Meeting Abstract
Gulf Flounder (Paralichthys albigutta) hatch at offshore spawning grounds and subsequently migrate to nursery habitats along the coast of the southeastern United States. Yet, the means by which juvenile flounder reach nursery habitats has remained enigmatic. Recent studies have demonstrated that migratory fishes such as eels and salmon navigate using Earth’s magnetic field. However, whether flounder – or any flatfish – possess a geomagnetic sense has not previously been investigated. We used a magnetic coil system to test whether flounder use Earth’s magnetic field for directional or “compass” orientation. Fish tested in a water-filled arena in the unaltered ambient magnetic field oriented toward magnetic west, a direction consistent with their onshore migration. When the coil was used to reverse the direction of the horizontal field, the fish showed a corresponding shift in orientation. These findings demonstrate that Gulf Flounder have a magnetic compass that can be used in orientation, and which may guide young fish as they migrate from the open sea to coastal nursery habitats. These results provide new insight into the migration ecology of flounder and suggest that a magnetic compass may facilitate the diverse migrations of marine flatfish.
