Quantcast
Environmental News for a Healthier Planet and Life

Help Support EcoWatch

Female Fish Eggs Found Inside of Male Fish Testicles

Science

A study published by the U.S. Geological Survey (USGS) and U.S. Fish and Wildlife Service found large-scale evidence of intersex in smallmouth and largemouth bass in the Northeast U.S., an indicator of endocrine disruption. The study, published in the journal Ecotoxicology and Environmental Safety, looks at 19 U.S. National Wildlife Refuges and is the first reconnaissance survey of this scope. The study found that the prevalence of testicular oocytes across all samples was 85 percent and 27 percent for male small- and largemouth bass, respectively.

Intersex occurs when one sex develops characteristics of the opposite sex. In the case of this study, researchers found testicular oocytes—female eggs found inside male testicles—in male smallmouth and largemouth bass. The study explains: “The presence of oocytes in the testes of male gonochoristic fish has been used as an indicator of estrogenic exposure.”

The source of the estrogen is hard to pinpoint, but pesticides are often cited as a cause given that they widely pollute waterways that fish populate. Those chemicals have properties that disrupt the endocrine system and affect the reproductive system, causing development issues such as testicular oocytes. According to USGS, “Intersex is a global issue, as wild-caught fish affected by endocrine-disrupting chemicals have been found in locations across the world.”

According to the USGS press release for the study, “Estrogenic endocrine-disrupting chemicals are derived from a variety of sources, from natural estrogens to synthetic pharmaceuticals and agrochemicals that enter the waterways. Examples include some types of birth control pills, natural sex hormones in livestock manures, herbicides and pesticides.”

While the study did not look for the sources of endocrine disruption, it did paint a picture of how widespread this abnormality really is, encouraging management actions to combat runoff. “It is not clear what the specific cause of intersex is in these fish,” Luke Iwanowicz, a USGS research biologist and lead author of the paper, said, in their press release. “This study was designed to identify locations that may warrant further investigation. Chemical analyses of fish or water samples at collection sites were not conducted, so we cannot attribute the observation of intersex to specific, known estrogenic endocrine-disrupting chemicals.”

Last summer, research by the USGS showed a strong correlation between the occurrence of intersex characteristics on fish, which have been found in the Chesapeake Bay region and areas of high agricultural use in Pennsylvania. In addition, a recent report by the Pennsylvania Department of Environmental Protection (DEP) found rare malignant tumors on smallmouth bass in the Susquehanna River, a river that flows through the northeast from upstate New York to the Chesapeake Bay. The Susquehanna River is a major source of agricultural runoff containing phosphorous, nitrogen and sediment pollutants, as well as natural animal hormones in manure. Pennsylvania DEP officials are looking to in-depth studies to identify the sources of the endocrine-disrupting compounds and herbicides likely contributing to the tumors.

This is a step that USGS would like to see taken as well. The study states, “A comprehensive re-evaluation that includes chemical analysis and seasonal snapshots of both sites is necessary to identify the likely cause(s) of elevated plasma vitellogenin in these male smallmouth bass.”

In addition to the Pennsylvania DEP study, other scientists are examining fish as a means of gauging water quality and chemical exposure. In 2008, USGS identified ten contaminants, including atrazine, chlorpyrifos and endosulfan, responsible for intersex fish in the Potomac River. Atrazine, one of the most commonly used herbicides in the world, has been shown to affect reproduction of fish at concentrations below U.S. Environmental Protection Agency’s water-quality guidelines. A November study found that commonly-used pesticides can persist in and impact the species of a waterway long after the chemicals are detectable or monitored by regulators.

YOU MIGHT ALSO LIKE

Groundbreaking Study Says Asian Carp Could Make Up One-Third of Lake Erie Biomass

Oppose Welfare Ranching, Not Wolves

Beloved Orca Found Dead Due to Entanglement in Fishing Gear

How the Wise Use Movement Is Tied to the #OregonStandoff

EcoWatch Daily Newsletter

Activists of Greenpeace and Fridays For Future demonstrate on a canal in front of the cooling tower of the coal-fired power plant Datteln 4 of power supplier Uniper in Datteln, western Germany, on May 20. INA FASSBENDER / AFP / Getty Images

The Bundestag and Bundesrat — Germany's lower and upper houses of parliament — passed legislation on Friday that would phase out coal use in the country in less than two decades as part of a road map to reduce carbon emissions.

Read More Show Less
Pixabay

By Tara Lohan

Would you like to take a crack at solving climate change? Or at least creating a road map of how we could do it?

Read More Show Less
Climate campaigners and Indigenous peoples across Canada have spent the past several years protesting the Trans Mountain pipeline. Mark Klotz / Flickr / cc

By Elana Sulakshana

Rainforest Action Network recently uncovered a document that lists the 11 companies that are currently insuring the controversial Trans Mountain tar sands pipeline in Canada. These global insurance giants are providing more than USD$500 million in coverage for the massive risks of the existing Trans Mountain pipeline, and they're also lined up to cover the expansion project.

Read More Show Less
Pexels

By Leah Campbell

After several months of stay-at-home orders due to the COVID-19 pandemic, many households are beginning to experience family burnout from spending so much time together.

Read More Show Less
Food Tank

By Danielle Nierenberg and Alonso Diaz

With record high unemployment, a reeling global economy, and concerns of food shortages, the world as we know it is changing. But even as these shifts expose inequities in the health and food systems, many experts hope that the current moment offers an opportunity to build a new and more sustainable food system.

Read More Show Less
Pexels

By Brian J. Love and Julie Rieland

The COVID-19 pandemic has disrupted the U.S. recycling industry. Waste sources, quantities and destinations are all in flux, and shutdowns have devastated an industry that was already struggling.

Read More Show Less

Trending

Pixabay

By Kris Gunnars, BSc

Unhealthy foods play a primary role in many people gaining weight and developing chronic health conditions, more now than ever before.

Read More Show Less