Cape Town – An orca whale killing spree of great white sharks that has gripped the Western Cape coast since May 2017 is not only threatening the already endangered shark species, but also the shark cage diving industry which is one of the Cape’s popular tourism offerings.
Orca predation of great white sharks – resulting in four sharks experiencing the same attack in which the sharks’ livers were neatly removed with the rest of the animal still intact – is “a first” of this kind of attack in South African waters.
The series of attacks which took place on SA’s Western Cape coast – three in May and one in June - also resulted in the first ever dissection of a great white shark following an attack of this nature.
As scientifically fascinating, and ecologically alarming and mysterious as these attacks may be, it also poses a threat to the country’s coastal tourism sector.
A further negative impact on the ecosystem, according to a report by Marine Dynamics and Dyer Island Conservation, is that great white sharks are a very necessary apex predator in helping keep the abundant Cape fur seal population in check.
The report by Marine Dynamics, which for the past ten years documents every shark sighted, says “The shark cage diving industry has a limited permitted area and sightings in the bay were affected as the white sharks, sensing a threat, temporarily left the area for a couple of weeks.”
“However, the sharks slowly started returning and sightings continued as usual” the report adds, but then a fourth attack happened and the sharks were scarce again for a few weeks before sightings resumed.
This in turn has started to impact the businesses of tour operators who rely on the appearance of sharks for cage diving and sighting opportunities for tourists.
“All operators in the Kleinbaai area of operation are affected,” says du Toit, adding that operators are only allowed to work within this bay due to permit conditions. “So while sharks may be sighted in adjacent bays this area is not in our permitted area,” she says, explaining to Traveller24 that "permits are based around seal colonies".
“The shark cage diving industry is also subject to weather and sea conditions which are a pressure on the businesses every year especially during the time of winter storms,” says Du Toit.
Managing the impact
“This scarcity of sharks as they move out of the area upon detecting a natural predator is unprecedented and we do not know the long term impacts.
"Operators are assessing the situation every day and being transparent with their clients, for whom many, seeing a white shark is one of the reasons they came to South Africa," Du Toit explains.
Wilfred Chivell, CEO of Marine Dynamics says,“It is important we manage client expectations at this time.”
Regarding managing business, Du Toit says that tour operators each have “their own refund policy” in place.
“Marine Dynamics has just amended their refund policy from 50% to 25% in the event of no sharks sighted,” says Du Toit, adding that the shark cage diving operator now runs “only one trip a day versus the two to three we normally do”.
“Clients are advised of the situation and understand the risk,” she says.
Marine Dynamics has a number of entertaining and informative sessions to make up for the lack of shark sightings, to ensure that tourist numbers are up.
To keep trips interesting Du Toit says a marine biologist is on board to educate visitors on everything the company has learnt over the past decade, and they also make a stop past the seal colony on Geyser Rock, which is what the sharks primarily feed on. They also talk about “seabirds, seals, whales and dolphins and everything else wonderful in our unique Dyer Island ecosystem,” she says.
"Many clients are not giving up on seeing a white shark and we know that the sharks will return to the bay as they always have, so we don’t want to miss out by not being on sea when they do. On our last trip we had a beautiful 3m shark. Some of our clients are choosing to do the whale watching or eco-trip with sister company, Dyer Island Cruises," says Du Toit.
Gansbaai businesses continue to operate
Glenda Kitley, manager at Gansbaai Tourism Bureau, confirmed with Traveller24 that the attacks have impacted business in the Gansbaai area, even though tourists continue to visit the town and shark sighting tour businesses continue to operate. "We still get tourists,” she says.
“The attacks did have an impact on shark cage diving,” she says. While tour operators continue with business, Kitley says there are fewer shark cage dives booked resulting in operators buying less fuel to go out into the ocean – this being an example of how there has been a “ripple effect on other businesses”.
