Salmon adapting to climate changes

 

CLIMATE change is contributing to an “alarming” increase in the numbers of wild salmon dying at sea, but there are indications that stock may prove to be more adaptable than man.

New evidence shows that the game fish is able to feed at depths normally inhabited by the sperm whale. It is also travelling close to polar ice fields, according to Ireland’s leading expert on wild salmon, Dr Ken Whelan.

“Not only can the fish dive to depths of up to 800 metres, but it will also feed there for up to 24 hours,” Dr Whelan told The Irish Times. “It tends to occur during the winter months, when feeding is less plentiful, but it must be using senses at these depths that we weren’t formerly aware of,” he said.

The stock is also moving further north, in response to a warming ocean, and feeding at the very edge of frozen polar ice fields.

Ireland is among a group of “southern stock states” where the wild salmon is threatened with extinction if high mortality at sea continues.

This was one of the key messages from a salmon summit in La Rochelle, France, attended by some 130 scientists and fishery managers, including Dr Whelan, research director of the Atlantic Salmon Trust and formerly of the Marine Institute. The summit was convened by the North Atlantic Salmon Conservation Organisation and the International Council for the Exploration of the Sea.

The findings of the EU-funded Salsea programme, which Dr Whelan led, were discussed at the summit, and these show a “very significant impact of climate change”, he said.

“We’re seeing a shift in terms of plankton in particular, due to changing ocean currents, which are in turn very dependent on wind,” he said.

“Surviving the first winter at sea seems to be the key challenge for these stocks, and the salmon in the northern states like Norway and Russia, seems to be less affected,” he added.

There have been reports of healthy returns of wild salmon this season to Irish rivers, and the fish is now spawning in Dublin’s Dodder river and has returned to the Tolka.

Dr Whelan said this was very welcome, and showed the positive impact of the EU water directive and related anti-pollution measures.