Endocrine Disruptors Fingered as Cause of Smallmouth Collapse in Susquehanna

A key issue for the Bay is the duration or geographic reach of endocrine disruptor effects as they travel down the Bay, and how is this influenced by factors such as stream flow, temperature, and salinity. If effects are long-lived, the collapse of the smallmouth bass populations in the Susquehanna River may just be the first step in a Bay-wide disaster.

From the LancasterOnline

Study: hormone-disrupting chemicals, herbicides, pathogens and parasites likely cause of Susquehanna bass collapse

Updated Dec 14, 2015

Herbicides, hormone-disrupting chemicals, as well as pathogens and parasites in the water, are the most likely causes for the decade-long decline of prize game fish in the Susquehanna River, a new study by state and federal agencies says.

 “This study does not identify a single smoking gun,” said John Quigley, secretary of the state Department of Environmental Protection. “But it does point the way toward likely causes, which we will continue to pursue.”

The study by the agency, the Pennsylvania Fish and Boat Commission and six partner agencies is the latest and most extensive probe yet into the cause of die-offs of smallmouth bass and the alarming appearance of tumors, lesions and bass with both male and female organs.

Affected fish have been found in various parts of the Susquehanna and Juniata rivers.

The search for a cause — and solution — has at times pitted state agencies against each other.

In 2013, the Fish and Boat Commission and environmental groups urged the Department of Environmental Protection to declare the lower Susquehanna from the Holtwood Dam to Sunbury as impaired, which would have forced the state to find a solution.

But the agency refused, saying not enough was yet known about the causes. But it promised to conduct an extensive study into the sources of the problem.

Neil Shader, agency spokesman, said the agency was considering the latest study as it prepares its next round of listing impaired bodies of water for the federal Environmental Protection Agency.

Some 14 possible causes were researched. Now considered unlikely are high flows, pH and dissolved oxygen. Invasive species, habitat and blooms of algae are deemed uncertain.

The federal Environmental Protection Agency aided in the latest study.

Endocrine disruptors are chemicals that, at certain doses, can interfere with the hormone system in fish and mammals.

The study said sources can be from pharmaceuticals, fertilizers, and household cleaning products. Discharges from sewage plants and farm runoff would be likely sources. Quigley said endocrine disrupters can also come from industry, residential/commercial landscaping, golf courses and roadways.

Since the smallmouth bass collapse surfaced in 2005, the study team has used more than 30,000 water-quality records and latest research findings to narrow the list of causes.

“The health of the smallmouth bass in the Susquehanna River continues to be compromised and this analysis rules out certain causes, prioritizes other uncertain causes for further study and, most importantly, identifies likely causes which can be targeted for action,” said John Arway, the Fish and Boat Commission’s executive director.

The next step will be to focus on identifying the sources of endocrine-disrupting compounds and herbicides, and what is causing the increased prevalence and lethality of the pathogens and parasites in smallmouth bass, according to a press release by the Department of Environmental Protection.

Tributaries to the Susquehanna will be monitored more closely to try to pinpoint sources.

“The Susquehanna River’s smallmouth bass fishery once attracted anglers from all over the world,” Arway observed. “I am confident that the results from the study along with the continued commitment by DEP to identify the causes and reduce the sources will provide for the recovery and return of that once world-class recreational fishery.”

About Bruce

Work for sustainable development of small islands and the Chesapeake Bay; ex-Peace Corps (Volunteer and staff) in LA & Caribbean; cruised Caribbean on S/Y Meander for three years; like small tropical islands, French canals, Umbria, Tasmania, and NZ. Married 52 years to the late Kincey Burdett Potter (see Kincey.org). President of the now-sunsetting Island Resources Foundation.
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