The coastal town of Hangsbaai in South Africa has perennially garnered renown for its shark-watching allure. Audacious tourists ensconce themselves within cages, plunging into the azure depths to observe the formidable great white sharks in close quarters. However, in recent years, a disquieting revelation has unfurled—there is a palpable diminution in the once-abundant shark populace. The great white sharks, erstwhile ubiquitous, have now become nearly imperceptible. Furthermore, scientific scrutiny has discerned an exodus of sharks akin to an affliction, with no less than 14 indigenous great white sharks emancipating themselves, while others shun Hang Si. This portends the presence of formidable forces within the oceanic realm, replete with predatory machinations. What compounds this disquietude is the relentless procession of deceased sharks, their lifeless forms marooned upon the shores. Whence comes the assailant of these majestic creatures? Following an exhaustive inquiry, scientists unearthed a relentless predation spanning a decade…
On February 9, 2017, denizens of Hangsbai, frolicking on the beach, chanced upon a piscine behemoth measuring 2.7 meters. A female shark, erstwhile a sovereign of the depths, writhed in the shallows, prompting immediate notification to the Marine Animal Response Society (MARS), a bastion of animal protection. By the time the erudite researchers from the Humane Society materialized, the great white shark had succumbed, marooned and lifeless.
Researchers expeditiously undertook an investigation within the maritime expanse, yet no precipitant of the great white shark’s demise materialized. Compelled to transfer the shark’s cadaver to the institute for postmortem analysis, researchers discerned negligible external injuries, save for inconsequential tooth marks adorning its cephalic region and two pectoral fins, non-fatal in nature. Why, then, did the great white shark meet its demise?
Inclination naturally leaned towards local fishermen as the perpetrators, yet within this protected enclave, no audacious poachers were apprehended. Stripping away anthropogenic intervention, conjecture ensued, speculating that the tragedy stemmed from internecine cannibalism among the great white sharks, precipitated by territorial disputes or mating skirmishes. However, this supposition swiftly unraveled, for the wounds bespeaking the great white shark’s demise were evidently not inflicted by conspecifics. The investigation teetered on the precipice of uncertainty, unaware that a sanguinary oceanic saga was clandestinely unfolding.
On May 3 of the same annum, reports once again trickled in, detailing the appearance of another deceased great white shark along the coast. Khaleesi, a prodigious specimen measuring nearly 5 meters and weighing over a ton, once a maritime marvel, met a lamentable demise. This invoked profound regret among marine aficionados and sharkologists, galvanizing their determination to unmask the perpetrator.
Marine biologist Alison Towner escorted Khaleesi to the institute for meticulous analysis. Post-autopsy, a disconcerting revelation unfolded—while the shark’s external semblance remained unaltered, an enormous laceration manifested upon turning its form. Delving into the abdominal cavity revealed the conspicuous absence of the shark’s liver.
Astoundingly, on May 4, a third carcass emerged. This great white shark, measuring approximately 4.2 meters, suffered a similar fate with its abdomen laid bare and its liver surgically excised. Pertinently, this male great white shark bore crucial clues, as its pectoral fins bore abrasions akin to those wrought by the teeth of an orca.
The sanguinary tempest showed no signs of abating. By the culmination of June, an assemblage of eight great white sharks were discovered lifeless along diverse coastal locations in Gansbaai. Save for the initial instance, all succumbed in identical fashion, disemboweled with their livers extirpated.
Subsequent to anatomical dissections, Alison proffered the deduction that the likely assailant was an orca. Addressing the enigma surrounding the first intact great white shark, it posited that the orcas had only recently commenced their predation on great white sharks, their modus operandi still inchoate. Following an altercation with an orca, the great white shark fled the scene, succumbing to its injuries.
To corroborate the precision of anatomical findings, Alison meticulously gauged every dimension of the deceased sharks.
“We sought any indicators of trauma negating an orca attack, such as boat-related injuries or fishing line entanglements—anything capable of precipitating the shark’s demise. Yet, as these colossal creatures lay prostrate, their 60-plus kilograms lay conspicuously bare. The voluminous liver had been extracted, a glaring testament. The assault upon these great white sharks targeted their ventral regions, where the assailant eviscerated the shark from beneath. It constitutes an optimal locale for liver extraction. I postulate that the hearts of two sharks and the testicles of one male were excised due to their proximity to the incision,” Alison communicated with a palpable disquiet, disseminating her revelations to the research consortium.
