Abstract

Information on movement and habitat use of large marine predators is needed to identify important areas for proper conservation and implement sound spatially explicit management strategies. Identifying important habitat(s) and the mecha-nisms responsible for movement is inherently difficult due to the mobility of large marine predators as they often move across multiple ecosystems or habitats. Moreover, patterns of habitat use and residency are influenced by dynamic oceano-graphic conditions (e.g., mesoscale eddies or currents) and distribution and movement of prey resources. The objective of this study was to better understand movement dynamics of Scalloped Hammerheads (Sphyrna lewini) throughout the Gulf of Mexico (GOM) using Smart Position or Temperature (SPOT) transmitting tags attached to the dorsal fin. A total of 38 Scalloped Hammerheads were captured and tagged throughout the northern GOM consisting of 33 individuals with move-ment data ranging from five to 479 days at large. Mean number of days at large was 146 ± 24.3 (standard error, SE) with a mean size at tagging of 159 ± 5.3 SE cm fork length (FL) (range: 102-220 cm FL). Movement patterns are being analyzed relative to remotely sensed oceanographic parameters including sea surface temperature, salinity, sea surface height anoma-ly, chlorophyll concentration and bathymetry. In addition, Bayesian state-space switching models are being used to examine directed movement and residency periods of individual sharks. Results will provide critical information on fine-scale habitat use and movement patterns that can be used to improve predictability models to highlight priority areas and environmental preferences of Scalloped Hammerheads throughout the GOM.

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