A virus that can cause disease and death in largemouth bass has been found in otherwise healthy northern snakeheads taken from two Virginia waterways. According to the U.S. Geological Survey (USGS), the finding raises the possibility that northern snakeheads could be carriers of the pathogen, capable of transmitting it to other fish in the Chesapeake Bay.
The pathogen, known as the largemouth bass virus, has been found in bass, sunfish and other members of the freshwater sunfish family, but largemouth bass are the only fish known to develop disease from it.
The largemouth bass virus appears to attack the swim bladder, causing fish to lose their balance and float near the surface of the water. According to the Virginia Department of Game and Inland Fisheries, the virus has been found in waters across the state, but its impacts are often short-lived and largemouth bass can build up resistance to the disease.
While the pathogen doesn’t seem to affect the health of northern snakeheads, the habitat of this invasive fish often overlaps with that of largemouth bass, which may favor transmission of the virus.
The northern snakehead – an invasive fish native to Asia – has been discovered for the first time in several Maryland and Delaware rivers that flow to the Chesapeake Bay.
This month, a team with the Smithsonian Environmental Research Center found a mature, egg-bearing snakehead in the Rhode River, just south of Annapolis. It was the first snakehead ever found in the Rhode River.
After the discovery of the Rhode River snakehead, officials with the Maryland Department of Natural Resources (DNR) confirmed that another snakehead had been found in the Northeast River in Cecil County this spring.
Also this month, a Delaware angler caught a snakehead in Marshyhope Creek, a tributary of the Nanticoke River. According to the Delaware Department of Natural Resources and Environmental Control (DNREC), this was the second snakehead found in the Nanticoke region. Last fall, DNREC staff found a snakehead in Broad Creek, near Laurel.
The northern snakehead was first discovered in the Bay watershed in a pond in Crofton, Maryland, in 2002. Since then, it has become established in the Potomac River and several of its tributaries in Maryland and Virginia. Snakeheads have the potential to be invasive because they breed rapidly and prey on native fish.
Snakeheads are freshwater fish, so the Bay’s brackish waters usually prevent them from leaving the Potomac River. But scientists believe it is possible that unusually low salinity in the Bay this summer allowed snakeheads to travel to new rivers.
It is illegal to move, possess or release snakeheads in Maryland and Delaware. It is also illegal to transport snakeheads across state lines without a federal permit. If you catch a northern snakehead in Maryland or Virginia, you are required to kill it. These laws are intended to help prevent this potentially invasive fish from spreading.
For more information about snakeheads, visit Maryland DNR’s website.