Fishing shrank Baltic cod through genetic changes

Decades of intense fishing and environmental changes have altered the genetic makeup of Baltic cod, leading to a significant decrease in their size. This is the first evidence of evolutionary changes in a fully marine species due to exploitation. Scientists found that cod genomes have changed, with fast-growing individuals nearly disappearing. This is because smaller, faster-maturing fish have a survival advantage under fishing pressure, resulting in a measurable impact on their DNA. The study, using otoliths from 1996-2019, shows that the cod's "shrinking" has a genetic basis. The findings highlight the need for sustainable fisheries management to conserve biodiversity and genetic resources, as recovery may be impossible.