Know your bottlenose from your humpback
Coordinator of the Garden Route Dolphin Research and Acoustic Monitoring Project Dr Alejandra Vargas Fonseca provided this latest update on her team’s marine mission, with pointers on how readers can get involved
The coastal zone along the Garden Route is well known for its high marine life diversity, including marine mammals, seabirds, fish, and invertebrates.
To conserve these precious coastal ecosystems, three Marine Protected Areas (MPAs) have been proclaimed: Goukamma (14km, est. 1990), Robberg (9.5km, est. 2000), and Tsitsikamma (57km, est. 1964-SA’s oldest MPA). MPAs serve as vital refuges for both fish and marine top predators (e.g. dolphins), but it is not certain whether their coverage meets the conservation needs of key species.
The Garden Route Dolphin Research project aims to better understand how these marine top predators use their habitat along South Africa’s coast. It is looking at the role of existing MPAs in terms of whether particular cetaceans are of conservation concern and require some form of management intervention.
For example, the International Union for Conservation of Nature (IUCN) Red List of Threatened Species currently lists the Indo-Pacific humpback dolphin (Sousa chinensis) as a near-threatened species, and the Indo-Pacific bottlenose dolphin (Tursiops aduncus) as “data deficient”, meaning that too little is currently known about its global and regional status.
So the study of dolphins and whales along the Garden Route is necessary to assess the role and effectiveness of MPAs for cetacean conservation; improve knowledge and understanding of the ecology and conservation status of various marine mammal species; and provide scientific information of practical relevance to regional conservation management.
The project is taking place from the eastern boundary of the Tsitsikamma MPA through to the western boundary of the Goukamma MPA, including the Robberg Peninsula MPA. All three MPAs are adjacent to a terrestrial Nature Reserve or National Park. The total research area covers ±170km of coastline.
The project aims to improve understanding of the population abundance, movement, habitat use, and genetic structure of the area’s Indo-Pacific bottlenose and humpback dolphins.
It assesses the connectivity between MPAs in terms of how dolphins move and utilise the study area, while identifying dolphin feeding hot- spots and associated areas of high ecosystem productivity.
Finally, it analyses vocalisations of the cetacean species present in the area throughout the year.
Methods employed to achieve these aims include bi-monthly boat surveys for two years to locate dolphins and conduct detailed observations. Animals are photographed and GPS coordinates, environmental variables, group size, composition (e.g. presence of mothers with calves), and behaviour from each encounter is recorded.
Monthly aerial surveys are conducted to search for the presence of animals along the coastline and an identification catalogue of bottlenose and humpback dolphins is being created based on both archived and new photos.
Dorsal fin photo-identification allows individual dolphins to be identified by unique patterns and markings (e.g. fin deformities, unusual fin shapes, scratches, etc.).
DNA laboratory analysis of skin and blubber samples will improve understanding of the different groups of bottlenose dolphins present in the area throughout the year.
Acoustic Monitoring Project
The Department of Environmental Affairs (Oceans & Coasts) has deployed three hydrophone moorings in the area. Hydrophones are similar to microphones, but instead detect underwater sound.
These instruments are constantly recording sounds from whales and dolphins that pass through the area during the year, and form part of a long term Passive Acoustic Monitoring (PAM) programme.
PAM is a cost-effective and non-intrusive method for obtaining important information about cetaceans.
Visit www.conserbio.org to listen to some of the sounds made by whales and dolphins as collected by the hydrophone.
Be part of the project! If you spot dolphins, please SMS the following information to 078 550 1742:
Type of dolphin/s (the most likely species to be seen along our coast are Indo-Pacific bottlenose, Indo-Pacific humpback, and Long-Beaked common dolphins).
Number of dolphins (approximate) and location, e.g. ‘Bottlenose, 30-40 animals, 100m off Sanctuary Beach’. If you are not sure of the species, just SMS number and location.
Sponsors to support the project are now sought – please email ale@earthcollective.net and visit www.conserbio.org for additional information.