Heaviside’s Dolphin is a coastal, shelf-dwelling species seen mainly in waters less than 100 m deep (Best and Abernethy 1994) throughout the cold, northward-flowing Benguela Current. More than 85% of sightings have been in water with surface temperatures of 9-15°C (Best and Abernethy 1994). Evidence from photo-identification (Elwen 2008, Elwen et al. 2009b) and satellite-linked tagging (Elwen et al. 2010, Davis et al. 2014) indicated small home ranges between 50 and 80 km along shore, but with some animals also moving offshore to at least the 100 m isobath.

Throughout most of their range, Heaviside’s Dolphins show a strong diurnal inshore-offshore movement pattern (Elwen et al. 2006, 2010) driven by resting and socializing inshore by day and nocturnal foraging in deep water on prey associated with the deep scattering layer. The dominant prey taken by Heaviside’s Dolphins are shallow-water species or life-stages, for example juvenile Hake (Merluccius capensis), Goby (Sufflogobius bibartus) and Horse Mackerel, as well as cephalopods, including octopus (Sekiguchi et al. 1992). Most fish eaten by Heaviside’s Dolphins are well below the modal length of commercially caught fish (Sekiguchi et al. 1992), and there is little spatial overlap in fishing effort and dolphin habitat (Fairweather et al. 2006).

Heaviside’s Dolphins are listed in Appendix II of the Convention in International Trade in Endangered Species.

More information is needed on the distribution of the species in Angolan waters in particular, as well as on the nature and extent of incidental catches. More research emphasis should in future also be placed on possible detrimental interactions due to the overfishing of prey stocks, especially Hake. Increased inshore fishing pressure will inevitably increase interactions between the fisheries and Heaviside’s Dolphins (Peddemors 1999).