When Sharks Attack 360: Perfect Storms & Wild Weather | MEGA EPISODE | National Geographic

Key Concepts

• Spearfishing and Shark Attacks: The relationship between spearfishing activities (sound of spearguns, presence of blood) and increased risk of shark attacks.
• Shark Sensory Systems: The importance of smell, hearing, and electroreception in shark hunting behavior.
• Shark Learning and Conditioning: How sharks can learn to associate specific sounds (spearguns, boat engines) with food sources.
• Breach Attacks: A hunting tactic used by great white sharks, involving launching themselves out of the water to attack prey.
• Lateral Line: A sensory organ in sharks that detects water movement and pressure changes.
• Juvenile vs. Adult Shark Behavior: Differences in hunting strategies, bite force, and prey selection between juvenile and adult sharks.
• Bait Balls: Dense aggregations of small fish that attract predators, potentially leading to increased shark activity.
• Mullet Run: An annual migration of mullet fish along the Florida coast, attracting sharks and increasing the risk of human encounters.
• El Niño and La Niña: Climate patterns that affect water temperature and marine life distribution, potentially influencing shark behavior.
• Shark Nurseries/Training Grounds: Shallow, warm-water areas where juvenile sharks learn to hunt and develop their predatory skills.
• Taste Testing/Exploratory Bites: The behavior of juvenile sharks biting multiple times to determine if a potential prey item is suitable.
• Contrast Vision: The ability of sharks to detect high-contrast objects, even if they cannot see color.
• Acoustic Deterrents: The potential use of specific sounds to deter sharks from certain areas.

Spearfishing and Shark Attacks: Alex Dodds and Brodie Paino's Experience

• Alex Dodds and Brodie Paino were spearfishing off the Beagle Islands in Western Australia when they encountered a great white shark.
• Brodie had an initial encounter where the shark sensed his fear but didn't attack.
• Alex was then attacked, resulting in a breach attack where the shark launched itself out of the water, biting his leg.
• Alex sustained severe injuries, including severed tendons and nerve damage, requiring reconstructive surgery.
• The team investigates whether the blood from the speared fish attracted the shark.
• The team also investigates whether the sound of the speargun attracted the shark.

The Role of Smell in Shark Attacks

• Sharks have highly sensitive olfactory organs, with 20% of their brain dedicated to detecting odorants.
• They can detect a single drop of blood in a backyard swimming pool (one part per billion).
• Blood dissipates slowly in seawater and requires a current to transport the odor over long distances.
• Alex and Brodie had caught a fish 20 minutes before the attack, potentially allowing enough time for the odor to dissipate.

The Sound of Spearguns as an Attractant: Lachlan Pye's Encounter

• Lachlan Pye was spearfishing in Lucinda, Queensland, when a bull shark bit his fin after he speared a dead fish.
• Presley Wilcox, who was in the boat, believes the shark was attracted by the sound of the speargun, not the smell of the dead fish.
• Kajiura finds other examples of spearfishermen being attacked shortly after firing their spearguns.
• Caroline Sullivan, a shark hearing expert, explains that sound travels faster and farther underwater, making it an important sensory cue for sharks.
• Sharks have internal ears with hair cells that detect sound vibrations.
• Sharks can learn to associate sounds with food items.

Experiment: Testing Shark Response to Speargun Sounds

• Kajiura and Caroline conduct an experiment in Florida to test if sharks are attracted to the sound of a speargun firing.
• They use an underwater speaker to play sound files of a speargun being fired and hitting a fish.
• A drone is used to spot lemon sharks in the area.
• One shark immediately turns toward the speaker after the sound is played, indicating it heard the sound.
• The experiment suggests that sharks can be attracted to the sounds of spearguns discharging underwater.

Tyler McQuillen's Attack: Challenging the Sound Theory

• Tyler McQuillen was spearfishing at Refugio State Beach when he was attacked by a great white shark before firing his speargun.
• This incident challenges the theory that the sound of a speargun is the primary attractant.
• Tyler defended himself with his speargun and managed to escape, but sustained injuries to his foot.

The Sound of Loading a Speargun

• The team considers if the sound of loading a speargun could attract sharks.
• They conduct another experiment in Florida, playing the sound of a speargun being loaded underwater.
• The sharks do not exhibit a clear response, possibly due to ambient noise from waves crashing on the beach.

