Scientists researching way to deter sharks from commercial lines
Carol Vaughn
Correction: An earlier version of this story incorrectly identified Bethany Brodbeck, a summer intern at the Virginia Institute of Marine Science.
Scientists at the Virginia Institute of Marine Science in Wachapreague are doing research this summer that could result in a way for commercial fishermen to keep sharks from interfering with their fishing lines.
VIMS Eastern Shore Lab has the advantage of being right on the water and near the last undeveloped stretch of barrier islands on the East Coast.
"There is only one lab in all of Virginia that has running seawater, which you need to keep sharks," said VIMS scientist Richard Brill.
That lab is in Wachapreague.
Brill, who works the rest of the year in Gloucester, Virginia, has spent his past several summers conducting shark research in Wachapreague.
"These kinds of places are really rare," Brill said of the waterfront research facility.
The sandbar sharks researchers are observing this summer in a tank at the Seawater Lab come from right off the dock. When the research is over, the sharks are returned to the same waters.
The research examines the response of the sharks to an electronic "tickler" device — officially called a bycatch reduction device.
The hope is that with the right combination of electronic signals, sharks will be discouraged from attacking a baited fishing line.
A camera over the tank captures footage of the sharks as they swim, including whether they avoid the bait when the device nearby is emitting various signals.
"It's a very tiny electrical field. They have an electrical sense that detects very, very tiny voltages," Brill said.
It's not a shock — there really is no human equivalent, but scientists sometimes refer to what the device does as being like a human being tickled.
"It's not like you stick your finger in a light socket and get a shock ... tickling is the best (human equivalent)," he said.
Reflective tape, like the tape commonly used on the back of tractor-trailers, is glued to the top of each shark's head. It shows up as a bright white dot as cameras capture the shark's movements, which can then be plotted on a chart to see if the device is keeping the shark away from the bait.
Brill and Peter Bushnell of the University of Indiana, South Bend, are working on the shark project this summer with two student interns from opposite sides of the continent — Brenda Pereda-Rodriguez, a rising senior at the Universidad Autonoma de Baja California Sur in Mexico, and Bethany Brodbeck, a rising sophomore at the University of New England in Maine.
"We are looking at trying to find a pattern ... there are four different types that have different stimulus patterns," Brill said, adding, "What appears to be the final decision for a shark of whether to eat something or not is based on what they are feeling in their electrical system. We are trying to get just enough of a reaction that they decide, 'I don't want this.' "
What makes the device potentially feasible in a commercial setting is the fact that battery-powered microcomputers the size of a human thumb are now available, "and they are down to $3 each," Brill said.
"The economics works out," he said.
"Picture this whole thing out on hook-and-line fishing gear ... with each one of those (devices) right by the hook," he said.
For commercial fishermen out to catch tuna or swordfish, hooking sharks that they don't want is a significant problem — if the devices work to deter sharks, it would be a boon.
"They don't want to deal with the sharks — every hook that has a shark on it doesn't have a fish that they want," Brill said.
Additionally, large sharks "are really active when they get caught, so they just tie the line into a knot — you can't get it back. You just have to cut it away as best as you can, so they lose a lot of gear that way," he said.
The research has been going on at the Wachapreague lab during summers for around seven years.
"We originally started with pieces of metal that make a constant electric field in the water — that works really well here in the lab, and it worked when we tried it in the estuary, and they took it to the Canadian fishery that is fishing for swordfish — and it didn't work at all," Brill said.
So it was back to the drawing board for a different idea — a device that can produce various electrical fields.
"And you can program that computer any way you like" — so if it doesn't work out with one set of programs, a different one can be tried, he said.
This summer the research is taking place mainly in the lab. Next summer, if the findings continue to look promising and funding is available, a prototype of the device will be tried in the field.
"The bycatch issue with sharks has been around forever — and now with computers that are that small and that cheap, now it all becomes feasible," Brill said.
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