Researchers led by fisheries biologist Rainer Froese (Kiel, Germany) have studied this question using the western Baltic Sea as an example. In this area, stocks of cod and herring have been at the lowest limit of reproduction for years: the number of mature animals and thus of offspring has collapsed drastically. In the same area, however, the stocks and reproductive success of the other commercial fish species are good or at least satisfactory—fish species with similar life history traits to cod and herring, suggesting that they also respond similarly to the stress caused by climate change or by fishing pressure.
The authors conclude that constant overfishing and inappropriate gear selectivity (too small mesh size) are responsible for the massively depleted stocks of mature cod and herring—not climate change.
Rainer Froese, Eva Papaioannou, and Marco Scotti (2022): Climate change or mismanagement? Environ Biol Fish, full text