Atlantic and Indian Ocean humpback dolphins Sousa teuszii (Kükenthal, 1892) and S. plumbea (Cuvier, 1829)

This chapter provides comprehensive reviews of Atlantic humpback dolphins (Sousa teuszii) and Indian Ocean humpback dolphins (Sousa plumbea). Major themes of the chapter include taxonomy, systematics, ecology, morphometrics, genetics and physiology, as well as issues relevant to their conservation and management. It builds on the first edition of the Handbook, with considerably more information becoming available for both species in the intervening period, including the taxonomic revision of S. plumbea as a distinct species separate from the Indo-Pacific humpback dolphin (S. chinensis). Both species have very wide ranges, with the Atlantic humpback dolphin occurring exclusively along the Atlantic coasts of Africa from Morocco to Angola, and the Indian Ocean humpback dolphin occurs along the coasts of the Indian Ocean from False Bay in South Africa to Sri Lanka, incorporating the Red Sea, Persian Gulf and Arabian Sea and many islands. Both species also occur exclusively in a range of tidally dynamic shallow water habitats, typically within the 20m isobath and within a few kilometres of shore. While the two species broadly share many ecological and physiological characteristics, they are significantly distinct in many other ways, including in terms of genetics, morphometrics, behaviour and diets. The nearshore niches of both species make them extremely vulnerable to anthropogenic pressures, and available data indicate that their modern population sizes are small, and that in many areas they are either declining or absent. Major threats include fisheries bycatches and coastal development across much of their ranges, with other poorly studied threats like pollution likely contributing to their decline. In some areas these species are also utilised for food by growing coastal populations. Management actions will need to be sustained across decades in order to conserve both species.