Vampire Fish Resurge in Great Lakes Post Pandemic

According to The Wall Street Journal, fishery managers have observed an increase in the population of the parasitic sea lamprey, aka Vampire Fish, across the Great Lakes, startling some anglers.

The Great Lakes, already a significant hub for international shipping, recreation, and fishing, face a renewed threat from an ancient adversary - the sea lamprey. This parasitic fish, often dubbed the "Vampire Fish," known for its propensity to latch onto and drain the life fluids of other fish, is resurging in numbers post-pandemic.

Sea lampreys (Petromyzon marinus) are an Atlantic Ocean native species with a lineage tracing back over 340 million years. Sea lampreys have remained unchanged through four significant extinction events, outliving many other species. Sea lampreys, although resembling eels, are distinct due to their unique skeletal structure of cartilage and a horrifying oral apparatus: a large sucking disk filled with sharp, horn-shaped teeth surrounding a razor-sharp rasping tongue.

Lake trout in a tank with sea lamprey attached. Credit: M. Gaden, GLFC

A sea lamprey's method of feeding is reminiscent of nightmarish vampire tales. They secure themselves onto their prey with their suction cup-like mouth, rasping through the fish's scales and skin with their sharp tongue. They feed off the host's body fluids by secreting an enzyme that prevents blood clotting, akin to the feeding mechanism of a leech.

In their native Atlantic Ocean habitat, sea lampreys have evolved alongside other fish, becoming parasites that typically do not kill their hosts. However, sea lampreys are far more lethal in the Great Lakes, where this co-evolutionary relationship is absent. Each sea lamprey can decimate up to 40 pounds of fish during their 12-18 month feeding period.

In the Great Lakes, fish often succumb to sea lamprey parasitism, dying directly from the attack or subsequent infections. Even the survivors show signs of weight loss and declining overall health. Predominantly, sea lampreys prey on large fish species found in the Great Lakes, such as lake trout, brown trout, lake sturgeon, lake whitefish, ciscoes, burbot, walleye, catfish, and several types of salmon.

Image: GLFC

The first recorded sighting of a sea lamprey in the Great Lakes was in Lake Ontario in 1835. Initially, the natural barrier of Niagara Falls restricted their spread. However, improvements in the late 1800s and early 1900s to the Welland Canal, bypassing Niagara Falls, granted sea lampreys access to the other Great Lakes. In just over a decade, they spread across all five Great Lakes, establishing a significant presence due to the availability of spawning and larval habitats, the abundance of host fish, a lack of predators, and their high reproductive potential.

The sea lamprey invasion in the Great Lakes has had catastrophic consequences on the local fishery. Prior to their invasion, annual harvesting of lake trout from the upper Great Lakes was about 15 million pounds. But by the early 1960s, this number dropped to approximately 300,000 pounds, about 2% of the original amount. Sea lampreys were responsible for the loss of hundreds of thousands of jobs, reduced property values, and forever altered the way of life for millions of people around the Great Lakes.

Sea lamprey control agents conduct secondary lampricide treatments. Credit: T. Lawrence, GLFC

In response to the devastation, the U.S. and Canada established the Great Lakes Fishery Commission in 1955 to regulate the sea lamprey population. The Commission implements an integrated control program focusing on the sea lamprey's vulnerability during their congregated phases in the Great Lakes tributaries. Using specific pesticides (lampricides), barriers, and traps, the Commission has effectively reduced the sea lamprey population by 90% in most Great Lakes areas.

Additionally, the Commission employs innovative methods to combat the sea lamprey infestation. By capitalizing on the sea lamprey's acute sense of smell, they manipulate pheromones and alarm cues to divert the parasites into traps or unfavorable spawning habitats, simultaneously repelling them from productive spawning grounds.

With this unexpected resurgence, it's evident that the battle with the sea lamprey demonstrates nature's resilience and unpredictability and that the work of conservation is never truly done.

Source:

Great Lakes Fishery Commission