The Namibian Dolphin Project | Population ecology of bottlenose and Heaviside’s dolphins

Projects

Population ecology of bottlenose and Heaviside’s dolphins, abundance, population structure and habitat use

Our core research revolves around investigating the conservation status of Namibia’s coastal delphinids. We are using multiple techniques to assess abundance, trends, habitat use, behaviour, acoustic communication and human impacts.

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In 2008 the NDP began investigating the conservation status, ecological interactions and population structure of dolphins inhabiting the coastal of Namibia. Initially the focus was the endemic Heaviside’s dolphin (Cephalorhynchus heavisidii) and a small resident population of bottlenose dolphins (Tursiops truncatus) in Walvis Bay. We have subsequently expanded out focus to include dusky dolphins and a secondary site down at Luderitz (the only other harbour in Namibia) and the the surrounding NIMPA, which is an ecologically important area for coastal dolphins due to the fish stocks associated with the area.

We already have 4 winter seasons of data and aim to continue monitoring these populations into the future. Long term population monitoring is necessary to assess conservation efforts so far, provide up to date information for the mitigation of new impacts in the ecosystem and investigate ecological relationships at a broad scale, relevant to impacts such as climate change & ecological regime shift.   Already, our data has allowed us to identify a critical resting habitat of bottlenose dolphins in Walvis Bay and negotiate with the marine tourism industry to declare this a ‘no-go’ zone for tour vessels to provide a sanctuary area for animals within Walvis Bay. More recently (2011 onwards).

We are using multiple techniques to investigate these populations including visual surveys by small boat to look at space use; moored hydrophones (CPODS) to look at habitat use in core areas over time; photographic identification to assess abundance through mark-recapture techniques and investigate social relationships and how these affect various aspects of the dolphins behaviour and even our data analyses!  We are also using stable isotope techniques to investigate changes in diet at broad scales throughout the Benguela ecosystem.

Below I’ve inserted some older maps produced by Theo Meyer (UP Honours student 2009) showing the differential use of Walvis Bay by Heaviside’s (blue) and bottlenose dolphins), so you can get an idea of how differently these animals are using (and thus interacting with) the environment – and then consider what this means for mitigating threats to these animals.