Interannual site fidelity of sand tigers (Carcharias taurus) to Delaware Bay

Sand tiger sharks (Carcharias taurus) typically inhabit nearshore waters including Delaware Bay for both nursery and foraging functions. Along the US East coast, sand tigers are believed to have experienced a marked population decline due to overharvest coupled with low reproductive rates. This decline has lead to calls for data to provide a better understanding of the movements and habitat requirements for sand tigers during their summer residency in Delaware Bay. A total of 69 sand tigers (1.35 - 2.83 m TL) were implanted with standard or pressure sensing acoustic transmitters (VEMCO Ltd V-16-6H) (battery life: 2.5 - 6 years) since the summer of 2006. Telemetered sand tigers generally occupied Delaware Bay from mid-May through mid-October. Return rates for sand tigers in Delaware Bay seemed to be influenced by sex and maturity with males, and mature individuals of both sexes returning more frequently. Through this multi-year effort we have documented high return rates (46/69; 70%) for telemetered sand tigers in years following transmitter implantation. Throughout the course of this study male sand tigers returned significantly (p<0.001) earlier than females while immature individuals returned significantly (p<0.001) earlier than mature individuals. These results stress the overall interannual importance of Delaware Bay to future conservation efforts for sand tigers by showing when sand tigers are present within Delaware Bay. Our results provide the first quantitative estimates for the site fidelity and residency timing of sand tigers in Delaware Bay, some of the tools required to more effectively manage sand tigers ultimately leading to the recovery of this unique apex predator.