This story originally was watching Yale Environment 360 and is part of climate desk Cooperation.
“Thousands of sea lampreys are being channeled upstream [on the Connecticut River] each year. This is a predator that has wiped out the Great Lakes lake trout fishery. [Lampreys] literally suck the life out of their host fish, namely small fish like trout and salmon. The fish ladders should be used to reduce lamprey.” So edited Eagle Tribune of Lawrence, Massachusetts on December 15, 2002.
If that’s true, why is this spring Trout Unlimited — the nation’s leading advocate for trout and salmon — supporting the city of Wilton, Connecticut, and an environmental group called Save the Sound in a project that will restore 10 miles of sea lamprey spawning habitat on the Norwalk River, which empties into the Long Island Sound?
Why will this summer be the first major returnees of stored Pacific lampreys – a species similar to sea lampreys – to scale specially designed lamprey ramps on Columbia River dams and surge into historic spawning habitats in Oregon, Washington and Idaho?
And why will the Connecticut River Conservancy, Fort River Watershed Association and Biocitizen Environmental School rescue stranded sea lamprey larvae when the sewer at Turners Falls on the Connecticut River is drained in September?
The answer is ecological awakening – the gradual realization that if all of nature is good, no part can be bad. In their natural habitat, sea lampreys are key species that support vast aquatic and terrestrial ecosystems. They provide food for insects, crabs, fish, turtles, mink, otters, vultures, herons, loons, ospreys, eagles and hundreds of other predators and scavengers. Lamprey larvae embedded in the creek bed maintain the water quality by filter feeding; and they attract spawning adults from the sea by releasing pheromones. As adults die after spawning, they infuse sterile upper reaches with nutrients from the sea. When sea lampreys build their communal nests, they remove silt from the river bottom and provide spawning habitats for myriad native fish, particularly trout and salmon.
Environmental consultant Stephen Gephard, Connecticut’s former anadrome fish chief, calls lampreys “environmental engineers” who are as important to native ecosystems as beavers.
Sea lampreys, our oldest at around 340 million years, rely on cold, free-flowing fresh water for spawning. They are boneless, jawless, eel-like fish with fleshy fins. They suck bodily fluids from other fish via toothed suction discs. Both sea lampreys and Pacific lampreys are widely vilified because they are perceived as “ugly” and because sea lampreys decimated native fish in the upper Great Lakes when they were accessed via man-made canals, most likely the Welland Canal, which bypassed Niagara falls obtained in these waters. Once there, they nearly wiped out valuable commercial and sport fisheries for lake trout (the largest species of char, not true trout like rainbow, cutthroat, and brown).
By the 1960s, non-native sea lampreys had reduced the annual commercial catch of lake trout in the upper Great Lakes from about 15 million pounds to half a million pounds. In 1955, Canada and the United States created the Great Lakes Fisheries Commission, which controls lampreys with barriers, traps, and a remarkably selective larval venom called TFM. Lamprey control costs $15 to $20 million a year; and without them, sustained recovery of lake trout would be impossible and populations of all other sport fish would collapse.