Baltimore scientists are changing the face of aquaculture. Are farm-raised blue crabs next?

Published on: November 08, 2022 6:00 AM EST|Updated on: November 08, 2022 2:24 PM EST

Two scientists and lab equipment in front of tank of fish

The salmon was anesthetized, but not enough. It lay still as a doctoral student scraped mucus from its side. But when a lab assistant snipped its tail, the fish aggressively jerked, nearly flying off a metal scale. Yonathan Zohar, a professor of marine biotechnology who has likened himself to an OB-GYN for fish, used both hands to hold it down.

“This is NOT the Aquarium,” reads a sign at the building’s entrance where Zohar performs his work. Unlike the National Aquarium — which also houses aquatic life, and sits just next door along the city’s Inner Harbor — the Institute of Marine and Environmental Technology, part of the University System of Maryland, is closed to the public. On the ground floor, behind several doors that need a keycard to enter, is an 18,000-square-foot floor laboratory that’s changing the face of the global seafood industry.

This lab, called the Aquaculture Research Center, is where the action is, said Zohar, who directs the center’s research. Here, Zohar and his team are trying to pioneer an environmentally responsible way to source seafood amid overfishing and declining fish populations across the globe. Inside the lab, there are thousands of underwater creatures that the general public rarely gets to see. Fish raised at the center have wound up on tables at Baltimore’s finest restaurants.

Temperature and salt levels in the tanks are precisely manipulated to reflect the natural spawning grounds of the salmon off the coast of Maine. In the wild, they usually spawn once a year. At IMET, scientists are tricking the animals, Zohar said, into spawning year-round, an innovation that would be a game changer for producers.

But the technology is not without controversy. Following attempts to build a salmon farm on the Eastern Shore, critics opposed what they call a “fish factory” in Maryland.

As he walks through the lab, Zohar, who was born in Israel and has lived in Maryland for three decades, often stops to grab a handful of feed pellets to throw into the tanks. Watching how they respond can provide insight into their wellbeing; stressed fish won’t eat much. That anesthetized salmon, for example, will need time to recover.

“Be careful, they splash,” Zohar said, beneath the hum of equipment.

The next frontier in aquaculture

To appreciate the lab’s significance, it helps to understand a few things about how Americans eat.

First, we consume a lot of seafood, especially salmon. Most of it is farm-raised, or aquaculture. At the moment, most of that farm-raised salmon that Americans are gobbling up is imported from abroad.

As a result, there’s growing interest right now in aquaculture in the U.S. and beyond. Zohar’s team recently received a $10 million grant from the U.S. government for his research on American diners’ favorite fish: salmon.

Their aim, Zohar said, is twofold: feed the world, and preserve wild stocks.

Traditional methods for farming fish like salmon — raising them in pens in open water — can wreak havoc on marine ecosystems. And fish raised that way are susceptible to environmental stressors such as disease.

The solution: recirculating aquaculture systems, like the ones Zohar uses to raise salmon. These are tanks on dry land. “Nothing goes back into the environment,” Zohar said. And the “environment doesn’t have any impact on the fish,” he said.

Fish poop and other detritus is continuously filtered out of the water and can even be converted into an energy source. To demonstrate, Zohar lights a Bunsen burner fueled by methane extracted from the fish sludge; the smell of gas commingles with the fishy smell emanating from the tanks.

At a U.S. Department of Agriculture lab in Maine, fish are selectively bred to grow fast. Here in Baltimore, scientists can play God, manipulating the conditions to get fish to spawn more frequently than they do in the wild.

Doctoral student Jonas Miller accompanied the salmon on the journey from Maine by road to Baltimore. Months later, “They’re doing swimmingly well,” Miller said with a grin.

Not everyone is on board. Norwegian firm AquaCon had planned to use IMET’s technology in building its first-ever salmon farm on Maryland’s Eastern Shore. The project drew skepticism from those who worried the project, which would release cold water into waterways, would pose a threat to local endangered sturgeon. Environmental groups including the Chesapeake Bay Foundation spoke out against it. Critics labeled it a “fish factory.” AquaCon recently withdrew its application for permits.

The situation highlights what Zohar sees as a public relations problem for land-based aquaculture, one he is working to address. Zohar blames a lack of understanding among the public about why land-based systems like the ones IMET is pioneering are an environmentally-friendly alternative to wild-caught fish as well as farm-raised fish kept in pens in the ocean.

Zohar acknowledges there is work still to be done. Tank-raised salmon can develop an off-flavor for reasons that Zohar and his team don’t fully understand. He’s collaborating with scientists in West Virginia to tackle that problem.

