Population biology, residency status, and management of bottlenose dolphins, Tursiops truncatus, in the Eastern Bay and Choptank River areas of Chesapeake Bay

Atlantic bottlenose dolphins, Tursiops truncatus, found in Chesapeake Bay are a part of the inshore migratory stock. In 1987--88 a catastrophic mortality event occurred, after which National Marine Fisheries Service declared the stock depleted. There were no studies of this species in Maryland waters prior to this study. From 1995 to 1998 a study utilizing photo-identification was conducted in the Eastern Bay and Choptank River areas of Chesapeake Bay. The objectives of this study were to: (1) confirm the presence of dolphins in this area; (2) determine if they were summer residents or transients; (3) match photo-IDs with other dolphin catalogs; (4) determine if the area was a nursery area; (5) determine if salinity or water temperature influenced dolphin presence in the area; (6) review what the State of Maryland could do to facilitate dolphin population recovery; and (7) develop a brief boating/marine mammal education plan.; It was concluded that bottlenose dolphins may occur in Maryland waters of Chesapeake Bay depending on temporal and physical factors, but they are transient to these waters. Twenty-seven individual dolphins were photographically identified. The majority of dolphins were in Maryland waters of the Bay for a 2--3 week period from mid-May to mid-July. There was a positive correlation between higher salinity levels and dolphin presence. In spite of observations of neonates, the protected waters of the Eastern Shore of the Bay do not appear to be a critical nursery area.; Fishery apparatus such as crab pots, eel pots, gill nets, and loose fishing gear, lines, and nets have potential for entanglement with dolphins. Due to the limited time the dolphins are in the area, the risk does not appear to be high. Boat/dolphin interactions have a relatively high potential for harm. The public needs to be educated on how to handle a vessel responsibly in the presence of marine mammals. Enclosing an educational handout with boating licenses is one method of increasing public awareness.