NUMBERS of endangered Humpback dolphins in South Africa are half the figure previously estimated, and unless some drastic interventions are implemented the picture will become even more bleak.
They are deemed to be the country’s most endangered resident marine mammal, facing a high risk of extinction.
This warning arose in a recently published scientific paper after 16 researchers working at 13 different locations on SA’s coast from Richards Bay to False Bay, collected and shared photographs of Humpback dolphins’ dorsal fins, used to identify individual dolphins.
Designated by the SouSA Project, the collaboration was established in May 2016 and findings led to previous estimates of 1 000 individual dolphins now assessed to be half that number.
‘We pooled all the photos taken between 2000 and 2016 with the aim of better understanding movement patterns at a national scale,’ said marine biologist Shanan Atkins of the School of Animal, Plant and Environmental Science at the University of Witwatersrand.
‘In these photographs, 247 distinctive individuals were identified and 61 of them had been sighted at more than one location.
‘We learnt that the dolphins frequently move distances of 150km and we documented journeys of up to 500km.
‘Another important finding was that some individuals are re-sighted at the same locality over very long periods of time.
‘Photos taken in Richards Bay in the early 2000s were compared with photos taken by marine biology devotee Dave Savides in 2016 yielding the longest time span of re-sightings of an individual in the same area.
‘In fact, three Richards Bay individuals were re-sighted over 16 years.
‘At the other end of the scale, the shortest time between sightings at different localities was one day to travel 45km.’
The researchers are now working in the research-action space, lobbying for conservation action by the national government and will be meeting with the Department of Environmental Affairs next week in Cape Town.
‘Richards Bay had the highest Humpback dolphin encounter rate of all the locations in SA; it is indeed an important place for these dolphins,’ said Atkins.
‘This means that the dolphin viewing platform on the pier at Alkantstrand is the best place in the country to see this rare gem.
‘However, shark nets are considered a major threat to Humpback dolphins and our current research aims to understand the dolphins’ behaviour around the net that is responsible for the most deaths.’
Be a citizen scientist
The camera at Alkantstrand is back up and running, watching for dolphins near the beach and in the harbour mouth.
The live footage can be viewed at conservedolphins.weebly.com and on our facebook page www.facebook.com\conservedolphins
If you spot a dolphin please let us know the date and time of your sighting via our website. Such alerts are extremely helpful.
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