Digging Deeper Than Essential Fish Habitats: Identifying Habitat Areas of Particular Concern for Sand Tigers

Sand Tigers (Carcharias taurus) are federally listed as a Species of Concern due to population declines and inherently low rebound potential. Essential fish habitat for Sand Tigers has been identified in several areas along the U.S. coast, however little information exists regarding their spatial and temporal usage. The relatively high abundance of Sand Tigers from June-October in the Delaware Bay and nearby coast suggests these areas are particularly important habitats. Passive acoustic telemetry was used to examine fine-scale movement patterns of 33 Sand Tigers (mean 201cm FL; range 146-246cm FL) along the Delaware coast during the summers of 2012-13. Activity space was relatively restricted, with 95% kernel utilization distributions (KUD) of 7.9-303.1km².  The majority (82%) of Sand Tigers core areas of use (50% KUD) were limited to a 12km² section of coast (<1.5km from shore) between the mouth of the Delaware Bay and Cape Henlopen, Delaware. Furthermore, 67% of individuals tagged in 2012 returned to the same nearshore waters in 2013.  The high degree of site attachment to this small coastal area coupled with threats from coastal development and shore fishing targeting Sand Tigers warrants this region’s designation as a habitat area of particular concern.