Inland Fisheries Ireland will be conducting further surveys of waterways in the Shannonside region in the coming weeks to discover how much an impact an invasive species has had.
A warning was issued in August 2020 about Chubb fish which were discovered in the River Inny in south Longford.
The species is seen as causing significant damage to Irish waterways and anglers are being asked to report any sightings or catches to the IFI.
Dr Cathal Gallagher is the head of research with Inland Fisheries Ireland.
He explains what will be happening in the coming weeks in local waterways:
We're going back again this month, in the next week or so, to do further work to understand where we're at to see if we can try and remove more of that population. We're in the early stages of trying to find out where they are, how many there are, how many generations there are, and if they have moved further throughout the Shannon catchment.
