A Seemingly ‘Harmless’ Shark Species Killed a Swimmer in First-Ever Instance — and Experts Know Why

“Help…they're biting me!” Beachgoers heard these words, erupting in screams from someone they couldn’t see, except for human arms flailing in the water off the coast of Hadera, Israel. Within a few moments, straight out of a scene from Jaws, some black dorsal and caudal fins emerged from the waters, which were turning the color of red wine. The case was clear. There was a shark attack, and a human was murdered. To investigate the assault, scientists collected photos and videos captured by the witnesses for clues, and recently documented their hypothesis in a case study in Ethology.

Despite their evil reputation, most sharks aren’t dangerous to humans, including in Hadera. Only a few shark species, such as white sharks, tiger sharks, bull sharks, and oceanic whitetip sharks, can be considered slightly, if not altogether, dangerous. Despite its large size, a dusky shark, also called Carcharhinus obscurus, is not usually associated with being traumatogenic to humans. But this incident, wherein the victim was found to be a 40-year-old male tourist, jolted the scientists to dive deep into shark behavior and initiate a case study for the murder incident. They started the study by researching the science of a “shark attack,” sometimes called a “predatory bite.”

To conduct a detailed study, scientists needed to understand a crisp differentiation between a normal bite and a predatory bite. A normal bite, they explained, happens when a shark is motivated by territorial dominance, competition, self-defense, or reflex behaviors. Whereas, a predatory bite is a shark actively seeking to feed on a human, which materializes as large tissue loss, often leading to the death of the victim, compared to other motivations where wounds are not fatal.

Photos and accounts from eyewitnesses suggested that the Hadera incident didn’t involve just one murderer. There was a group of several dusky sharks involved in the murder. In the animal kingdom, this type of attack is referred to as a “feeding frenzy.” In the case of ocean dwellers like sharks, it is an aggregation of aquatic predators, which get excited by a feeding stimulus, leading to frenetic and agonistic behaviors to access the food, biting within biting range. Not every prey, however, invites such a frenzy.

According to an episode related in the study, scientists mentioned a 2003 trip to New Caledonia where they presented a dead deer carcass underwater to a group of bull sharks. The sharks, perhaps, didn’t find this meal catered to their luxurious gourmet standard, for they refused to touch it. The scientists then inserted a dead fish into the mouth of the dead deer. The first shark approached to bite the fish, triggering a feeding frenzy that invited several bull sharks. Together, the party finished up the fish and the carcass in just a few minutes.

In addition to “predatory bite” and “feeding frenzy,” scientists explored the concept of “trigger” in this study. The trigger is that one thing or that initial point that provokes the predators to aggregate in the frenzy. In the Hadera case, the trigger couldn’t be fully identified. But all the collected data suggested that it was likely the man’s GoPro camera. According to their hypothesis, the electromagnetic signal emitted from the camera likely triggered the olfactory senses of the sharks, who mistook it for a spearfisherman with a wounded fish.

Hadera’s coast, the researchers noted, is a hub of power plants that dump waste into the waters. The warmed waters act as delicious invitations for sharks. Sharks develop a “begging” behavior, in which they expect the fisherman to feed them freshly wounded fish. However, even with this behavior, the probability of them killing the fisherman is negligible. Therefore, what exactly provoked the Hadera sharks remains a mystery. 

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