Sandbar Shark (Carcharhinus plumbeus) Demographics, Habitat Use, and Movements Around Nantucket, MA.

Collatos, Caroline*^1,2, J. Kneebone², N. Whitney², ¹School for the Environment, University of Massachusetts, Boston, MA, ²Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, MA

Overfishing throughout the 1980s to 90s caused sandbar shark (Carcharhinus plumbeus) populations from MA to FL to drastically decline, prompting them to be listed as a prohibited species. Recently, sandbar sharks have shown signs of recovery and are becoming more common in regions where they were once scarce, including Nantucket, MA. In order to better understand the importance of Nantucket to their continued recovery, we used acoustic telemetry and catch data to describe sandbar shark demographics, habitat use, and movements. From July - September 2020, 2021, and 2022, 111 sandbar sharks [64% female, 36% male; 72% juveniles, 28% adults; 119 - 184 cm fork length (mean ± SD: 145.8 cm ± 13 cm)] were caught. In 2021 and 2022, a subset of 42 sharks was tagged with VEMCO V16 acoustic transmitters and monitored with an array of 12 to 14 acoustic receivers deployed around Nantucket Island. In 2021, 1,757 detections were collected from 8 sharks on 7 receivers around the southeast area of Nantucket, with more detections recorded in August (80%) than July (15%) or September (5%). Sharks were detected from initial tagging date July 13th to September 16th, 2021. Sharks were detected for up to 14 days (mean = 6.5), with some present for up to 7 consecutive days (mean = 1.9). 2022 acoustic data is still being collected. These preliminary data suggest that the waters around Nantucket are a recurring habitat for adult and juvenile sandbars from June to September and may be an important area for their species recovery.