Pollution leads to Spain fish sex change

A study that began in 2007 has finally proven that some water contaminants produce sex changes in some fish species in the Basque Country.


Researchers at the Cell Biology in Environmental Toxicology department of the University of the Basque Country have proven that some contaminants in the water bring about a ‘feminization’ in some of the local fish.

The study started in 2007 after the first cases of the mutations were found in Urdaibai during a random quality analysis.

Analysts took water samples in six different zones on the coast of the Basque Country. Urdaibai is one of the areas with the highest sex change rates within the studied estuaries.

The study has proved crucial as Urdaibai has been named as a Biosphere Reserve.

Head researcher of the study, Miren P. Cajaraville, confirmed in a statement that the contaminants pose a serious risk.  

The diverse list of pollutants consists of pesticides, birth control pills, perfumes and detergents. These products make their way into the rivers and end up affecting the estuaries.

Also worrying is the fact that a high percentage of contaminants came from treatment plants, which are failing to decontaminate the water properly.

These chemicals, though different in structure, all act as endocrine disruptors, meaning that they affect fish by producing the same effects as oestrogen.

Between 12% and 64% of the fish in the studied areas had been changed by the chemicals.  

Another change was the presence of vitellogenin in the liver (a protein that is usually only in females), which was present in 60-91% of the male fish.

The study is ongoing and it has yet to be determined what action should be taken.  

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