More than size matters to larval sea lamprey!
Ann Arbor, MI — Although most familiar as a lake-dwelling parasite of Great Lakes fishes, sea lampreys actually spend the majority of their life as harmless, filter-feeding larvae burrowed in the soft sediments of streams.
Prior to entering the lakes, larvae of the invasive sea lamprey undergo a change called metamorphosis. They transform from burrowed filter feeders to free-swimming parasites that feed on the blood of Great Lakes fishes.
For years, sea lamprey management agencies have relied on lampricide (a selective chemical used to kill sea lamprey larvae) treatments within streams to reduce the numbers of larval sea lamprey prior to their metamorphosis. Understanding when sea lampreys will metamorphose from the larval form to the parasitic form helps to direct these lampricide applications. Until now, larval length has traditionally been the sole indicator of when larvae would be ready to begin the parasitic stage of their life.
"It turns out that other factors such as age, water temperature, and the density of larvae in the river also play an important role, and there can be a big difference in the lengths of transforming lamprey across the Lakes," says Andrew Treble, a fisheries assessment biologist with the Department of Fisheries and Oceans Canada in Sault Ste Marie, Ontario.
"By incorporating measures of a river's larval density, geographic location, drainage area, and habitat suitability, along with individual lamprey length, we can greatly improve the accuracy of our predictions concerning the number of larvae that will transform into parasites the following year," he added.
The ability to more accurately forecast the timing of metamorphosis (change) from larvae to the parasitic form of the sea lamprey should improve how treatment resources are allocated, leading to improved levels of sea lamprey suppression, and thus better survival of fish and a healthier Great Lakes ecosystem.
Original Publication Information
Results of this study, "Development and Evaluation of a New Predictive Model for Metamorphosis of Great Lakes Larval Sea Lamprey (Petromyzon marinus) Populations," are reported by Andrew J. Treble, Michael L. Jones and Todd B. Steeves in the latest issue (Volume 34, No. 3, pp. 404-417) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2008.
Contacts
For more information about the study, contact Andrew Treble, Fisheries and Oceans Canada, Sea Lamprey Control Centre, 1 Canal Drive, Sault Ste Marie, ON P6A 6W4; , (705) 941-3020.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.
Links
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.