MSU’s Wagner Uses ‘Smell’ to Stop Sea Lamprey Invasion
Michael Wagner, MSU AgBioResearch fish ecologist, has been studying sea lamprey in the Great Lakes for over 13 years. Native to the coastal waters of the Atlantic Ocean and found throughout much of southwestern Europe, the sea lamprey is relatively unique among fish. Lacking jaws, paired fins and bone structure, this eel-like creature has remained relatively unchanged for over 340 million years, including at least four major extinction events.
Over the course of their adult lives (between 12 and 18 months), one sea lamprey can kill up to 40 pounds of fish. The sea lamprey was first sighted in the Great Lakes in 1835, in Lake Ontario, where it likely traveled upon the opening of the Erie Canal. In the early 20th century, it spread to Lake Erie through newly improved canals, and soon after, into the remaining three Great Lakes.
Through a grant from the Great Lakes Fishery Commission (GLFC), he has turned his attention toward developing a new style of dam that prevents sea lamprey from traveling to their spawning grounds while preserving the connection between the rivers and lakes.
“One of the great challenges facing ecosystem management in the Great Lakes is there are competing interests in restoration,” Wagner, associate professor in the MSU Department of Fisheries and Wildlife, said. “One is reconnecting rivers with the lakes, and the other is the necessity of blocking lamprey access to a number of rivers, in order to keep their population manageable.”
Providing fish with ways to circumvent dams has been an ongoing challenge in North American fisheries for 100 years, and in Europe for four times as long. The most common passage is a structure called a fish ladder, a series of stepped pools that fish such as salmon and trout can jump up to get past the dam.
Unfortunately, these are an imperfect barrier for sea lamprey. In addition, other fish cannot jump or swim hard enough to pass over the barrier.
Wagner said he realized his team would have to pioneer an entirely new, selective fish passage that could act as a biological filter, keeping out sea lamprey while allowing other species free access. It presented a significant challenge, but one the team was prepared to address.
“Lamprey have two things going for us that allow us to separate them from other fish,” Wagner said, “First, they swim radically differently, by full-body undulation. That means they can do something no other fish can, which is climb a studded ramp. That gives us a physical way to sort them from the rest. Second, they have a very strong antipredator response that’s driven by only one sense – smell.”
Many fish produce an alarm cue, an odor released when their skin is ruptured, warning others of their species downstream of the attack. In most fish, sensing that odor causes them to slow their movement, reduce the amount of time they spend foraging and look for threats.
Sea lamprey, which migrate primarily at night in dark conditions, use smell, which limits their anti-predator options. Instead of slowing down upon detecting the alarm odor, sea lamprey bolt away from it. Wagner and his team constructed a trial fish passage on the Ocqueoc River in the northeast Lower Peninsula.
They divided the fish passage into two channels – one side that allowed fish free movement upstream and the other ending at a studded ramp only sea lamprey could climb. The team released a plume of sea lamprey alarm odor in front of the open side of the passage, hypothesizing that it would drive the lamprey toward the ramp. It did and the rest of the fish continued through the passage unabated.
“We’re trying to do two things no one has ever done before,” Wagner said. “One is creating a fishway that allows fish to travel through at high numbers and diversity, and the other is to create one that excludes a particular undesirable species. It’s the kind of high-risk, high-reward project I love, and we’re seeing good results so far.”
To determine if the device has wider applications for sea lamprey management, it has to be tested at a larger scale. Wagner has joined a team led by the GLFC to design a large selective fish passage facility at the Boardman River’s Union Street Dam site in Traverse City.
Through a nearly $12 million grant from the Great Lakes Restoration Initiative, the facility will be used to test Wagner’s unique approach to blocking invaders while allowing desirable species to pass.
“Controlling invasive species like sea lamprey is a really hard game to win,” Wagner said. “It’s all or nothing. We’re trying to find a means by which we can help reconnect our lakes and rivers without harming our ability to protect them from sea lamprey.”
Bringing the best ideas to the table
Sea lamprey are far from the only invasive species threatening the Great Lakes. Asian carp, a group of four invasive carp species causing ecological problems in the United States, has been another high-profile invader for decades.
While most came to North America as stowaways in ship ballasts, the grass carp was intentionally brought from eastern Asia to control weeds in aquaculture facilities. The grass carp is now found in 45 states.
They were first discovered to be reproducing in Lake Ontario in 2013, and have since been caught in lakes Erie and Michigan. Seth Herbst, an aquatic invasive species coordinator with the Michigan Department of Natural Resources (MDNR), has been monitoring grass carp in the lakes since they were discovered.
“With grass carp, we’re not seeing the same population explosion we’ve seen in other Asian carp species, but it’s still higher than it’s ever been.” Herbst said. “By feeding on plants, they directly modify the habitats of commercially and ecologically critical native fish species.”
Grass carp can consume up to 90 pounds of plant matter daily, but they only digest about half of what they eat. The remainder is expelled back into the water, where it fuels toxic algal blooms. Lake Erie is the epicenter for grass carp in the Great Lakes, a complex environment in which to study and manage any fish population.
“It’s one of the largest bodies of water in the world, not exactly a confined space where you can easily find and remove the fish you’re looking for,” Herbst said. “It involves multiple states and provinces, who all need to make sure their efforts are coordinated.”
To address these challenges, Herbst reached out to Kelly Robinson and Michael Jones, MSU AgBioResearch scientists with the Quantitative Fisheries Center, to come up with a plan. Starting in December 2016, Robinson led a series of structured decision-making workshops over the course of nine months. She guided participants as they broke down the issue and brainstormed ways to tackle it.
“Structured decision-making is a five-step process that helps you divide a decision into discrete parts, work on each of them separately and then put it back together into a cohesive whole,” Robinson, assistant professor in the MSU Department of Fisheries and Wildlife, explained. “It’s a good framework for working through complex issues in a formal manner.”
Structured decision-making begins with identifying the problem, a step that may seem obvious, but when a diverse group of stakeholders comes together, they often have different ideas regarding the specific nature of the problem.
The group then lays out the values, such as economic or social concerns, that are most relevant to the issue. In the third step, they determine objectives, in this case reducing the grass carp population, and in the fourth, they consider how different management techniques might impact those objectives. Finally, the group reevaluates and reprioritizes their objectives in light of the impacts management techniques may have on them.
What has begun to emerge is an adaptive management plan that would provide fisheries managers with a multitude of tools to control grass carp. Examples include modifying the flow of rivers to make them less suitable for spawning and conducting the targeted removal of fish using methods such as bioelectrode fishing.
Concurrent with the workshops, Robinson’s post-doctoral researcher Mark DuFour has worked to create a grass carp population model in Lake Erie capable of simulating both the size and characteristics of the population, as well as the impacts of the various management practices.
“The Great Lakes are such an important resource for so many people. Anything that could damage them is something we all need to take seriously,” Robinson said. “The plans emerging from these workshops could determine the course of grass carp management in the lakes into the future, and protect the industries and natural resources that depend on them.”
- – Excerpted from James Dau via AgBioResearch Website, “Aquatic Invaders: Defending the Great Lakes from invasive species”