The U.S. Fish and Wildlife Service (Service) is helping to lead a battle against a destructive aquatic enemy threatening both native life in the Great Lakes and the livelihoods of people dependent on the lakes.
A primitive parasitic fish, the sea lamprey has been wreaking havoc in the Great Lakes since the 1940s. Using their powerful suction mouth and tiny sharp teeth, sea lamprey feed on native fishes such as sturgeon, trout, salmon and perch depleting populations of these species and taking a significant bite out of the multi-billion dollar Great Lakes fishery industry.
Service biologists are working with other federal agencies in the United States and Canada joined by sportsmen groups, tribes and conservation groups from both nations to rid the Great Lakes of sea lamprey once and for all. Under the auspices of the Great Lakes Fishery Commission, the Service, through its Sea Lamprey Control offices in Marquette and Ludington, Michigan, is seeking a safe and effective way to manage this exotic aquatic pest.
The foundation of success in maintaining healthy fisheries both commercial and recreational--in the Great Lakes is most certainly sea lamprey eradication, said William Hartwig, the Services regional director in the Great Lakes-Big Rivers region. The $15 to $16 million in funds the Service and its partners share each year for sea lamprey control efforts is well worth it when you consider the Great Lakes fishery is a $4 billion dollar a year industry.
Because the fish and other resources of the five Great Lakes respect natures boundaries, not international ones, the governments of the United States and Canada established the Great Lakes Fishery Commission in 1955 to manage fish in their shared lake system.
Headquartered in Ann Arbor, Michigan, the commission, through its members and working with other partners, conducts research on sustaining Great Lakes fish stocks. The commissions other main task, one that has taken on increasing urgency as native fish populations continue to decline is developing a comprehensive sea lamprey control program to manage this voracious pest.
The Fish and Wildlife Service, whose mission is to conserve, protect and enhance native fish and wildlife and their habitat, is especially concerned with stemming the destruction caused by the non-native sea lamprey.
Sound pest management practices rely on integrated control strategies, so the Great Lakes Fishery Commission has developed and implemented an integrated approach to managing sea lamprey. It involves barriers to block the upstream migration of adults, trapping and removing migrating adults, lampricide applications to destroy larval populations, the release of sterile males to reduce reproduction, and a strong research program that supports new, cutting edge science and alternative control techniques.
The Great Lakes Fishery Commissions integrated strategy for managing sea lampreys has successfully reduced lamprey abundance to levels that allow for a thriving sport and commercial fisheries, said Hartwig. However, sea lampreys remain a threat and continue to cause high death rates among valuable fish stocks in the Great Lakes. The Service is committed to working with our federal, state and private partners to help stop the spread of sea lampreys.
Considered one of the most important fishery resources in the world, the Great Lake Basin provides recreational opportunities to 5 million anglers and supports 75,000 jobs in commercial fishing, tourism, retail and other outdoor-related industries. More than 30 million people live in the Great Lakes Basin, which encompasses eight U.S. states, the Canadian province of Ontario and lands ceded to several Native American tribes.
The first sea lampreys made their way from the North Atlantic Ocean to the lower Great Lakes in the 1800s, slipping through manmade locks and shipping canals. By the 1950s, the non-native sea lampreys had devastated native lake trout populations in the Great Lakes-and had begun attacking other species.
With its large, disk-shaped mouth, tiny sharp teeth and insatiable appetite for the fluids of other fishes, a single aggressive sea lamprey can destroy more than 40 pounds of fish during its 18-month adult life, latching onto its helpless victim and rasping through scales and skin to feed on blood and body fluids.
For more than a century, sea lampreys which have no natural predators continued to multiply in the Great Lakes, leaving devastated commercial and recreational fisheries in their wake. Sea lampreys were a major cause of the collapse of lake trout, whitefish and chub populations during the 1940s and 1950s obliterating a 15 million pound-per-year harvest.
To break the sea lampreys deadly grasp on Great Lakes fisheries, biologists have tried myriad tactics. Their methods have been successful in dramatically reducing sea lamprey numbers in the Great Lakes, but have not completely removed the threat of sea lamprey. The Great Lakes Fisheries Commission is working cooperatively to identify and implement the most successful methods possible to control sea lampreys.
Early efforts to control sea lampreys focused on preventing them from spawning in the hundreds of Great Lakes tributaries they had already invaded, said Gerry Jackson, Assistant Regional Director (ARD) for Fisheries for the Great Lakes-Big Rivers Region.
Biologists constructed mechanical and electric weirs along streams and rivers of the Great Lakes to block adult lampreys from getting to their spawning grounds during spring and summer.
However, floods, logs and other floating debris and loss of electrical power often prevented the weirs from operating properly, allowing adult sea lampreys to make their way upstream and spawn anyway, Jackson said.
He said that as sea lampreys continued to plague the Great Lakes and attack vulnerable species, biologists discovered a selective toxicant, known as TFM, that could be applied to streams to kill sea lampreys while still in their infant or larval stage. Shown to kill sea lampreys without significantly affecting other aquatic species, TFM is still used today. Some 200 out of the 5,747 streams and tributaries of the Great Lakes are regularly treated with TFM.
Since the first stream treatment with TFM in the late 1950s, sea lamprey populations in the Great Lakes have fallen dramatically. TFM remains the primary means of controlling sea lampreys. But it still is not enough.
The newest weapon in biologists arsenal against sea lampreys is sterilization. Beginning a decade ago, biologists started capturing sea lampreys in stream traps on Lake Superior, injecting them with a sterilant, tagging and releasing them. These sterilized males have completed their parasitic phase and will die after spawning.
The sterile males aggressively compete with unsterilized males to mate with females often winning the battle, said Jackson. Those females that mate with sterilized males waste their reproductive potential. Biologists have demonstrated that release of sterilized males reduces the number of lampreys produced.
Preliminary assessment of the sterilization and release program shows that it has been successful so far; combined with trapping, chemical control and sterilization has reduced lamprey populations in the St. Marys River the largest single source of lamprey production in the Great Lakes by up to 90 percent.
The Sea Lamprey Management Program and the Great Lakes Fishery Commission are extremely important parts of our efforts to conserve the invaluable natural resources of the Great Lakes, said Regional Director Hartwig. Together with our partners the Fish and Wildlife Service will continue to protect these important resources and ensure a healthy future for Great Lakes anglers.
