Meeting Abstract
Many animals migrate between habitats during their lifetime, encountering challenges to survival along the way. How do performance and body shape of animals help them to overcome the challenges of moving to a new habitat? To study which traits aid in migration, we examined a group of goby fishes that migrate from the ocean where young fish develop, to freshwater streams where fish live as adults. As fish migrate, they must overcome fast stream flows and piscivorous predators. Some species also ascend waterfalls to reach upstream habitats. We measured variation in performance and body shape across six species and two life stages to address two main questions. First, is there a point during migration when the strongest performing fish tend to move upstream? For this study, we collected climbing and escape response data from fishes throughout migrations. Climbing performance peaks 3-5 days after a migration begins, whereas escape performance remains constant throughout a migration. Second, can the predator regime to which fish are exposed influence the performance and/or body shape of fishes that survive to adulthood? We found that fishes living in regimes of consistent predation through their life cycle had low accelerations, but tall bodies, which may gape-limit their predators. Gobies that migrate to habitats with diminished predation showed the highest accelerations, as well as elongated posterior body shapes that may aid in producing higher thrust compared to fishes that live in predator-free habitats. These two analyses show how both morphology and performance relate to migratory behavior in fishes, potentially aiding management decisions for these taxa.
