STOCK DEFINITION AND GEOGRAPHIC RANGE
There are two hematologically and morphologically distinct bottlenose dolphin ecotypes (Duffield et al. 1983; Duffield 1986) which correspond to a shallow water or nearshore/coastal ecotype and a deep water or offshore ecotype; both ecotypes have been shown to inhabit waters in the western North Atl...
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| Format: | Text |
| Language: | English |
| Published: |
2003
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.227.8169 http://www.nefsc.noaa.gov/nefsc/publications/tm/tm182/pdfs/86.pdf |
| Summary: | There are two hematologically and morphologically distinct bottlenose dolphin ecotypes (Duffield et al. 1983; Duffield 1986) which correspond to a shallow water or nearshore/coastal ecotype and a deep water or offshore ecotype; both ecotypes have been shown to inhabit waters in the western North Atlantic Ocean (Hersh and Duffield 1990; Mead and Potter 1995; Curry and Smith 1997). The offshore and nearshore ecotypes are genetically distinct using both mitochondrial and nuclear markers (Hoelzel et al. 1998). Bottlenose dolphins which stranded alive in the western North Atlantic in areas with direct access to deep oceanic waters had hemoglobin profiles which matched that of the deep, cold water ecotype (Hersh and Duffield 1990). Hersh and Duffield (1990) also described morphological differences between the deep, cold water ecotype dolphins and dolphins with hematological profiles matching the shallow, warm water ecotype which had stranded in the Indian/Banana River in Florida. Based on the distribution of sightings during ship-based surveys (Figure 1) and survey personnel observations (NMFS unpublished data), the western North Atlantic offshore stock is believed to consist of primarily of the offshore ecotype. However, the range of the coastal and offshore ecotypes overlap to some degree. 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. |
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