Sexual 'love potion' aims at destroying Great Lakes lampreys
Pheromone helps trap females who think a potential mate is nearby
By Jordana Huber, Vancouver Sun; Canwest News ServiceJune 1, 2009
Researchers in northern Michigan are testing a "love potion" to lure female sea lampreys into traps -- and eventual doom -- in an effort to curb the population of the destructive, invasive species in the Great Lakes.
In 10 Michigan streams, male sea lampreys are facing competition from researchers, who are using a copy of the natural scent males give off during mating to lure females into traps.
"We are trying to fool them into a fatal love," said researcher Nick Johnson, who will spend the next three years evaluating the effectiveness of using the patented pheromone to help control sea lampreys.
Jawless and aggressive, the sucker-mouthed creature attaches to fish and rasps through scales and skin to suck out the blood and body fluids of its prey. They spend their adult life in the lakes and swim into streams to spawn and die.
In some test streams, very early results show pheromone-baited traps are catching two and three times as many sea lamprey as unbaited traps. In other streams there isn't a clear advantage, Johnson said.
"In the streams with fewer lampreys, the pheromone baited traps seems to be a little bit more effective because there are fewer males in that stream that are also releasing that same love potion," Johnson said.
Indigenous to the Atlantic Ocean, and likely introduced through man-made shipping canals, sea lampreys were first seen in the Great Lakes in the 1830s.
By the 1940s and '50s, sea lampreys had decimated lake trout, white fish and other populations of valuable, large fish.
Since 1955, Fisheries and Oceans Canada and the U.S. Fish and Wildlife Service have worked closely on the Great Lakes Fishery Commission to control the sea lamprey population.
Lampricides, which kill sea lamprey larvae while they are still in streams, are primarily used to control the population, along with barriers to block migration. Male sea lampreys are also collected, sterilized and released. Over the last five decades the population has been reduced by 90 per cent.
Still, without continuing control measures, the population could bounce back, said Mike Steeves, section head of assessment at the Fisheries Department's Sea Lamprey Control Centre in Sault Ste. Marie, Ont.
"The problem is persistent," Steeves said. "It's certainly not as bad as it was, but it is still something we have to remain vigilant about."
Steeves said the pheromone could potentially be used to draw sea lamprey from areas that are problematic to treat with lampricide into specific streams.
The pheromone will be tested in 10 streams around the Great Lakes in Canada next summer.
While sea lampreys remain a destructive and invasive parasite in the Great Lakes, they are considered a delicacy in some European countries.
Steeves said there are requests from European fisherman periodically for Great Lakes sea lamprey.
"We've looked into it," Steeves said.
"The problem with sea lamprey is they are full of contaminants, heavy metals and mercury. They're actually unfit for even the pet food industry."
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