Chemical sex smell can lure "Vampire fish" to doom

London, Jan 21 (ANI): Scientists have said that a synthetic "chemical sex smell" could help rid North America's Great Lakes of the sea lamprey, a devastating pest, dubbed as the "vampire fish".

The sea lamprey has parasitised native species of the Great Lakes since its accidental introduction in the 1800s.

The sea lamprey's natural life cycle takes it from birth in a stream to adulthood in the ocean, where it gains its vampirical appellation.

Circular jaws lock on to another, larger fish, and a sharp tongue carves through its scales.

From then on, the lamprey feeds on the blood and body fluids of its temporary host, often killing it in the process.

The Great Lakes on the US-Canada border support recreational fishing worth billions of dollars a year, which the lampreys would wreck but for a control programme costing about 20 million dollars annually.

Now, according to a report by BBC News, US researchers have deployed a laboratory version of a male sea lamprey pheromone to trick ovulating females into swimming upstream into traps.

This is thought to be the first time that pheromones have been shown to be the basis of a possible way of controlling animal pests other than insects.

"There's been extensive study of pheromones in animals and even in humans," said lead researcher Weiming Li from Michigan State University in East Lansing, US.

"But most researchers have presumed that as animals get more complex, their behaviour is regulated in a more complex way, not by just one pheromone," he told BBC News.

Professor Li's team released the synthetic version of a lamprey hormone from a trap placed in a stream where lampreys come to breed.

Females scenting it would swim vigorously upstream until they found the source, some becoming trapped in the process.

"Why we're so enthusiastic about the pheromone work is that we see it as another tool in the arsenal," said Dr Marc Gaden from the Great Lakes Fishery Commission (GLFC), the body responsible for controlling the lamprey problem.

"We see it as away of tricking these spawning lampreys, and then you can do things to manipulate their behaviour in ways that would work against them. For example, you could lure them into streams without suitable spawning habitat, or just into traps," he added.

Professor Li's team is now planning a larger experiment, using the pheromone to trap female lampreys in 20 streams feeding into the lakes, which will take three years to complete. (ANI)