Date of Award
2024
Degree Type
Thesis
Degree Name
Master of Science in Biological and Environmental Sciences (MSBES)
Department
Biological Sciences
First Advisor
Brad Wetherbee
Abstract
Sand tigers (Carcharias taurus) are often taken as bycatch in commercial fisheries and captured by recreational anglers despite being prohibited. They also have one of the lowest rates of reproduction among elasmobranchs, producing two offspring every two or three years. These traits have generated concern about the sustainability of sand tiger populations, both globally and along the US East Coast, and interest in characterizing movements and essential habitat for this species. A total of 396 sand tigers, ranging from 78 - 246 cm fork length and 100.33 - 285 cm total length, were tagged with acoustic transmitters from 2007 - 2019. From 2007 - 2020, these sharks were detected over four million times on acoustic receivers from Massachusetts to Florida. Different demographic groups of sand tigers exhibited distinct and consistent spatial and temporal migrations, moving seasonally between northern and southern habitats. While mature sharks were primarily detected in Delaware Bay in summer, juvenile sharks were also detected further north in nursery habitats, as far as Massachusetts. Sharks primarily wintered in North Carolina waters. Eight of 81 individual mature females remained in North Carolina in summer rather than migrating north to Delaware Bay. These sharks, which did migrate north in subsequent years, were hypothesized to be pregnant due to the knowledge that sand tigers pup in North Carolina waters. Timing of migration to and from northern and southern habitats also differed between juvenile and mature sharks, suggesting spatial segregation between age classes. Juveniles began northward migration and arrived in northern habitat earlier than mature sharks. These results provide insight for protecting seasonal habitats occupied by this highly migratory species.
Recommended Citation
DeLoof, Bethany, "MIGRATORY PATTERNS OF SAND TIGER SHARKS (CARCHARIAS TAURUS) ALONG THE US EAST COAST" (2024). Open Access Master's Theses. Paper 2541.
https://digitalcommons.uri.edu/theses/2541