Smallmouth bass has cancerous tumor

This photo, distributed by the Pennsylvania Fish and Boat Commission on Monday, shows a malignant, or cancerous, tumor on a single smallmouth bass caught in the middle Susquehanna River by an angler late last year.

SUNBURY — The Pennsylvania Fish and Boat Commission says it has found a cancer-stricken smallmouth bass in Duncannon, where the Juniata River flows into the Susquehanna River north of Harrisburg, evidence cited Tuesday by commission Executive Director John Arway that the health of fish in the river is being compromised.

Arway maintains that the river is impaired and should be designated as such, but impairment is a label yet to be used by the state’s Department of Environmental Protection.

“The impairment designation is critical,” he said, “because it starts a time line for developing a restoration plan. We’ve known the river has been sick since 2005, when we first started seeing lesions on the smallmouth bass. Now we have more evidence to further the case for impairment.”

Two independent laboratory tests confirmed a malignant, or cancerous, tumor on a single smallmouth bass caught in the middle Susquehanna River by an angler late last year and provided to the fish commission. The announcement was made during the commission’s quarterly business meeting on Tuesday.

Cancerous growths and tumors on fish are rare in Pennsylvania and throughout the U.S., but they do occur. This is the only documented case of this type of tumor found on smallmouth bass in Pennsylvania. The finding was confirmed by the U.S. Fish and Wildlife Service and the Aquatic Animal Health Laboratory at Michigan State University.

In response to the findings, Amanda Witman, a spokesman for DEP, said in an email late Tuesday: “DEP continues to work in partnership with PFBC to use a science-based approach to determining the causes of impacts to fish health in the Susquehanna. DEP’s biological studies include assessments of fish, aquatic insects, mussels and algae. Science will guide all of the department’s work in assessing the overall health of the river.”

Witman did not reply to a followup question about what it would take for DEP to declare the river impaired.

Since 2005, PFBC biologists had observed more than 22,000 adult smallmouth bass as part of routine surveys in the Susquehanna River basin and had not documented any fish with obvious signs of tumors. However, the biologists continued to find sores and lesions on young-of-year bass during late spring and early summer surveys.

“As we continue to study the river, we find young-of-year and now adult bass with sores, lesions and more recently a cancerous tumor, all of which continue to negatively impact population levels and recreational fishing,” Arway said. “The weight of evidence continues to build a case that we need to take some action on behalf of the fish.”

Meanwhile, Dr. Karen Murphy, acting secretary of the Pennsylvania Department of Health, said: “There is no evidence that carcinomas in fish present any health hazard to humans. However, people should avoid consuming fish that have visible signs of sores and lesions.”

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