Sea lamprey (Petromyzon marinus) relies on a suite of complex chemical cues to mediate the reproductive stage of its complex life cycle. Pheromones are essential to ensure successful reproduction as anosmic individuals fail to locate spawning streams and mates. Three separate sets of pheromones have been characterized in lamprey: 1) A migratory pheromone released by stream resident larvae as metabolic byproducts that attracts adults into suitable spawning streams, 2) a sex pheromone comprised of bile acids released by sexually mature males that attracts females to a male nest and induces a suite of reproductive behaviors, and 3) a pheromone present in milt that is released during spawning events and hypothesized to signal sperm availability to females. In this dissertation, I test the overall hypothesis that different pheromones or their components function in their respective contextual factors (migration vs. reproduction, signaling location, and male spawning status) to influence female behavior and mate preferences. In Chapter 1, I provide a comprehensive review on our current understanding of chemical cues used by sea lamprey, what insights we have gained from management scale tests utilizing chemical cues, and the current unknowns and future research needs that should be addressed in order to implement chemosensory cues into the sea lamprey control program. In Chapter 2, data from field tests confirmed that sensory traps lead to reliable communication as females disassociated sexual and non-sexual signals using a pheromone antagonist during mating but not during reproductive migration. These results also suggest that the pheromone antagonist, PZS, may only be effective in controlling spawning populations and not for manipulating behavior during reproductive migration. Chapter 3 characterizes the functions of pheromones released via milt during spawning. Milt pheromones allowed females to discriminate among potential mates based on spawning status and milt pheromone concentration and attracted females to a nest while retaining them there for times consistent with the entire multicomponent bile acid pheromone. In Chapter 4, behavioral tests confirmed that a male's nesting location impacted access to mates to a greater degree than the signal attribute of pheromone concentration, which is known to influence female preferences. These results highlight the dynamic nature of animal communication and the importance of integrating aspects such as a signaler's location, signal attributes, and transmission through the environment to understand how the interactions or lack thereof between them influence receiver responses. The studies conducted here broaden our understanding of sea lamprey pheromone evolution, the function of sea lamprey pheromone components, and sea lamprey reproductive ecology. This knowledge may be used when designing and implementing management tools that utilize pheromones or other chemosensory cues as supplemental controls. The implementation of chemosensory cues into control efforts is aided by a holistic understanding of the multiple chemosensory communication networks sea lamprey utilize which provides information on what aspects of chemical communication networks to target for manipulation and in what contexts these efforts may be most effective.℗
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