What over-fishing has done to the size of cod in just 30 years
Excessive fishing has caused Baltic cod to undergo genetic changes, halving their size over the past 30 years.
A study published in Science Advances is the first to demonstrate that decades of overfishing and environmental changes can profoundly alter the genetic makeup of a fully marine species.
Researchers found a 48 per cent decrease in the asymptotic body length of Eastern Baltic cod between 1996 and 2019, with genetic variations indicating evolution driven by human interference.
The study revealed that the genomes of fast-growing cod systematically differed from slow growers, with fast-growing individuals nearly disappearing from the Baltic Sea.
This phenomenon is described as evolution in action driven by human activity, where the consistent removal of larger fish gives smaller, faster-maturing fish an evolutionary advantage.
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