Interannual site fidelity and habitat utilization of sand tigers in Delaware Bay

Although found globally in most temperate and tropical marine waters Delaware Bay is relatively unique as one of few locations in North America where sand tigers are commonly encountered.  There are growing concerns over the trends in sand tiger abundance leading to our focus on the role of Delaware Bay in this species’ successful management.  We implanted long lived acoustic transmitters in sand tigers and have been monitoring their movements via both manual and passive telemetry.  Telemetered sand tigers exhibited a high degree of philopatry with 62% returning to Delaware Bay after one year of liberty and 60% returning after two years.  These findings emphasize the relatively unique role that Delaware Bay plays in the life history of sand tigers.   Sand tigers were resident within Delaware Bay beginning in mid May and had departed by the end of October.  Unlike other large estuarine systems where sand tigers are a more transitional component of the elasmobranch community, the vast majority of telemetered individuals were regularly detected in Delaware Bay during the summer months.  When combined, our findings support the key role that Delaware Bay plays in ongoing conservation and recovery efforts for sand tigers.