Meeting Abstract
Many animals incorporate migratory phases into their life history. Migrations often involve traversing treacherous habitats to reach environments that provide resources that promote fitness. However, when animals migrate in large groups, passage through such habitats may occur along a temporal gradient. In the Hawaiian Islands, migrations of the goby species Sicyopterus stimpsoni are stimulated by flash floods. Following a flood, a migration pulse ensues in which hordes of juveniles migrate from the ocean to upstream adult habitats. Along their migration path, fish must evade picivorous predators and climb waterfalls while swimming upstream against ambient stream flow. It is possible that performance in both of these variables may vary over the course of the migration pulse. To test this prediction, we collected fish across migration pulses lasting 2-6 days and measured their performance in both burst escape performance and climbing trials. Results suggest that escape performance is independent of migration timing, but that climbing performance is greatest among fish collected near the end of migration pulses. If fish with variable performance are able to reach adult habitats as a result of differential timing of migration, it could explain the genetic and morphological variation previously recorded among adult populations. Understanding when fish are most likely to succeed in migrations could also improve management decisions for the protection of migratory species.