But the branzino, said chef Spike Gjerde, was delicious.

Gjerde, the James Beard Award-winning co-founder of Baltimore’s Woodberry Kitchen, first learned about Zohar’s work from the book “Four Fish: The Future of the Last Wild Food” by author Paul Greenberg. He soon came by IMET to meet with the scientist and tour the laboratory. “I was just flabbergasted by the level of research,” Gjerde said.

Although Gjerde doesn’t eat imported branzino or salmon for environmental reasons, he relished the fish from IMET. His Baltimore restaurant — Woodberry Kitchen, which is currently closed for renovations — even put the lab’s branzino on the menu years back.

Tony Foreman — whose Foreman Wolf restaurant group owns some of Baltimore’s top restaurants, including Charleston and Petit Louis Bistro recalls serving dorado, also known as sea bream, sourced from IMET a few years ago. He was impressed with the quality as well as the freshness, which he called “the biggest battle” in sourcing fish.

While customers may be squeamish about the concept of fish raised on land, the benefits are clear from a restaurateur’s perspective, Foreman said. It’s consistent in both availability and quality, factors of vital importance for feeding large numbers of people.

“If it’s environmentally sustainable and it eats well, what else do you want?”

Beyond salmon and branzino, IMET researchers are studying tilapia and shrimp, too, as well as Maryland’s favorite crustacean: the blue crab.

Everyone loves eating blue crabs — even blue crabs

Blue crabs pose a far greater challenge for commercial aquaculture than salmon for one relatively simple reason: they’re cannibals.

“Everybody loves a blue crab, even a blue crab,” said Kelly Lucas, director of the Thad Cochran Marine Aquaculture Center at the University of Southern Mississippi.

A blue crab hatchery in Mississippi was established using technology developed by Zohar and his team in Maryland. Lucas, a marine scientist, has looked for ways to prevent crabs from eating each other, such as placing artificial seagrass and allowing space for them to hide in their tanks.

Lucas believes her research shows that cannibalism is no longer a barrier to raising crabs. Instead, what’s required is a long-term funding source, “but that takes someone willing to commit to that funding,” she said.

Within two or three years, Zohar thinks it should be possible to use a recirculating aquaculture system like the ones at IMET’s lab to raise soft-shell crabs. “Doing good science, you will get there, step by step,” he said.

The key, he said, rests in a single biological mystery.

Mysteries of the blue crab

Like insects, crabs have a hard exterior. “In order to grow they need to shed,” said J. Sook Chung, an IMET biologist who spent years studying insects before moving on to crustaceans — which are, in a way, insects of the water. Today, she studies mainly crabs and shrimp.

Within a group of crabs, they’ll molt at different times. That compounds the cannibalism issue, since crabs are most vulnerable to being eaten when they’re soft-shelled. “Hard shell eats soft shell,” Chung said. “Stronger will eat smaller ones.”

For scientists, the core issue is how to get the crabs to shed their shells at the same time. Figure out that problem and “the sky is the limit,” Zohar said. He believes that IMET needs only two or three more years before scientists are able to grow soft-shell crabs in recirculating aquaculture systems.

Chung isn’t so sure. “Yoni’s way more optimistic than me,” she said with a laugh.

Still, with blue crab populations dropping to record low numbers this year, some see aquaculture as the answer to restoring its population.

If anybody’s eating crabs in 20 years, it’ll be a farm-raised crab,” said Patrick Hudson, who co-owns the True Chesapeake Oyster Co. farm and the Baltimore restaurant of the same name.

“The trend is clear,” Hudson said. “With every single year there are less and less and fewer and fewer — to think the wild fishery is able to keep up with the demand, it’s just not going to happen.”

Hudson has raised oysters for years in Southern Maryland. He would love to add farm-raised blue crabs to his repertoire, and envisions a future in which aquaculture crabs are commonplace.

But for now, IMET and other researchers are spending the bulk of their resources researching salmon — fish that get along just fine in close quarters.

Back in the aquaculture research center, Miller, the doctoral student, used a net to capture a large fish from the tank. As he carried it to a plastic bin filled with anesthetized water, it squirmed and splashed water across the floor and Miller’s plastic coveralls.

After taking samples from the body, the team would use a sonogram to monitor the fish’s reproductive system. Inside were thousands of eggs, grainy dots on the black-and-white screen.

The very future of the global seafood industry.

christina.tkacik@thebaltimorebanner.com

An earlier version of this article provided an incorrect age for the salmon brought to IMET from Maine. They were brought to Baltimore as adults, not babies. In addition, the dorado raised at IMET were sea bream, not mahi-mahi. The Baltimore Banner regrets the errors.