A new study has begun that will examine the health of humpback dolphins to better assess the threats this species faces and prescribe an effective conservation plan.
Researchers from along South Africa’s east and south coasts gathered together at the Nelson Mandela University’s Ocean Sciences Campus in August 2018. They met to discuss how to conduct a country-wide assessment of skin diseases and other injuries observed in these dolphins.
Guided by Ocean Health Researcher, Dr Stephanie Plön, they developed a strategy to assess the diseases, ailments and injuries visible on the skin of the dolphins, and how these vary through time and space. One particularly intriguing skin disease, tattoo skin disease, presents as an intricate stippled pattern in an oval shape (see photographs).
Humpback dolphins are endangered because they only occur in a narrow band of very shallow coastal waters, close to shore, and are exposed to the negative impacts of human activities occurring both on land and the marine environment. Worrying threats include overfishing which leads to a reduction in dolphin prey, pollution from the land such as pesticides, noisy boat traffic, and shark nets. There may be as few as 500 adults left and they are slow to reproduce.
Few people have even heard of humpback dolphins, they are quite rare and shyer than their better-known cousins, the bottlenose dolphins.
Local researchers sharing concern for this species decided to join forces and formed the SouSA Consortium (the humpback dolphin’s scientific name is Sousa plumbea) in 2016. “We needed to draw the local research groups together to create a systematic, national research agenda so that we could answer questions at a more appropriate scale for conservation”, said Dr Simon Elwen from the Mammal Research Institute, University of Pretoria and SeaSearch Research and Conservation. Sixteen researchers from 12 institutions share their data and work together to improve the Dolphins’ situation.
This is a unique initiative, admired by international researcher Dr. Gill Braulik from the International Union for the Conservation of Nature’s Cetacean Specialist Group who says “This collaborative effort is truly inspiring and our South African colleagues are leading the way.”
The dolphin researchers have been out on boats collecting photographs of humpback dolphins at 13 sites within the dolphins’ range from KwaZulu-Natal, Eastern Cape, and Western Cape. These photographs have already been used to determine how far and how frequently dolphins move along our coast and now the researchers have new plans.
“We are going to scrutinise the photographs for signs of skin disease as indicators of the health of the animals as well as signs of injury, either from human or natural causes,” says Nelson Mandela University’s Dr. Stephanie Plön (AEON- Earth Stewardship Science Research Institute). World leader on dolphin skin diseases, Dr. Marie-Francoise van Bressem from the Peruvian Centre for Cetacean Research, will contribute her veterinary expertise. Eyes will be peeled for gruesome sounding diseases such as Lobomycosis (caused by a fungus) and the less innocuous sounding Tattoo Skin Disease (caused by a poxvirus), and for external parasites. Other things they will be on the lookout for include evidence of shark bites, propeller injuries and amputated fins.
Photograph: Dolphin tattoos. Endangered humpback dolphins have tattoos that are caused by a poxvirus.
Photo Credit: Brett Atkins.
News supplied by Pat Fletcher, Howick resident and a member of the Humpback Dolphin research group based in Richards Bay.