IMPACTS OF ROTATIONAL IMPOUNDMENT MANAGEMENT (RIM) AND SUMMER DRAWDOWNS ON THE MIGRATIONS OF JUVENILE FISHES IN INDIAN RIVER LAGOON MOSQUITO CONTROL IMPOUNDMENTS

Impoundments in the Indian River Lagoon, originally built to control saltmarsh mosquitoes, led to the isolation of fish nursery habitats. Rotational Impoundment Management (RIM) aims to mitigate this by hydrologically reconnecting impoundments during mosquito non-breeding seasons. However, current practices may not effectively facilitate juvenile fish emigration. This study incorporates summer openings (drawdowns) of culverts into RIM to improve the emigration of juvenile tarpon and snook. Tagged fish were monitored with RFID technology for 18 months in four impoundments. The abundance and size distribution of tarpon and snook populations differed among impoundments, reflecting variations in habitat structure and water quality. Summer drawdowns did not significantly increase emigration rates. However, tarpon detections increased during closed-culvert periods in all impoundments, and snook detections increased in one impoundment. Despite low emigrations, the study offers insight into the behavior of juvenile fish in these impoundments and suggests ways to enhance their nursery functionality.