An orca attack on white shark in EC waters raises fresh questions about ‘seascape of fear’

Orcas. (Photo: Zafar Monier)

By Ed Stoddard

19 Jun 2024

Amid debates about whether South Africa’s white shark population has shifted partly east or gone into a precipitous decline, sightings off the Eastern Cape – followed by a vanishing act in the wake of a confirmed orca attack – add credence to the view that the sharks move on when they become prey.

In late April this year, Steve Benjamin, founder of Animal Ocean, an outfit which offers wildlife marine expeditions in South African waters, noticed an intriguing trend as he and his colleagues tracked the annual sardine run from a helicopter off the Eastern Cape coast.

In the 16 years that he has been in the business, Benjamin had never seen so many white sharks from the air around Chintsa Bay, which lies about 45km north of East London.

“We noticed by chance that there was an exceptional number of white sharks in Chintsa Bay. My colleague Aiden Biccard counted 46 on one flight. That was the maximum we saw on one flight but we were flying for three weeks and every day we were seeing 10 or 20 or 30 white sharks,” Benjamin told me in a telephone interview.

“We were looking for sardines and spotted 46 white sharks on one flight around the end of April. On other days we saw up to 30. It was quite variable but each day we saw huge numbers of white sharks,” he said.

https://www.youtube.com/watch?v=9SM_q4aXO48&feature=youtu.be

The video footage that Benjamin and his crew took, as well as stills, have been examined by shark experts including Dr Alison Kock, a marine biologist at SANParks. She confirmed that most of the sharks spotted – when they could be seen clearly – were white sharks.

“In my experience, it’s unusual to see other sharks visible near white sharks. When I did aerial surveys in False Bay I would count up to 50 and they were all white sharks. Other species remained cryptic. When there were no white sharks, I would see bronze whalers, seals, stingrays etc,” Kock told me.

orca white shark A white shark savaged by an orca in Chintsa Bay, Eastern Cape, with a common dolphin found inside the shark. (Photo: Kevin Cole / East London Museum, 28 May 2024.)

Then, in late May, literally out of the blue, a shredded 4.6-metre-long white shark washed up in the area bearing all the hallmarks of orca predation, including the clinical removal of its liver.

The shark had an entire common dolphin in its belly, diced into four consumable pieces. But this alpha predator had become prey.

Kevin Cole, the principal natural scientist at the East London Museum, said he was alerted to the carcass on 28 May.

Cole said it appeared to show all of the signs of an orca attack, notably the missing liver – an unprecedented event in his 33 years of examining dead sharks and dolphins on the Eastern Cape coast.

This was confirmed by Dr Alison Towner, a shark scientist at Rhodes University who has extensively studied the impact of orca predation on white shark behaviour and distribution.

This research has linked the appearance of a pair of orcas in Gansbaai in 2017 – a white shark hotspot favoured by the cage-diving industry – to the subsequent dramatic decline in sightings of the species there. Between February and June 2017, five white shark carcasses washed up on beaches in Gansbaai, four with ripped-out livers.

In a peer-reviewed 2022 study in the African Journal of Marine Science, with the punchy headline “Fear at the top”, Towner and other researchers including Kock raised the possibility that the white sharks had vacated the area because the species had suddenly gone from being the apex carnivore in the ’hood to being on the menu.

“Risk-induced fear effects exerted by top predators are pervasive in terrestrial and marine systems, with lasting impacts on ecosystem structure and function,” the authors wrote.

Kock said that “... the landscape – or seascape – of fear is often more pervasive than direct numbers killed.”

“A landmark study over 30 years from the Serengeti showed that lions suppress wild dog populations in significant ways. It also showed that the same was not true for cheetahs – highlighting different impacts on different species. There are numerous studies across the territorial and marine realms, across mammals, invertebrates and reptiles, that demonstrate this landscape of fear.”

Amid growing concerns about white shark numbers in South Africa, a 2023 study that Towner and Kock contributed to in the journal Ecological Indicators suggested that there was no clear trend in the population and that some of the animals may have been shifting eastward.

A seascape of fear in the EC?

And, intriguingly, the recent surge of sightings in the Eastern Cape waters suddenly stopped in the wake of the orca predation incident – mirroring the observations off the Western Cape coast.

“They seem to have disappeared from the area. I have spoken to other colleagues who are flying in the area looking for sardines and they haven’t seen any white sharks,” Benjamin said.

Pointedly, he also noted that there were still lots of sardines in the area, plus the usual suspects such as dolphins and various bird species. But no white sharks.

Towner told me that this sequence of events in the Eastern Cape – with the sharks seemingly vanishing once an orca with a hankering for their liver rocked up – fitted what she and other scientists predicted.

“It’s literally the exact replica of what’s happened in the Western Cape – the difference now is that it’s the first time in the Eastern Cape. And it’s like a typical repeat pattern… “It starts with an aggregation of white sharks and at some point, the killer whales come in, and then you get a dead white shark, and then they vanish,” Towner said.

A Great white shark (Carcharodon carcharias) in Gansbaai, South Africa, on 19 June, 2010. (Photo: EPA / Helmut Fohringer)

“We predicted this; we hypothesised that the Eastern Cape would be next. It would be the logical place that some of the sharks would move to and the orcas would follow. And lo and behold, we now have evidence of it.”

An ocean of debate

What has been happening with white sharks in South African waters is highly contested scientific terrain – a veritable seascape of intense debate.

The paper last year – which found no evidence of a decline in the population but rather a shift in its distribution – triggered a letter by a group of scientists who expressed concern that such a view would, among other issues, detract from the need for urgent measures to conserve the species.

