The Making of an Oyster
In hatcheries, science works to jumpstart nature
Restoring oysters and an oyster economy in the Chesapeake starts in hatchery labs, where scientists are filling the gap in hopes nature will take over from there.
The University of Maryland Center for Environmental Science Horn Point Hatchery in Cambridge — expanded last year to produce up to two billion spat a year — grows the larvae, nursing the tiny babies as they attach to a hard surface — old oyster shell. Other oyster babies are grown in a smaller state hatchery at Piney Point in St. Mary’s County.
When larvae bond to shell, they become spat, on the way to growing into new Bay oysters.
1. Where Life Begins
To jumpstart Mother Nature’s cycle, adult oysters are collected and conditioned to spawn. Controlled rise in water temperature signals the change of season that triggers the oysters to release their gametes. If the oysters are stubborn, the hatchery puts sperm or eggs in the tank to start the chain reaction of the release. Talk about an aphrodisiac.
2. The Larvae Tanks
Scientists then combine the correct ratio of eggs and sperm into 30-gallon buckets carried to 10,000-gallon tanks, where larvae form and grow.
Horn Point’s Remote Setting Program also transports tanks to aquaculturists in the field, like the Witts in Shady Side.
As the larvae grow, the big tanks are drained through a sieve. The larvae are sifted by size, the large ones moving on and the small ones going back to keep growing.
3. An Algae Banquet
In a greenhouse, the hatchery also grows the algae the larvae eat. Algae is bottled at different concentrations and fed into the larve tank.
4. The Teen Years
Teen larvae go to settling tanks to attach to oyster shells, becoming spat. The Oyster Recovery Partnership now takes over, filling tanks with oyster shells and ambient river water. Air blowers keep the water moving, making for more spat and an even distribution of salt.
5. Going in the Bay
After abour 48 hours, a sample of shell from the tanks is measured for the amount of set spat. At Horn Point, program director Donald Meritt analyzes the shell to count how many larvae have connected.
If the spat need more time to grow, the oyster cages go to the Choptank River in the shallow nursery area to grow larger in a protected area while freeing up the tanks for the next batch.
Once big enough, spat goes out for planting in sanctuaries, citizen and community oyster gardens and in aquaculture operations.