SOME OF the mysterious migratory habits of wild Irish salmon have been revealed for the first time following research by Inland Fisheries Ireland in collaboration with Norwegian scientists.
Until now scientists knew very little about this fish after it left Irish rivers, relying mostly on data collected from occasional specimens caught close to land.
This new data released yesterday comes from the fishery body’s pilot tagging programme started in collaboration with the University of Tromsø, Norway. Seventeen previously spawned adult salmon (kelts) were captured in the Blackwater and Suir rivers in March 2010, tagged and released into the Atlantic. Their journey has now been tracked on satellite. It was found they make their way to feeding areas south and southwest of Iceland and Greenland.
The information is captured by a tag attached by metal wire to the fish’s dorsal fin. The tag is then safely released at a pre-determined time. Once released, it floats to the surface and all data recorded on the salmon is transmitted by satellite to the lab. “We only get data once when the tag pops off but it will have been collected from the moment the fish was released to sea,” said Dr Paddy Gargan, senior research officer at inland fisheries.
“Because the tags transmit data via satellite we don’t need to retrieve them.”
One of the most interesting facts to emerge from the project, said Dr Gargan, is that wild salmon dive to deeper than 900m to seek food.
“In two cases we saw the temperature rise rapidly to 35 degrees and 18 hours later the tag was released. It turns out that they were eaten by a whale and had passed through.”
Ten more salmon from the Suir, Nore and Barrow rivers were tagged in March and released off Dunmore East, Co Waterford.
