Pheromone Management: The Answer to Controlling Sea Lamprey Populations?

April 16, 2010

Pheromone Management: The Answer to Controlling Sea Lamprey Populations?

David Lung

The sea lamprey (Petromyzon marinus) is a parasitic jawless fish that originated from the Finger Lakes and Lake Champlain in New York and Vermont but was introduced accidentally when canals between these lakes extended into the Laurentian Great Lakes. The sea lamprey sticks to a fish with its suction cup-like mouth and then uses its sharp tongue and saw-like teeth to cut through tissue in order to obtain blood from its prey. Because of its aggressive feeding patterns, the lamprey has decimated native fish populations, hurting both the fishing industry as well as the tourist industry. Current methods of controlling the population of sea lampreys include barriers and lampricides, however, the population of the lampreys, according to Johnson 2009, is still too high to be considered controlled by these methods.

Scott Rong, an undergraduate student at Duke University, proposes the use of traps laced with mating pheromones as a means of controlling the population of sea lamprey instead of traditional traps without chemicals. Currently, mating pheromones of the male sea lamprey have been synthesized in a laboratory and Rong hopes to “survey the effectiveness, practicality, and economic costs of the integration of pheromone-based management with trapping.” Rong hopes to analyze 3 objectives: 1) Find out what concentrations of pheromones are needed to lure sea lampreys to the traps at a particular distance, 2) figure out which trap is most effective in catching the sea lamprey, 3) and ultimately discover whether traps with pheromones are more effective at trapping sea lampreys than traps without the pheromones.

Rong’s experiment will take place at the St. Mary’s River where most sea lampreys go to spawn near the Great Lakes region. He will also conduct his experiment during the sea lamprey’s spawning season to ensure that many of the lampreys will congregate into an area where the possible wide distribution of the lamprey will not be a factor in the sensing of the pheromones. A minimum of 2 years will be required to carry out the experiment with the first year observing the effectiveness of traps without pheromones and the second observing traps with pheromones.

For his first objective, Rong will find out the concentration needed for a significant reaction to mating/migratory pheromones. He will do this by placing 5 males and 5 females into an Olympic-size swimming pool with pheromones into the corner of the pool. He will gradually increase the concentration of the pheromones to find the concentration with the most reaction from the lampreys and repeat this experiment several times. For his second objective, Rong will create 3 lanes as a simulation of stream conditions with different traps with and without chemicals as well as sea lampreys, eventually choosing which trap was most effective at capturing the sea lampreys. For the third objective, Rong will use the most effective traps without pheromones the first year of experimentation and with pheromones for the second year.

Rong hopes that the results of his proposal can develop a pheromone-based management of sea lamprey that will be more economically feasible than the use of barriers and lampricides. The utilization of pheromones will allow greater movement for native fish species that are blocked off by barriers and also reduces the possibility of harming other aquatic organisms with lampricides. Overall, Rong sees pheromone-based management having great potential for controlling sea lamprey populations in the Laurentian Great Lakes and restoring this aquatic environment close to its pre-invaded condition.

March 24, 2010

Understanding how lampreys use pheromones to navigate and find suitable spawning grounds is an important step in understanding their migration patterns and what steps to use in order to control their spread and reproduction. Fine, Vrieze, and Sorensen (2004) found that lampreys were attracted to pheromones given off by larvae of the same species, implying that migratory pheromones are species specific. This makes sense, they argue, because each species has different requirements for spawning and larval habitat requirements. In areas where lampreys are a problem, isolating the pheromone can be useful in more effectively controlling the spread of the species: since the lampreys will migrate to areas with the greatest concentration of pheromone, artificial pheromones could be introduced to theoretically control and decrease spawning runs, thus decreasing the overall concentration of the lamprey population. In areas where lampreys are at risk (in coastal areas), the opposite could be true: using the pheromones to direct lampreys to favorable streams could help increase spawning runs and population growth for threatened species.

Fine J, Vrieze L, Sorensen P. Evidence that Pteromyzontid lampreys employ a common migratory pheromone that is partially composed of bile acids. Journal of Chemical Ecology, Volume 30, Number 11, November 2004.