Scientists deploy ‘Frankenturtles’ in Chesapeake Bay to boost survival of loggerheads

A part of David Kaplan recognizes that his new research into sea turtle mortality is pushing the envelope.

The assistant professor and his graduate student, Bianca Santos, are doing something never before attempted: repurposing the carcasses of two dead loggerheads, outfitting them with GPS devices and setting them adrift in the Chesapeake Bay, all in the name of science.

“Most people have not had the reaction that this is disgusting,” Kaplan said one recent morning from the boat basin at the Virginia Institute of Marine Science in Gloucester Point.

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“It’d be interesting to see what the public thinks, because I think of it as a really great thing. I mean, it’s pretty gruesome, but it’s taking animals that died tragically and reusing them for the [greater] good. A better purpose.”

That purpose? To see where the winds blow these dead animals — nicknamed “Frankenturtles” — in hopes of extrapolating where and how sea turtles are most likely to die in the estuary.

“We know where they’re washing up,” said Santos. “We just don’t know where they’re dying.”

Between 100 and 300 dead loggerheads are found every year on Virginia beaches. Some bear obvious signs of trauma — typically a lethal boat strike — while others are killed by encounters with fishing gear, chilly water temperatures, disease or pollutants.

But Kaplan said such numbers are probably the tip of the iceberg, representing only those bodies that float to the surface, drift into the coastal zone, get beached and are discovered.

“For all of those things to happen, it’s fairly unlikely,” Kaplan said. “Many of them probably drift out to sea, are eaten by other animals [or] drift into marshy areas. There’s lots of ways we can miss dead turtles.”

He estimates loggerhead mortality could reach 1,000 individuals or more out of a seasonal bay population put at 5,000 to 20,000 — mostly juveniles who arrive every summer to forage and feast before migrating to warmer waters for the winter.

It’s just one of the reasons the loggerhead is listed as a threatened or endangered species under federal and international laws.

The Frankenturtles, then, are an attempt to help boost the survival of the species.

The carcasses came from the Virginia Aquarium and Marine Science Center in Virginia Beach, which heads up the state’s Stranding Response Team. Both were juvenile males, died from boat strikes and underwent necropsies.

The remains were secured with wire mesh and plastic zip ties, then filled in with plastic spray foam insulation. Each had a Styrofoam buoy attached by strong rope, with a satellite tracker and a number to call at the Virginia Institute of Marine Science should the carcasses be found washed ashore.

Then they were frozen until their deployment in the mainstem of the bay.

Deploying along with them were nonorganic “drifters” — small, orange buckets filled with weights, and mock turtles built of wood and Styrofoam. Santos said the drifters came from the Northeast Fisheries Science Center of the National Oceanic and Atmospheric Administration, which is helping in the research.

The buckets are designed to submerge and drift with the current alone. The mock turtles float on the surface.

“What we want to see is the difference in these two,” Kaplan said. “And that will tell us the correction we need to put into the [existing] model of drifting objects, which just models the currents.”

Kaplan earned a doctorate in physics from UC Santa Barbara, and specializes in meta-population modeling.

With any luck, said Santos, what researchers learn from the turtles will one day go toward crafting mitigation measures, devices to reduce sea turtle deaths as fishery bycatch, and possibly even legislation to help set aside protected areas in the bay for loggerheads.

The Frankenturtles will be tracked for a few days, and then their GPS devices will be recovered. The sea turtles themselves won’t be — Santos’ other research into the decay rate of dead loggerheads indicates the carcasses won’t last more than five to 10 days on the water.

“These two,” Kaplan said, “it’s their only and maiden voyage.”

Dietrich writes for the Daily Press in Newport News, Va.

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