IFI insists native brown trout numbers are 'stable' on Galway's Lough Corrib
Inland Fisheries Ireland (IFI) has downplayed new research showing just over two per cent of fish surveyed on Lough Corrib was brown trout.
Local trout anglers have expressed alarm that the recently published fish stock survey for Ireland’s second largest lake reveals the vast majority of fish surveyed were coarse and non-native invasive species.
But IFI insisted this week that the latest fish survey, conducted in 2024 and published in February 2026, showed native brown trout numbers were “stable” over the past 18 years.
On Lough Corrib upper, just 20 of the 994 fish surveyed were brown trout. On the lower lake, just 22 of the 765 fish surveyed were brown trout.
IFI’s own survey confirmed that about 93% of fish in the lake are non-native, predatory and invasive.
In a statement to the Tribune, IFI said fish stock surveys have been conducted on Lough Corrib since 2008 and all major species on the lake have remained ”relatively stable”.
“The 2024 survey was the sixth such survey conducted on the lake since 2008. It reveals that stocks of all the major species in the lake have remained relatively stable across time, with some evidence of an increasing population of roach, particularly in the lower lake.
“The population of brown trout has remained stable over that time frame, and no population trends are apparent,” IFI said.
It said the overall mix of species is influenced by factors such as climate change and nutrients input but “in lakes where roach and perch are found, these species typically dominate fish populations”.
IFI said the species mix in a lake was an indicator of lake ecological health and helps determine the designation of Water Framework Directive (WFD) Status. And it confirem the fish ecological status of both the upper and lower loughs was ‘Good’ in 2024.
“WFD surveys are designed to provide an estimate of fish stock structure on Irish lakes and are carried out over a relatively brief period to minimise the risk of fish mortalities.
“Brown trout were the fourth most-commonly encountered fish species during the Lough Corrib survey – their relative numbers only being surpassed by percid (perch) and cyprinnid (roach, bream, hybrids) species.
“Where these species occur in Ireland, they commonly outnumber all other fish due to their high fecundity and adaptability,” IFI said.
In its statement, IFI said it takes the view that “more fish population modelling and ecological studies are required on Irish lakes to fully evaluate the interactions between salmonids, percids, cyprinnids and pike”.