Shark Cognition and Learning: Culum Brown's Research

• Melissa Márquez speaks with Professor Culum Brown, a shark cognition expert, about his experiment on shark learning.
• Brown's experiment showed that baby Port Jackson sharks could learn to associate jazz music with the arrival of food.
• This suggests that sharks can be conditioned to associate man-made noises, such as spearfishing sounds, with a food reward.

Case Studies: Sound Cues and Shark Behavior

• In the Bahamas, sharks have learned to steal catches from sport fishermen by associating the sound of boat engines with food.
• Caroline Sullivan's research shows that low-frequency sounds can deter sharks.

Synthesis: Sound and Spearfishing

• The team concludes that the odors given off by struggling speared fish would travel too slowly to have caused the attacks.
• Instead, the sounds associated with spearfishing, such as loading and firing spearguns, are key to attracting sharks.
• Sharks can be conditioned to associate these sounds with food, increasing the likelihood of an attack.

Juliun Perkins' Shark Attack: The Squeaky Surfboard Theory

• Juliun Perkins was surfing at Pounders Beach in O'ahu, Hawaii, when he was attacked by a tiger shark.
• Juliun suspects his soft top surfboard, which makes squeaky noises, may have attracted the shark.
• Yannis Papastamatiou, a shark hunting behavior expert, explains that sound is an important stimulus for sharks.
• Kajiura analyzes the sound frequencies produced by the soft top board, finding that most peaks are above 500 Hz.
• Sharks can hear up to 800 Hz, but are more attracted to low-frequency sounds (20-100 Hz).
• The team rules out the squeaky noise as the primary cause of the attack.

The Whale Calf Mistaken Identity Theory

• The team considers if the size and shape of Juliun's soft top board, which resembles a baby humpback whale, may have attracted the shark.
• Kajiura finds a case of a great white shark attacking a kayak, mistaking it for a whale calf.
• Julia Hartl, a shark scientist, explains that humpback whales migrate to Hawaii between December and April, while Juliun's attack was in September.
• The team rules out the whale calf mistaken identity theory.

The Pregnant Tiger Shark Theory

• Yannis's tagging data shows that pregnant female tiger sharks from the Northwest Hawaiian Islands migrate to the main Hawaiian Islands in October and November.
• Juliun's attack was in September, so the dates don't match up.

The Bait Ball Theory

• The team considers if Juliun was attacked while near a bait ball, which can provoke frenzied behavior in sharks.
• Drew, one of Juliun's friends, recalls that the water was somewhat murky but there was no bait ball.
• The team rules out the bait ball theory.

The Hurricane Theory

• Mitchell, one of Juliun's friends, remembers that there was a hurricane that had just passed at that time.
• Kajiura finds that there was a tropical depression off the west coast of Mexico that turned into a full-blown hurricane.
• Sharks are sensitive to changes in pressure, including atmospheric pressure, and typically move to deeper water during storms.
• The team considers if the storm steered the tiger shark to Pounder's Beach.

The Lateral Line and Pressure Changes

• Kajiura explains that sharks have a lateral line, a sensory organ that detects water movement and pressure changes.
• Ryan Johnson and Gibbs Kuguru conduct an experiment to show how sharks respond to pressure changes.
• They create a "wall of water" using compressed air and observe how a great white shark reacts.
• The shark turns away when its lateral line detects the high-pressure wall.

Tiger Sharks and Hurricanes

• Dr. Mike Heithaus explains that tiger sharks in the Bahamas stay in shallow water during hurricanes, while other sharks leave.
• Tiger sharks are scavengers and may be attracted to the dead animals and debris left behind by hurricanes.
• They also have access to deep water, allowing them to escape the most dangerous parts of the storm.
• Tiger sharks have a broad diet and are adaptable to changes in the environment.

Synthesis: The Hurricane and Juliun's Attack

• The team concludes that Juliun was attacked because the tiger shark was scavenging for food left behind by the hurricane.
• The water pressure changes caused by the storm created the perfect circumstances for the attack.

Nemanja Spasojevic's Shark Attack: The High-Contrast Theory

• Nemanja Spasojevic was diving for crabs in Gray Whale Cove, California, when he was attacked by a juvenile great white shark.
• Nemanja was bitten on the right leg, where he had his bright yellow dive bag.
• Kajiura suspects that the yellow dive bag may have attracted the shark.

