Pennsylvania Studies Blotchy Bass

The Express, Study analyzes blotchy bass syndrome in Commonwealth, and its cause

During a public meeting with the Pennsylvania Fish and Boat Commission on Tuesday, Jan. 7, the prevalence of blotchy bass syndrome within smallmouth bass in the Susquehanna and Juniata rivers was brought up.

Blotchy bass syndrome is hyper-pigmented melanistic skin lesions, which was first documented in the 1980s in the Hudson River in New York, and was first seen in Pennsylvania in 1986.

While it has been observed since 1986 in the Commonwealth, committee member Geoff Smith who gave the presentation regarding the syndrome noted that it was not something that came up locally until the 2010s.

 

“It really came to prominence locally in 2012 and it kind of set off the media attention with young-of-year smallmouth bass mortality,” Smith said. “We added it to our study of fish heal analyses we did in the field and (are) keeping track of it to better understand what was going on.”

At that time, contaminants to various issues was blamed for the cause, but a wide range of environmental and fish health analyses was already in place. According to pathology, aggregation of melanocytes in the upper two layers of the skin was to blame. It was non-cancerous and didn’t appear harmful, but it was unknown as to why. “When we requested funding, it didn’t allow us to look specifically at this, so we linked it into other studies and used existing funding,” Smith said.

 

Water quality and temperature were issues that were brought up to a cause, and an experiment was conducted alongside Lock Haven University to take wild fish and move them to a hatchery setting. It removed the water quality element. It helped to see whether that would make the blotches go away or not. “We had fish that lost color and some that gained color. It was our first suggestion that the condition itself was transmissible. It was a disease, which was something we did not expect,” Smith said.

USGS started looking at affected and unaffected tissues, affected tissues had viral particles. Further analysis saw they were from a class known as adomaviruses, something that was relatively new in North America according to Smith during his presentation.

There was a slightly different virus in largemouth bass.

This is the first I've heard of it. If I caught a bass like that, Smallmouth, Largemouth, or Striped, I would just assume it was it was a genetic or developmental fluke.