Global warming may make some fish species 98% male

Global warming may increase the proportion of male fish up to 73 or 98% in some types of fish, which could seriously jeopardize the survival of some species, according to a study prepared by a team of researchers at the Spain’s Higher Council for Scientific Research (CSIC), which publishes the journal Public Library of Science.

The study reveals that with an increase of 1.5 degrees centigrade in water temperature would increase the proportion of males up to 73% in some species whose sex is determined by temperature.

What is serious is that this is something that has already been assumed, according to the forecast of the Intergovernmental Panel on Climate Change, IPCC the temperature will rise 1.5 degrees this century.

But at an increase of 4 degrees, which the IPCC seen as likely, that proportion would go up to 98%, and would leave only 2% of females, thereby seriously compromising the survival of the species.

To scientists studied through simulations in 59 species of fish determining the temperature dependent sex (TDS). The next step was to determine whether the predicted effects on the sex ratio due to higher temperatures can be observed in natural populations of different species.

However, according to the experts there is already data from a South American species, the silverside, one of the most sensitive to temperature change suggesting that these changes are already occurring in some natural populations.”

Another conclusion that scientists have reached is that the water temperature is not a very decisive factor in shaping the sex of many fish species as was believed.

Until now it was thought that a large number of fish species, as in reptiles, sex of individuals was determined by the temperature and not by genetic information, which ensures that the determination of sex is predominantly genotypic.

The authors of the study suggest that the patterns of response to temperature increase that had been given so far were disturbed by the living conditions of fish in laboratory experiments.