BOTTLENOSE DOLPHIN (Tursiops truncatus): Northern Gulf of Mexico Oceanic Stock
Thirty-eight stocks have been provisionally identified for Gulf of Mexico bottlenose dolphins (Waring et al. 2001). Gulf of Mexico inshore habitat has been separated into 33 bay, sound and estuarine stocks. Three northern Gulf of Mexico coastal stocks include nearshore waters from the shore to the 2...
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| Format: | Text |
| Language: | English |
| Published: |
2003
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.228.7065 http://www.nefsc.noaa.gov/nefsc/publications/tm/tm182/pdfs/143.pdf |
| Summary: | Thirty-eight stocks have been provisionally identified for Gulf of Mexico bottlenose dolphins (Waring et al. 2001). Gulf of Mexico inshore habitat has been separated into 33 bay, sound and estuarine stocks. Three northern Gulf of Mexico coastal stocks include nearshore waters from the shore to the 20 m isobath. The continental shelf stock encompasses waters from 20 to 200 m deep. The Gulf of Mexico oceanic stock encompasses the waters from the 200 m isobath to the seaward extent of the U.S. Exclusive Economic Zone (EEZ; Figure 1). Both “coastal/nearshore ” and “offshore ” ecotypes of bottlenose dolphins (Hersh and Duffield 1990) occur in the Gulf of Mexico (LeDuc and Curry 1998). The offshore and nearshore ecotypes are genetically distinct using both mitochondrial and nuclear markers (Hoelzel et al. 1998). In the northwestern Atlantic, Torres et al. (2003) found a statistically significant break in the distribution of the ecotypes at 34 km from shore. The offshore ecotype was found exclusively seaward of 34 km and in waters deeper than 34 m. Within 7.5 km of shore, all animals were of the coastal ecotype. If the distribution of ecotypes found by Torres et al. (2003) is similar in the northern Gulf of Mexico, the oceanic stock consists of the offshore ecoptype. Based on research currently being conducted on bottlenose dolphins in the Gulf of Mexico, as well as the western North Atlantic Ocean, the structure of these stocks is uncertain, but appears to be complex. The multi-disciplinary research programs conducted over the last two decades (e.g., Wells 1994) are beginning to shed light on stock structures of bottlenose dolphins, though additional analyses are needed before stock structures can be elaborated on in the Gulf of Mexico. As research is completed, it may be necessary to revise all the stocks of bottlenose dolphins in the Gulf of Mexico. POPULATION SIZE Estimates of abundance were derived through the application of distance sampling |
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