Climate change: Anchovies, herrings and pilchards are shrinking and could face extinction
Rising sea temperatures mean fish are becoming smaller and are finding it difficult to adapt to suitable environments.
Monday 9 August 2021 23:10, UK
Popular dinner-table fish including anchovies, herrings and pilchards could shrink because of climate change, new research suggests.
Small fish species may eventually face extinction as warming oceans increase pressure on their survival and hamper their ability to adapt.
Professor Chris Venditti, an evolutionary biologist at the University of Reading, and co-author of the study said: "Warming waters are a double whammy for fish, as they not only cause them to evolve to a smaller size, but also reduce their ability to move to more suitable environments.
"Our research supports the theory that fish will get smaller as oceans warm under climate change but reveals the worrying news that they will also not be able to evolve to cope as efficiently as first thought.
"With sea temperatures rising faster than ever, fish will very quickly get left behind in evolutionary terms and struggle to survive.
"This has serious implications for all fish and our food security, as many of the species we eat could become increasingly scarce or even non-existent in decades to come."
The study comes on the same day as the UN's Intergovernmental Panel on Climate Change (IPCC) warned the world will reach or exceed temperature rises of 1.5C in the next two decades.
Scientists used statistical analyses of a large dataset of globally distributed fish species to study their evolution over 150 million years and suggest the study provides the first solid evidence of how historical global temperature fluctuations have affected them.
The study focused on highly diverse fish schools found all over the world, including anchovies, Atlantic herring, Japanese pilchard, Pacific herring and south American pilchard.
But the researchers warned that their findings have implications for all fish species.
Previously, fish only had to deal with a maximum average ocean temperature increase of around 0.8C per millennium, far lower than the warming rate reported by the National Oceanic and Atmospheric Administration of 0.08C (0.13F) per decade since 1880.
The findings support the expectation that fish will get smaller and move less due to global warming because the need to increase their metabolism and therefore require more oxygen to sustain body functions.
This will impact larger fish and their ability to travel longer distances and smaller fish which will be less able to seek out new environments with favourable conditions as the climate changes.
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