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Global warming threatens trout and salmon

Cardiff -- Welsh scientists say trout and salmon populations have decreased during recent decades and new evidence shows global warming might put both species at risk.

Cardiff University Professor Steve Ormerod and colleagues said habitat loss and overfishing have been previously blamed for the drop in numbers of trout and salmon, which are among the world's most familiar freshwater fishes. But the researchers said they have developed new evidence that shows climate change might place the fish at risk of extinction.

The scientists studied populations of young salmon and trout in the River Wye in Wales, traditionally one of the U.K.'s best angling rivers. The researchers found salmon numbers fell by 50 percent and trout numbers by 67 percent between 1985 and 2004, with the fish hit hardest following hot, dry summers such as during 1990, 2000 and 2003.

Ormerod said the findings suggest warmer water and lower river levels combine to affect both species. As both trout and salmon favor cool water, they face potentially major problems if climate warming continues as expected in the next two to three decades.
"Salmon and trout fishing also generate many jobs and large economic benefits," Ormerod said. "Any risk of eventually losing these species to climate warming is therefore one we must consider very seriously."

The research is detailed in the journal Global Change Biology.

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