Study Site
Spotted dolphins frequent the waters north of West End, Grand Bahamas Island, in an area known as the Little Bahamas Bank. It encompasses an extensive (45 km2), shallow sand bar approximately 64.5 km (40 miles) north of Grand Bahamas Island. This sand bar ranges from three to 10 m, with an average depth of six meters. Bordered by deep water of the Gulf Stream that drops rapidly from seven meters to well over 66 m, the Little Bahamas Bank lies in the warm (>28°C) Sargasso Sea.
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Little Bahamas Bank and Grand Bahamas Island, Bahamas. The shaded oval labels the area on the Little Bahamas Bank where our research vessel is usually anchored, and where more than 90% of the data is collected. |
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Study Animal
At birth, spotted dolphins are counter-shaded: coloration is white ventrally and gray dorsally with bands of dark gray pigment around the eye and between the eyes and flippers, and dark stripes along the melon anterior to the blowhole (Perrin, 1970). Born spotless, dark gray to black spotting appears in the throat and belly regions, typically before 3-4 years of age. As an individual reaches adulthood, the spots enlarge and coalesce, often obscuring the underlying counter-shaded pattern. Individual spotted dolphins are unique in their spotting patterns. These variations, and their subsequent annual changes, may be photographed underwater and used similarly to dorsal fin patterns from surface observations of other dolphins. The dorsal fins, pectoral fins, flukes, body scars, and other marks may also be used to identify different individual spotted dolphins.