IFI picks up trail of salmon that swam from Greenland back to Mayo

INLAND Fisheries Ireland (IFI) scientists have tracked a migrating salmon that swam from Greenland back to its native river in Mayo.

The State environmental agency has acoustic tracking technology set up at the entrance to Killary Harbour which picks up signals from any tags attached to fish.

Glen Wightman, IFI research officer, said: “We recorded a mystery fish at Killary Harbour that had been tagged near Qaqortoq, in southern Greenland.

“Although it had not been tagged in fresh water in Ireland, we know that when salmon migrate from the sea, they are using their strong homing instinct and typically returning to their river of origin.”

The town of Qaqortoq is more than 1,242 nautical miles (2,300km) from Co. Mayo.

IFI sensors traced the fish again in recent weeks as it swam up the River Erriff in Co. Mayo, which is IFI’s National Salmonid Index Catchment.

Glen added: “These tags are pinging a unique code every 60 to 90 seconds. Our acoustic arrays can record them moving into and through monitored rivers when they swim by.

“Our salmon research colleagues working in Greenland said this fish weighed 3.3kg and was 64cm long when it was tagged in September 2023. It may be a 5kg salmon now, having spent two winters at sea.

“We believe this feeding visitor to Greenland has now migrated upstream to spawn in the River Erriff, to pass on its genes to the next generation of salmon.”

IFI corresponded with overseas organisations, including the USA federal agency NOAA Fisheries, Fisheries and Oceans Canada, the Atlantic Salmon Federation, and the Association of Fishermen and Hunters in Greenland, to identify the tag and find out how far the fish had travelled.

Tim Sheehan of NOAA Fisheries said: “This tagging effort furthers one of our main goals - to develop a better understanding of the factors driving salmon abundance and the challenges they face.”