BOTTLENOSE DOLPHIN (Tursiops truncatus) Indian River Lagoon 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 bays, sounds and estuaries. Except for animals residing within the Southern North Carolina and Northern North Carolina Estuarine Systems (e.g., Waring et al. 2007), 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 of the southeastern United States (e. patterns have been observed in bays and estuaries along the Gulf of Mexico coast (e.g., Wells et al. 1987; Balmer et al. 2008). Recent genetic analyses using both mitochondrial DNA and nuclear microsatellite markers found significant differentiation between biopsies collected from bottlenose dolphins along the coast and those collected within the estuarine systems at the same latitude (NMFS unpublished data). Similar results have been reported for the west coast of Florida (Sellas et al. 2005). The Indian River Lagoon Estuarine System (IRLES) stock on the Atlantic coast of Florida extends from Ponce de Leon Inlet in the north to Jupiter Inlet in the south and encompasses all estuarine waters in between, including but not limited to the Intracoastal Waterway, Mosquito Lagoon, Indian River, Banana River and the St. Lucie Estuary. Five inlets and the Cape Canaveral Locks connect the IRLES to the Atlantic Ocean. This definition of the IRLES has been used by a number of researchers (e.g., Kent et al. 2008) and is the most expansive definition. Some researchers truncate the southern border at the St. Lucie Inlet. Multiple studies utilizing varying methods such as freeze-branding, photo-ID and radio telemetry support the designation of bottlenose dolphins in the IRLES as a distinct stock. Odell and Asper (1990) reported that none of the 133 freeze-branded dolphins from the IRLES were observed outside of the system during their 4-year monitoring period from 1979 to 1982 and suggested that there may be an additional discrete group of dolphins in the southern end of the system. A stranded dolphin from the IRLES that was rehabilitated, freeze-branded and released into the IRLES was recaptured 14 years later in the IRLES during a health …