Aquaculture of oysters has long been employed to fill the demand for fresh seafood. In the period of American industrialization during the 1950’s commercial harvesting intensified to fill demands from a growing population. Within 20 years Dermo and MSX, diseases that are specific to bivalves, in conjunction with drastic effects of pollution sent oyster populations plummeting. In response to these hard years aquaculture technique were pioneered to farm oysters. Oysters are renowned for their resilience to environmental stress, they can tolerate great variations to temperature, salinity and dissolved oxygen for these reasons they are easy to cultivate, you don’t even have to feed them.
Today there are two groups interested in oyster aquaculture, a private sector industry and conservation efforts that have emerged to rebuild reefs of the Chesapeake Bay. Aquaculture for ecologic restoration of the Chesapeake Bay is based upon using the oyster’s natural filtration capacity to improve water quality and bring habitat back from the base up. This article focuses on conservation partnerships in Maryland that work to restore oyster reefs for ecological benefit within protected leases.
The Maryland Department of Natural Resources, University of Maryland, Maryland’s Oyster Advisory Committee, Maryland Waterman’s Association, NOAA, U.S. Army Corps of Engineers, and the Chesapeake Bay Foundation cooperate with Maryland Sea Grant which runs the Horn Point Oyster hatchery. Located in Cambridge, Maryland the hatchery supplies oyster spat and larvae to multiple actors restoring the Chesapeake Bay’s oyster reefs.
At the hatchery scientists use a stock of mature oysters floating in bays on the Choptank River and bring them into a laboratory. By controlling water temperature the laboratory induces spawning and collects the sperm and eggs. The eggs are kept in tanks and sustained with cultured algae. The fertilization process is completely controlled to produce larvae more efficiently than in natural habitats. While some of these larvae are exported to community projects or researchers, most stay on site, and are further cultivated in large controlled tanks filled with shells and algae, the food source. photo (setting_slider_image.jpg)
Spat on shell is the term used to describe Horn Point’s product, dead shells with small oysters about a centimeter in diameter growing on them. Spat on shell are considered stable enough to grow in the bay, but are still vulnerable to disease and predation.“In 2012, the hatchery produced more than 880 million oyster spat” (University of Maryland Oyster Aquaculture and Maryland Sea Grant) Different oyster reefs are maintained by groups of local partners; these volunteer based organizations support a majority of ecologically focused reefs.
Community partners like Marylanders Grow Oysters and the Chesapeake Foundation work with Horn Point on oyster gardening projects. Expert advice from Horn Point’s scientists is distributed to over 1,500 waterfront property owners who keep cages or floats of these immature spat oysters below their docks. The spat are vulnerable to predation until they are bigger, so the cages provide protection until they are placed on the reef. At 30 locations bay wide, groups of locals assist each other with cleaning and turning the cages removing algae and improving water flow. Once a year, a full day of collective effort is spent moving the now mature oysters to the reef, extending it in according to expert advice. The cages and floats are refilled with a fresh batch of spat on shell. In 2014, DNR reported 2 million new oysters planted in the 30 tributaries participating in oyster gardening projects.
The partnerships between Horn Point, DNR-MD, ocal homeowners and University of Maryland are mutually beneficial and indefinitely improve the shared waters. While scientists have multiple study sites that are protected from harvesting, communities and the state of Maryland benefit from water quality improvement on local creeks and improved habitats for fish and crabs.
The geospatial map sited below maps Maryland’s oyster aquaculture projects, including those mentioned in this article. http://gisapps.dnr.state.md.us/Aquaculture/index.html