(WFXR) — The Virginia Department of Wildlife Resources (DWR) believes it has found the most likely cause of lesions found on smallmouth bass and other fish earlier this summer on the Jackson River below Covington. DWR biologists think the culprit is a bacterium known as Aeromonas.

The issue first came to light in early June when fishing guides began reporting large numbers of smallmouth bass they were catching had open sores. DWR took fish from the river for testing.

In addition to smallmouth bass, redbreast sunfish and rock bass were also found with the lesions.

After testing at a U.S. Fish and Wildlife lab in Pennsylvania, viruses and parasites were ruled out. The affected fish came back positive for Aeromonas bacteria.

The timing of when the lesions appeared is because it is the end of the spawning season for smallmouth bass. Spawning stresses fish and can make them susceptible to Aeromonas infection.

In severe cases, Aeromonas can cause death. However, there were no fishkills reported in this instance.

As water temperatures rise, Aeromonas concentrations reduce. With fewer fish with lesions being reported on the Jackson River, the issue appears to be resolving itself.

The Jackson River sportfishery is vital, providing a multi-million dollar boost for the Alleghany Highlands region.