Survival of large lake trout as good as the small ones in Lake Michigan
Ann Arbor, MI — Great Lakes' lake trout populations are being enhanced through stocking of hatchery-reared fish to rebuild populations and develop self-reproducing stocks. In Lake Michigan over 2 million lake trout have been stocked annually for decades by the U.S. Fish and Wildlife Service for this restoration effort. These fish enter the lake as yearlings (about 14 months old) and were previously stocked at size of 44 fish/kg. It was thought that raising and stocking larger fish (about 24 fish/kg) would increase the post release survival of these fish in the lake, which would require fewer fish to be raised and reduce crowding at the national fish hatcheries.
Fishery biologists from the U.S. Fish and Wildlife Service and the Wisconsin Department of Natural Resources teamed up to test whether survival of the larger lake trout was greater than the smaller fish. Paired stockings of uniquely tagged small and large lake trout were released in Lake Michigan and recovered over many years to determine relative survival. Recapture rates indicated that relative survival of the two groups was similar, and that stocking larger fish did not benefit the restoration program.
"Apparently the size difference we tested did not benefit survivorship of lake trout, and their overall health condition at stocking is likely more important than size," according to U.S. Fish and Wildlife Service Biologist Charles Bronte.
Original Publication Information
Results of this study "Relative Survival of Lake Trout Stocked at Different Sizes and Quality in Lake Michigan," are reported by Charles R. Bronte, Patrick C. McKee, Mark E. Holey, Michael L. Toneys and Paul E. Haver in the latest issue (Volume 32, No. 2, pp. 386-394) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2006.
Contacts
For more information about the study, contact Charles R. Bronte, U.S. Fish and Wildlife Service, Green Bay Fishery Resources Office, 2661 Scott Tower Drive, New Franken, WI 54229-9565; charles_bronte@fws.gov; (920) 866-1761.
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.