Can swimmers and sharks coexist? Smarter maps can help

Can swimmers and sharks coexist?  Smarter maps can help

Medici’s death was Massachusetts’ first shark fatality since 1936. “We’re on our way, aren’t we?” says Doyle. “It was three bites in 14 months.” After her boyfriend’s paddleboard fear, Doyle co-founded Cape Cod Ocean Community, a group that eventually became a nonprofit dedicated to increasing public safety. The group helped connect pilots with lifeguards to warn them of possible sharks. It has raised money for drones and giant car-sized balloons with high-definition shark-spotting cameras, and has advocated for devices like the smart buoy, a marine monitoring and warning system that detects the large marine life in the water.

But half a year study Commissioned by the Outer Cape Towns and released in October 2019, it looked at the efficacy of more than two dozen shark reduction strategies, including the Clever Buoy, as well as nets, virtual barriers, electromagnetic devices to deter sharks. and drones, among others. The report ultimately concluded that most either didn’t have enough evidence that they actually worked, had limited efficacy, or wouldn’t work on the Cape Cod shoreline — except one: modifying human behavior.

This is the primary way public safety officials have mitigated shark risk in the past eight to nine years, said Suzanne Grout Thomas, director of community services for Wellfleet, a fishing village about 24 miles from the tip of Cape Cod. Since Medici’s death, cities have tightened their protocols, limiting distances for people to swim and sometimes closing beaches for swimming several times a day. Lifeguards and even some members of the public are trained in “stop the bleedingpractices for bites, while signs warn of the presence of sharks. “Our biggest contribution to this is to educate the general public about how sharks can behave,” Thomas says. And she’s already seeing signs that it’s working. People swim closer to shore, or don’t swim at all, and they react more quickly when the lifeguards blow their whistles to clear the water.

Last summer, Wellfleet had two buoys signaling lifeguards. If a tagged shark came within 200 meters, they could call swimmers out of the water. “There were hundreds and hundreds of sharks pinging those buoys last summer,” Thomas says. Her goal is to have one on every beach.

But this approach, she admits, has its limitations. Not every great white shark has been tagged, and cell phone network service on the Outer Cape beaches is still spotty at best, meaning live notification systems can be difficult to share widely.

While researchers and residents are considering the best mitigation strategies, one strategy — culling — has been left off the table. That’s an approach some countries have tried. Western Australia, for example, implemented a regional policy in 2012 to locate, capture and destroy sharks that posed an “immediate threat” to beachgoers. According to the International Shark Attack File, a global database, shark attacks in Western Australia are on a downward trend, but in the past few years they have increased again. Although it is difficult to estimate the effects, many experts say that projects are being culled do not work.

Now, technological advances and a growing understanding of animal intelligence give researchers hope that another management option is on the table, one that seeks to understand rather than modify shark behavior.

The ocean floor of the Cape is an immense patchwork of sandbanks, shallows and deep ditches. Sharks have learned how to navigate this underwater labyrinth. They now hunt in what some call “the trough,” a deep water area that forms like the letter C between the outer sandbar and the beach. Because seals are often found in these shallow waters close to shore, the sharks have learned how to attack sideways rather than ambushed from below. In fact, unlike other parts of the world, sharks on Cape Cod spend about half their time in water shallower than 15 feet, according to a recent study. study who analyzed data collected on eight great whites.


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