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Crew checks Nemadji River for sea lamprey

A U.S. Fish and Wildlife Service assessment crew will conduct work on the Nemadji River in Douglas and Carlton counties Aug. 8-17 to estimate the abundance of sea lampreys. Information gathered is the first step to determine the need for sea lamprey control.

Sea lampreys invaded the Great Lakes during the 1920s and have been a permanent, destructive element of the fishery ever since. Sea lampreys attach to fish with a suction cup mouth, rasp a hole through the fish's scales and skin, and feed on blood and body fluids. The average sea lamprey will destroy up to 40 pounds of fish during its parasitic phase.

Fishery biologists and technicians conduct surveys for sea lamprey larvae in hundreds of Great Lakes streams each year. Most surveys are conducted by electrofishing, but in deep water crews use Bayluscide 3.2 percent Granular Sea Lamprey Larvicide, a lampricide approved by the U.S. Environmental Protection Agency and Health Canada Pest Management Regulatory Agency.

The lampricide is specially formulated onto sand granules and covered with a time-release coating, which is sprayed over a measured surface area of water where it sinks to the bottom, rapidly dissolves, and causes the larval sea lampreys to leave their burrows and swim to the surface where they are collected.