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Cod in the North Sea are getting smaller

Alex Mustard / naturepl.com

Fish are growing smaller as sea temperatures rise, with adults now reaching a smaller maximum size than in 1970.

Idongesit Ikpewe at the University of Aberdeen in the UK and his colleagues have found that warmer seas are linked to changes in fish size. Their analysis looked at trends in four commercially fished species – of cod, haddock, whiting and saithe – in the North Sea and in waters west of Scotland.

The researchers examined existing data for the fish between 1970 and 2017, looking specifically at the average length-at-age …