The following article was submitted by an engineering student at Cape Cod Community College...
At around noon on September 15th of last year Arthur Medici, a student at Bunker Hill Community College, was surfing with friends roughly 40 yards from shore near Newcomb Hollow Beach in Wellfleet, Mass. when he was bitten by what is assumed to be a white shark. This incident became the first fatal shark attack on Cape Cod in 82 years, and the only fatal attack nationwide in 2018. In the aftermath there are questions of what will be done and what solution will solve the problem. These questions skip a fundamental step in the decision-making process. Before a solution can be agreed upon the community must decide what outcome it is looking for; a balance between conservation, safety and public image.
Suggestions for solutions range from culling the booming seal population, seal birth control, physical barriers, and even autonomous detection networks including sonar equipped buoys or drones. More pragmatic suggestions include an extension of lifeguard presence, evolving the tourist industry around a pro-shark mentality and adding emergency call boxes, medical stations and better signs to beaches informing visitors of the dangers of swimming in oceanic waters.
The seal population in the Gulf of Maine had a major die off recently, it will be interesting to see how that affects the population growth over the next few seasons. If the goal is a one hundred percent attack prevention rate, there are very few options: cull the seals and sharks until there is not a native population, ban swimming in the ocean completely in favor of pools and ponds, or put up a physical barrier that completely walls in a section of beach. None of these are particularly appealing, especially if we amend the goal to include doing no harm to the native marine population while still allowing humans to enjoy the waters if they choose.
Most of the technological, non-invasive suggestions have their own limitations in practical application. The main suggestions are spotter drones and a sonar based Clever Buoy system. The system consists of a buoy, a ground station and a series of sonar emitters to create a virtual fence that can detect sharks and other marine animals that enter their field of view, which is 120* horizontal by 10* vertical, with a purported 120-yard maximum range.
According to Australian surfer Ian Cairns, who played a role in bringing Clever Buoy to Newport Beach, Calif. “It works better in deeper water. Over 30’ is best.”
Cape Cod has gently sloping coastlines, which means the 500-yard trial fence currently being marketed around Cape Cod, which covers about 500 yards in length would need to be 880 yards from shore to be at the correct depth. White sharks have a cruising speed of 8-12+ mph with a pursuit speed of more than 25 mph and burst speeds recorded at over 35 miles per hour. Assuming a shark enters the roughly 500 by 120-yard patch, they can travel the entire 1,000-yard distance from the end of sonar range to shore in 4 minutes at a cruise, down to under a minute at full speed, leaving little time to evacuate the beach.
The US Navy was banned from using low frequency sonar in 2016 because it was found to be killing whales and dolphins. We do not know the effect of lining a coast with higher frequency sonar emitters.
Consumer grade drones have different limitations, they are much cheaper and have a range of 5 or more miles, they can be employed dynamically in a variety of situations to aid rescue workers. Their ability to detect sharks is vision based, and therefore only works in shallower, clearer waters; FLIR, an infrared based vision system can also be used for search and rescue. The technology to automate the flight grids already exists, the tech to detect sharks from a video feed, which is similar to facial recognition software, is just being tested by the Australian government; but is not available, nor is it ready to be relied on as an absolute defense. The same problem as before applies, the closer to shore you deploy a drone, the less response time there is. Someone could fly the drone manually, eliminating the need for automation, but hovering over a beach for 8 hours a day is boring, plus, what do you do every 20 minutes when the battery needs to be changed? Drones capable of flying further and longer exist, but the price tag quickly jumps from thousands to tens of thousands and even millions of dollars per unit.
Director of Florida’s Shark Research Program Gavin Naylor was quoted in a recent Washington Post article, speculating about what he believes may have happened to Arthur, saying, “A 12-foot-long, 1,200-pound white shark moving at 20 knots with an open mouth does a bit of damage…” Would you be willing to get into a pool full of aggressive juvenile sharks? What if someone on the other end of the pool would shout to you if one got close? Maybe we as humans need to reconsider our demands to enter these animals’ domains and expect a guarantee of safety.