% of our inland waterways and have become the commonest freshwater fish in Ireland.
Dace are smaller and, though many coarse anglers enjoy fishing for them, they don’t generate quite the same enthusiasm as roach. However, by the 1980s they started to appear in other rivers. They turned up in Co Clare, in Doon Lake and the Ahaclare River, in 1980 and, shortly after, in other tributaries of the lower Shannon and in the Shannon itself.
However, so far they don’t seem to have made it above the dam at Ardnacrusha to invade the main Shannon catchment.
However, they were confirmed from the River Barrow in 1994 and a recent survey has shown they have managed to colonise a 70km stretch of the river in 14 years. They’re also thriving in the Nore, which shares a common estuary with the Barrow. There are reports of them in the Suir, the third of the Three Sisters, though I haven’t seen any scientific confirmation of this. There are also unconfirmed reports from the Liffey and the Boyne.
Coarse anglers generally welcome the arrival of dace but game anglers claim they compete with trout and juvenile salmon for food and spawning gravel.