Shark Vision and Color Perception

• Kajiura consults with Dr. Christine Bedore, an expert in shark vision, to understand what sharks can see.
• Bedore explains that sharks cannot see color because they only have one type of cone cell in their eyes.
• Sharks have a 270-degree visual field around their body, but a blind spot in front of their nose and behind their body.
• Sharks have low visual acuity, meaning they cannot see as much detail as humans.

David Alexander's Kayak Attack: The Yum Yum Yellow Theory

• David Alexander was kayaking in Shelter Cove, California, when a great white shark attacked his yellow kayak.
• The team considers if the color yellow may have attracted the shark.

Ryan Johnson and Gibbs Kuguru's Experiment: Testing the Yum Yum Yellow Theory

• Ryan Johnson and Gibbs Kuguru conduct an experiment in South Africa to test if great white sharks are attracted to yellow.
• Ryan wears a black wetsuit and then a yellow wetsuit to see if the sharks respond differently.
• The experiment is a bust, but they receive footage from a friend showing a shark interacting with a diver in a yellow wetsuit.
• The shark shows distinct interest in the diver in the yellow wetsuit, exhibiting behaviors such as head movements and rolling.

The High-Contrast Theory

• Kajiura and Bedore explain that sharks have excellent contrast vision and are attracted to high-contrast objects.
• To sharks, yellow objects may appear as dark, high-contrast items.
• The team concludes that Nemanja was attacked because the shark was attracted to the high contrast between his bright yellow dive bag and the surroundings.

Simon Nellis' Shark Attack: The La Niña and Bait Fish Theory

• Simon Nellis was swimming at Little Bay in Sydney, Australia, when he was attacked and killed by a great white shark.
• The attack was the first fatal shark attack in Sydney in 60 years.
• The team investigates why a great white shark committed to a full-scale attack on a human.

Identifying the Shark

• Kajiura examines the bite force of different sharks, ruling out bull sharks as the culprit.
• Eyewitness accounts confirm that the shark was a large great white.

Little Bay's Geography

• Melissa Márquez and Dr. Phoebe Meagher discuss Little Bay's geography, noting that it is close to the continental shelf and has deep channels.
• This blending of shallow and deep water habitats attracts a variety of fish and animals, including seals.
• The team considers if the shark mistook Simon for a juvenile seal.

Great White Hunting Techniques

• Ryan Johnson and Gibbs Kuguru investigate how great white sharks hunt seals in deep water.
• They use a camera rig to film a seal decoy from above and below, capturing footage of great whites launching themselves straight up at the seal.
• The footage reveals a steep angle of attack, concealing the incoming shark until it's too late for the seal to avoid.

The Wetsuit Theory

• The team considers if Simon's wetsuit may have attracted the shark.
• Kajiura explains that from the great white's point of view, wearing a wetsuit makes no difference, as the silhouette of a swimmer looks the same from below.

The Water Temperature Theory

• Melissa Márquez explains that great white sharks prefer cooler temperate waters, and the water in Little Bay was unusually warm on the day of the attack.
• The team considers if the warm water may have influenced the shark's behavior.

El Niño and La Niña

• Melissa Márquez explains that El Niño and La Niña are climate patterns that affect water temperature and marine life distribution.
• During La Niña, stronger trade winds push warm water towards Australia, potentially influencing shark behavior.

The Sardine Run

• Kajiura finds a case of Tony White being bitten by a shark during the sardine run in South Africa.
• The sardine run is an annual migration of sardines that attracts a variety of predators, including sharks.
• The team considers if Simon Nellis may have swum into a bait ball.

La Niña and Bait Fish

• Mackenzie Smith explains that during La Niña, stronger ocean currents push bait fish closer to shore.
• This can attract predators, including great white sharks, to sheltered bays.

Synthesis: The La Niña and Bait Fish Theory

• The team concludes that Simon Nellis was attacked because the La Niña conditions brought bait fish closer to shore, attracting a great white shark to Little Bay.
• The shark may have mistaken Simon for a seal due to the murky water and the shark's hunting technique.

