Maryland oysters are having a bad year, and here’s why

Salisbury — People, aside from oyster researchers and farmers, likely won't feel the impact for at least another 18 months.

But, eventually, everyone will know just how bad a year it has been for Maryland oysters.


Thanks to record levels of persistent rainfall throughout the bay watershed, salinity levels in the Chesapeake Bay have remained perilously low since May 2018. The absence of salt in the bay and its tributaries has been annihilating oyster spat production and oyster growth at hatcheries and farms around the region.

At the University of Maryland's Horn Point Hatchery, the largest oyster hatchery in the state, the carefully controlled operation is on course to produce hundreds of times fewer larvae this year than it would during a regular season, its manager said. This is bad news both economically and as an indicator of bay health, which data shows has suffered greatly under the deluge.


So far this year, the Cambridge hatchery has produced only about 6.5 million oyster spat-on-shell. That's 200 times less than last year, and almost 300 times less than the year before, said hatchery manager Stephanie Tobash Alexander, a senior faculty research assistant at the University of Maryland.

Researchers are quickly trying to discover the cause of the problem before the chance to produce more larvae has passed.

Oyster seasons can be variable, but this is the first time in 15 years that the hatchery will likely fail to meet its annual goal of putting 500 million spat-on-shell out into the bay, Tobash Alexander said.

The absence of spat this year is a looming specter over the oyster industry, which will begin to face harvesting difficulties in about 18 months to three years (the amount of time it takes an oyster to grow to a harvestable size).

This year's failed production has been humbling, Tobash Alexander said. Reaching out to colleagues and friends in various research fields for help hasn't provided any answers, she added.

"We've put our pride to the side; we need help, " Tobash Alexander said. "There's something that, for some reason, our collective brains can't figure out when we have not changed a thing. Everything we're doing is what we did last year, what we did the year before and the year before that. So, it's got to be environmental. It's got to be something with the water."


While weather each year on the bay varies, from July 2018 through June 2019, the bay watershed experienced more rain than has been recorded since record keeping began.

Much of the Chesapeake Bay watershed received 60-80 inches of rain during that time period, about 110% to 150% of normal, according to the National Weather Service. Importantly, the intensity was consistent, with Mother Nature delivering above-average rainfall in 10 of the last 12 months.


With so much rain, traipsing around in nature in the last year could be like walking on a soaked sponge. With the ground unable to take any more, the fresh water flowed straight into the rivers.

The runoff and flooding brought excess nutrients and sediments into the waterways feeding the bay, and the bay's overall health suffered significantly as a result, the Chesapeake Bay Foundation's 2018 "State of the Bay" report states.

As northern tributaries injected fresh rainwater into the bay, the amount of salt dissolved in the normally brackish bay water became severely diluted. The bay's salinity still hasn't recovered, with data from mid-June 2019 showing salinity just approaching the historical average range, theVirginia Estuarine and Coastal Observing System reports.

"There have been other years where there have been challenges. None have lasted as long as this," said Don Webster, an expert on commercial aquaculture development at the University of Maryland.

Oysters need salinity at 8-10 parts per thousand at minimum to survive, Tobash Alexander said. Normally at this time of year, the brackish water Horn Point brings in from the Choptank River would be 10-12 parts per thousand.

This year, it's at about a 7.


Horn Point salinates the water in which the oyster spawn grow, but it would be cost prohibitive to salt the adult oysters' water, which flows in and out of the hatchery back to the river, Tobash Alexander said.

When the adult oysters are under stress from low salinity, they put less energy into reproduction and more into pure survival, she said. Getting viable reproductive cells is harder when the oysters are just trying to stay alive.

Climate change modeling suggests the region will experience more frequent and severe storms in the future, and understanding those patterns will have far-reaching implications for bettering the bay's health, the Chesapeake Bay Program Science and Technical Advisory Committee found in 2008.

The situation is raising the question of whether the extra-wet year was a fluke, or if researchers and watermen should prepare their facilities to deal with these conditions more often.


Behind a metal gate and down a road lined symmetrically with large trees, research assistants, technicians and interns at Horn Point Hatchery lean over tanks filled with adult oysters ready to reproduce.

But in the high-ceilinged room dedicated to housing oyster larvae, many large plastic tanks stand empty of the greenish melange that would signify a growing batch of larvae.


The hatchery program at UMD has been in existence since 1974, but began its heyday after the Aquaculture and Restoration Ecology Laboratory was constructed in 2003. It produces oyster larvae mainly for research, restoration and education, but a portion also goes to public and private fisheries for harvesting.

Since then, the facility has dramatically increased its oyster production: in its 2016-17 season, Horn Point Hatchery produced 1.8 billion spat-on-shell, its record to date.

"In 2017, we probably could have done 2 billion," Tobash Alexander said. "But we literally ran out of bottom. . So we stopped the hatchery early that year."

