The Bar Reef Marine Sanctuary lies off the north-west coast of Sri Lanka. In the first dedicated cetacean survey of this area, monthly boat-based surveys were carried out over 1 year (April 2004 to March 2005) both within the Sanctuary and seawards in deeper offshore waters. The survey established that the Sanctuary has year-round abundance of cetaceans. Eight species were observed, including three species of large whales. Live sightings of Sousa chinensis in this area were documented for the first time in Sri Lanka, as were the first live sightings of Kogia sima and Peponocephala electra off the west coast of the island. This area appears to be an important habitat for Balaenoptera acutorostrata in Sri Lanka's waters. Several threats to marine mammals were also identified and some were found to be localized and specific to this area. The results of this study were used to produce a set of management recommendations.

There have been few studies of trace elements in cetaceans from Chinese waters despite considerable potential for contamination by this class of pollutant. Between 1993 and 1996, blubber, liver and/or kidney tissues were collected from 11 Indo-Pacific hump-backed dolphins (Sousa chinensis) and 20 finless porpoises (Neophocaena phocaenoides) stranded in Hong Kong. These tissues were analysed for 12 trace elements (As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, Sn and Zn). In general, concentrations of trace elements were similar to those of other cetacean populations and were deemed not to be of any toxicological significance. However, concentrations of mercury in the liver tissues of certain individuals were at levels which could constitute a health risk to the animals (up to 906 mg g-1 dry weight). Cadmium, mercury and selenium were observed to bio-accumulate with age, whereas concentrations of copper were highest in neonatal animals.

Population biology and socio-ecology of Indo-Pacific humpback dolphins Sousa chinensis were investigated during a 3-year study period in the Algoa Bay region, South Africa. The dolphins inhabit a narrow strip of coastal waters, mostly less than 15 m deep. Groups are small (mean = 7 animals) and their daily activities concentrate around shallow rocky reefs—the primary feeding grounds. Dependence on these restricted, shallow-water habitats is evident throughout the year. Site fidelity is generally weak and is subject to seasonal migration, although female site fidelity seems to be related to reproductive stage. Births occur predominantly in summer. The social system is highly fluid, structured to some degree by sex and age, ‘matesearching’ behaviour being the most likely male reproductive strategy. The dolphins inhabiting Algoa Bay are part of a substantially larger population that uses a considerable length of the coastal zone. Estimated population parameters are generally low, as are modelled population growth rates, and an increase in the population size seems unlikely. Humpback dolphins appear to be vulnerable to negative environmental pressure and the alteration/destruction of inshore habitats is probably among the greatest threats to them. Conservation of this species should be given high priority and be seen as an important part of integrated coastal zone management. Establishment of multiple-use management areas with controlled ecotourism and several priority sites declared as strict reserves seems to be the most effective conservation approach. In order to be successful, conservation and management policies need to recognize the needs and lifestyles of the local inhabitants.

Group dynamics of humpback dolphins Sousa chinensis inhabiting the Algoa Bay region on the south Eastern Cape coast of South Africa, were investigated by means of boat-based photo-identification surveys undertaken between May 1991 and May 1994. Groups of humpback dolphins varied in size from three to 24 animals (x = seven), with adults representing almost two-thirds of the group members. Births occurred predominantly in summer. Some females, however, may also cycle outside of the apparent summer breeding season, perhaps indicating a secondary winter season. Circumstantial evidence suggests a minimum of a 3-year calving interval. Maternal care lasts at least 3–4 years, but female–calf separation is seemingly not related to the female's next pregnancy. Humpback dolphins displayed varying degrees of residence/fidelity to Algoa Bay. Although a few individuals may possibly be classified as ‘resident’, most dolphins were infrequent visitors in the Bay and seem to be transient. The social system of humpback dolphins appears to be fluid with only casual and short-lasting affiliations. Strong bonds between individuals other than mothers and calves are uncommon. Lack of consistency in the group membership appears to be the general pattern. The weak site fidelity and possibly extensive long-range movement of the majority of dolphins may contribute to the dynamic nature of humpback dolphin groups. There is probably some form of segregation between sex and/or age classes among humpback dolphins in Eastern Cape waters. The nature and extent of this segregation, however, is not yet sufficiently understood. It is likely that the degree of site fidelity displayed by female humpback dolphins is related to their reproductive stage and increases during the nursing period. Mate-searching behaviour of male humpback dolphins is the most likely reproductive strategy of the species.