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Marylanders Grow Oysters Program Thriving - November 16, 2014

   In 1608, John Smith started mapping the Chesapeake Bay. However, it was very different from today’s bay; the water was cleaner, the diversity of animals even more astounding and the landscape dominated by forests and marshes. Huge oyster reefs were plentiful throughout the bay and made navigation for Captain Smith difficult, leading to him remark that the oysters “lay as thick as stones.”

   Flash forward nearly 400 years and the story is completely different. Oyster populations have been decimated. Overharvesting, diseases and poor water quality have led to a sharp decline in oyster populations. However, there are many dedicated people and organizations encouraging the resurgence of the oyster.

   In oyster hatcheries like Horn Point Lab, the future of our oyster population is being born and raised. Mature oysters release sperm and eggs in a reproduction tank. The eggs become fertilized and are then moved to another tank, where they will grow into veligers. The veliger phases are the only phases in an oyster’s life cycle where it is at least partially ­mobile.

   The oyster will go through several veliger phases before eventually turning into a pediveliger, which has a muscular foot, similar to a clam, which allows it to crawl. The pediveliger will then be placed into a different tank where weathered oyster shells have been placed. The pediveliger will eventually settle onto these old shells and mature into spat on shell.

   Once the spat establishes itself, it will no longer be mobile and will start to mature into an adult oyster. The entire process, going from free-floating sperm and egg to settling down and turning into spat on shell, takes anywhere from two to three weeks. Once the spat is established, it can take one to three years for it to turn into a mature oyster capable of reproduction. Mature oysters can live for decades in the right conditions, and during this time they can even switch genders if needed for reproduction.

   Oysters in the bay are a keystone species. Oysters are amazing filter feeders and an individual oyster can filter nearly 50 gallons of water a day. Collectively, the oyster population of the Chesapeake Bay used to filter all the bay water within about a week, however due to a decrease in population and stress on the oysters, it takes about a year now for the same volume of water to be filtered. 

   Not only do they filter the water, but they also provide much needed habitat for many species of animals. Oyster reefs are one of the few areas of hard substrate on the bottom of the Chesapeake Bay. These reefs provide places for other benthic organisms, like crabs and worms, to live and they also provide shelter and food for larger fish as well.

   Estimates put upwards of 90 percent of our historic oyster reef habitat as lost, and the remaining oyster reefs are diminishing due to severe stress. While the oyster populations here in Maryland waterways have declined dramatically over the centuries, there are organizations trying to combat the loss of this important species. 

   One program doing a lot of great work in restoring oyster populations is the Marylanders Grow Oysters (MGO) program. The program was initiated in 2008 by Governor O’Malley, and has grown in size and popularity each year since. The program is set up so homeowners can grow young oysters in pre-made cages off their docks and jetties before the oysters are re-collected and re-distributed onto oyster sanctuary zones. The oyster sanctuaries are areas in need of major restoration so these areas are specifically targeted for oyster replenishment and are off limits for commercial and recreational oyster harvesting. 

   The MGO Program consists of volunteers who get oyster spat on shells, provided by the University of Maryland Center for Environmental Sciences Horn Point Laboratory and the Oyster Recovery Partnership, around September and let them grow throughout the fall and winter. 

   The spat on shell oysters come in a pre-made, mesh wire cage and are already attached to old, re-used oyster shells. Each cage of oyster spat can contain about 70-80 old oyster shells, with about five spat attached per shell, for a rough total of around 350-400 oyster spat per cage. The volunteers will then tie the cages to docks and jetties to allow for these oysters to feed and grow, occasionally cleaning the cages by knocking off any sediment or debris that collects on them. After about a nine-month growing period, MGO volunteers will collect up the oysters and then take them out to be distributed in the oyster sanctuary areas. 

   When the program started in 2008 it had only 850 cages in its first year, however it now has over 7,500 cages tended by 1,500 MGO volunteers throughout Marylands waterways. The program started along a singular tributary for the Chesapeake Bay and has now moved into 24 Chesapeake bay tributaries plus several coastal bays tributaries as well. Last year alone, the MGO program grew over 2 million young oysters to distribute onto oyster sanctuaries, helping to replenish the quickly dwindling native population. 

   So far, oyster restoration efforts have been slowly bringing back the oyster population in the bay, but there is still much more work to be done before this valuable shellfish has made a full ­recovery.


Harrison Jackson is the Coastal Stewards Coordinator for the Maryland Coastal Bays Program. 


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