Risks and Rewards: Experimental Studies of Odor-Mediated Movement and Habitat Selection in Migrating and Spawning Sea Lamprey

Animal decision-making involves active trade-offs between risks and opportunities revealed by multiple sources of information and embedded within the natural milieu of the principle life activities (e.g., foraging, reproduction, migration, etc.). Because the sea lamprey (Petromyzon marinus) invests the entirety of its lifetime fitness into a single reproductive episode at the conclusion of a long migration, and does not provide parental care, its ability to detect habitats with conditions favorable for reproductive success is paramount. It does so via a set of odor cues that guide the selection of high quality reproductive habitat (revealed by the odor released by prospering larvae), localize sexually ready mates (revealed by a sex pheromone released by nesting males), and allow for the avoidance of risks along the migratory route (revealed by a conspecific alarm cue). I report and discuss the findings from a long series of field and laboratory experiments that implicate these odors as habitat-specific labels that mediate decision-making at key steps along the migratory route, and integrate the findings into a conceptual model of migration and habitat selection in sea lamprey.