After examining fish in 19 national wildlife refuge locations in the U.S. Northeast, a team of researchers from the U.S. Geological Survey and the U.S. Fish and Wildlife Service revealed that approximately 60 to 100 percent of the male smallmouth bass they examined possessed female egg cells growing in their testes. The condition, called intersex, has been linked to manmade environmental chemicals that either mirror or block sex hormones, although the exact causes are still yet to be determined.
In addition to the current study, feminized fish have been discovered in 37 species of male fish over the past decade in lakes and rivers across North America, Europe and numerous other parts of the world. The new findings suggest that this problem may be even more widespread than initially believed.
"There are no truly untouched areas," said Luke Iwanowicz, who led the current study. "I think the take away here is that everything we do, everything we use or put on the land, ends up in the water at some point."
Currently, scientists are unaware of just how much damage these feminized fish have on the health of the species, environment and humans.
"When fish are getting intersex, it's probably a good indication that something is wrong in the environment," said Vicki Blazer, a researcher at the U.S. Geological Survey.
One potential danger is that the alteration of male behavior, which is essential to build and guard spawning nests for their offspring, could disrupt global marine ecology and ultimately endanger the fish populations around the world, according to Planet Experts.
Some of the potential causes of these feminized fish include chemicals stemming from agricultural runoff and hormone-based pharmaceuticals that are unable to be filtered by sewage treatment plants, according to NorthJersey.
The findings were published in the February issue of Ecotoxicology and Environmental Safety.
