The sea lamprey invaded the Great Lakes in the mid-twentieth century, devastating Great Lakes fisheries. Since that time, scientists have developed methods to bring sea lamprey under control such that fisheries have rebounded.
Today, sea lamprey control efforts continue to sustain healthy freshwater ecosystems, protect valuable fisheries, and provide economic benefits to millions living throughout the Great Lakes region. Consequently, the development of safe and cost effectively sea lamprey control is critical to the natural resource agencies of the eight Great Lakes states, the Great Lakes Fishery Commission, and the U.S. Fish and Wildlife Service. Despite being one of the most successfully controlled invasive species in the world, sea lamprey in the Great Lakes destroy about 12 million pounds of fish every year, threatening still a fishery valued at $7 billion annually. The USGS Great Lakes Science Center (GLSC) continues to improve and develop new control technologies for sea lamprey.
Fatal attraction: 3kPZS
The sea lamprey mating pheromone, called 3kPZS, is naturally released by male sea lamprey and attracts female sea lamprey. The pheromone has been isolated, identified, and synthesized in labs and is now being used in minute amounts (milligrams) to increase catches of sea lamprey in traps. In some streams, it has increased catch rates by as much as 35%. In 2016, 3kPZS was registered as the first ever vertebrate pheromone biopesticide with the U.S. Environmental Protection Agency and Health Canada. In 2017 and 2018, GLSC researchers are optimizing application rates of 3kPZS across the Great Lakes basin to yield large and consistent catches of sea lamprey in traps.
“The Great Lakes Fishery Commission is very excited about this accomplishment,” said Dr. Robert Hecky, chair of the commission. “U.S. EPA registration of the sea lamprey mating pheromone opens the door for use of the pheromone in the commission’s sea lamprey control program, which protects Great Lakes fisheries from destruction caused by invasive sea lampreys.” Dr. Hecky also emphasized the critical role of partners. “This achievement has been many years in the making and could not have occurred without the excellent work of our collaborators at the U.S. Geological Survey, Michigan State University, and Bridge Organics Company.”
Dr. Suzette Kimball, former director of the USGS, praised registration of the sea lamprey mating pheromone as “a milestone for control of invasive species and protection of natural biodiversity.” She further emphasized the significance of this event saying, “Registration is the culmination of great leadership and innovation among the Great Lakes Fishery Commission, the USGS, and our university and private-sector partners. Development of the sea lamprey mating pheromone is exactly the type of cutting-edge research that places each partner at the forefront of science.”
The shocking truth: Electrical guidance
The USGS worked with private industry to develop a system combining a sea lamprey trap with pulsed direct current electricity to guide sea lamprey more efficiently into traps. The system was tested in 2016 and was able to catch up to 75% of tagged sea lamprey in free-flowing streams. Non-target species mortality was rare and the impact on migration of non-target species was minimal.
The system is completely portable, which means it can be deployed in target streams during migration seasons. In addition, annual cost is low: about $4,800 U.S. dollars.
Use of the technology is poised to advance control of sea lamprey in the Great Lakes in combination with other strategies and technologies. It may also prove useful in efforts to restore sea lamprey populations in Europe where the species is a native species in peril. The system may be even more broadly applicable with efforts to control other invasive fishes or restore valued fishes worldwide.
David Ullrich, chair of the Commission stated, “While the concept is not new, the technology has come a long way and our understanding of how to use it properly has improved tremendously, thanks to this research.”
In the next few years the array will be optimized and used to block or remove up to 100% of sea lamprey in a stream, while allowing passage of valued fishes.
The use of pheromone and electrical guidance in sea lamprey trapping efforts represent the next generation of tools to further reduce the impact of invasive sea lamprey on Great Lakes fisheries.