Self-transsexual fish are related to population and agriculture in the Potomac River basin

For years, scientists have been investigating why so many small-mouthed male bass in the Potomac River basin have immature egg cells in their testes - this is a form of current self-transsexual statues. They had nearly come to an answer.

The study by the US Geological Survey (USGS) shows that transgender phenomenon occurs in the Potomac River basin, which is popular in agricultural areas, conducted on a large scale and in densely populated areas. highest population. The study also found that this type of sex change is the most common, also known as testicular oocytes (TO) , which occurs in the spring - just before and during the spawning season.

USGS scientist Vicki Blazer, who led the study, said: 'We caught the bass in the Shenandoah River, the southern branch of the Potomac River, and the sea bass in the Potomac River basin for comparison. The fish at the highest population density and the most cultivated area have the highest rate of transsexuals , the largest rate in the Shenandoah River at 80-100%. '

For the Potomac River basin, where the population is most concentrated with farmland being implemented with the largest scale, the rate of TO is 75%, the less populated areas have the rate of 14-35% of males have BIG. The areas along the southern Potomac River branch have a ratio of 47-77%. Once again, it is confirmed that the number of transsexuals is proportional to population growth and agricultural development.

Sea bass small mouth.Scientists have recently discovered clues that explain why so many male bass have immature egg cells in their testes - a form of transgender phenomenon.(Photo: iStockphoto)

Seasonal differences are also remarkable. According to the study, USGS observed 6 locations. In each place, the percentage of males was significantly higher in spring, the period before and during spawning, from 69% to 100%. While in summer, the time after spawning, this ratio is only from 25% to 67%. The unusual reproduction of small mouth bass in the Potomac River is not detected by an overall inspection of a fish that was discovered by chance. In 2003, when scientists investigated the fact that fish died of mass and large lesions inadvertently, many fish were accidentally noticed by observing the tissue in the testes of males under the microscope. vi.

Transgender phenomenon does not only appear in the Potomac River basin, nor is it the small mouth bass species. According to documents recorded this phenomenon is also present in some fish species in the wild including spotted tilapia fry at St. River. Lawrence, white dust fish in the Colorado River, sturgeon in the Mississippi River, white perch in Great Lake, rutilut in England and Denmark, sharp-toothed catfish in South Africa, barbs in Germany and bearded fish in Italy. Some species of fish that live in the sea and in brackish waters in Japan, the United Kingdom and the Mediterranean can also transgender themselves.

In many of these areas, transsexuals in fish are related to endocrine disruptive compounds that have been identified or suspected to be in the untreated wastewater, and also like waste from farming activities . Compounds can contain estrogen in birth control pills and hormones, pesticides, fertilizers used for crops as well as hormones from livestock activities.

Scientists are still continuing to assess the level of TO for sea bass in the Potomac river system. They are examples of studies collected at locations both inside and outside the river basin to determine the basis of the TO phenomenon for both large-mouth bass and small-mouth bass; thereby identifying potential causes. They also assessed their general status as well as their reproductive activities in places where TO, despite low or high rates and land use risk assessment.

Article 'Self-transgender (testicular oocytes) in small mouth bass in Potomac River and some adjacent river basins' was published in the Journal of Aquatic Animal Health.

The study of fish status is part of a large study of USGS's Chesapeake Bay to provide a scientific basis for raising awareness and managing the bay ecosystem. The report ' Circular 1316 USGS ', ' Summary of USGS scientific research on Chesapeake Bay ecosystem and environmental management ' will soon be released by USGS.