EPA approves pheromone pesticide for invasive lampreys

By: Kevin Bunch | Roseville - Eastpointe Eastsider | Published March 14, 2016

The effort to control invasive sea lampreys in the Great Lakes and their waterways has a new arrow in the quiver following the U.S. Environmental Protection Agency’s approval of a new biopesticide.

The pesticide is a synthesized version of the lamprey’s mating pheromone, which can be used to attract male and female lampreys into traps or unsuitable breeding grounds, according to Great Lakes Fisheries Commission Communications Director Marc Gaden. In nature, larval lampreys emit the pheromone to let adults know that they are in a suitable breeding ground.

It is also the first such pesticide approved for a vertebrate species — a creature with a backbone.

“What scientists hypothesized probably about 15 years ago — at least — was that the lamprey has pheromones unique to it that it gives off that affects mating behavior,” Gaden said. “If we could zero in on what that pheromone is and synthesize it and then use it in the field, we could have a control technique to keep the lamprey population in check.”

Currently, the invasive lampreys — which have infested Great Lakes waters since the 1800s — are controlled using a “lampricide” pesticide that specifically kills that species’ young. Using it has reduced the lamprey population by 90 percent from its peak in the 1950s, when it was responsible for wiping out about 100 million pounds of fish annually.

In comparison, before the lamprey invasion, about 20 million pounds of fish were being commercially harvested annually from the upper Great Lakes, Gaden said. With the lampricide, the invasive species has only been killing about 10 million pounds of fish. Lampreys kill fish by latching onto them and using rows of teeth and a rasping tongue to stab a wound into the fish, sucking out blood.

Scientists have also been damming the entrances to waterways suitable for lamprey spawning, though not all dams or locations are suitable for that effort. Gaden said testing with the mating pheromone has seen a dramatic increase in the number of fish being trapped and removed, and they hope to continue testing it to figure out the best way to utilize it over the coming years.

“They make their nests upstream (in rocky cobbles) and need sandy areas where the larvae bury themselves before going into the open lake,” he said. “If you lure them into a stream without that, even a concrete culvert, they would be wasting energy and spawning potentially in a place they’d never find a mate.”

Gaden added that there is also work being done at Michigan State University researching the “death pheromone” that lampreys give off when they are being attacked and killed. The pheromone drives all other lampreys away from that location, and Gaden thinks it could be used in concert with the mating pheromone to drive lampreys away from suitable spawning grounds and into bad habitats or locations where they can be trapped.

Matt Einhauser, an ecologist with the Clinton River Watershed Council, said that larval sea lampreys have been detected in smaller tributaries of the river where they can survive and avoid predation.

“Very recently, sea lamprey were detected in Paint Creek, which is a tributary to the Clinton River,” Einhauser said in an email. “Last year, they were treated in Paint Creek by the U.S. Fish and Wildlife Service.”

Einhauser did want to clarify that native lampreys are also found in the Clinton River watershed, so not all lampreys found there are invasive.

According to a Michigan Sea Grant fact sheet, sea lampreys tend to be larger than native lampreys — around 1 foot to 2 feet long as adults — with a blue or black color on top and a yellow to brown color on the belly. They also have a separated dorsal fin and caudal, or tail, fin.

The most common native lamprey species in the metro Detroit area are the silver lamprey and northern brook lamprey.

Looking ahead, Gaden said this biopesticide research with lamprey pheromones could be a major breakthrough in battling other invasive species, such as using pheromones to drive Asian carp away from Great Lakes waters.

“This is being done nowhere else in the world. If we can do this successfully and harness the power of pheromones, who knows where this could take us,” Gaden said. “This is really the beginning of something that could be very big in invasive species control.”