Doyle Nielsen's Shark Attack: The Mullet Run Theory

• Doyle Nielsen was surfing in Ponce Inlet, Florida, when he was attacked by a blacktip shark.
• The team investigates why the shark bit Doyle.

Identifying the Shark

• Kajiura examines Sam Scribner's footage to identify the shark, concluding that it was a blacktip shark.

Blacktip Shark Migration

• Yannis Papastamatiou explains that blacktip sharks migrate to South Florida in the winter and spring, but Doyle's attack happened in September.
• The team rules out the migration of blacktips as a contributing factor.

Cole Smyth's Shark Attack

• Kajiura finds another shark attack in Ponce Inlet, almost exactly one year before Doyle's bite.
• Cole Smyth was also surfing when he was attacked, but he identified the shark as a bull shark.

Bull Sharks and Blacktips

• The team considers what could make both bull sharks and blacktips bite someone in the same place.
• The waters at Ponce Inlet can get murky, potentially causing the sharks to mistake surfers for food.

Shark Sensory Systems

• Kajiura explains how sharks use different senses to hunt, including smell, lateral line, and electroreception.
• He conducts an experiment to measure the electric fields produced by a human and compare it to the electric fields produced by a fish.
• The results suggest that electroreception is unlikely to have played a role in the bites on Doyle and Cole.

Shark Attack Data

• Kajiura examines shark attack data for Florida, finding that there is a spike in attacks in August and September.
• This suggests that there may be a seasonal factor influencing shark behavior.

The Mullet Run

• Kajiura flies an aerial survey along the Florida coastline, observing vast amounts of prey fish.
• He explains that the mullet run is an annual migration of mullet fish that attracts predators, like sharks.
• Doyle and Cole were both in the water at the same time as the mullet run.

Synthesis: The Mullet Run Theory

• The team concludes that Doyle and Cole were attacked because they were in the water during the mullet run, when sharks are actively hunting.
• The sharks may have mistaken the surfers for prey fish.

Joe Hoffman's Shark Attack: The Juvenile Training Ground Theory

• Joe Hoffman was surfing at Crescent Head on Australia's east coast when he was attacked by a juvenile white shark.
• The team investigates why a juvenile white shark attacked Joe.

Identifying the Shark

• Kajiura examines Joe's surfboard, concluding that the bite was most likely from a juvenile white shark.

Keane Webre-Hayes' Shark Attack

• Kajiura finds another shark attack in California, where Keane Webre-Hayes was attacked by a juvenile white shark while lobster diving.
• Keane suffered multiple bites, suggesting that the shark was inexperienced.

Shark Taste Buds

• Kajiura explains that sharks have taste buds along the margin behind their teeth, allowing them to determine if a prey item is suitable.

Ryan Johnson and Gibbs Kuguru's Experiment: Testing Shark Taste

• Ryan Johnson and Gibbs Kuguru conduct an experiment in South Africa to show what happens when an adult great white likes what it's biting.
• They use a seal decoy with a pipeline to inject different flavors into the shark's mouth.
• The experiment shows that adult great whites bite once and determine if the prey is suitable, while juvenile sharks bite multiple times.

Juvenile White Shark Bites

• Kajiura examines the distribution of white shark bites around the world, finding that two-thirds of the bites are from juvenile white sharks.
• This suggests that there may be juvenile training grounds where the sharks are learning how to feed.

Chantelle Doyle's Shark Attack

• Chantelle Doyle was surfing at Shelly Beach when she was attacked by a juvenile white shark.
• Her partner, Mark Rapley, punched the shark in the eye, causing it to release her.
• Chantelle suffered multiple bites to her leg.

Juvenile Training Grounds

• Melissa Márquez explains that juvenile great white sharks need shallow, warm-water areas with plenty of fish to learn how to hunt.
• These areas serve as training grounds where the sharks can grow and develop their predatory skills.

Shark Vision

• Dr. Christine Bedore explains that juvenile sharks have poor eyesight and cannot see as much detail as adult sharks.
• This may cause them to mistake humans for seals or other prey items.

Synthesis: The Juvenile Training Ground Theory

• The team concludes that Joe, Keane, and Chantelle were all attacked by juvenile great white sharks in training grounds.
• The sharks mistook the humans for prey items due to their poor eyesight and lack of experience.
• The juvenile sharks took multiple exploratory bites to determine if the prey was suitable.

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