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APPLICATION OF NATURAL MALE MATING PHEROMONE AT MANAGEMENT-SCALES TO INCREASE SEA LAMPREY CAPTURE AND COMPARE EFFECTIVENESS TO SYNTHESIZED 3kPZS.
1 USGS, Great Lakes Science Center, Hammond Bay Biological Station, 11188 Ray Road, Millersburg, MI 49759
2 Michigan State University, Department of Fisheries and Wildlife, 13 Natural Resources Building, East Lansing, MI 48824
3 Great Lakes Fishery Commission, 2100 Commonwealth Blvd., Suite 100, Ann Arbor, MI 48105
Many pheromones have been characterized in invertebrates and used for pest control, but less is known about vertebrate pheromones. Spermiating male sea lamprey (Petromyzon marinus) release sex pheromones of which a component has been identified, 7α, 12α, 24-trihydoxy-3-one-5α-cholan-24-sulfate (3kPZS), and shown to induce long distance preference responses in ovulated females. However, other pheromone components exist and when 3kPZS alone was used to control invasive sea lamprey populations in the Laurentian Great Lakes, trap catch significantly increased, but was generally underwhelming. We hypothesized that free-ranging sea lamprey populations discriminate between a partial pheromone mixture and complete pheromone mixture while migrating to spawning grounds and searching for mates at spawning grounds. As a means to test our hypothesis and to test two possible uses of the pheromone, we asked whether the full sex pheromone mixture released by males (spermiating male washings; SMW) is more effective than 3kPZS in capturing animals (1) en route to spawning grounds and (2) at spawning grounds. Here, the ability of synthesized 3kPZS and SMW to increase sea lamprey trap catch was compared over two years, on three streams, and in two environments; at migration barriers and spawning areas. At barriers, where sea lampreys are en route to spawning grounds, SMW-baited traps captured significantly more sea lampreys than paired 3kPZS-baited traps (about a 10% increase). At spawning grounds, no significant difference in trap catch was observed. The lack of an observed difference at spawning grounds may be attributed to increased pheromone competition and involvement of other sensory modalities in sea lamprey reproductive ecology. Because fishes often rely on multiple and sometimes redundant sensory modalities for critical life history events, successful use of pheromones in fisheries management will require thorough understanding of the chemical ecology and reproductive ecology of target species.