Researchers warn against falling for 'fool's gold' of rising fish numbers spurred by marine heatwaves.
Booming fish stocks in colder waters are a warning sign, not good news, scientists say.-Climate change is hitting fish populations harder than we previously realised - and a deceptive natural phenomenon may be hiding the true scale of the problem. A major new study looked at nearly 34,000 fish populations across the Northern Hemisphere over almost three decades. The findings are striking: for every 0.1°C of ocean warming sustained over a decade, fish numbers fall on average by more than 7 per cent. In some instances, that loss can reach nearly 20 per cent in a single year. “The long term is bad news for fish,” says lead author Dr Shahar Chaikin, a marine ecologist at Spain's National Museum of Natural Sciences. The study, based on data from scientific bottom‑trawl surveys around the world, was published in the journal Nature Ecology and Evolution. Marine heatwaves create ‘winners and losers’ The researchers identified two distinct aspects of ocean warming that are often confused. The first is the slow, steady rise in temperatures over decades. The second is the sudden, intense marine heatwaves that have become more frequent and more severe. Both are harmful - but in different ways.Gradual long-term warming is a universal threat. No matter where a fish population lives - in warm tropical seas or cold northern waters - sustained rising temperatures cause fish numbers to fall.
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