The Trouble with Cormorants
They eat gamefish, destroy habitat, and pollute waters. Are these birds really "an environmental success story?"
In the epic poem Paradise Lost, the devil sat like a cormorant on the Tree of Life, ready to despoil the Garden of Eden. It’s an analogy that is still apt today, as burgeoning populations of double-crested cormorants are being demonized for everything from laying waste to once-verdant nesting islands to ravaging valuable fisheries.
From the Deep South to New England, anglers in particular believe the one to two pounds of fish that cormorants eat each day come at their expense. But perhaps nowhere are the big, black, migratory water birds more reviled than in the Great Lakes, where cormorants nest in dense colonies on guano-caked islands and their population has grown from a handful 30 years ago to several hundred thousand today.
“They’re the bird from hell,” says New York fishing guide Tony Buffa. “They deplete our fisheries. They push out more desirable birds. And they spread disease wherever they congregate because they produce so much waste.” The U.S. Fish and Wildlife Service (FWS), however, maintains cormorants have only a minor impact on fish populations, and that they are an environmental success story. Pollution, the pesticide DDT, and persecution by humans nearly wiped out cormorants on the Great Lakes in the 1960s. But that changed in the early 1970s, when the Clean Water Act became law, DDT was banned, and cormorants became federally protected under a migratory bird treaty signed with Mexico.
On Lake Ontario, for example, only about 10 nesting pairs remained by 1972. Last year, biologists counted 18,831 nests and estimated the lakewide cormorant population at nearly 100,000, with about 25,000 crowded onto 56-acre Little Galloo Island in New York. Cormorants have also spilled over onto other nearby waters, notably Lakes Champlain and Oneida, and biologists say the spread of new colonies is almost inevitable.
Federal biologists note that cormorants rarely take more than 5 percent of the number of fish caught by anglers, but recent studies show that cormorants are adversely impacting some fisheries. Cormorants have been linked with a drop in Oneida Lake’s walleye fishery, and a study released in December concluded that they have contributed to a sharp decline in smallmouth bass in Lake Ontario, where cormorants ate an estimated 87.5 million fish last year, including 1.3 million smallmouth bass averaging 7.9 inches.
“These studies show cormorants are having a significant impact on warm-water fish populations,” said John Cahill, commissioner of the New York Department of Environmental Conservation, which spearheaded the study. “It is now clear that some type of management action will be needed” to reduce their impact on fish.
That is something many anglers have been advocating for years, but their calls for cormorant control have been coolly received by federal officials. Frustration on both sides boiled over last July when about 1,000 cormorants were illegally shot on Little Galloo Island, further polarizing the issue and drawing the condemnation of many environmental groups.
Proponents of control have found supporters in Congress, notably Representatives John McHugh (R-NY) and Collin Peterson (D-MN), who are working on legislation that would modify treaty obligations and allow cormorants to be hunted. For its part, the FWS plans to complete a cormorant population management plan, and last year it issued a depredation order that allows catfish farmers in the South and baitfish growers in Minnesota to shoot pillaging cormorants. Yet that is little consolation for fishing guides like Buffa, who have watched their business dwindle as cormorants have flourished.
“We manage sport fishing for humans, so don’t tell me it’s not a form of aquaculture, like catfish farms,” he says. “They both come down to dollars and cents.”