Credible reports of snakehead sightings and results from a Maryland Department of Natural Resources and U.S. Fish & Wildlife Service survey indicate that the non-native snakehead species has spread into the C&O Canal
and thereby the Upper Potomac River.
Last fall, anglers reported catching two northern snakeheads between mile marker 19 and 22 in the C&O Canal. Following the reports, biologists from the agencies surveyed about eight miles of the canal between Great Falls and Violettes Lock, and found a seven-inch juvenile snakehead. Subsequently, a park visitor photographed an adult northern snakehead guarding a school of fry in the same section of canal.These discoveries validate concerns that this non-native species could gain a foothold in the non-tidal Potomac River above Great Falls, a site where it had never before been reported.
First discovered in the tidal Potomac River watershed in 2002, the northern snakehead fish is now firmly established in the Patuxent River, and has spread to other fresh and low-salinity tidal waters in Maryland and Virginia.
There are many sources of water exchange between the canal and the Potomac, particularly during flood events, and it is nearly certain that the species has now gained access to the Upper Potomac River.
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