**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**
A Field Test of the Potential for Sea Lamprey Pheromones to
Promote Trapping Success in Natural Streams
C. Michael Wagner1, Michael L. Jones1, Michael B. Twohey2, and Peter W. Sorenson3
1 Michigan State University, Department of Fisheries and Wildlife, 13 Natural Resources Building, East Lansing, Michigan 48824, USA
2U.S. Fish and Wildlife Service, 1090 Wright St., Marquette, Michigan 49855, USA
3Department of Fisheries, Wildlife and Conservation Biology, University of Minnesota, 1980 Folwell Ave, St. Paul, Minnesota 55108, USA
Pheromone-baited traps have proven highly effective for managing insect pests by selectively removing reproductively active adults prior to mating. Recent studies have demonstrated that two pheromones produced by the sea lamprey, Petromyzon marinus, may be useful for trapping-based removal in tributaries to the Laurentian Great Lakes. Here, we report the findings from two series of field experiments designed to determine whether the efficacy of the pheromones will be mediated by competition with natural sources of pheromone. First, we produced simulated natural backgrounds of larval odor (migratory pheromone) in the Ocqueoc River, MI, a tributary to Lake Huron that currently lacks larval lampreys, and selectively amplified the signal on one side of the channel to ascertain whether migrants exhibit spatially-explicit preference for large pheromone signals. When given a choice between the presence and absence of odor on opposite sides of the channel, 91% of the migrants moved along the activated portion. However, when the entire channel was activated with a background odor of 10-12 M, lampreys did not prefer the side amplified five times greater than the background (50:50 distribution). When one side of the channel was amplified to 10-times the background (10-11 M), a small preference for that side became apparent. The distribution of migrants passing along the 10-11 M and 10-12 M sides of the channel achieved a 1:0.6 ratio (mean ∀___ 1SE: 12.2∀1.1 vs. 7.2∀1.4), indicating ~13% of the lampreys exhibited a preference for the more concentrated larval odor (t-test: t1,5 = 2.86, P=0.02). In the second series of experiments, we determined whether the previously reported preference for traps baited with several spermiating males represents a female preference for large mating pheromone signals or for multiple signalers. A two-choice maze test confirmed no preference for signals generated by groups of males vs. single males. A further field experiment determined that ovulating females will consistently locate and prefer to associate with traps baited with six or more males, whether a background of male odor is present or absent. Overall, these findings suggest different approaches to applying the migratory and mating pheromones to sea lamprey control. The migratory pheromone appears to operate as a generalized cue. Its presence establishes the eligibility of a stream for spawning, but we may not be able to attract a migrant directly to a trap in the presence of a competing source of odor. Conversely, the highly specific response of the ovulating female to the exact location of large mating pheromone signals was robust in the presence of a background. However, the capture efficiency of a male-baited trap placed amidst background odors is reduced by ~50%, likely due to the females willingness to give up and seek the source of other signals she detects.