Collaboration on humpback dolphin (Sousa plumbea) research and conservation in South and East Africa

Humpback dolphins in the Indian Ocean were recently recognised as a distinct species (Sousa plumbea) that occurs in coastal waters from South Africa to India. The species occurs in very near-shore habitat, generally in water less than 30 m deep and typically less than 2 km from shore, and is therefore exposed to high levels of human activity throughout its range. The conservation status of all four Sousa species is currently being assessed for the Red List, and S. plumbea has been proposed (but has not yet been listed) as “Endangered”.

Humpback dolphins are considered to be South Africa’s most endangered marine mammals. They were recently re-assessed for the South African National Red List, and the status was changed from Vulnerable to Endangered due to declining sighting rates and group sizes, in comparison to previous assessments, as well as newly available estimates of abundance from discrete areas that suggest the overall population size in South Africa is very small [1].

In early 2016, a Memorandum of Understanding (MOU) that established the “SouSA Consortium” was signed by 16 scientists and research groups in South Africa.

Figure 1: Some of the signatories of the SouSA Consortium Memorandum of Understanding in South Africa

The consortium is designed to facilitate the collection and sharing of humpback dolphin data across the country, which is hoped to make a substantial contribution towards the conservation of this species. Specifically, the consortium aims to generate data and analyses on a larger geographical scale, something that is impossible for individual research groups. The specific objectives of the project are to:

• produce an estimate of the total population size and trend of humpback dolphins in South African waters
• characterize the movement patterns of humpback dolphins along the entire South African coastline
• determine spatial and temporal patterns of humpback dolphin distribution and assess connectivity between areas
• evaluate population viability (incorporating estimates of abundance, reproduction and survival) of humpback dolphins in South Africa.

In Kenya and Tanzania (East Africa), knowledge of humpback dolphins is less extensive than in South Africa, but populations appear to be similarly small and subject to many threats [2]. Funding is secured and plans are in place to sign a MOU to establish an East African Cetacean Working Group that will collaborate on coastal dolphin research and conservation in Kenya and Tanzania. The East African working group will have similar objectives to the South African SouSA Consortium, and the two groups intend to work together in future to answer broad-scale regional questions related to humpback dolphin conservation.

These types of collaborations are important and to be encouraged in areas where knowledge and resources are limited, but conservation concerns are high, something that is true for many regions and marine mammal species. Fisheries bycatch and the loss of habitat through coastal development are major conservation concerns for coastal small cetaceans that can rarely be addressed adequately by projects working in isolation. Recent reviews of the status of all four species in the genus Sousa (S. teuszii [3]; S. plumbea [2]; S. chinensis [4] and S. sahulensis [5]) provide evidence for significant declines in most areas, and much more work is needed to increase scientific knowledge and raise public awareness.

References

1. Plön, S., V.G. Cockcroft, and W.P. Froneman. 2015 Chapter Six – The Natural History and Conservation of Indian Ocean Humpback Dolphins (Sousa plumbea) in South African Waters, in Advances in Marine Biology, T.A. Jefferson and B.E. Curry, Editors, Academic Press. p. 143-162.
2. Braulik, G.T., K. Findlay, S. Cerchio, and R. Baldwin. 2015 Chapter Five – Assessment of the Conservation Status of the Indian Ocean Humpback Dolphin (Sousa plumbea) Using the IUCN Red List Criteria, in Advances in Marine Biology, T.A. Jefferson and B.E. Curry, Editors, Academic Press. p. 119-141.
3. Collins, T. 2015 Chapter Three – Re-assessment of the Conservation Status of the Atlantic Humpback Dolphin, Sousa teuszii (Kükenthal, 1892), Using the IUCN Red List Criteria, in Advances in Marine Biology, T.A. Jefferson and B.E. Curry, Editors, Academic Press. p. 47-77.
4. Jefferson, T.A. and B.D. Smith. 2016 Chapter One – Re-assessment of the Conservation Status of the Indo-Pacific Humpback Dolphin (Sousa chinensis) Using the IUCN Red List Criteria, in Advances in Marine Biology, T.A. Jefferson and B.E. Curry, Editors, Academic Press. p. 1-26.
5. Parra, G.J. and D. Cagnazzi. 2016 Chapter Seven – Conservation Status of the Australian Humpback Dolphin (Sousa sahulensis) Using the IUCN Red List Criteria, in Advances in Marine Biology, T.A. Jefferson and B.E. Curry, Editors, Academic Press. p. 157-192.