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RSS FeedsDNA analysis may explain salmon sea deaths
Cutting-edge DNA analysis is being used in an attempt to explain why alarmingly high numbers of salmon are dying at sea.
Marine scientists have adopted the skills used to track criminals for a ground-breaking survey following young fish from rivers into the North Atlantic.
Researchers from Ireland, Norway and the Faroe Islands will take part in three studies over the next year with the main Irish leg of the survey leaving today from Killybegs, Co Donegal.
Its mission is to map the migration and the distribution of salmon stocks at sea using genetic fingerprint technology instead of conventional tags.
Dr Ken Whelan of the Marine Institute said: “An increasing proportion of salmon are dying at sea. In some southern rivers on both sides of the North Atlantic wild salmon face extinction and no one fully understands why.”
The research programme Salmon at Sea (Salsea) involves scientists attempting to follow small juvenile salmon, known as smolts, from southern Europe to the Barents Sea in the far north.
Using methods similar to DNA analysis, individual fish caught at sea are identified by matching their natural genetic code with the region or river of origin.
It has already allowed scientists to map all of the major salmon stocks in Europe.
Dr Whelan, who is also chairman of North Atlantic Salmon Conservation Organisation research board, said it was hoped the expedition would shed light on the mysterious life of the salmon and why the number dying at sea is rising.
“There are many theories and far more questions, but as yet no sound research base on which rational action can be taken. That is what Salsea-Merge is all about – to provide answers,” he said.
Geneticists, ecologists and oceanographers from the three countries have pooled their talents to take part in the programme.
Eamon Ryan, Minister for Communications, Energy and Natural Resources, who backed a ban on drift net fishing to preserve salmon stocks, said it was an innovative research idea.
“The determined and at times very painful efforts we have made over recent years to conserve our wild salmon stocks are totally dependent on scientific advice,” he said.
“If that scientific advice ends at the estuary and ignores the oceans, we are going to find it very difficult to manage our stocks.”
Agriculture Minister Brendan Smith also welcomed the research.
“Salmon act as ’aquatic canaries’, picking up a wide range of biological signals relating to the health of the oceans,” he said.
“Ireland’s key involvement in this initiative signifies very clearly the major role that Irish scientists are playing in the ecosystem-based management of our valuable marine stocks.”
A sister programme will be launched in August with Canadian and US scientists setting out to track salmon in the western Atlantic.
During the spring, large numbers of smolts around 24cm long leave Irish rivers to migrate north following ocean currents to rich feeding grounds in the Norwegian Sea and the North Atlantic.
Some fish, known as grilse, return to their river of origin after one year while others spend several years at sea.
