A newly published research paper co-authored by experts in Ireland highlights the importance of ferox trout to the fisheries of Lough Corrib and Lough Mask.
Ferox trout are highly prized by trophy anglers, and Loughs Corrib and Mask have recorded the majority of Irish specimens since angling records began in the 1950s.
The large, long-lived, fish-eating trout are normally found in deep lakes and are believed to be genetically distinct from normal brown trout, having evolved after the last Ice Age 12,000 years ago.
Little was known about the spawning location of Irish ferox trout compared to normal brown trout, and a radio tracking study was initiated in both catchments in 2005.
Local anglers and Inland Fisheries Ireland (IFI) staff helped catch large ferox trout on both lakes in order to insert radio tags.
The fish were released after tagging and then tracked with help from the Irish Air Corps helicopter unit and by walking spawning streams with a radio tracking antenna to determine in which streams ferox spawned.
Scientists from Inland Fisheries Ireland worked with colleagues at the Norwegian Institute for Nature Research on the data collected in this study.
Results from radio tracking showed that the majority (92%) of ferox trout tagged in Lough Corrib spawned in a single spawning stream, the Cong River, while the majority (76%) of ferox trout tagged in Lough Mask spawned in the Cong canal and Cong River.
These results, as published in the Journal of Fish Biology, indicate that these streams are most likely the principle spawning locations of ferox trout in both lakes.
Dr Paddy Gargan, senior research officer at Inland Fisheries Ireland and lead author on the publication, said: “The occurrence of ferox trout predominantly in single spawning rivers in both catchments highlights the vulnerability of the ferox populations with estimates of their population size thought to be small”.
IFI’s head of research Dr Cathal Gallagher welcomed the findings and said: “It was important that conservation measures, based on this research, have been introduced in the Corrib and Mask catchments continue to protect ferox trout.
“These conservation measures have reduced the number of ferox trout being killed and claimed as specimens and support the conservation of this unique trout.”
