Oysters are currently
at historic low abundance due to disease-related mortality, habitat
degradation, reduced water quality and harvest pressure. Based on recent
scientific review of restoration alternatives for the native oyster in
Chesapeake Bay, the ecological restoration team works with our many partners to
optimize ecological benefits and enhance population recovery while minimizing
costs. We work closely with our partners to rehabilitate degraded habitat using
natural oyster shell and/or alternate substrates and to target the
planting of hatchery-produced oysters. Please explore this page to learn more
about our restoration activities.
Recent bottom survey
data, oyster population surveys and water quality data along with
historical oyster bar locations are used to help determine the best sites for
restoration. Knowing the salinity patterns in a tributary allows us to select a
restoration approach that appropriately addresses disease and recruitment
issues for each tributary. Although successful recruitment occurs in higher
salinities, oysters there may be subject to greater disease pressure.
Conversely, oyster populations in lower salinities experience less disease
pressure but are recruitment-limited and may suffer from freshet mortality.
Many partners, including federal and state agencies, non-profit
organizations and educational institutions are involved in completing any
Oyster shell, either
new (shucked) or from buried deposits, is the predominant and preferred cultch
for oyster habitat projects in the Bay. From 1960-2006, the dominant source of
shells for restoration was dredged shells from buried deposits in the Upper Bay.
More recently, permit issues and reduced sites with buried shell available are
limitations to the use of dredged shell. Recycling shell from shucking houses,
restaurants, festivals and the public is currently being utilized for
restoration. Improving degraded oyster habitat across large areas will require
more shell than is available.
of the shortage of oyster shell, Maryland is using alternate substrates to
rebuild degraded oyster bars. Clam shell, mixed shell (clam, conch and
whelk), fossil oyster shell from out-of-state and granite are some options
to provide a firm base for the placement of spat-on-shell. These materials have
proven effective not just as a base for spat on shell, but also for the
settlement of natural oyster larvae.
order to meet the demands of an aggressive restoration agenda and a rapidly
Grow Oysters program,
Maryland must have access to large quantities of oyster larvae (over 2 billion
per year) for restoration. Larvae produced in hatcheries are released into
large tanks, which are filled with shells. The larvae settle upon the shells
creating spat-on-shell (baby oysters), which is then planted on various
(Photo credit: http://hatchery.hpl.umces.edu/purchasing-information/spat-on-shell-sales/)
As a part of the 2014 Chesapeake Bay
Watershed Agreement, Maryland committed to restoring oyster populations in five
tributaries in Maryland’s portion of the Chesapeake Bay by 2025. The
tributaries chosen for restoration are Harris Creek, Little Choptank, Tred Avon,
Upper St. Mary’s and Manokin Rivers.
December 15, 2017 press release, DNR announced the intention to design and
develop oyster management plans for restoration efforts in sanctuaries in
addition to the five tributaries. Specifically, the press released stated the Nanticoke
and Severn rivers would have plans developed to determine how the strategic use
of state investment and resources could restore oyster populations, using planted
seed, shell and spat to spur natural oyster growth and reproduction.
September 5, 2018 press release, DNR announced the intention to study and
survey existing state oyster sanctuaries in Anne Arundel County, including the
Severn River Sanctuary and to work with the local watershed associations to
maximize the restoration potential in the tributaries.
580 Taylor Ave., Annapolis MD 21401
Call toll-free in *Maryland* at 1-877-620-8DNR (8367)
Out of State: 410-260-8DNR (8367)