How Did Sea Lamprey Get Into the Great Lakes?
The sea lamprey, a parasitic fish native to the Atlantic Ocean, invaded the Great Lakes primarily through the Welland Canal, a critical waterway circumventing Niagara Falls. This artificial bypass, initially built in 1829 and subsequently deepened and improved, provided a route for the lamprey to bypass the natural barrier that had previously confined them to the Atlantic.
The Unwanted Intruder: Sea Lamprey’s Journey West
The sea lamprey’s arrival in the Great Lakes is a cautionary tale of unintended consequences arising from infrastructure development. While the Welland Canal facilitated commerce and transportation, it inadvertently opened a pathway for an invasive species with devastating effects on the native ecosystem.
The Welland Canal: An Open Door
Prior to the construction of the Welland Canal, the formidable Niagara Falls presented an insurmountable obstacle to upstream migration for sea lampreys. The canal, designed to allow ships to navigate between Lake Ontario and Lake Erie, effectively neutralized this barrier. The first confirmed sighting of sea lamprey in Lake Ontario occurred in the 1830s shortly after the canal’s initial development. It took decades for them to make their way to the other Great Lakes.
Gradual Expansion and Explosive Growth
While the initial invasion of Lake Ontario was relatively slow, subsequent expansions and improvements to the Welland Canal, particularly in the early 20th century, greatly enhanced the lamprey’s ability to spread. By the 1920s, sea lampreys had established themselves in Lake Erie. They then progressively moved into Lakes Huron, Michigan, and Superior, culminating in a population explosion that decimated native fish populations. The peak of the lamprey infestation occurred in the 1940s and 1950s, causing immense damage to the Great Lakes fisheries.
The Devastating Impact on the Great Lakes Ecosystem
The arrival of sea lampreys had a profound and detrimental impact on the Great Lakes ecosystem. As parasitic feeders, they attach to fish, rasp through their scales and skin, and consume blood and body fluids. This often results in the death of the host fish.
Predatory Behavior and Prey Selection
Sea lampreys prefer large-bodied fish species, including lake trout, whitefish, and salmon. These fish were crucial components of the Great Lakes food web and commercially important to the region’s fishing industry. The lamprey’s relentless predation led to dramatic declines in these populations, disrupting the ecological balance and causing significant economic losses.
Disruption of the Food Web
The decline of apex predators like lake trout had cascading effects throughout the food web. This disruption allowed populations of smaller fish, such as alewives (another invasive species), to proliferate. The altered ecosystem became less resilient and more susceptible to further invasions.
FAQs: Deepening Your Understanding of Sea Lamprey
Here are some frequently asked questions about sea lamprey and their impact on the Great Lakes:
FAQ 1: What exactly is a sea lamprey?
A sea lamprey (Petromyzon marinus) is a jawless fish native to the Atlantic Ocean. It has an eel-like body, lacks paired fins, and possesses a suction cup mouth armed with rows of teeth. Unlike most fish, sea lampreys have no bony skeleton; their support structure is composed of cartilage. As adults, they are parasitic, feeding on the blood and body fluids of other fish.
FAQ 2: How long does a sea lamprey live?
The lifespan of a sea lamprey is typically 6 to 10 years. Their life cycle includes a larval stage (ammocoete), a metamorphic stage, a parasitic adult stage, and a spawning stage.
FAQ 3: How many fish can a single sea lamprey kill?
An adult sea lamprey can kill up to 40 pounds of fish during its parasitic feeding phase, which typically lasts for 12-18 months.
FAQ 4: Are sea lamprey still a problem in the Great Lakes?
Yes, sea lamprey remain a significant threat to the Great Lakes ecosystem. While control measures have significantly reduced their populations, they have not been eradicated. Ongoing control efforts are essential to prevent a resurgence.
FAQ 5: What methods are used to control sea lamprey populations?
The primary control method involves the use of a lampricide called TFM (3-trifluoromethyl-4-nitrophenol), which selectively kills sea lamprey larvae in streams and rivers where they spawn. Other control methods include barriers to prevent upstream migration and the use of pheromones to attract lampreys to traps.
FAQ 6: How effective is the lampricide TFM?
TFM is highly effective at killing sea lamprey larvae at specific concentrations. It is carefully applied to minimize harm to non-target species. The Great Lakes Fishery Commission (GLFC) continuously monitors the effectiveness of TFM and researches alternative control methods.
FAQ 7: Are there any natural predators of sea lamprey in the Great Lakes?
Unfortunately, there are very few effective natural predators of adult sea lamprey in the Great Lakes. Native fish species have not evolved to effectively prey on them. Some birds and larger fish may occasionally consume lampreys, but their impact on lamprey populations is minimal.
FAQ 8: How much money is spent each year on sea lamprey control?
The Great Lakes Fishery Commission spends millions of dollars annually on sea lamprey control efforts. This investment is considered crucial to protect the Great Lakes fisheries and ecosystem.
FAQ 9: What happens if sea lamprey control efforts are stopped?
If control efforts were stopped, sea lamprey populations would likely rebound dramatically, leading to a collapse of the Great Lakes fisheries and severe ecological damage. The cost of inaction would far outweigh the cost of continued control.
FAQ 10: What is the role of the Great Lakes Fishery Commission in sea lamprey control?
The Great Lakes Fishery Commission (GLFC) is an international organization responsible for coordinating fisheries research, management, and sea lamprey control in the Great Lakes. The GLFC plays a vital role in setting priorities, funding research, and implementing control programs.
FAQ 11: How can I help in the fight against sea lamprey?
You can support organizations like the Great Lakes Fishery Commission through donations and by advocating for continued funding for sea lamprey control programs. You can also learn more about invasive species and take steps to prevent their spread, such as cleaning your boat and fishing gear after each use. Educating others about the threat posed by invasive species is also crucial.
FAQ 12: Are there any potential future solutions being explored to control sea lamprey?
Researchers are actively exploring alternative control methods, including the use of pheromones to disrupt lamprey spawning behavior, genetic control strategies, and improved barrier technology. These innovative approaches hold promise for more sustainable and effective long-term control. These solutions are still being developed and perfected before widespread implementation.
A Constant Vigil: Protecting the Great Lakes
The story of the sea lamprey in the Great Lakes serves as a stark reminder of the interconnectedness of ecosystems and the potential consequences of human actions. While the lamprey’s invasion was a historical accident, the ongoing fight to control their populations requires constant vigilance and innovation. The continued health and prosperity of the Great Lakes ecosystem depend on it.