**The title, authors, and abstract for this completion report are provided below. For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**
Effectiveness of sterile-female release in reducing sea lamprey reproduction in the Trout River
Matthew J. Symbal2, Michael B.Twohey2, and Roger A. Bergstedt3
2 U.S. Fish and Wildlife Service
Marquette Biological Statin
3090 Wright St.
Marquette, Michigan 49855
3 U.S. Geological Survey
Great Lakes Science Center
11188 Ray Rd.
Millersburg, Michigan 49759
A sterile-female-release technique (SFRT) was evaluated for use as an alternative method to control invasive sea lamprey (Petromyzon marinus) populations in the Trout River from 2007 to 2010. Large numbers of sterilized female lampreys were released annually into the Trout River during the spawning migration. Nest observations were recorded daily once sterile lampreys were released and numbers of sterile female, untreated female and male lampreys were documented. Eggs were removed from nests and evaluated to calculate average viability of eggs in specific nests. Backpack electrofishing surveys conducted in 2010 provided larval lamprey abundance estimates used to rank the Trout River for lampricide treatment during 2011. We found that after applying the SFRT to the Trout River for four consecutive years, that sterilized females appeared on nests in high ratios to untreated females, but at lower ratios than expected. Viability estimates of eggs in nests were low; however, larval sea lamprey abundance was not significantly different from abundance levels when the technique was not applied. Ultimately, application of the technique did not eliminate or forestall the need to treat the Trout River with lampricide.