To Alison’s consternation, whether through visual surveillance or tracker records, the great white sharks within the waters of Gansbaai were conspicuously absent. Originally, this region hosted the preeminent congregation of great white sharks globally, a spectacle frequently witnessed by tourists and researchers. Alas, this time, the great white sharks vanished for nearly a lunar month. They appeared to recoil from an unseen terror, a nocturnal exodus from the maritime domain. What nexus existed between the vanishing shark cohort and the stranded, lifeless great white sharks?
At this juncture, Salvador Jorgensen, a venerable scientist at the Monterey Bay Aquarium in the United States, proffered a hypothesis—that the disappearance and demise of the great white shark constituted the orchestration of the orca, a “magnum opus” in his parlance. Employing trackers on great white sharks in proximity to the Farallon Islands, he ascertained that their trajectories indicated precipitous flight upon an orca’s passage.
Tracker data unveiled that in 2009, when a pod of orcas traversed the Farallon Islands, 17 great white sharks in close proximity expeditiously vacated the bountiful waters within mere hours. Conventional behavior dictated a protracted sojourn of weeks or even months. Concurrently, Jorgensen’s team documented a conspicuous decline in the consumption of walruses or seals by tracked great white sharks. In the year the orcas emerged, their predation reduced the tally by approximately 40 to 70 percent. Ergo, the great white sharks, it surmised, were averse to the orcas.
Continual data substantiated this conjecture, unveiling the instantaneous exodus of sharks whenever orcas manifested in a given maritime expanse. The sharks, in familial cohesion, would promptly forsake the locale, abstaining from return until at least the ensuing season, even if the orca’s sojourn lasted less than an hour.
Unraveling the perpetrator:
The great white sharks inhabiting the Farallon Islands exhibited aversion towards orcas. Did a similar aversion persist among the great white sharks in South Africa? These suppositions, albeit plausible, remained unsubstantiated conjectures. To validate their suspicions, Alison’s team embarked on an odyssey to uncover pertinent evidence.
Amidst their investigation, Alison unearthed a pivotal discovery—on November 9, 2015, divers photographed the carcasses of flathead sharks at the western aggregation site in Fore Bay. These sharks, too, bore sizable lacerations in their pectoral girdles, with their livers conspicuously absent. After a span exceeding a month, no living sharks remained in the vicinity.
In 2016, the flathead shark population in Fore Bay witnessed a remarkable resurgence. In April of the same year, divers stumbled upon the cadavers of five sharks. Analogous to prior instances, the fatal wounds encompassed lacerations to the pectoral girdle and the absence of the liver. However, this iteration bore bite marks on the pectoral fins.
Two instances of mass shark mortalities within the same domain prompted earnest concern, leading researchers to scrutinize photographs from November 2015. This retrospective analysis revealed identical bite marks on the pectoral fins of the deceased sharks. Conclusively, researchers attributed these marks to orcas.
These findings propelled Alison to designate orcas as the primary culprits. While extant studies documented orcas preying on diverse marine mammals and fish, encompassing cetaceans and higher-order cartilaginous fishes, scant records chronicled their predation on sharks.
Some scholars dissent from Alison’s proposition, asserting that the extensive demise of sharks in South Africa bears no correlation with killer whales. Based on meticulous observations and records, a cohort of whales annually undertakes a migratory voyage from the Indian Ocean to the Atlantic Ocean between August and November. During this journey, indigenous killer whales engage in the pursuit of cetaceans. Notably, great white sharks frequent the vicinity when these killer whales hunt cetaceans, yet a deliberate and safe distance is always maintained.
Nevertheless, some erudite scholars contend that the count of killer whales preying on sharks has been egregiously underestimated due to the clandestine nature of their underwater activities. Concurrently, New Zealand marine biologists have ascertained through their studies that certain populations of killer whales disproportionately target sharks as their prey, including blue sharks, shortfin mako sharks, and tuna. Notably, these specific killer whales predominantly inhabit deep-sea expanses and seldom venture into coastal regions.
Alison, confronted with this divergence of scholarly opinion, contemplated the possibility that such killer whales ventured into the bay and executed the sharks. Subsequently, she requisitioned all photographs taken in Fore Bay in 2015 from the Marine Life Research Center. This meticulous examination revealed the presence of two distinctive male killer whales in January 2015, whose dorsal fins bore unique characteristics. One fin inclined towards the left, denominated “Port,” and the other inclined towards the right, christened “Starboard.” Alison surmised that these killer whales appeared proximate to two instances of mass deaths of flathead hana sharks in Fore Bay.
