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How are Sea Lampreys Controlled

The Great Lakes Fishery Commission works with Fisheries and Oceans Canada, the U.S. Fish and Wildlife Service, and the U.S. Army Corps of Engineers to undertake sea lamprey control. The control program uses several techniques to attack sea lampreys. This effort (known as "sea lamprey control") includes: Lampricides

Granular bayulcide sprayer boat Tributaries harboring larval sea lampreys periodically are treated with lampricides to eliminate or reduce the populations of larvae before recruitment to the lake as parasitic adults.

Currently, the primary method to control sea lampreys uses the lampricide TFM. TFM kills sea lamprey larvae in streams with little or no impact on other fish and wildlife. TFM is not harmful to humans or other mammals at the concentration applied. It is registered as a lampricide with the U.S. Environmental Protection Agency and with Health Canada.

About 175 Great Lakes streams are treated at regular intervals with TFM to kill larval sea lampreys. Despite the success of TFM, it is a costly control method and the commission is seeking to reduce its use by relying on alternative methods (described below). Click here for a map showing tributaries in which sea lampreys have been found.

In recent years the combination of improved analytical and predictive techniques has allowed treatment crews to reduce lampricide concentrations by about 20%.

In areas where TFM is not effective (i.e., the St. Marys River and in lentic areas), a different lampricide-granular Bayluscide-is used. Granular Bayluscide is a time-released lampricide that coats a grain of sand. The lampricide is applied to sea lamprey larval "hot spots" and dissolves above those spots to remove the larvae. Barriers

Low-head lamprey barrier damn at whitefish river

Sea lamprey barriers have been constructed to block the upstream migration of spawning sea lampreys; most barriers allow other fish to pass with minimal disruption. Barriers have reduced or eliminated altogether lampricide treatment on many streams.

The benefits of sea lamprey barriers include:
  • improved passage for non-target species;
  • more efficient control on streams where physical characteristics make lampricide treatment difficult, expensive or ineffective;
  • savings in time, manpower and related costs through a reduction in stream miles requiring periodic lampricide treatment;
  • reduced dependency on lampricides;
  • reduced lampricide purchases in the face of rising costs and potentially limited supply; and
  • reduced quantity of lampricides added to the environment.
Newer barrier designs include velocity barriers that take advantage of the lamprey's poor swimming ability, electrical barriers that repel sea lampreys during the spawning run without risk to other fish or animals, and adjustable-crest barriers which can be inflated during the spawning run and then deflated to allow other fish to pass during the rest of the year.

Trap full of sea lampreys Sea lamprey traps are operated at various locations throughout the Great Lakes, often in association with barriers. Traps are designed to catch lampreys as they travel upstream to spawn. Sea lampreys caught in the traps are used for research.

Today, traps are operated by the U.S. Fish and Wildlife Service, Fisheries and Oceans Canada, and the U.S. Army Corps of Engineers.


A fish biologist demonstrating lamprey assessment Sea lamprey control begins when biologists go into the field and determine which streams contain sea lamprey larvae. This assessment data is then used to help the commission decide which streams to treat for sea lampreys. Assessment of adult spawning populations is also carried out to measure the lakewide sea lamprey populations and to assess the overall success of the sea lamprey control program.

The collection of quantitative sea lamprey information is critical to integrate sea lamprey management with fishery-management goals of Great Lakes agencies. Improving the amount and quality of the information collected and using these new computer-based tools will facilitate setting realistic target levels for sea lamprey control in each lake, and will result in the most efficient and effective control program at the lowest cost. To meet treatment permit requirements, the control agents carry out pre- and post-application assessments to determine the impact of lampricide treatments on non-target species. In addition to using this information to measure changes in key indicators of efforts of the regular control program and/or new alternative control efforts, it is also used to meet risk monitoring and environmental assessment needs.

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Lamprey control