June 25, 2026 — In many fish species, water temperature determines the sex of offspring. As oceans warm, that mechanism has raised a troubling question: could entire fish populations collapse simply by running out of females?
A new ten-year study offers an unexpected and cautiously hopeful answer.
In European seabass exposed to elevated temperatures, the initial spike in male births reversed itself by the third generation, with females coming back in greater numbers.
The warming effect, it turns out, is not necessarily cumulative.
The findings emerged from an international experiment conducted across Spain, France, and Brazil involving more than 3,000 European seabass over a decade.
Brazilian contributors to the study included Maira da Silva Rodrigues, who analyzed the gonads of the third generation of fish during her doctoral studies at the Botucatu Institute of Biosciences of São Paulo State University, under the guidance of Rafael Henrique Nóbrega.