BOTTLENOSE DOLPHIN ( Tursiops truncatus ) Jacksonville Estuarine System Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE The coastal morphotype of bottlenose dolphin is continuously distributed along the Atlantic coast south of Long Island, New York, to the Florida peninsula, including inshore waters of the bays, sounds and estuaries. Except for animals residing within the Southern North Carolina and Northern North Carolina Estuarine Systems (e.g., Waring et al. 2009), estuarine dolphins along the U.S. east coast have not previously been included in stock assessment reports. Several lines of evidence support a distinction between dolphins inhabiting coastal waters near the shore and those present in the inshore waters of the bays, sounds and estuaries. Photo-identification (photo-ID) and genetic studies support the existence of resident estuarine animals in several areas and similar patterns have been observed in bays and estuaries along the Gulf of Mexico coast (Wells et al. 1987; Balmer et al. 2008). Recent genetic analyses using both mitochondrial DNA and nuclear microsatellite markers found significant differentiation between animals biopsied along the coast and those biopsied within the estuarine systems at the same latitude (NMFS unpublished data). Similar results have been found off the west coast of Florida (Sellas et al. 2005). The Jacksonville Estuarine System (JES) stock is bounded in the north by the Florida/Georgia border at Cumberland Sound, abutting the southern border of the Southern Georgia Estuarine System stock, and extends south to Jacksonville Beach, Florida. This encompasses an area defined during a photo-ID field study of bottlenose dolphin residency patterns in the area (Caldwell 2001). The habitat is comprised of several large brackish rivers, River is a deep, swift moving river with heavy boat and shipping activity (Caldwell 2001). The remainder of the area is made up of tidal marshes and riverine systems averaging 2m in depth over sand, mud or oyster beds, and is bisected by the Intracoastal Waterway. The borders are subject to change upon further study of dolphin residency patterns in estuarine waters of southern Georgia and Florida. The JES stock has been defined as a separate estuarine stock primarily by the results of photo-ID and genetic studies. Caldwell (2001) investigated the social structure of bottlenose dolphins inhabiting the estuarine waters between the St. Mary's River and Jacksonville Beach, Florida, using photo-ID and behavioral data obtained from December 1994 through December 1997. Three behaviorally different communities were identified during this study, namely the estuarine waters north of St. John's River (termed the Northern area), the estuarine waters …