Read more in Daily Maverick: Scientists challenge research showing SA’s white shark population is stable

The authors of the original article maintained they were not implying that conservation measures should be relaxed and that they were distilling what the data showed.

“We have addressed their critiques using scientifically accepted analytical understanding to demonstrate why our ecological conclusions remain unchanged: (1) the relative abundance of white sharks has not exhibited systematic increases or declines at a regional level since protection in 1991, and (2) observed data on human-shark incidents are consistent with the hypothesis that white sharks have partially redistributed along the South African coastline,” they said in their response to the letter.

“Ultimately, the lack of abundance following protection remains concerning and necessitates continued conservation efforts,” they noted.

The point here is that while white sharks have been a protected species in South Africa since 1991, numbers are not increasing as a result. So the authors are not suggesting a sense of complacency.

Regarding the potential significance of the recent events in the Eastern Cape, there is scientific scepticism.

Dr Enrico Gennari, a marine ecologist from the Oceans Research Institute in Mossel Bay and the lead author of the critique of the 2023 article positing a possible shift in white shark movements, told me that he found the Eastern Cape incident unconvincing.

“It is not a pattern in the Eastern Cape but one single observation,” he said.

Gennari has co-authored papers with Towner and other scientists on orca effects on white sharks and does not discount it as a factor. But he feels undue attention has been paid to the issue, and that has pushed other pressing matters such as bycatch – or illegal targeting of the species – from commercial fishing and mortality from lethal gill-netting by the KZN Sharks Board below the public sonar.

Read more in Daily Maverick: Sea change: Why the case for shark nets no longer holds water

Read more in Daily Maverick: The price of fish & chips: The shark slayers and an unfolding disaster for the love of fried fish

Researchers such as Towner and Kock have flagged these issues, but orcas as a charismatic species perhaps catch the public eye.

Orcas. (Photo: Zafar Monier)

“To blame the orcas is like pointing fingers at nature itself when the finger should be pointing back at us. The KZN Sharks Board and other fisheries have been killing far more white sharks,” Gennari said.

As to the issue of the 46 sighted in one count, Gennari said this was not uncommon 15 years ago in many Western Cape hotspots.

“It could be the last 46 and they are all together because there is some food there,” he said.

Gennari also said the white sharks spotted were perhaps there because those waters are subjected to less intensive commercial fishing than elsewhere.

Instead of responding to an orca in their midst, he suggested the sharks had presumably moved east as they followed the sardines – a logical conclusion. But this does not dovetail with the observations of Benjamin and others who say the sardines have remained abundant in the area.

It’s also important to note that white sharks move over vast marine territories.

In this correspondent’s native Canadian province of Nova Scotia, there has been a perception that white shark numbers are on the rise, fuelled in part by a 2021 attack on a woman that is suspected to have been by a great white.

However, a 2022 study in the Canadian Journal of Fisheries and Aquatic Sciences found that shark numbers appeared to be steady in Canadian waters.

This mirrors in some ways the findings in South Africa, but against the backdrop of conflicting public perceptions, with Nova Scotians believing their numbers are growing in coastal waters and many South Africans holding the view that they must be in local decline.

Heather Bowlby, a shark research scientist with Canada’s Department of Fisheries and Oceans, who was also the lead author of the 2023 study suggesting a shift rather than a decline in South Africa’s white shark population, told me by email how she saw such perceptions being shaped.

“Different individuals have access to different sources of information, which affects their perspective. In the Canadian context, there has been a huge increase in the amount of white shark research occurring during the last eight or so years.

“This has been associated with more people looking for and thinking about white sharks, plus annually increasing media coverage. There are also increasing numbers of acoustically tagged animals, so detections of these animals are more and more frequent,” she said.

“In South Africa, nearly all information about white sharks was coming from very specific sites associated with ecotourism operations. Obviously, when conditions at these sites change in a way that the sharks appear to be gone, it is very easy to have the perspective that they have died or that abundance declined rapidly in the entire population... When sightings become rare when they used to be abundant, it is logical for the public to be worried about extinction.”

All the scientists involved in this debate are highly regarded in the field of white shark science, underscoring the need for more research to provide a firmer understanding of the ecological dynamics on this front. An orca could swim through the gaping holes in the nets of our knowledge, which are still scouring the oceans for insight.

One issue perhaps at play here is what scientists call “changing baseline syndrome”, which speaks to our propensity to regard the natural world of our lifetimes as the norm.

I have previously drawn attention to the fact that in 1969 an American video crew, with the famed natural history writer Peter Matthiessen in tow, came to South Africa specifically to find and film white sharks from a cage.

Read more in Daily Maverick: Quest for elusive white shark decades ago raises questions about the species today

They chose to follow the last of South Africa’s whaling vessels from Durban, and never even considered going to Gansbaai or False Bay – which subsequently became famed as white shark hotspots. That strongly suggests the species was not as abundant at that time in those waters, or the South African public was not entirely aware of the sharks’ presence there.

The sharks come and go, and the vastness of the world’s oceans is their range.

I was interviewing Towner on a WhatsApp video call as she sat on her deck overlooking Gansbaai, and she swung her device in the direction of the coast.

“I used to see white sharks here all the time; now we are lucky if we get a sighting or two in a single year,” she said.

Who knows, the white sharks may return – or maybe they won’t. And the same goes for the orcas. DM

https://www.youtube.com/watch?v=REeWvTRUpMk

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A seascape of fear in the EC?

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