Production of oyster larvae at the Horn Point Lab in Cambridge stalled this summer, creating a shortage that has stunted oyster plantings throughout the bay.
The state’s goal is to plant oysters on 110 acres across six sanctuaries this year, and so far they’ve completed less than two acres. The Oyster Recovery Partnership announced last week they would need to delay the planting of 10 million oysters in the Severn River until 2020, citing the shortage at Horn Point.
Oyster hatchery manager Stephanie Alexander said oysters haven’t been spawning, and when they have, larvae haven’t been eating and moving.
“We have put six and a half million oysters overboard so far, we should have 500 million at this point,” she said.
The lab produced nearly 1.3 billion larvae last year.
The prevailing theory is that record rainfall and low salinity are to blame — the facility uses water that is piped in from the Choptank River just outside. But no one knows 100% what’s going on, Alexander said, and trying hundreds of experiments to pinpoint the issue has been like finding a needle in a haystack.
She is hoping for a good August. Inexplicably, they hit a corner this week. The larvae are acting normally.
“Hopefully we’re going to turn it, but I don’t know,” she said.
And though things are looking up, they still haven’t determined exactly what’s going on. They’ve experimented with different water, salinity, salt sources and now they’re looking at probiotics, she said.
“Because of all the freshwater, perhaps the bacterial community has shifted and there’s no good bacteria available for the larvae,” she said.
The algae that larvae feed on also have been affected, Alexander said.
“We’ve had some algae not grow at all. We’ve had some not seem affected by it,” she said.
Maryland Department of Natural Resources Shellfish Division Manager Chris Judy said there have been mid-summer slumps before, but a shortage of larvae on this scale is unprecedented. Programs that rely on Horn Point, including commercial programs and community-based programs such as Marylanders Grow Oysters, have been delayed because of the lack of larvae, he said.
Judy said they have planted oysters on 1.7 acres so far, while their goal this year is to plant 110 acres across six sanctuaries.
“That’s just the sanctuary program,” he said.
The state wants to restore those tributaries by 2025, and Judy said they expect to get back on track because of the hatchery’s excellent record.
“We’re viewing it as an anomaly,” he said.
Chesapeake Bay Foundation scientist Doug Meyers said they were able to plant 3.4 million oysters near Fort Carroll Baltimore Harbor July 31 by cobbling together larvae from the Piney Point lab and a second lab in Virginia. They were two or three months behind schedule, he said. And they’re only now getting a line about a second larvae delivery.
To satisfy a long-term grant for NOAA, Meyers said they need to plant 20 million oysters in the Choptank. They haven’t even begun that project, he said, and at best they will have two or three million to plant if they get larvae in the next few days.
“These persistent freshwater conditions do strange things to oyster physiology,” he said. “That will have ripples through the population and restoration program, and we’re documenting that as we go.”