Kitley says that sharks have become scarce in the area since February this year. “Sharks have returned to a certain extent but sightings and cage diving can only happen when weather permits,” she says.
When asked how Gansbaai Tourism is dealing with the impact of the attacks on the tourism industry, Kitley says that the tourism bureau is yet to meet with the affected parties. “We want to get shark cage diving tour operators together to see what can be done,” she says. Kitley adds that the impact of the attacks is something that “we have to look at seriously”.
However, she assured Traveller24 that the “shark cage diving industry still exists” and there have been “no extreme cases” of the attacks impacting business.
How and why are Orcas targeting Great White Sharks?
Known as the “Wolves of the Sea”, orcas are the true apex predators of the ocean, and the only known predator of the great white shark.
They are extremely intelligent, specialised hunters, feeding above sharks on the overall oceanic food chain. They hunt in organised social groups, using echo-location, strategy, and teamwork to kill their prey, which can be anything in the ocean, from seals, to dolphins, dugongs, otters, turtles, birds, squid, and sometimes even land mammals.
According to the DEA statement, the orcas were targeting the squalene rich livers that assists sharks with their buoyancy. This substance is also highly nutritious pound for pound, compared with the muscle tissue. Although this type of selective feeding on livers is extremely rare in orca whales, seals have been known to predate sea birds where they often remove and consume only the stomach/abdominal content and not the rest of the carcass.
Orcas are also suspected to be responsible for a decline in Cape Town’s cow shark population, and have been known to predate these sharks. Alison Kock, a Marine Scientist for Shark Spotters, reported recovering several cow shark carcasses in a similar condition with their livers removed, in False Bay subsequent to a series of orca sightings.
How the orcas are able to extract the livers so neatly from the sharks is a bit of a mystery. But footage off the coast of California showed team-work between the orcas pushing a white shark to the surface, belly up, biting into its flesh, before letting the buoyant, oil-rich liver float out of the cavity.
Orca vs Great White Shark
According to Marine Dynamics, an orca grows to about 9,5m and is a bigger contender than the great white shark - although the largest female predated on was quite large at 4,9m.
"Orca’s are known skilled hunters and will hunt in pairs or a pod making them no match for a solitary great white. However, as a mammal, Orca’s do need to surface breathe and cannot go to the depths that a white shark is capable of, making depth and exit the best strategy for a white shark," says the report.
The orca pair believed to have killed the fourth great white shark have been nicknamed Port and Starboard, and were spotted around the time when the shark carcass was spotted.
SEE: Eye-to-eye with the 'world's most misunderstood animal': Why this ocean photographer is swimming with sharks
What does this mean for Great White Sharks in South Africa?
Orca whales are widely distributed in the ocean, extending from the Arctic to the Antarctic, into the tropics, and are present in both coastal and oceanic waters.
According to figures from the DEA, orca whales are fairly common along the coast of South Africa, and some 785 sightings have been recorded ranging from the Western Cape all the way to Northern KwaZulu-Natal.
“The sightings of Orca pods appears to be increasing in South Africa,” says the DEA in a recent statement, but these sightings could also be attributed to more people on the ocean with eyes on the water.
Du Toit says "Great white sharks are migratory but return to the area over the years so we see growth and maturity of the white sharks." She also says that there have been weeks where sharks became scarce since 2016 and "now we can connect this back to sightings of the orca".
The incidents have already affected the number of great white sightings, as the sharks leave the bay to avoid the orcas. The last shark sighting by Marine Dynamics was on 14 July. "Keep updated on our daily blog on the Marine Dynamics website," says Du Toit.
The killings are a blow to the already struggling population of great white sharks in South Africa, a local population which some scientists say is facing extinction.
The DEA, along with various shark scientists and marine mammalogists, is currently collating all the scientific information about the incidents, and they are urging the public to be aware that this is a natural phenomenon, and might have to do with changes in seasons or temperatures and prey regimes of the orcas.
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