**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 full‐scale field test of the efficacy of the male mating pheromone compound 3‐ketopetromyzonal‐sulfate in trapping‐for‐control scenarios
C. Michael Wagner1, Adam F. Thomas1, Michael Twohey2, Roger Bergstedt3, Rod McDonald4, and Weiming Li1
1 Michigan State University, Department of Fisheries and Wildlife, 13 Natural Resources Building, East Lansing, MI, 48824
2 Marquette Biological Station, 3090 Wright Street, Marquette, MI 49855
3 Hammond Bay Biological Station, 11188 Ray Road, Millersburg, MI 49759
4 DFO‐Canada, 1 Canal Drive, Sault Ste. Marie, ON, CANADA, P6A 6W4
1. The sex pheromone produced by the male sea lamprey has been investigated for over 20 years in hopes of developing a viable control option based on pheromone‐baited trapping. To date, a single component, 3‐keto‐petromyzonol sulfate (3kPZS), has been elucidated, synthesized, and functionally evaluated. Here, we report the results of two field experiments designed to ascertain whether and where 3kPZS is likely to be useful when baiting free‐standing traps in a stream subject to sea lamprey infestation.
2. In 2008 we deployed arrays of 3kPZS‐baited and unbaited traps across three zones that represent a natural gradient in competition with spawning males (Objective 1). Zone 1 was upstream of the spawning grounds and immediately downstream of an impassable barrier (no competition), Zone 2 encompassed an annually occupied sea lamprey spawning ground (direct competition), and Zone 3 was downstream of the spawning ground and subject to indirect competition with spawning males (male odor carried downstream). Our purpose was to demonstrate that 3kPZS can be useful when trapping amongst spawning males (compare baited vs. unbaited traps), and to determine whether there were any exploitable patterns in capture rate relative to trap position in the stream (compare capture rates across zones). We identified three such patterns.
3. First, traps arrayed near the barrier (Zone 1) consistently captured more lamprey than traps placed among or below the spawning grounds. Second, 3kPZS‐baited traps consistently captured more lampreys than unbaited traps, and captured significant numbers of males. Finally, most captures were made at night.
4. Based on these findings we concluded sea lampreys should be vulnerable to additional trapping using 3kPZS during the post‐migratory period, and prior to spawning, as they move downstream of a barrier to locate spawning habitat. Here, as lampreys reverse their migration, they will pass through plumes of 3kPZS emitted from traps without direct competition from downstream spawning males or indirect competition with the odor of upstream spawning males. We term this tactic the Reverse‐Intercept Approach (RIA).
5. In 2009 we performed a field test to ascertain whether this tactic will prove effective in the Ocqueoc River, MI. We created two trap arrays (six traps in close proximity = one array), one below the barrier and the other at the head of the spawning ground. We predicted the upstream array would outperform (relative to the downstream array) when the lampreys were passing downstream, and would principally attract maturing females.
6. Increased captures in the upstream array were clearly linked to onset of downstream movements, and this movement appeared correlated with increased responsiveness of female lampreys to sex pheromone components during maturation (captures were 70% female and 65% fully mature).
7. Overall, the Reverse‐Intercept Approach proves a novel and viable tactic for deploying a partial pheromone in sea lamprey control in the Great Lakes. The tactic will likely be improved via discovery of the apparent but undescribed components of the male sex pheromone.