Washington, Dec 26 (ANI): A new study has determined that global warming might be leading to the birth of too many male fish.

According to a report in Live Science, some experts believe that the gender of many fish is determined by temperature, because temperature-dependent sex determination, or TSD, occurs in many species.

But, a critical analysis of the fish literature by Natalia Ospina-Alvarez and Francesc Piferrer, both of the Marine Science Institute in Barcelona, Spain, casts doubt on that assertion.

The pair point out that fourteen of the twenty diverse fish genera previously reported as having TSD in fact have sex chromosomes, and that it takes unnatural temperatures found only in the laboratory to masculinize their genetic females.

But, the six genera that do show true TSD, including the Menidia silversides and the Apistogramma cichlids, could see their sex ratios skewed by global warming.

Ospina-Alvarez and Piferrer found that males were hot in all six.

The researchers calculated that in such temperature-sensitive fishes and there might well be many more than just six genera a rise of 7 Fahrenheit degrees predicted by some models for the end of the century would yield three males for every female, a ratio unfavorable for maintaining populations. (ANI)