LAUSR

The silky shark, Carcharhinus falciformis (Muller and Henle, 1839), is a large circumtropical, oceanic, and coastal-pelagic species whose spatial ecology is not well understood. In Cuba, silky sharks are captured in local fisheries and are subjects for shark-based diving tourism off the Caribbean coast. Our study tracked three female C. falciformis (ranging 174–200 cm precaudal length) using satellite-linked tags to characterize the movement patterns and behavioral ecology of this species off the southeast coast of Cuba. Field work was conducted in the Jardines de la Reina (Gardens of the Queen) archipelago and utilized a novel in-water method for attaching pop-up satellite archival tags to free-swimming sharks. Results from both archival and position-only tags suggest the sharks traveled <30 km from the tagging site during the month-long deployments. The depth and temperature ranges recorded for two specimens were 0–640 m and 11.5–27.5 °C. Time-at-depth/temperature data revealed preferences for the upper-mixed layer (down to 150 m) and a temperature range of 24–27 °C. A diel vertical movement pattern was observed with silky sharks spending greater time at depth during the day than at night. Plasticity of vertical habitat utilization was noted with occasional forays to depths in excess of 550 m during both day and night. Daytime forays to surface waters were also observed and were most common during the morning hours between 09:00 and 11:00, possibly due to the ecotourism industry's use of bait during that time to attract sharks to the dive area.