Use of Acoustic Telemetry to Examine Habitat Preferences and Migration Patterns of Finetooth and Blacknose Sharks

The value and function of shoal complexes for highly migratory species such as sharks are unknown.  These structurally complex, sand rich resources are often targeted for dredging and beach nourishment projects.  The movements and broad habitat preferences of federally managed shark species within the Canaveral Shoals complex off Cape Canaveral, Florida, were assessed using the Florida Atlantic Coast Telemetry (FACT) array.  Thirty-five finetooth (Carcharhinus isodon) and 32 blacknose (Carcharhinus acronotus) sharks were acoustically tagged December 2013 through May 2014 and January through March 2015. Within Canaveral, both shark species were detected in greater numbers on nearshore than offshore receivers, although the number detected on offshore shoal vs. non-shoal receivers was comparable.  Finetooth detections in Canaveral decreased as water temperatures warmed in late spring.  Seventy-five percent of finetooths were detected on Atlantic Cooperative Telemetry (ACT) Array receivers in Georgia and South Carolina from April through July, including in estuarine waters such as Charleston Harbor, Port Royal Sound and the Savannah River, with 31% returning to Florida waters in July and August.  Blacknose sharks showed less movement, remaining in Canaveral through August.  Acoustic detections and mark recapture data suggest possible higher site fidelity of blacknose than finetooths while in Canaveral waters.