This story originally appeared in Yale Environment 360 and is part of climatic table collaboration.
“Thousands of sea lampreys pass upriver [on the Connecticut River] every year. This is a predator that wiped out the Great Lakes lake trout fishery. [Lampreys] they literally suck the life out of their host fish, namely small-scale fish like trout and salmon. Fish scales should be used to decrease lamprey.” Thus editorialized the Eagle Tribune Lawrence, Massachusetts, on December 15, 2002.
If that’s true, why this spring is Trout Unlimited, the nation’s leading advocate for trout and salmon, helping the town of Wilton, Connecticut, and an environmental group called Save the Sound on a project that will restore 10 miles of sea lamprey spawning habitat in the Norwalk River, which empties into Long Island Sound?
Why will the first large returns of populated Pacific lampreys, a species similar to sea lampreys, scale specially designed lamprey ramps at Columbia River dams and into historic spawning habitat in Oregon, Washington and Idaho this summer?
And why, when the channel at Turners Falls on the Connecticut River opens in September, will the Connecticut River Conservancy, Fort River Watershed Association, and Biocitizen Environmental School rescue stranded sea lamprey larvae?
The answer is the ecological awakening: the gradual realization that if all of nature is good, no part of it can be bad. In their native habitat, sea lampreys are “keystone species” supporting vast aquatic and terrestrial ecosystems. They provide food for insects, crayfish, fish, turtles, mink, otters, vultures, herons, loons, ospreys, eagles, and hundreds of other predators and scavengers. Lamprey larvae, embedded in the stream bed, maintain water quality by filter feeding; and attract reproductive adults from the sea by releasing pheromones. Because the adults die after spawning, they infuse the barren headwaters with nutrients from the sea. When sea lampreys build their communal nests, they clean sediment from the river bottom, providing spawning habitat for countless native fish, especially trout and salmon.
Environmental consultant Stephen Gephard, a former Connecticut anadromous fish chief, calls lampreys “environmental engineers” as important to native ecosystems as beavers.
Sea lampreys, our oldest by some 340 million years, depend on cold, free-flowing freshwater for spawning. They are boneless, jawless, eel-like fish with fleshy fins. They extract body fluids from other fish through sucking discs with teeth. Both sea lampreys and Pacific lampreys are widely reviled because they are perceived as “ugly” and because sea lampreys decimated native fish in the upper Great Lakes when they accessed those waters through human-built channels. , most likely the Welland Canal overlooking Niagara. falls. 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 established the Great Lakes Fishery Commission, which controls lampreys with booms, traps, and a remarkably selective larval poison called TFM. Lamprey control costs between $15 and $20 million a year; and without it, the ongoing recovery of lake trout would be impossible, and populations of all other sport fish would collapse.
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