Mating pheromones will be used to manipulate lamprey behavior. Photo: C. Krueger, GLFC.

By Howard Meyerson

Grand Rapids, Mich – A sea lamprey mating pheromone used experimentally to manipulate lamprey behavior got a green light last month from the U.S. Environmental Protection Agency. It can now be used as a wide-spread management tool in Great Lakes and other waters.

“Until now it has been experimental,” said Marc Gaden, spokesman for the Great Lakes Fishery Commission, which funded development of the male sex pheromone known as 3kPZS. “Its use has been in the lab or on a stretch of river like the Ocqueoc where there has been very limited use. We now have approval to use it on a management scale. This brings us one step closer to using it as management technique.”

The EPA approved registration of 3kPZS as a bio-pesticide in December, 2015. Researchers note that it is the first-ever vertebrate pheromone bio-pesticide.  It is not a compound that kills lamprey in the manner of FM or Bayluscide, which are regularly used on Michigan waters.  The pheromone has been tested as an attractant odor to draw sea lampreys into traps so they can be removed from river systems. Its use improved trapping efficiency by 53 percent, according to Dr. Weiming Li, the Michigan State University professor who discovered the pheromone.

“I started to work on this in 1998,” said Li, E.J. Fry Chair of Environmental Physiology at the university. “Previous work (research) showed it’s often the male that gets to the spawning ground before the female. It was speculated that males were releasing pheromones (to attract the females). Many knew that males got to spawning grounds and started to build nests. The females joined them later. (Another researcher) showed on a small scale that females are attracted to males when they are sexually mature.”

Sea lamprey larvae wash up on the banks of the Manistee River after a successful lampricide treatment. Photo: R. McDaniels, GLFC.

Molecular structure identified

Li’s MSU laboratory isolated the pheromone and identified its molecular structure. Bridge Organics, a contract research and chemical manufacturing company in Vicksburg, then synthetically created 3kPZS for testing and approval. The company now will produce the pheromone for management use by federal agencies like the U.S. Fish & Wildlife Service which handles sea lamprey control in Michigan.

Great Lakes lamprey control efforts cost $20.5 million a year, according to Gaden. That is the cost of research, conducting stream assessments, lamprey control and maintaining lamprey control centers in Marquette, Sault Ste. Marie and Ludington. Lamprey management historically has been done using traps, barriers, and lampricides like TFM, which is applied to infested rivers to kill off lamprey larvae.

The GLFC funded lamprey pheromone research – with additional support from the Great Lakes Restoration Initiative – hoping it could provide another tool to use for managing lampreys. Different pheromones are used to achieve different goals.

Research on alarm-cue pheromones, for example – the compounds released when lampreys die – have tested the idea that they can be used to keep lampreys from migrating up certain streams. If so, the pheromones eventually could be used to keep them out of prime spawning habitat, while 3kPZS, or another attractant pheromone, is released to draw them up a different tributary where the habitat is not good, in turn reducing the potential need for expensive TFM treatments.

Further studies

“Our (river) studies are still going on. We see the same thing working with all of the odors,” said Mike Wagner, associate professor in the Department of Fisheries and Wildlife at MSU.  “In some circumstances they work well and sometimes less well.”

Wagner has been field-testing the effectiveness of alarm-cue pheromones as a lamprey deterrent on the Jordan, Ocqueoc and Manistique rivers. His research on the Carp Lake River outlet in Mackinac City has tested whether alarm-cue pheromones could be paired with attractant pheromones in a “push-pull” arrangement that would drive lamprey to one side of the river so they migrate upstream into traps.

“Our intent once we know it works and under what conditions, is (eventually) to send it (the alarm-cue pheromone) to the EPA for registration.  3kPZS was the first compound in the queue. It’s a new pitch that we are learning to throw, as well as whom to pitch it to. It’s effective, but so far doesn’t look like it does enough by itself to deploy basin-wide. But it is necessary as part of a management package.

__________________________

© 2016 Howard Meyerson

Appears in Michigan Outdoor News.