WHILE much of the focus is on South Africa’s Big 5 as iconic wildlife, rays also hold the potential to drive tourism revenue, but more needs to be done to protect these endangered species from unsustainable fishing.
The country is home to the world’s largest rays: manta rays, which filter feed on zooplankton and play a crucial role in ocean health.
“Most South Africans don’t realise they can see manta rays without leaving the country,” said Dr Michelle Carpenter, a collaborator of the Marine Megafauna Foundation (MMF), Clansthal Conservancy, and Manta Trust.
“We’re home to the reef manta ray (Mobula alfredi) and the oceanic manta ray (Mobula birostris), the latter reaching an impressive 8 metres wingtip to wingtip, making it the largest ray in the world.”
Carpenter was speaking after a nationwide collaborative study by marine biologists, which has uncovered some of the mysteries of South Africa’s manta rays, was released this month.
Human impacts have, unfortunately, caused significant population declines, making this the most threatened population of this species in the world. It is listed on the IUCN RedList, indicating the species is globally threatened. Trawling, tuna purse seine nets, gill nets in Mozambique, shark nets in South Africa, and seismic testing by oil companies all threaten the vulnerable population.
The study uncovered unique characteristics of South Africa’s mantas, including highly mobile reef mantas, rare black oceanic mantas, newfound feeding aggregations, and potential baby manta nurseries.
In iSimangaliso Wetland Park in northern KZN, manta ray feeding aggregations were found in a marine sanctuary protected from fishing and recreational diving for over 50 years. It is here that 89% of South Africa’s reef manta sightings have been recorded, where mantas feed and have parasites removed by cleaner fish.
“This aggregation area within a restricted-access sanctuary is a haven amid threats along the coastline,” says Nakia Cullain of the Marine Megafauna Foundation (MMF), that participated in the study. “The whole park was recently named a Mission Blue Hope Spot, joining a network along South Africa’s coast that includes Aliwal Shoal and Cape Town.”
Cullain says South Africa’s sanctuary demonstrates how effective marine protection can support not only manta ray aggregations, but other species as well, providing a valuable model for countries like Mozambique, which currently lacks extensive marine protection.
Research in iSimangaliso and other areas like Aliwal Shoal has shown significant connectivity to Mozambique. Some key findings include:
- One manta travelled 1 305 km multiple times between Zavora, Mozambique, and iSimangaliso.
- Another travelled over 600 km from Pondoland MPA to iSimangaliso.
- A juvenile seen in Pondoland MPA in 2016 was later seen again as a pregnant adult in iSimangaliso.
- Two mantas made repeat trips between Zavora and iSimangaliso (870 km round trip).
- 28 mantas were identified in Mozambique, with most linked to Zavora.
Carpenter says the movements were potentially driven by the availability of zooplankton, which are transient along the coastline and with seasonal patterns.
“While mantas have been officially documented in South Africa since the 1950s, shifts in their movements could be linked to climate change, with rising water temperatures affecting currents and food availability.”
Dr Ryan Daly, a specialist in shark and ray movement patterns, emphasises the importance of cross-border conservation efforts: “Because these animals cross borders, conservation management plans need to be aligned between South Africa and Mozambique to protect their populations.”
Oceanic mantas are infrequent in South Africa with sightings concentrated in Ballito, Aliwal Shoal MPA, and Pondoland MPA. The researchers were excited to discover rare melanistic (black) oceanic manta rays in Aliwal Shoal in February 2020 and Ballito in November 2021.
Carpenter says it was not previously known that melanistic oceanic mantas inhabited those waters. “Genetic studies suggest no distinct population groupings, but regional differences in melanism are likely tied to localised groupings, with gene flow facilitated by long-distance travel. ”We love that these melanistic mantas contribute to South Africa’s beautiful ‘RAYnbow’ Nation,” she said.
Mantas face threats from fishing, seismic testing, and climate change. Collaborative research and effective marine sanctuaries like the iSimangaliso Wetland Park provide hope for their future.
Carpenter says there is no shortage of work to do with sharks and rays along South Africa’s coastline. "I encourage South Africans and international students eager to make a difference to join us. It’s hard work but immensely rewarding.”