From the Bay

Underwater Drones In Chesapeake Oyster’s Future

People have been farming oysters in the Chesapeake Bay since at least the 1800s, and some of the methods and tools in use today haven’t changed much.

Now, some researchers and entrepreneurs are working to bring oyster aquaculture into the 21st century.

Just as agriculture increasingly uses new technology such as airborne drones to monitor crop growth and equipment that applies fertilizer more precisely, scientists hope to boost the aquaculture industry’s output and profitability by employing remote sensing, robotics and other cutting-edge technology.

Such innovations are important for both oyster growers and the Bay. With the Chesapeake bivalve population suffering from pollution, habitat loss and disease, oyster farming has become a vital complement to the wild fishery.

And, if the new efforts succeed, the growth of aquaculture can further ease harvest pressure on ecologically important wild oysters and help restore their abundance in the Chesapeake.

Eyes underwater

Working with a $10 million grant from the National Institute of Food and Agriculture, a group of researchers from the University System of Maryland and other institutions on the Gulf and West coasts is developing a submersible drone that could increase the efficiency of planting and harvesting oysters on the Bay’s bottom.

“Basically, what we’re trying to do here is very similar to land-based precision farming,” said Miao Yu, a professor of mechanical engineering at the University of Maryland College Park campus and research team leader.

Oyster farmers, especially those who cultivate the mollusks the old-fashioned way — loose on the bottom of creeks and coves — often check on their crop’s progress by pulling some of them out of the water, using scissorslike tongs similar to what watermen wielded in the 1800s and 1900s. Or they may send divers down to inspect the oyster beds, though the water is often too murky to see much.

Don Webster, an aquaculture specialist with University of Maryland’s extension system, said it’s time for oyster farming to catch up with land-based agriculture.

With shellfish aquaculture, Webster said, “we’re somewhere between Amish horse-drawn implements and a 1950 Farmall H,” he said, referring to the classic red farm tractor once widely used to till fields and harvest row crops.

Crop farmers today “don’t walk thousands of acres of corn and soybeans,” Webster pointed out. “You send a drone out, [which] can do in minutes what used to take hours.”

The team has been working to develop the ability to “see” the bottom of a murky waterbody, using an underwater drone equipped with cameras and sonar.

In early March, they began testing their underwater autonomous vehicle at the Horn Point Laboratory of the University of Maryland Center for Environmental Science, on the Choptank River outside Cambridge, MD. There, alternately fitted with a camera and sonar, they tested its ability to “see” through water of varying clarity to spot shells scattered on the sand-covered bottom of a giant fish tank.

Matt Gray, an assistant professor at Horn Point, said the initial tryout went well.

“We’re just getting started,” he said. The goal, he explained, is to perfect machine learning algorithms that can enable the device to analyze what its sensors pick up and quickly distinguish between live and dead oysters.

Another goal is to give it the ability to determine whether the bottom is soft mud, firm sand or covered with shells, which can help farmers maximize the survival of hatchery-reared spat, or juvenile oysters, they put in the water. In order to survive and grow, oyster larvae need to settle on hard surfaces, or substrate, on the bottom.

“We want to be able to identify suitable substrate for them,” Yu said.

The team is working on “smart” harvesting as well, using remote sensing to identify where the most oysters of marketable size can be dredged from the bottom with the least expense of fuel and labor.

In a November 2019 field test, the team deployed their underwater drone in the Bay, where it was able to see oysters on the bottom and allow for some tentative assessment of their condition. But Yu said the water was unusually clear at that time, unlike the algaefilled murk that typically clouds the Bay in late spring

and summer when a lot of oyster farming activity occurs. So, more testing is planned this summer under “more challenging conditions,” she said.

Sensor-equipped drones are likely to be too expensive for many oyster farmers to own outright. Rather, Yu said she envisions the technology would support a consulting service for oyster growers. They would pay a fee to have their leased bottom and oyster beds surveyed, with the results available for download to a computer or smart phone.

(Top) Using a video game controller, University of Maryland research fellow Randy Ganye pilots “underwater autonomous vehicle,” or drone, around tank at UMCES’ Horn Point lab. Watching the action are UM fellow Behzad Sadrfaridpour, UMCES Assistant Professor Matt Gray and UMCES graduate student Laura Wiltsee.

Photo by Dave Harp. (Right) An underwater drone spotlights oyster shells in a tank at the Horn Point laboratory of the University of Maryland Center for Environmental Science. Through the use of “machine learning,” researchers hope to get the device to “see” through murky Bay water to identify live oysters on the bottom and find favorable spots to plant more.

Photo by Dave Harp

Tim Wheeler is the Bay Journal’s associate editor and senior writer, based in Maryland. You can reach him at 410-409-3469 or twheeler@bayjournal.com. For more information on what is happening in the Chesapeake Bay, logon to bayjournal.com.