Glowing Oysters may be a New Weapon Against Poaching Around the Chesapeake Bay

Jan 21, 2020

Rings of fluorescent dye can be seen each time the oyster larvae has been incrementally dipped in the dye to tag them.
Credit Jason Spires

Wild oyster sanctuaries are being built all around the Chesapeake Bay. The goal is to give the bivalves a fighting chance since about 99 percent of the population has disappeared over the last century, mostly from over-harvesting, pollution and disease.

To ensure their survival, scientists are devising a very unusual way to track them.

The demonstrations scientist Jason Spires gives to visitors at a National Oceanic and Atmospheric Administration lab in Maryland tend to get more oohs and ahhs than the presentations of his colleagues. "Because they're showing them posters describing their research or computer models. And I'm putting live oysters in people's hands and turning the lights out and they glow in the dark," Spires explains.

Marine researchers tag species like sharks and striped bass to collect data. It's also been tried with limited success with blue crabs before they molt their hard shells.  "If you are a fisherman, if you are an outdoors person if you are a hunter you have heard of organisms being tagged. People catch fish with tags in them, people shoot ducks with bands on their feet."

Oyster larvae tagged with fluorescent dye.
Credit Jason Spires

But tagging oysters is not so easy. They start out as tiny larvae that swim to a hard surface where they attach and spend the rest of their life growing their shell, all while filtering the rivers and creeks of the Chesapeake Bay. So, Spires and his colleagues came used a synthetic dye approved by the FDA and U.S. Fish and Wildlife Service that infiltrates adult oyster shell and glows under a special light. The dye can also be used for oyster larvae.  "You may be familiar with visiting your ophthalmologist or a radiologist and having them inject a dye in you that fluoresces. It's the same technology," Spires says. "So, we're just getting, in this case, the oysters to form a new shell that has flourochrome dyes that glow under a blue light."

The technology will benefit researchers and fisheries managers who monitor the health and populations of wild oysters. And it also has implications for oyster poachers, who might be tempted to harvest from new sanctuaries.  "When oysters are at the dock you have no idea where they came from. But if there was something in them that couldn't be removed or seen with the naked eye, it would give enforcement agencies a way to track movement of certain organisms."

Jason Spires counting baby oysters at NOAA's Cooperative Oxford Laboratory in Maryland.
Credit Shawn McLaughlin/NOAA

More research needs to be done but so far the technique, which involves soaking oysters in the dye for 24 hours is cost effective.  "You can mark thousands of individuals for hundreds of dollars. And you can reuse the chemical," he says.

And for all you oyster lovers, Spires promises you won't glow in the dark after a night at the local oyster bar.

This report, provided by Virginia Public Radio, was made possible with support from the Virginia Education Association.