Public Urged Not to Disturb Spawning CT River Sea Lamprey

Photo by USFWS midwest, via

The Vermont Fish & Wildlife Department is reminding anglers and the general public to avoid disturbing spawning sea lamprey that may currently be found in the Connecticut River and several of its tributaries. All of which begs two questions: have you ever seen a sea lamprey, and if so, why on earth would you want to disturb one?

All kidding aside, sea lamprey play a vital role in the aquatic ecosystem, says Lael Will, a fisheries biologist with Vermont Fish & Wildlife. “Vermont is also home to a separate population of non-native sea lamprey that are actively controlled as a nuisance species in Lake Champlain. Confusion can arise over the differing management goals for these two populations of sea lamprey. We believe it’s important to highlight and contrast the conservation value of Connecticut River sea lamprey, educate the public, and encourage folks to do their part to protect this important population of fish.”

Each spring, sea lamprey spawn in the main stem of the Connecticut River as far upstream as Wilder Dam, as well as in many of its tributaries, including the West, Williams, Black and White Rivers. Upon returning to freshwater to spawn, adult sea lamprey are non-parasitic and die shortly after spawning, and their carcasses play a critical role in cycling important marine nutrients into freshwater ecosystems.

In the Connecticut River, larval lamprey live in freshwater the first few years of their lives, remaining sedentary and burrowed in sandy substrate while filtering detritus from the water for nutrition. At around 5 years of age, they transform into juveniles and emigrate to the ocean where they attach to and feed on fish as parasites. In turn, lampreys are a food source in the estuarine and marine environment for a number of fish, marine mammals, and bird species.

While existing for over 350 million years in the Atlantic, anadromous sea lamprey have co-evolved with their oceanic hosts and are considered to be in balance.

The species is currently managed under the Connecticut River Atlantic Salmon Commission, which includes four state agencies, two federal agencies and representatives of the general public. Among other efforts, Vermont Fish & Wildlife has been working to improve fish passage facilities within the Connecticut River drainage to enable native sea lamprey to successfully complete their migrations to spawning habitat.

“In 2016, the dams at Vernon and Bellows Falls passed about 5,500 and 1,600 sea lamprey respectively, and our goal is to continue to improve fish passage and flows on the river to not only help lamprey spawning, but to support all migrating fish species,” Will said.

Learn more about Vermont Fish & Wildlife’s various fisheries management programs.