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Story highlights

Lab tests confirm the fish caught in the Susquehanna River had a malignant tumor

Officials are worried about the health of the river's smallmouth bass population

(CNN) —  

It’s a catch that would make any angler gasp – and not with pride.

A smallmouth bass that was pulled out of the Susquehanna River in Pennsylvania had a large cancerous tumor protruding from its jaw.

The fish was caught back in November, northwest of Harrisburg, and the Pennsylvania Fish and Boat Commission announced this week that independent laboratory tests had confirmed that the tumor was malignant – an unusual and worrisome development.

“Cancerous growths and tumors on fish are extremely rare in Pennsylvania and throughout the U.S., but they do occur,” the commission said in a statement, noting that this was the only documented case of a tumor found on a smallmouth bass in Pennsylvania.

Fishery at risk

Officials said the discovery, although a one-off at this stage, tapped into broader concerns about the health of fish in the Susquehanna.

“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,” said John Arway, the executive director of the commission.

“If we do not act to address the water quality issues in the Susquehanna River, Pennsylvania risks losing what is left of what was once considered a world-class smallmouth bass fishery,” he warned.

Health warning over fish with sores, lesions

The commission said it is working with state and federal agencies, as well as other organizations, to try to get to the bottom of what’s affecting the smallmouth bass in the middle Susquehanna and lower Juniata rivers.

Dr. Karen Murphy, the acting secretary of the Pennsylvania Department of Health, said there was no evidence that cancerous growths in fish are a health hazard to humans. But she warned that people should avoid eating “fish that have visible signs of sores and lesions.”

Arway said it was up to individual anglers to decide whether to eat the fish they catch. But he noted that catch-and-release regulations for smallmouth bass are in effect for a 98-mile stretch of the Susquehanna, including the area where the cancerous fish was caught.