MINNEAPOLIS, MN. Eurasian ruffe release a potent pheromone when they are injured that repels other ruffe and could be useful in controlling this exotic nuisance fish. University of Minnesota Sea Grant researcher Peter Sorensen and his colleagues reported their findings in the latest issue (Vol. 26, No. 2) of the "Journal of Great Lakes Research."
They found that damaged ruffe skin emits an odor, or alarm pheromone, repugnant to other ruffe that dramatically suppresses their swimming and feeding activities.
"In large laboratory tanks, ruffe avoid the alarm pheromone upon contact," said Sorensen, professor of fisheries and wildlife at the University of Minnesota. "Clearly, this cue has potential for managing ruffe. The key remaining question is how effective it will be in the large open spaces of the lake," he said.
Peter Maniak, Ryan Lossing, and Sorensen, all with the University of Minnesota, have been studying pheromones -- chemical signals that pass between organisms of the same species and are detected by an animal's sense of smell. Fish commonly use pheromones to coordinate activities, such as mating and schooling, in waters that are often turbid, vast, and relatively featureless. Alarm pheromones signal the presence of potential danger.
"To the best of my knowledge, no one is actively managing ruffe right now," said Sorensen. "They have given up for lack of ideas or funding." Since the alarm pheromone is non-toxic, specific, and easy to collect and apply, Sorensen hopes it will re-inspire efforts to manage ruffe.
Authorities in Alpena, Michigan, have approached Sorensen about using the alarm pheromone to exclude ruffe from areas where they are not wanted, such as docks where ships take on ballast water. Sorensen has also identified a ruffe sexual attractant that might be used in conjunction with the alarm pheromone.
The perch-like Eurasian ruffe became part of the fauna in the Duluth-Superior harbor in the early 1980's. Presumably, they crossed the Atlantic Ocean as accidental passengers in the ballast tanks of cargo ships. Within a decade of their detection, Eurasian ruffe became the most abundant fish trawled from the bottom of the harbor. Their impact on native aquatic species remains unclear but is under investigation. Currently, ruffe have spread along Lake Superior's south shore to the Fire Steel River, east of Ontonagan, MI; to several harbors along the north shore to Thunder Bay, Ontario; and to Alpena, MI, on Lake Huron.
The study was funded by Minnesota Sea Grant. Sea Grant is a university-based program that promotes the wise use and stewardship of coastal and marine resources through research, outreach and education.
For More Information Contact:
Marie Zhuikov
Minnesota Sea Grant Communications
(O) 218-726-7677
Email: mzhuikov@d.umn.edu
Journal
Journal of Great Lakes Research