US Fish and Wildlife crew to assess lamprey in Douglas County rivers
Assessing the abundance of sea lampreys is the first step to controlling the invasive aquatic pest that destroys Great Lakes fish, officials say.
SUPERIOR — A U.S. Fish and Wildlife Service assessment crew will be working Aug. 16-26 in Douglas County to estimate the abundance of sea lampreys in the Amnicon, Poplar, Brule and Middle rivers.
Information gathered will be used to determine the need for sea lamprey control, according to a news release. It’s the first step to determine the presence of lamprey larvae.
Sea lampreys invaded the Great Lakes in 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 though 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.
Sea lamprey larvae hatch from eggs laid by adult lampreys in gravel nests, and drift into silty bottom areas where they burrow and live for several years. Also, larvae sometimes drift out of streams and settle in the immediate offshore areas near stream mouths. Failure to detect and subsequently eliminate larvae allows the lampreys to transform into parasitic adults and kill Great Lakes fish.
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 waters crews use Bayluscide 3.2% Granular Sea Lamprey Larvicide, a lampricide approved by the U.S. Environmental Protection Agency and Health Canada Pest Management Regulatory Agency, the news release said. It is specially formulated onto sand granules and covered with a time-release coating, and 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.
The U.S. Environmental Protection Agency and Health Canada Pest Management Regulatory Agency have reviewed human health and environmental safety data for the lampricides, and in 2003 concluded that Bayluscide poses no unreasonable risk to the general population and the environment when applied at concentrations necessary to detect larval sea lampreys.
Applications are conducted in accordance with state of Wisconsin permits.
The sea lamprey control program is formulated and implemented by the Great Lakes Fishery Commission, in partnership with the U.S. Fish and Wildlife Service, Fisheries and Oceans Canada, U.S. Army Corps of Engineers, and U.S. Geological Survey.
The commission initiated chemical control of sea lampreys in 1958.