The longline fishing industry faces an ongoing problem with sharks – some of them endangered and protected species – interfering with commercial fishing gear and being caught unintentionally as “bycatch.” Not only do the sharks require better protection, but they are also eating too much of the fishing boats’ bait and their intended catch.
Enter the shark ticklers.
A team of IU South Bend scientists have been vital collaborators in a larger initiative with the goal of developing an industry-deployable, microprocessor-based, shark bycatch reduction device. These units, nicknamed “shark ticklers,” are being assembled, modified, and refurbished in a lab in the basement of Northside Hall on campus. They are then deployed for experiments in waters ranging from the east coast of the United States to the west coast of Mexico to a lagoon in Hawaii.
The local leaders of the project are IU South Bend physics professors Ilan Levine and Brian Davis and emeritus biology professor Peter Bushnell. The shark ticklers they have developed emit an electric field that sharks can sense but regular fish cannot. Sharks have sense organs, called the ampullae of Lorenzini, which allow them to ‘feel’ electric fields. If the shark ticklers are next to the baited hooks, they can deter sharks as they approach, in a phenomenon akin to sonic devices which humanely scare away birds.
Video footage of field testing shows sharks approaching the bait and shark tickler, only to veer away at the last moment, repelled by the electric field. As the data continues to roll in, the team learns more about when the units are working the best, and where they still need tweaking. Levine envisions eventually customizing units for maximum efficacy.
“Down the line, maybe there might be a shark tickler for certain species of sharks in a warm-water environment and a different one that would go to the deep sea, and those kinds of sharks,” Levine says.
A group of undergraduate science students is working alongside their senior colleagues, whether processing data or using soldering irons to fix shark ticklers that have been partially mangled by a shark chomp.
“It’s important to involve undergraduates in research as early in their careers as possible,” Levine says. “This allows them to do some real science, not just take science courses – it gives them a sort of “test drive” of their intended profession.”
Biology major Tori Hartl was with the team for testing in Outer Banks, North Carolina, and she has had a hands-on role in the lab, tending to shark ticklers that have been returned from far-off waters.
“I’ve worked on hundreds of these things, looking at them to see what might have gone wrong,” Hartl says. “Every time they come back, we get more feedback. We’re always making adjustments. We do a lot of soldering, we work with epoxy, we do everything right here.”
The collaboration recently completed a large-scale experiment in which they instrumented the hooks on a commercial longline fishing vessel presenting thousands of hooks with active and inactive shark ticklers. They are currently analyzing their data and writing a paper, but it is already apparent that there are significant bycatch reductions.
The National Oceanic and Atmospheric Administration has committed to prioritizing shark bycatch management, and with continued support from the NOAA, the North Carolina Sea Grant, and other initiatives, the IU South Bend team plans to hone their work with the shark ticklers well into the future.
The team plans to study whether there are differences in deterrence based upon environmental conditions, age, sex, or species of shark as well as any ways to increase bycatch reduction. If the shark ticklers continue to work effectively and can be made available to the fishing industry at affordable prices, they could successfully address a problem that has plagued marine biologists and fisheries for decades.
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