The Atlantic salmon of Scotland are hardy and determined animals. Each spring and summer, they return from the North Atlantic Ocean to breed in Scotland’s shallow rivers, leaping up waterfalls and over weirs, propelling themselves upstream in a Herculean effort. Some fail, others triumph, but today they face yet another challenge.

During the mid-1980s, there were between eight and ten million salmon swimming around Scotland’s Atlantic coast; that number has now dropped to two to three million. There’s evidence of rising at-sea mortality as climate change warms and acidifies oceans, reducing the availability of the salmon’s prey. New research suggests climate change is also bearing down on rivers.

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