50 year old lamprey control being reviewed

From Great Lakes Wiki

Sea lampreys have been wounding and killing fish in the Great Lakes for nearly a century. At one time, sea lampreys were so rampant that it was nearly impossible to catch a lake trout in the Great Lakes, in part due to sea lamprey predation.

In the mid-1950's, a short-lived chemical called 3-trifluoromethyl-4-nitrophenol (TFM) was discovered that selectively targets lamprey populations . Following the wide-spread use of TFM throughout the Great Lakes basin, sea lamprey populations declined drastically. Fifty years later, scientists are reassessing sea lamprey control, and contemplating some alternative methods.

Dr. Mike Jones is a professor of Fisheries and Wildlife at Michigan State University, and studies fish population dynamics for the Great Lakes Fishery Commission (GLFC), an international organization responsible for controlling sea lampreys in the Great Lakes. Jones says that when managing a pest, “understanding factors in nature that determine the abundance of the species of interest is an important part of that puzzle.”

This is why Jones and his team are currently researching the environmental and ecological factors that influence sea lamprey growth. With his research, the GLFC hopes to understand how much control is necessary to protect fish populations that people care about, such as salmon and trout.

One facet of understanding sea lampreys is getting accurate estimates of populations. Jones is working to better this process so that estimates are more reliable. Jones says, “Counting fish is no more difficult than counting trees, except that trees don’t move and fish are under water.”

Jones’ research will hopefully asses the success current control methods. He says that populations have reduced drastically from historic levels. Current estimates of sea lamprey populations are between 150-300 thousand, but before control methods were applied there were as five to ten times as many. So control methods are working, but at what cost?

One drawback to the most popular method, application of TFM, is that it is a toxin, and while it largely targets sea lampreys it is also killing lamprey species native to the Great Lakes. Besides TFM, scientists are trapping adult sea lampreys, constructing low-head barriers in rivers where lampreys spawn, impeding their reproduction but allowing other larger fish to pass, and sterilizing male sea lampreys so that they will compete with unsterilized males to reproduce.

All of these methods are labor intensive and very costly. The GLFC spends approximately $18 million a year on sea lamprey control, so other methods are being researched.

Researchers at Michigan State University are looking in to the use of two pheromones to control lamprey. One pheromone is amigratory pheromone that larval lampreys release in rivers. Researchers believe this pheromone helps adults find their way to rivers that can successfully support lamprey populations. The other pheromone is released by spawning adult males and attracts females to their nests.

What purpose could these pheromones serve? Jones says, “The reason that this interesting, not just because it is very cool biology, but also because if you can imagine that if these pheromones cause a very strong behavioral reaction in adult lampreys if we could synthesize the pheromones we could use them to lure lamprey into traps.”

Preliminary research on the pheromones has been promising. Jones says, “It could completely change the way we control lampreys and put much more emphasis on trapping.”

Would this just be another control method to add to the long list? Jones says, “If we can get this to work as well as biology would suggest it might work we could potentially eradicate lamprey from the Great Lakes.”
More about Sea Lamprey:
Listen to this lamprey story reported in July, 2007, by Michigan NOW

--Pencekar 18:14, 4 Dec 2006 (EST)