Influence of Water Temperature on Behaviour and Migration of Adult Lemon Shark (Negaprion brevirostris) Throughout the U.S. Eastern Seaboard

Large aggregating groups of adult lemon sharks ( Negaprion brevirostris ) are annually present off the coast of Jupiter, Florida, during the winter months. These aggregations are composed of individuals known to exhibit seasonal north - south migrations along U.S. eastern seaboard. Through a combination of passive acoustic telemetry, Pop-off Satellite Archival Tags (PSAT), temperature and current profilers, water temperature appeared to be the environmental cue correlated with the timing, duration and locations of many adult N. brevirostris seasonal behaviours. Adult N. brevirostris of the Jupiter aggregations appear to have a water temperature preference of ~23/24°C, which in turn determines the timing of the annual aggregation period and may well be the driving variable for both latitudinal and vertical depth movements. Archived depth and temperature profiles demonstrated that individual sharks adjusted their depth to remain in water with a temperature of ~24°C. Seasonal migrations north in the summer months and south in the winter months follow the annual changes in coastal water temperature, with the location of the winter aggregations in Jupiter located at the most southerly distribution of cooler water temperatures. Thermal preferences seem to dictate aggregating periods, latitudinal migrations, and vertical movements, indicating that temperature is a strong driving factor in both the annual and day to day distribution of mature N. brevirostris attending the seasonal aggregations.