Migration and Residency of Sandbar, Atlantic Sharpnose, Bull, and Nurse Sharks in the Northern Gulf of Mexico

Abstract

AbstractAcoustic telemetry was used to monitor the movements and residency of Sandbar Sharks Carcharhinus plumbeus, Atlantic Sharpnose Sharks Rhizoprionodon terraenovae, Bull Sharks Carcharhinus leucas, and Nurse Sharks Ginglymostoma cirratum around artificial reefs in the northern Gulf of Mexico. Transmitter‐tagged sharks were monitored from November 2012 to July 2019. Residency comparisons were based on the percentage of days that an individual was present in the study area for each month. Sandbar Sharks had greater residencies in fall than spring and winter, Bull Sharks had greater residencies in summer, and Nurse Sharks had greater residencies in the fall. No seasonal patterns were detected for Atlantic Sharpnose Sharks, but one individual returned to the study area in all 5 years that the transmitter was active. One Sandbar Shark and one Nurse Shark had long‐term preferences (>3 years) for specific sites. Long‐distance migrations (n = 7) away from the artificial reef area in the northern Gulf of Mexico were observed for three Sandbar Sharks (588, 589, and 1,894 km), two Bull Sharks (927 and 968 km), and two Nurse Sharks (903 and 943 km), with six of these migrating sharks returning to their tagging areas. Specifically, two Bull Sharks and two Nurse Sharks made winter migrations to the southern end of Florida (Florida Keys), and two Sandbar Sharks migrated to the middle of the west coast of Florida. A third Sandbar Shark made the longest distance migration and moved out of the Gulf of Mexico, into the Atlantic Ocean, and up to the South Carolina coast. Importantly, this Sandbar Shark returned to the same artificial reef where it was tagged and released in the northern Gulf of Mexico after its 3,788‐km round trip migration. These long‐distance migrations and subsequent homing behaviors, coupled with local residencies, indicate that the artificial reefs in the northern Gulf of Mexico may have significance extending well beyond the localized areas of reef deployment.