Last year, conditions were also less than ideal, with low salinity beginning to affect the process in May. But because of the normal spring, the facility still produced 1.3 billion spat-on-shell, Tobash Alexander said.

Most of the spat-on-shell Horn Point Hatchery produces goes to a Chesapeake Bay restoration program. According to the National Oceanic and Atmospheric Administration, harvests of oysters are now at 1% or less of historical levels due to harvesting, disease and changes in water quality, among other factors.

With diminishing overall oyster populations, the ecosystem services they provide are similarly reduced. Each adult oyster can filter up to 50 gallons of water a day, straining algae from the water as food.


Oysters are the "coral reefs of the bay," Tobash Alexander said, since oyster bars provide habitat and food for many types of marine plants and animals. Because other species in the bay ecosystem depend on oysters performing their role, they are considered a keystone species.

Some years, Horn Point sends larvae to private oyster growers who seed public oyster bars and private farms that grow oysters for the half-shell market. Whether they are able to do this depends on the sources of the hatchery's funding, Tobash Alexander said.

At the hatchery, adult broodstock oysters are kept in water cool enough to discourage them from releasing their eggs or sperm until they are ready for spawning. Once a group of adults is conditioned, they are transferred to warmer water and made to release their gametes.

Once fertilized, the eggs are transferred to 15-foot tanks, where they feed on hatchery-grown algae until they are large enough to affix themselves onto a substrate. In the hatchery's case, this is recycled oyster shell, either whole or ground up into a sand-like texture called cultch.

The affixed "spat-on-shell" gets transported to sanctuaries in the bay for oyster restoration. For harvest oysters, the hatchery sends growers unattached larvae that they may set on shell and plant in the bay themselves.

While the freshness of the water is likely driving the production problem, it may not be the only cause of this particularly bad oyster year, Tobash Alexander said. The stress caused by low salinity could be making the oysters more vulnerable to another type of problem, so technicians at Horn Point Hatchery have been experimenting with various possible new angles.


"It's pretty much looking for a needle in a haystack, so we're just going through pulling out little pieces of straw, testing every parameter we can think of," Tobash Alexander said. "My gut tells me it's not a simple answer."


For more than a century, oysters have made up one of the Chesapeake Bay's most valuable commercial fisheries alongside blue crab, striped bass and Atlantic menhaden. In 2017 (the most recent data available), Chesapeake watermen landed over 4.3 million pounds of oysters valued at $55.7 million; of that, about 660,000 pounds worth $10.3 million were landed in Maryland, according to NOAA.

For Eric Wisner, who farms about 600 acres on the Nanticoke River and normally receives larvae from Horn Point, a low larvae production year meant he needed to find a new supplier.

Except there aren't that many new options to turn to, especially in Maryland, Wisner said. That leaves out-of-state hatcheries, which are hard to get larvae from due to their commitments to their established clientele, he said.

"They're already geared up to produce a certain amount of larvae ... they can't just double their production all of a sudden when there's a demand for it," Wisner said.

Wisner managed to get a small amount of larvae from a hatchery in Virginia, but is paying twice his usual price, he said.


In two to three years, when the fruits of this meager planting are turned into a small harvest, the effect on his business will likely be in the neighborhood of $100,000-$200,000, he said.

While it's not precisely clear how much of an increase market forces will dictate on oyster prices for the consumer, Marylanders looking for half-shell should expect to begin paying a premium beginning in 2021.

The shortage has affected businesses up and down the bay.

For Maryland Watermen's Association President Robert T. Brown, who with his wife, Victoria, owns Shop Cove Aquaculture on St. Mary's River, the shortage means an inability to fulfill oyster planting contracts with the state under the Oyster Recovery Partnership.

Four million Horn Point larvae usually result in 1 million to 1.5 million successful spat-on-shell, Robert T. Brown said. The bad growing conditions have meant the business has not been able to fulfill a single contract in the last two years, Victoria Brown said.

"It takes three years for an oyster to grow, so this has put us back," she said. "So what we planted three years ago ... a lot of it died. We lost over 50% on a lot of our pieces."


When Maryland first began to develop a large-scale sanctuary network around 10 years ago, it was promised to the public that the sanctuaries would help farmers by putting off natural larvae into the public waterway, Victoria Brown said. Outside of high-salinity areas, this has not happened, she said.

"I have planted oyster on bottom for over six years. I have yet to have one natural spat set on any of our leases," Victoria Brown said. "So, it's not working."

Researchers at Horn Point Hatchery recognize their important role in keeping the wheels turning on oyster restoration in the bay. While limited by resources and funding, experiments at Horn Point seek a greater understanding of the challenges oysters face to thrive.

No one is certain of when the rain will slow and salinity will return to normal. All are looking forward to the day oysters begin to bounce back.

“But our season’s not over yet,” Tobash Alexander said. “We’re not throwing in the towel. We’re trying to be positive that we’ll be able to produce something.”