Crayfish dine on Great Lakes trout and salmon (eggs)!
Ann Arbor, MI — The reproductive season for salmon and trout brings about new dining opportunities for both exotic and native species of crayfish in the Great Lakes.
Individual crayfish consumed from 1 to 6 lake trout or rainbow trout eggs per day, depending on the ambiance of their environment. Considering that crayfish densities on rocky spawning reefs at several sites in northeastern Lake Michigan varied from 4 to 54 per square yard, crayfish could be responsible for consuming as many as 324 eggs per square yard of fish spawning habitat.
In laboratory studies, fewer eggs were consumed in cold water than warm water. The introduced rusty crayfish (named because of dark rusty patches on both sides of their body) ate more eggs at warmer temperatures compared to native species. Native crayfish were better at feeding in cold water relative to rusty crayfish, which are less adapted to the Great Lakes region. Rusty crayfish also preferred to dine alone, eating fewer eggs in the presence of others.
Lake trout are the focus of intensive management efforts to restore reproducing populations in the Great Lakes. "This information will be useful for modeling the expected survival of spawned eggs," said primary investigator Brian Ellrott.
Original Publication Information
Results of this study "Effects of Temperature and Density on Consumption of Trout Eggs by Orconectes propinquus and O. rusticus," are reported by Brian J. Ellrott, J. Ellen Marsden, John D. Fitzsimons, Jory L. Jonas and Randall M. Claramunt in the latest issue (Volume 33, No. 1, pp. 7-14) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2007.
Contacts
For more information about the study, contact Jory Jonas, Charlevoix Great Lakes Station, Michigan Department of Natural Resources, Charlevoix, MI 49720, JonasJ@michigan.gov, (231) 547-2914.
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.