In the never-ending battle to prevent blood-sucking sea lamprey from wiping out some of the most popular fish species in the Great Lakes, biologists are developing new weapons that exploit three certainties in the eel-like parasites' lives: birth, sex and death.
Researchers are beginning the third and final year of testing lab-refined mating pheromones — scents emitted by male lampreys to attract females. They're also working on a mixture with the stench of rotting lamprey flesh, which live ones detest, and another that smells of baby lampreys, which adults love. If proven effective, the chemicals will be deployed across the region to steer the aquatic vermin to where they can be trapped or killed.
Sea lamprey have been rising in numbers in Lake Michigan and in Lake Superior once again despite a cost of $21 million per year to control the blood sucking varmints, so this is welcome news.
The eel-like, blood-sucking, fish-killing sea lamprey is making an unexpected comeback on Lake Superior.
Lamprey numbers have exploded -- nearly doubling in western Lake Superior -- during the past year as state and federal biologists try to determine whether the increase is a temporary spike or a major problem for lake trout and other fish.
And scientists are starting to battle lamprey larvae in new locations, including in the lake itself and not just in streams.
Crews trapped 9,478 lamprey in the Brule River lamprey trap this year, three times last year's catch and the most ever in the barrier's 20-year history, said Mike Seider, Lake Superior fish biologist for the Wisconsin DNR.
"It's not just the trapping numbers," he said. Lamprey-caused wounds also are up, especially on the larger trout to which lamprey attach. In the lake's western area, the number of lamprey scars on big lake trout is up more than 400 percent -- 26.9 scars per 100 trout compared to 6.4 per 100 trout last year.
They entered Lake Ontario from the Atlantic via the Erie Canal in 1825, and made their way into Erie and the upper Great Lakes via the Welland Canal in 1919, and from there their populations exploded.
To get an idea of why we work so hard and spend so much to control the sea lamprey:
Sea lampreys feasted on lake trout...
Lake trout were the staple of the great Lakes commercial fishery before sea lamprey invaded. Anglers harvested some 15 million pounds of lake trout each year in Lakes Michigan, Huron, and Superior. By the early 1960s, the lake trout catch dropped to 300,000 pounds. The lake trout harvest in Lake Huron dropped from 3.5 million pounds in 1935 to 1000 pounds in 1949. The catch in Lake Michigan dropped from 5.5 million pounds in 1946 to 402 pounds in 1953. In Lake Superior, the catch dropped from an average of 4.5 million pounds annually to 368,000 pounds in 1961. An unsightly fish with no commercial value was making quick work of the most valuable sector of the Great Lakes commercial fishery, lake trout.
-- Jeff Alexander, Pandora's Locks
It takes a massive, annual effort to beat back the sea lamprey and keep them in check. They spawn in rivers and streams, with the females laying over 60,000 eggs each. There's really no hope of full eradication.
Let's put this into perspective. Michigan alone has 3,288 miles of coastline, plus thousands more miles of river systems.
If ONE fertilized female survived anywhere in the the tens of thousands of miles of coastline and river systems everywhere in the Great Lakes, we'd be right back where we started.
We're never going to get rid of the sea lamprey. The best we can hope to do is control it. And the moment we stop finding ways to control the sea lamprey, or some crazed deficit hawk thinks cutting the control program is a good idea, the animal will come back in force to eradicate native species and the 7 billion dollar Great Lakes fishing industry.