Reduced sea lamprey control during the COVID-19 pandemic led to a spike in the number of the parasitic predators in the Great Lakes.
Researchers estimated that the Upper Peninsula’s Manistique River contributed nearly half of Lake Michigan’s adult sea lamprey abundance, and the Manistee River (located in lower Michigan, directly across from a point about halfway between Kewaunee and Two Rivers) nearly 25%.
Additionally, sea lamprey escapement was documented upstream of the sea lamprey barrier on the Kewaunee River.
These were among the facts learned from an annual report to the Great Lakes Fishery Commission compiled by Jess Barber of the U.S. Fish and Wildlife Service in Marquette, Mich., and Tonia Van Kempen of Fisheries and Oceans Canada in Sault Ste. Marie, Ont.
Lake Michigan has 511 tributaries, and 129 of them have records of larval sea lamprey production.
Of those, 78 tributaries have been treated with lampricides at least once in the past decade. Thirty-four tributaries are treated every three to five years.
Great Lakes Fishery Commission chair Ethan Baker, the mayor of Troy, Mich., said populations of the non-native fish-killers are above targets in all five of the lakes as a direct result of reduce control by federal field crews in 2020 and 2021.
A return to more normal control in tributaries the past three years gives the commission reason to believe that lamprey numbers are now on the way back down, or will be in the next year or two.
“The COVID-19 pandemic provided an unintentional, but valuable, lesson,” Baker said. “Restricted control effort during 2020 and 2021 allowed millions of larval sea lampreys, that would have otherwise been removed, to survive and parasitize millions of pounds of valuable fish.”
Lampreys entered the upper Great Lakes through shipping canals around 1921.
Researchers estimate the average adult sea lamprey is capable of killing up to 40 pounds of fish during its parasitic stage.
Sea lamprey control began in 1958, a year after a chemical compound called TFM was discovered and found to be effective at killing larval sea lampreys without harming other species. After biologists assess the presence and abundance of lamprey larvae in streams, the lampricide is applied in those tributaries every three to five years.
Before control, lamprey killed more fish than commercial and sport fishermen did, causing considerable economic and ecological damage.
Today, the multi-million-dollar annual control program — paid for by the Governments of Canada and the United States — has reduced populations by about 90% or more in most of the lakes.
“The sustained increase in sea lamprey abundances following a lapse in annual control effort highlights the continued need for ongoing sea lamprey control and continued research into new and innovative control methods in the Great Lakes,” said Jim McKane, the Commission’s vice-chair. “Maintaining consistent sea lamprey control is essential to sustaining the robust fishery that provides jobs, sustenance, and recreation for the people of the Great Lakes basin.”
Sea lamprey control is conducted in partnership with Fisheries and Oceans Canada and the U.S. Fish and Wildlife Service, with research support from the U.S. Geological Survey and other agencies and institutions.
Future control methods are a priority for the commission and its science program.
Learn more about the potential methods at www.glfc.org/future-control-methods.php.
Archery and crossbow deer hunts close in many counties Jan. 5, but remain open in some others, including Brown, Door and Kewaunee through Jan. 31.
Wild turkey hunting remains open until Jan. 5 in Zones 1-5.
That’s the same closing date as the pheasant and Zone A ruffed grouse seasons.
The Canada goose hunt in the southern zone ends Jan. 9.
Ongoing hunting seasons include cottontail rabbit, gray and fox squirrel, crow, raccoon, fox, coyote and bobcat (with permit).
Designated early season trout streams open to catch-and-release fishing with artificial lures Jan. 4.
Participants need a 2024-2025 fishing license and an inland trout stamp through March 31. Beginning April 1, anglers will need a 2025-26 fishing license and inland trout stamp.
Both can be purchased online through gowild.wi.gov or at a license sales location.
Take a closer look at Wisconsin inland trout fishing online at dnr.wisconsin.gov/topic/Fishing/trout/index.
The musky season closed Dec. 31, and won’t reopen until May 3 in the southern zone and May 24 in the northern zone.
You can learn more about muskies at dnr.wisconsin.gov/topic/Fishing/musky.
Comments
No comments on this item Please log in to comment by clicking here