A team of shark researchers has identified a nearly 12-foot female mako shark as the predator responsible for a series of violent attacks on large marine animals off the coast of New York, ending speculation that nuclear waste dumped in an underwater canyon had produced a genetically altered monster.
The investigation, launched on September 20, 2025, following reports of large marine animals being attacked off Long Island, was led by shark scientist Craig O’Connell. A humpback whale was found with a 24-inch bite mark, a gray seal suffered a 22-inch wound, and a 400-pound tuna was discovered ravaged in the water.
O’Connell and his team nicknamed the suspected predator ‘Sharkzilla.’ The hunt is the subject of a Discovery Channel Shark Week episode, Sharkzilla Takes New York, airing on Friday at 9pm ET.
The Hudson Canyon theory
The team traveled roughly 100 miles offshore to the Hudson Canyon, an underwater gorge that begins at a depth of about 900 feet and plunges to around 4,000 feet. O’Connell noted that in the late 1960s, 15,000 barrels of nuclear waste were dumped there, and when authorities checked a decade later, the barrels were all leaking.
O’Connell raised the possibility that radioactive contamination could have affected wildlife in the canyon. He said that if animals were subjected to nuclear waste, it could cause genetic mutations and abnormal growth, potentially producing a predator that was faster, stronger and deadlier than any other. He stressed that the theory was controversial and unproven.
With a storm approaching, the team had just 30 hours to find the creature, tag it, and collect tissue samples for radioactive testing.
Into the water
The team lowered a baited camera into the canyon at 4am. Six hours later, footage captured more than 600 feet underwater showed a large great white shark emerging from the darkness to bite the camera. A mako shark also appeared.
O’Connell and his crew entered the water to hand-feed the sharks, placing themselves within striking distance. A 10-foot female mako moved toward the divers. Makos are the fastest sharks in the ocean, capable of exceeding 40 miles per hour, which led O’Connell to suspect that Sharkzilla could be one of them.
Two makos then appeared together, an unusual sight because the animals are typically solitary hunters. They vanished abruptly, raising fears that something larger had frightened them away. An enormous shadow then cruised past the team and disappeared into the darkness before it could be identified.
Sharkzilla identified
As daylight faded, the team deployed a device they called a ‘blubber blaster,’ designed to mimic the aftermath of a dead whale releasing material at the surface. A giant female mako then charged toward the boat. O’Connell identified her as Sharkzilla.
When the shark refused to approach the cage, O’Connell swam outside to attach a tracking tag. His first attempt failed when the tag bounced off her body. When the mako returned, he successfully attached the tag and obtained a tissue sample.
Tracker signals showed Sharkzilla traveling back toward Montauk. Laboratory tests found no evidence of radioactive mutations, ruling out the team’s most alarming theory.
The investigation did reveal that the waters served as a mako breeding ground. O’Connell concluded that the predators were hunting to feed their developing pups, offering a natural explanation for the attacks. Sharkzilla was not a radioactive mutant, but a large pregnant mako patrolling its home waters.
