**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**
Identifying the most effective mixtures for use of the sea lamprey migratory pheromone in trapping and redistribution management scenarios
C. Michael Wagner1, and Trevor D. Meckley1
1 Michigan State University, Department of Fisheries and Wildlife, 13 Natural Resources Building, East Lansing, MI, 48824
1. The sea lamprey (Petromyzon marinus) completes its life‐cycle after a long migration from offshore feeding areas to riverine spawning grounds. This movement is guided by a migratory pheromone composed of at least three sulfated steroids (bile acids) produced by larvae living in stream sediments. Two functional hypotheses have been set forth for the migratory pheromone. First, at the transition from lacustrine migration to riverine migration the presence of migratory pheromone induces staging and/or entry into activated streams by migratory sea lampreys. Second, after the onset of the riverine migration the presence of migratory pheromone mediates tributary selection by altering movement pathways in streams. Here, we report a series of field and laboratory experiments designed to test the validity of each hypothesis.
2. In 2007 we examined the relative attractiveness of three combinations of synthesized pheromone components (PADS, PADS+PSDS, PADS+PSDS+PS) at two concentrations (10‐13 M, 10‐12 M) vs. a methanol control in a Michigan stream. We expected the compounds to prove attractive per pervious work using whole larval odor (Functional Hypothesis 2). Migrating lamprey exhibited no preference for the synthesized compounds while continuing to exhibit a strong preference for larval odor in a natural stream. These findings were presented to GLFC staff and base on several discussions we decided to focus our collective efforts in 2008 on ascertaining whether the negative result was due to a failure in the identification and/or synthesis of the compounds.
3. In 2008 we examined the behavioral responses of migratory adult sea lamprey to synthesized migratory pheromone components and larval odor in the laboratory using two‐choice test protocols developed by Peter Sorensen and colleagues. We were unable to generate results comparable to those previously published using purified natural compounds.
4. In 2009 we initiated a pilot‐project to investigate whether the addition of synthesized migratory pheromones would induce staging behavior at a river mouth (Functional Hypothesis #1). We tracked 20 acoustically‐tagged lacustrine migration phase lampreys as they approached the mouth of a small river that recently underwent lampricide treatment to remove the larval population. Following treatment we tracked the movements of migratory sea lamprey as they approached, entered, or bypassed the river mouth under two conditions: 1) with greatly reduced or absent larval odor following treatment (ten lampreys); and, 2) after the addition of the synthesized pheromone components PADS and PSDS at ‐12 M (ten lampreys). We were able to describe two clear, search‐related modes of behavior in migratory sea lamprey: coastal searching and river‐mouth locating. Further, river‐mouth locating occurred more frequently on nights when synthesized pheromone components were added to the Black Mallard River discharge. These data are not confirmatory of Functional Hypothesis #1; our sample size was too small to offer any substantial conclusion. However, the patterns we observed are consistent with Functional Hypothesis #1 and merit further investigation.