BY DAVID KEFFER, LUDINGTON BIOLOGICAL STATION
Credit: John Stegmeier, USFWS
In late February, Biological Science Technicians, John Stegmeier, Gary Haiss, and Tim Granger from the Ludington Biological Station’s larval assessment team, started their field season two months early. Facing air temperatures as low as 20°F, water temperatures near freezing, and snow showers, the crew worked in the frigid waters of the White and Pentwater rivers, located in the southwestern portion of Michigan’s lower peninsula. Wrapped in many layers, they donned backpack electrofishing equipment and began collecting larval sea lamprey for use in several research projects. With the assistance of volunteers from Michigan State University and the Great Lakes Fisheries Commission’s (GLFC) Secretariat, they have overcome the harsh conditions and managed to collect 10,000 of the 25,000 larvae requested by researchers. The larvae were transported to the US Geological Survey’s Hammond Bay Biological Station near Millersburg, Michigan, where they are being held in several tanks, known as the “pheromone farm”. Researchers collect water from the holding tanks and pump it through a series of resin filled columns designed to collect biological compounds released from the larvae. The extracted compounds are further isolated in the lab and used for field research.
Larval collections for research are a common part of the annual responsibilities of the larval assessment team. In previous years, up to 35,000 larvae have been collected for various GLFC funded projects and the collections have been a valuable method of training new employees on the use of the electrofishing equipment. However, this has been the earliest and coldest time of the year that larvae have been collected to support ongoing research.
So why do researchers want the larvae to be collected so early in the year? Recent research, being led by Dr. Weiming Li at Michigan State University, has demonstrated that compounds released by larval sea lamprey burrowed into the stream sediment may be critical to initiating the upstream movement of migratory adult sea lampreys into streams before the onset of the spawning season. Measurement of the quantities of compounds excreted from late winter to early spring will be used to investigate the hypothesis that the release of attractive migratory compounds by larval sea lamprey may peak during this time of year. Results from this research could be used to disrupt spawning runs of sea lamprey and improve efforts to control sea lampreys in the Great Lakes.