The Daily Item, Sunbury, PA

News

November 17, 2013

Susquehanna River bass show spike in melanosis

SUNBURY — Recent sampling of adult smallmouth bass on the West Branch of the Susquehanna River has shown an high prevalence of melanosis, according to a Pennsylvania Fish and Boat Commission biologist.

“We noticed it in a few of our sampling locations,” Geoffrey Smith said. “We were out almost every night over the last two months and once we started to see (fish with melanosis), we saw it in almost every survey.”

Smith could not provide information on the cause of the melanosis, the abnormal or excessive production of melanin in the skin or other tissue.

Pathologists from the U.S. Geological Survey and U.S. Fish and Wildlife Service who examined the fish tissues agreed that the smallmouth had melanosis, Smith said.

“As far as a cause, I am not certain there has been any movement on that front.”

The concern is whether the melanosis represents melanoma, which would be skin cancer in wild fish.

“If it does,” said William Yingling, a retired physician and avid fisherman from Freeburg, “we need to know why they have cancer. We really need to know why so many wild fish in the Susquehanna have begun showing up with these black spots in large numbers since March 2010, almost four years ago.”

Yingling said he has fished the Susquehanna watershed since he was a teenager and never saw the condition in smallmouth bass until 2010.

“I fish now exclusively between Winfield and Port Trevorton,” Yingling said. “Twenty to 25 percent of the smallmouth bass I catch over 15 inches in length, older fish, have some degree of pigmentation.”

Smith, the biologist, did not say how many smallmouth were studied or what techniques were used to examine the tissues.

“We just submitted some more fish for analysis last week to continue to document the condition and keep an eye on the pathology to see if anything is changing,” Smith said.

Four different sets of tissue are being analyzed, those from spring 2012, fall 2012, and this spring and fall, Smith said.

“I have not heard about the fish from spring 2013 yet, but that is a much larger sample size so there is likely more information there than in the others,” Smith said.

Different types of environmental data have been collected in the watershed in 2013 for varied efforts, Smith said. The U.S. Geological Survey and state Department of Environmental Protection have sampled sediment and water contaminants throughout the basin in 2013 as part of studies related to smallmouth bass investigations, he said.

Sample collection is ending for 2013. Data will be examined over the winter, Smith said.

“With all the different, yet cooperative, work going on during 2013,” Smith said, “this was a heavily studied stretch of river.”

Yingling claims Smith did not use the newest staining techniques for the diagnosis of melanoma.

“It can be very difficult to differentiate between benign melanin deposits and malignant melanoma,” he said.

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