Simon Erwin, the director of the scientific group Sea Search, opined on their origin, stating, “They could originate from diverse locales such as West Africa, East Africa, or the Southern Ocean. In southern Africa, from Namibia in the west to Elizabeth in the east harbor, both port and starboard are observable.”
Alison sought the expertise of biologist Dave Hurwitz, the first to document the sightings of “port and starboard” killer whales. He elucidated to Alison, “When these enigmatic killer whales initially surfaced in Fox Bay, they appeared otherworldly, as I had witnessed the local killer whale pod expelling them.”
Suspecting that these two killer whales were responsible for the demise of great white sharks and flathead hana sharks, Alison embarked on an active quest for information about them. She uncovered that Port and Starboard first surfaced in Port Elizabeth, Cape Town, in 2009, establishing themselves as inseparable companions. Despite primarily feeding on small fish and marine mammals, they exhibited behavior similar to other killer whales, stalking fishing boats, rushing into schools of fish, and ambushing sea lions. Alison’s initial hypothesis was dismissed due to the absence of corroborative evidence, but her commitment to the research remained unwavering.
In subsequent years, whenever shark carcasses with missing livers washed ashore, sightings of killer whales on the port and starboard sides were reported in nearby waters. Their distinct dorsal ridges rendered sightings nearly foolproof. Could these records substantiate their culpability in shark killings? While the answer inclined towards affirmation, conclusive evidence remained elusive for Alison.
The long-awaited incriminating evidence finally materialized on May 16, 2022. On this day, a drone pilot and a sightseeing helicopter pilot captured images of Port and Starboard hunting great white sharks in Mossel Bay from diverse vantage points. To Alison’s astonishment, the great white sharks did not recoil when approached by the killer whales; instead, they adopted a defensive strategy reminiscent of seals and turtles evading sharks. Regrettably, this stratagem proved ineffectual against killer whales.
In a choreographed attack, Port and Starboard, displaying a tacit understanding, doomed at least two great white sharks during a 71-minute hunt. Alison asserted, “We believe these two killer whales have learned to immobilize the sharks using their pectoral fins. The shark’s liver, being oily and slippery, easily slides out, allowing the killer whales to savor the delicacy of shark liver.” This unprecedented behavior, captured in detail from the air, affirmed that, post-2015, Port and Starboard abandoned their conventional hunting methods in favor of the more nutritious pursuit of shark livers.
Biologists speculate that the predilection of Port and Starboard for hunting sharks may stem from a hormonal deficiency in their bodies, with shark livers containing ample squalene essential for hormone synthesis. Although the exact reasons for the predation on the port and starboard sides remain elusive, their hunting prowess continues to evolve.
Between February 3 and 22, 2023, 17 shark carcasses, primarily comprising sevengill sharks and a solitary spotted dog shark, were discovered along the Hangsbaai coast. Alison promptly conducted autopsies, attributing the liverless state to the adeptness of Port and Starboard. The shift in prey selection may be attributed to the advanced age and diminished physical prowess of the sharks.
On October 19, a great white shark devoid of its liver washed ashore on Bridgewater Bay Beach in Melbourne, Australia, coinciding with the presence of a nearby pod of killer whales. This development perturbed shark experts, hinting at the potential dissemination of Port and Starboard’s hunting techniques among orcas, posing a significant threat to the ecosystem.
Research indicates that, prior to 2015, hundreds of great white sharks inhabited Cape Town waters throughout the year. By 2020, their numbers dwindled to near-zero due to the predatory pressure exerted by Port and Starboard. This decline not only devastated the tourism economy but also disrupted the local ecological chain. The eradication of great white sharks, a pivotal link in the food chain, triggered an imbalance, leading to a proliferation of lower-tier fish populations and impacting numerous marine species.
A confluence of factors, including climate warming, overfishing, and the relentless massacre of sharks by Port and Starboard, has pushed three-quarters of species in Cape Town to the brink of existential crisis. Despite the adverse consequences, marine animal experts and the tourism bureau express contrasting sentiments. While the relentless shark hunting by Port and Starboard is a cause for complaint, it also presents a rare and enduring subject for extensive observation and research.
Furthermore, the departure of great white sharks from the bay has engendered unexpected behavioral shifts in various species. Seals and fur seals venture far from the coastline to pilfer fishermen’s catches, small sharks appear in kelp forests, and short-tailed sharks materialize near the shore. Scientists, fascinated yet frustrated by the predation of one endangered species by another, maintain that the actions of the two killer whales may not lead to the extinction of a species, but the enduring impact on the environment remains uncertain. Nature’s enigma, as always, necessitates the passage of time for the revelation of ultimate truths.