Migration and Management of Caribbean Amphidromous Fishes

Rivers on many tropical islands are dominated by amphidromous fauna that make regular transitions between freshwater and marine habitats.  Caribbean amphidromous fishes appear to be obligate estuarine or marine inhabitants for two to three months after hatching, and juveniles recruit to freshwater shortly after metamorphosis.  Adult migratory patterns are poorly understood for all Caribbean amphidromous fishes.  Riverine connectivity is critical for amphidromous recruitment to freshwater habitats at higher elevations, suggesting that entire basins must be considered to manage these species.  However, if regional subpopulations of adults are more generally closed to migration, then regional fisheries management may be effective.  The bigmouth sleeper, Gobiomorus dormitor, is a native Caribbean amphidromous species with sport fish potential, but little is known of its life history, population dynamics, and habitat requirements.  We tagged bigmouth sleeper with passive integrated transponders (PIT tags) and monitored their movements using three remote PIT antenna arrays along a longitudinal gradient in Río Mameyes, Puerto Rico.  Our findings indicate that bigmouth sleeper are relatively sedentary, and movements become more restricted at higher elevations.  Long distance movements of adults from headwater to estuarine habitats were not evident.  These results suggest that regional management units should be considered to manage bigmouth sleeper adults, while maintaining recruitment by limiting impediments to juvenile dispersal from downstream.