Warming seas forcing salmon epic distances to find food

 

Wild Irish salmon will be hit hard by climate change as they are forced to travel even more epic distances to find cold-water feeding grounds.

A study of eight countries with populations of Atlantic salmon found those from Ireland and Spain, the most southerly, travelled the farthest, with one of the tagged Irish fish covering 2,400km from the River Suir.

That makes them more vulnerable as seas warm, extending their journey to the rich feeding grounds where the warmer Atlantic meets the Arctic.

Scientists warn that the boundary between the two water bodies could move northward because of warming.

“The capacity for populations to adapt to an increased migration distance is unknown,” they said. “Given increased migration time, especially for southern populations, the time available for accumulating important energy reserves will likely be reduced.”

They fear southern salmon will be at a double disadvantage because temperatures in their freshwater spawning grounds are also likely to rise more, stunting their growth and making migration even harder.

Dr Paddy Gargan of Inland Fisheries Ireland (IFI), one of the study’s authors, said: “As we know, water temperatures have increased in the north Atlantic over the last few decades. This new research is suggesting that this type of climate change may have greater impact on salmon populations originating farther south, like Ireland.”

Ireland’s wild salmon numbers have dropped considerably over the past 40 years, as have the wider Atlantic salmon populations, and they are classified as vulnerable.

IFI said the findings suggested there was not one common marine factor responsible for the decline. “This means conservation efforts should be focused locally, such as during the freshwater phase,” it said.

The full study - ‘Redefining the oceanic distribution of Atlantic salmon’ - was publiahed in the journal Nature.

Source – The Irish Independent