THERE are fewer than 500 Indian Ocean humpback dolphins (Sousa plumbea) remaining in South African waters, and science alone will not bring them back from the brink of extinction.
It will take a multi-stakeholder Conservation Management Plan to boost their numbers.
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This is according to the SouSA Consortium, a formalised network of 17 scientists and conservationists from 11 institutions across South Africa.
They are focusing on the conservation status of the little-known humpback dolphin, found from False Bay to Kosi Bay, with Richards Bay one of the prime viewing areas.
The International Union for the Conservation of Nature and the Red List of Mammals of South Africa has listed the humpback dolphin as the first, and to date only, endangered marine mammal resident in South African waters.
The consortium conducted a Swot (Strengths, Weaknesses, Opportunities and Threats) analysis to identify what should be done to improve the conservation of these dolphins, with the findings published in the journal, Frontiers in Marine Science.
‘Although environmental factors almost certainly play a role in the declining numbers of the species in our waters, individual threats and solutions are challenging to identify,’ said lead author and Associate Professor Stephanie Plön from the Department of Pathology at Stellenbosch University (SU) and the Bayworld Centre for Research and Education in Port Elizabeth.
‘This is because the South African marine environment is undergoing significant changes, often as a result of human activities such as coastal construction and pollution. There are also major changes in the distribution and availability of prey species.
‘We concluded that no single cause for their rapid decline could be identified and that the cumulative effects of multiple stressors, which are difficult to pinpoint, are impacting population numbers.’
Shanan Atkins from the School of Animal, Plant and Environmental Sciences at the University of the Witwatersrand, who heads the research at
Richards Bay, added, ‘The main strength is the diversity of specialist skills within the consortium, while the main weakness is dealing with multiple impacts and engaging with policymakers and funders.’
Opportunity
‘The fact that the dolphin’s ‘Endangered’ status is formally recognised presents a key opportunity to facilitate action with regards to governance,’ said Dr Els Vermeulen from the Mammal Research Institute at the Faculty of Natural and Agricultural Sciences at the University of Pretoria.
The consortium is hopeful that recent developments present instruments to facilitate a shift in species conservation, such as the newly-declared Important Marine Mammal Areas.
However, the main threat to the species’ conservation is the impact of human activity in the coastal zone.
One example is ‘Operation Phakisa’ – an initiative to stimulate economic growth in the marine environment – which is likely to increase the noise level in the oceans.
‘Growth in sectors like oil and gas exploration, marine transport, harbour development and fishing or aquaculture will increase noise levels in the ocean, introduce pollutants and could result in unintentional habitat partitioning,’ said co-author Dr Gwenith Penry from the Institute for Coastal and Marine Research at Nelson Mandela University.
‘The consortium is working towards high-level interdisciplinary engagement to ensure any potentially harmful effects are appropriately mitigated.’
The consortium hopes the study forms the basis of a Conservation Management Plan that will ensure healthy gene flow in the population, prevent population segregation and improve habitat quality in critical coastal areas.
Plön says the consortium will continue to engage with government to declare humpback dolphins a priority species for conservation.
