New oval bycatch reduction device could bring relief to diamondback turtles

  • A special trap:

    Michael Gibson ’23 is preparing to install a crab trap at a test site off the York River. The team uses special traps fitted with a wire snorkel (right) that allows turtles to rise to the surface of the water and breathe. He is part of a team comparing two designs of devices intended to prevent turtles from entering the traps of crabbers.
    Photo by Madeline Reinsel

by Joseph McClain


September 22, 2021

Diamondback turtles have always struggled to take a break.

Until the first third of the last century, turtles were at the top of the luxury food list. Joseph Mitchell had a 1930s piece in The New Yorker a report on a Fulton Fish Market company that sold 2,000 liters of diamondback turtle stew per year.

A patchwork of state and federal regulations prevent the only true American Estuarine Turtle from being served as seafood, variously classifying the turtle as Endangered, Threatened, or Special Concern across the species’ range. on the East coast.

{{youtube: large: center | uf6kPOavS7k}}

Randy Chambers explains that diamondback turtles continue to be unwitting victims of the seafood industry as they end up drowning as bycatch in crab pots. Chambers, the director of William & Mary’s Keck Environmental Field Laboratory, leads a team trying to find a way to keep turtles out of traps in the first place.

Madeline Reinsel, a research assistant at the Keck Lab, explained that the turtles entered the metal traps attracted by the bait attached to the blue crabs. Like crabs, turtles can’t get out. Unlike crabs, turtles cannot breathe underwater and drown in traps.

Much of the effort to keep sea turtles out of traps has focused on bycatch reduction devices, or BRDs. Chambers said the crabeater community has resisted voluntary adoption of BRDs and has also resisted any proposed regulations.

Chambers, Reinsel, and two undergraduates from William & Mary hope to win over even BRD’s most hard-line skeptics. This summer they tested a new BRD, designed by Reinsel. Its design has an oval opening, a departure from the usual rectangular BRD.

“The oval BRD design was originally envisioned by JD Kloepfer of the Department of Wildlife Resources, who asked me if anyone had ever considered using oval BRDs on crab pots,” Chambers said. . “I thought it was a great idea and decided that it would be helpful to compare the effectiveness of oval BRDs versus rectangular BRDs. “

Reinsel created the original 3D print design on Tinkercad, then worked with students and Makerspace staff at the Swem Library to print approximately 50 oval BRDs to use during the summer experience.

Oval vs. Rectangular: Studies show that both designs work equally well in preventing the turtle from entering crab traps, but the oval is much easier to set up.  (Photo by Madeline Reinsel)The principle of a BRD is to narrow the oval opening in a crab trap so that crabs – even jumbos – can get in, but not turtles. Chambers explained that there are no good statistics on the toll of crab pots on the Virginia turtle population. Reinsel added that there are several reasons for the dearth of data, starting with the fact that since any Virginian can operate two crab pots without a crab license, there is no way of knowing how many Recreational crab pots do exist, especially in shallow water. , estuarine waters where blue crab and turtle turtle habitats overlap.

“We don’t know if more turtles are being killed by recreational crabbers or by commercial crabbers who venture into shallow water to fish for crab,” Chambers said. “Another problem is that commercial crabbers lose a lot of their traps every year because of storms, propellers cutting the lines of floats, etc. . “

Michael Gibson ’23 and Natalie Klesch ’23, spent their summer working in the field to collect data for a study comparing rectangular BRDs to the oval design. They received funding from the William & Mary’s Charles Center and the Committee on Sustainability for their research; the project itself received support from the PADI Foundation.

Gibson and Klesch worked from a canoe at Indian Field Creek and Felgates Creek in the Yorktown Naval Weapons Station on the York River, an estuary in Chesapeake Bay. Chambers noted that the group had received special permission to conduct the study in areas closed to commercial and recreational fishing.

The study used traps much like a commercial or recreational crabeater, but fitted with a snorkel that allows a trapped turtle to swim to the surface of the water and breathe. Working with Chambers and Reinsel, Klesch and Gibson maintained the traps daily, hauling the traps up, extracting crabs and turtles, re-baiting and resettling. They measured their catches – crabs as well as turtles – and recorded the data.

“At the end of the summer, they did a preliminary data analysis and presented their results at the Mid-Atlantic Diamondback Terrapin Task Force conference in late August,” added Chambers. Reinsel documented the work in a video, which was submitted to the Coastal and Estuarine Research Federation Film Festival.

Preliminary results show that the oval design was as effective as traditional rectangular designs excluding turtles, but the new design has a significant advantage.

“It’s much easier to install,” Reinsel said, “because the oval shape of the funnel lends itself better to an oval BRD. Unless you have very small hands, it can be difficult to fit rectangular BRDs into crab pots – it’s literally a square peg and round hole phenomenon. It takes about half the time to install an oval BRD compared to a rectangular funnel BRD.

Comments are closed.