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 scissors-like 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 algae-filled 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.
Harnessing the sun
Meanwhile, two Baltimore area companies are looking to boost oyster farming and restoration by developing a solar panel-equipped barge capable of raising nearly 6 million bivalves at a time in waters normally too deep for farming.
If the effort succeeds, it could help the industry continue to expand by steering clear of conflicts with watermen and waterfront property owners over leasing near-shore waters.
The venture, dubbed Solar Oysters, LLC, is a partnership of Maritime Applied Physics Corp., an engineering outfit that builds unmanned boats for the Navy, and EcoLogix Group, Inc., an environmental consulting firm.
Mark Rice, president of Maritime Applied Physics, likened the barge to a floating factory. Solar energy would power an electric motor to slowly rotate columns of submerged oyster-filled cages, lifting each cage to the surface for a brief period every couple of days. There, they’d be hosed down and exposed to sunlight to rid them of fouling organisms that limit the oysters’ growth. The entire operation would be automated, taking much of the dirty, back-breaking labor out of conventional oyster cage maintenance.
Working with UMCES experts, the partners launched the venture with an $80,000 matching grant from a state-funded program that enlists university faculty to help companies develop new technologies.
In summer 2019, they field-tested small-scale barge prototypes at the UMCES Chesapeake Biological Laboratory. The lab is in Solomons near the mouth of the Patuxent River, and in such open water the barges took a beating from winds, waves and boat wakes.
Rice said they plan to try again this summer, with an investor lined up to finance the construction of a 40-foot by 22-foot barge. It will be moored to a dock in the more sheltered waters of Baltimore Harbor and will initially be used to raise oysters for restoration work with the Chesapeake Bay Foundation, he said.
With the lessons learned from that, the partners intend to build a full-scale barge, 90-by-53 feet. Rice envisions an oyster farmer using four barges at a time, with a crew of about 10–12 workers to maintain the equipment and handle the sorting and harvesting of oysters.
Tom Miller, a fisheries scientist and director of the Solomons lab, said that with their ability to operate further offshore, the barges might help defuse nagging battles over leasing near-shore waters. Watermen have objected to giving up areas where they crab and harvest wild oysters, while waterfront property owners have fought against having aquaculture operations within sight or sound of their homes.
Even so, Miller said the venture faces significant challenges — among them, finding water deep enough for the barges where they would not block navigation or suffer too much exposure to the elements. Above all, the system must be able to produce oysters at a cost that ensures a profit for the farmer.
The average depth of the Bay is 21 feet, he noted, and much of it is too shallow to accommodate cage arrays going down 20 feet. And the full-sized barges are projected to cost about $900,000 each, a hefty upfront investment when compared the cost to pursue traditional oyster farming.
But Rice said the partners figure if the barges are big enough, they’ll be able to keep the per-oyster cost low enough to market them at a competitive price.
“It’s just like agribusiness,” Rice said. “If you can get a big tractor [you can] plow a lot of land with little labor.”
Reef health checks
Besides helping oyster growers, new technologies also help efforts aimed at restoring the Bay’s wild oyster population.
In a partnership with the Chesapeake Bay Foundation, teams of engineers with Northrop Grumman, better known for its work on air and space technology, are developing systems for assessing and improving restored oyster reefs. In the last year they have field tested three sensors.
One is an off-the-shelf side-scan sonar unit that’s been tweaked to improve the resolution of its readings. It can be towed behind a boat to map underwater reefs. Another is a high-resolution hydrophone that can be deployed on buoys to listen for the sounds associated with healthy oyster reefs. The third is a “light field imaging camera,” which can render three-dimensional images of reefs, allowing researchers to assess the volume and complexity of the underwater structure and possibly even count individual oysters.
To date, assessment of reef vitality has been a laborious and time-consuming, relying on repeated sampling of the bottom with mechanized tongs, dredges or divers.
Doug Myers, a senior scientist at the Bay Foundation, said the Northrop Grumman partnership promises “a whole different paradigm” for monitoring oysters in the Bay, offering hope that quicker, more comprehensive checkups can aid in restoration.
“Large geographic areas can be covered in a single day,” he said. “We’re not interested in how many oysters to scoop up. We’re interested in the reef.”
Miller, the Solomons lab director, said that if all these new technologies improve oyster survival and growth by even a small amount, it could have big consequences, both for aquaculture and for trying to restore the Bay’s depleted oyster population.
Of the 2.5 billion hatchery-spawned juvenile oysters that have been planted in a huge Harris Creek oyster restoration project in Talbot County, MD, only 3–5% survived beyond two years, Miller said.
“Whether it’s improved survival in the hatchery, improved placement or protection against predators, whether it’s the substrate you plant them on or continued closure to fishing,” he said, “whatever it is, you turn 3% into 10% and you change the game.”
This article originally appeared on BayJournal.com on Monday, April 19, 2021.