Sea Lampreys: A Persistent Threat to the Great Lakes
Invasive Bloodsuckers
Sea lampreys, parasitic fish native to the Atlantic Ocean, have become a major threat to the Great Lakes ecosystem. They were first introduced to the lakes in the 1800s through shipping canals and have since spread throughout the entire system.
Destructive Impacts
Sea lampreys attach to fish using their suction cup mouths and rasp away at their flesh with their sharp tongues, feeding on their blood and body fluids. A single sea lamprey can kill up to 40 pounds of fish per year. Their voracious feeding habits have devastated fish populations in the Great Lakes, particularly trout and whitefish.
Population Control Challenges
Since 1958, the Great Lakes Fishery Commission has implemented a dedicated control program to combat the sea lamprey population. Lampricide, a pesticide specifically designed to target sea lamprey larvae, has been used along with traps and barriers to reduce their numbers. These efforts have successfully reduced the sea lamprey population by 90-95% in the Great Lakes basin.
Covid-19 Disruption
Travel restrictions during the Covid-19 pandemic hindered the application of lampricide and other control measures, leading to a resurgence in the sea lamprey population. This increase became evident in 2022 due to the two-year lag in the animals’ spawning cycle.
Ongoing Control Efforts
Despite the challenges posed by Covid-19, the Great Lakes Fishery Commission has resumed its aggressive control program in 2022 and 2023. They are hopeful that the recent population spike was a temporary blip and that the control measures will continue to keep the sea lamprey population in check.
Ecological Role in Native Range
In their native Atlantic Ocean habitat, sea lampreys play a beneficial role as keystone species and ecosystem engineers. They support both aquatic and terrestrial ecosystems by providing food for other creatures and creating spawning habitats for fish. Their larvae also help maintain water quality.
Evolutionary Resilience
Sea lampreys have existed on Earth for over 340 million years and have survived four major extinction events. They have remained largely unchanged since they evolved, demonstrating their remarkable evolutionary resilience.
Historical Spread in the Great Lakes
Sea lampreys were first documented in the Great Lakes in 1835 in Lake Ontario. Niagara Falls initially served as a natural barrier to their spread, but improvements to the Welland Canal in 1938 allowed them to bypass the falls and invade the entire system. By the 1960s, sea lampreys had devastated the upper Great Lakes’ trout fishery, reducing the take of lake trout from 15 million pounds to just half a million pounds.
Economic Impacts
The decline in fish populations due to sea lampreys has had a significant economic impact on the Great Lakes fishing industry. The rebuilding of the fishery through control efforts has led to a resurgence in the fishing economy, benefiting both commercial and recreational fishers.
Continuing Vigilance
While the Great Lakes Fishery Commission has made significant progress in controlling the sea lamprey population, continued vigilance is necessary to prevent future outbreaks. The commission is committed to monitoring the population and implementing adaptive control measures as needed to protect the Great Lakes ecosystem and its valuable fisheries.