Movement Patterns of Atlantic Tarpon (Megalops atlanticus) in Brewers Bay, St. Thomas US Virgin Islands

Background Atlantic tarpon (Megalops atlanticus) are highly migratory species ranging along continental and insular coastlines of the Atlantic Ocean. Despite broad geographic distribution and importance as recreational fisheries, little is known about space-use patterns of tarpon within the Eastern Caribbean. Acoustic telemetry was used to track tarpon (n=14, 61- 95cm-FL) from September 2015 to February 2018 in St. Thomas, U.S. Virgin Islands to understand horizontal and vertical movements during diel, crepuscular and seasonal periods and under different environmental conditions. ResultsEight tarpon were transient while four had >80% residency and average activity space of 0.76 km2 (range = 0.075-1.174 km2) within a small (~1.8km2) bay. Tarpon occurred in <18 m depth with occasional movements to deeper water, including during hurricanes. Activity was greater during day compared to night, with peaks during crepuscular periods. During the day tarpon primarily utilized the waters along the St. Thomas airport and at night tarpon typically remained in a small shallow lagoon. However, when temperatures in the lagoon exceeded 30 °C, tarpon moved to cooler, deeper waters outside the lagoon. ConclusionThis study showed distinct and mostly non-overlapping home ranges except when seasonally abundant food sources were present and provided a unique perspective on the effects of extreme environmental conditions on tarpon movement and habitat use. These metrics are useful for management of tarpon, particularly under changing climatic conditions.