Researchers Test Electromagnetic Shark Barrier

CHATHAM – In the growing body of research, one thing is abundantly clear: white sharks are present, in large numbers, in the immediate vicinity of many bathing beaches on the Cape. Keeping them separated from people is the prime challenge facing beach managers, and a research project off Chatham last summer showed some promise.

Developed by Craig O’Connell of the O’Seas Conservation Foundation, the system involves an interconnected “exclusion barrier” of electromagnetic pipes running from the seafloor to just above the surface. The pipes would be arranged one meter apart from one another to form a kind of fence around swim areas.

“That visual component deters visual predators, and the great white shark is a visual predator,” O’Connell said. But because the water is sometimes murky, the visual element is not enough. “That’s where the second part of the barrier, the electromagnetism, becomes very important,” O’Connell said. Each pipe includes a permanent magnet and a solar-powered electromagnet; when sharks get within two feet of the pipes they receive a small shock, “and the shark swims away,” he said. Because the system targets the shark’s unique electroreception sense, it is designed to exclude them but not fish, seals or whales, O’Connell said.

While electromagnets have been used as a shark deterrent in various exclusion nets and other technologies, O’Connell developed the prototype exclusion barrier as a non-lethal barrier stretching from the bottom to the surface, designed to resist surf and currents. Following a trial on bull sharks in the Bahamas, O’Connell and his team secured permission to install a trial array in Chatham last summer. The area they chose was the stretch of beach on the east side of Monomoy Island known as “Shark Cove.”

Working in August and September, the researchers, assisted by volunteers from Cape Cod Ocean Community and the Explorers’ Club, conducted 35 two-hour trials. Using an underwater video system and observations from a boat, researchers deployed shark bait and saw six to 10 white sharks in the area, with none passing through the barrier but 21 passing through an adjacent area without the powered barrier.

Last summer’s trial involved stretches of barrier installed parallel to the shore; in the next phase of the study, O’Connell hopes to arrange the barriers to form an exclusion area, essentially a box around a stretch of beach. He’s hoping that trial will take place around October, possibly in Chatham or in California. If the findings continue to be promising, the barriers could be put around swim areas or other places where sharks need to be kept at bay.

“It would likely be in very small sections, about the length of a football field,” O’Connell said. Because the poles have telescoping top halves that float, the barrier remains constant to the surface of the water regardless of tides and waves, with only a small portion visible from the surface.

“You don’t want to have a very ugly shoreline where there’s a lot of pipes coming out of the water at varying heights,” he said. The pipes are used instead of ropes or cables in order to eliminate the risk of entanglement, O’Connell added.

Aside from their effectiveness in deterring sharks, the barrier had to be tested to see whether it would remain in place in punishing surf and tide conditions.

“I was nervous, myself” about how well the system would fare when exposed to direct Atlantic waves at Shark Cove, O’Connell said. Initially, researchers deployed the array only on calm days, but when there were no signs of movement in the barrier, they began to leave it out in poor weather. “We deployed it in a period when there were multiple tropical storms going by,” he said. For four days, the crew couldn’t leave port to check on the barrier, because of swells up to nine feet and breaking waves of around five feet.

“The barrier was fully intact. It did not move,” O’Connell said.

If the technology proves viable, the barrier will only be offered to communities that express interest in using it, as expressed in public meetings, he said. The O’Seas Conservation Foundation is raising funds so that the barrier can be donated to those communities, he added. Conservation is at the heart of the project, and proponents hope it will be used in places like Australia and South Africa where sharks are killed to keep them away from swimmers and surfers. While it would not be installed in areas large enough to truly disrupt the predator-prey relationship, the goal is to create zones that “allow people and sharks to coexist,” he said.

O’Connell said his findings will be submitted to a peer-reviewed scientific journal before the end of the year, but he has not yet selected a specific journal.