Spatial Distribution of Indo-Pacific Humpback Dolphins (<I>Sousa chinensis</I>) at Richards Bay, South Africa: Environmental Influences and Behavioural Patterns

Area utilization patterns of humpback dolphins (Sousa plumbea) in Richards Bay, KwaZulu-Natal, South Africa

“…Earlier work by Durham (1994), Keith et al (2002) and Atkins et al (2004) indicates that the Richards Bay area is preferred by humpback dolphins, with foraging/feeding occurring predominantly close to shore. To gain greater insights into the population ecology of humpback dolphins at Richards Bay, it is important to understand their spatial use in the environment where several potential threats are concentrated within a spatially-limited area.…”

Molecular ecology meets remote sensing: environmental drivers to population structure of humpback dolphins in the Western Indian Ocean

“…We test the above mentioned issues of population structure in relation to environmental heterogeneity in the Indo-Pacific humpback dolphin (Sousa chinensis), which is distributed in the coastal waters of the Indian Ocean basin from South Africa to China and along the coasts of Australia (Karczmarski et al, 1999a;Jefferson and Karczmarski, 2001;Atkins et al, 2004;Hung and Jefferson, 2004;Parra et al, 2004;Sutaria and Jefferson, 2004;Wang et al, 2004;Amir et al, 2005). The taxonomy of the genus is largely unresolved and there are presently two recognized species, the Indo-Pacific and Atlantic (Sousa teuszii) humpback dolphins (Jefferson and Karczmarski, 2001).…”

“…Humpback dolphins inhabit the warm and shallow waters of the continental shelf, typically up to depths of 25 m, and are frequently seen in the proximity of rivers, deltas and estuaries (Karczmarski et al, 2000;Atkins et al, 2004;Stensland et al, 2006). They usually form small groups ranging between 2 and 13 individuals along the eastern African coastline (Karczmarski, 1999;Peddemors, 1999;Stensland et al, 2006), although larger group sizes have been frequently recorded around the Arabian Peninsula, and in particular along the Arabian Sea coast of Oman (Baldwin et al, 2004).…”

“…In the southern portion of their range, they are typically observed feeding in shallow rocky reefs (Karczmarski et al, 1999b), but further north are inevitably closely associated with areas where fresh and salt water mix (Peddemors and Thompson, 1994;Parsons, 1998;Karczmarski et al, 1999b;Atkins et al, 2004). Around the Arabian Peninsula, humpback dolphins are mostly seen associated with shallow waters and sandy and vegetated substrates (Baldwin et al, 2004).…”

“…Moreover, foraging specializations have been shown to influence population structure patterns in common bottlenose dolphins (Tursiops truncatus) and Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Australia (Chilvers and Corkeron, 2001;Chilvers et al, 2003). Humpback dolphins have been observed feeding on productive areas (that is, reefs, estuaries, mixing areas), and their movement patterns are significantly influenced by the seasonal presence and abundance of prey species (Karczmarski et al, 1999a, Environmental drivers to population structure M Mendez et al 1999b; Atkins et al, 2004;Guissamulo and Cockcroft, 2004;Parsons, 2004). Therefore, we suggest that the differences in the environmental features between sampling areas point to differences in productivity, and that such heterogeneity likely influences humpback dolphin distribution and population structure patterns.…”