Oyster populations throughout Maryland’s portion of the Chesapeake Bay have generally improved over the past decade, according to a report from the state’s Department of Natural Resources (DNR). But while oysters within state-designated sanctuaries have continued to thrive in recent years, populations in areas open to harvest have declined.
Three types of oyster management areas are designated in Maryland: active aquaculture, or oyster farming; sanctuaries, where harvesting is not allowed; and Public Shellfish Fishery Areas, or PSFAs, which are open to public harvesting.
Low disease mortality combined with successful reproductive seasons in 2010 and 2012 helped boost populations of the Bay’s iconic bivalve in both fished and sanctuary areas. But as oyster biomass in sanctuaries continued to increase through 2014 and 2015, populations in areas open to fishing declined in those years. According to the report, this is likely due to the harvest of those oysters born in 2010 and 2012—inside the sanctuaries, these older oysters were continuing to grow and reproduce.
In 2010, Maryland adopted an updated oyster management plan, expanding the range of sanctuaries and designating areas to remain open to harvest. The study marks the first evaluation in DNR’s commitment to review the plan’s effectiveness every five years and to propose adjustments if necessary. But the report suggests it’s too early to conclude that oyster restoration efforts have been successful.
“Given the complexity of the Chesapeake Bay ecosystem, five years has not been long enough to show how oyster populations respond to the absence of harvest,” the report states. Still, the report recommends making adjustments to current sanctuary boundaries, while continuing to maintain sanctuaries in 20 to 30 percent of the Maryland portion of the Bay.
The State Oyster Advisory Commission, a 23-member group created to advise DNR on oyster-related matters, is expected to review the report and make recommendations on the state’s oyster restoration efforts, including postponed work in the Tred Avon River.
The report is available on the Maryland Department of Natural Resources website.
On July 19, 2016, the White House’s Council on Environmental Quality hosted a roundtable on natural resource investments in the Chesapeake Bay watershed. The group discussed ways that private capital and markets can be involved in addressing the watershed’s natural resources challenges such as water quality and habitat protection.
Chesapeake Bay Program officials were in attendance to discuss such topics such as agricultural nutrients, urban stormwater and financing opportunities. Sessions highlighted innovative projects and programs in development—including their challenges and opportunities—and specific actions to take which would increase incentives and reduce barriers.
The roundtable participants included officials from the District of Columbia, Maryland, Pennsylvania, Virginia and local governments. Federal agencies in attendance included the Environmental Protection Agency, Department of Agriculture, Army Corps of Engineers and Office of Management and Budget. There also were numerous representatives from non-governmental organizations and private investment companies.
Dr. Bill Harman, Director of the State University of New York (SUNY) at Oneonta Biological Field Station in Cooperstown, New York, holds a flip-flop recovered from Otsego Lake and covered with invasive zebra mussels.
Zebra mussels (Dreissena polymorpha) are freshwater bivalves found in lakes, rivers, streams and reservoirs. Native to Europe, zebra mussels were found in the Great Lakes region in 1988 and later discovered in the upper Susquehanna River in 2002. Since then, the invasive mussel has spread further into the Chesapeake region’s rivers and streams. In 2011, the mussel was spotted for the first time in the Eastern Shore’s Sassafras River. And in 2015, two watermen found zebra mussels colonizing on their fishing gear in the Susquehanna Flats.
Efficient filter-feeders, zebra mussels can remove a lot of plankton—an important food source for other critters—from the water. They also attach themselves to native mussels and to manmade structures, clogging intake pipes and encrusting boat hulls and buoys. Scraping, power-washing and chemical treatments can be used to control zebra mussels, but once a population has been established, it can be almost impossible to eradicate.
To prevent the spread of zebra mussels and other invasive species, make sure boat hulls, trailers and other equipment are thoroughly cleaned before moving them to a new body of water.
Image by Will Parson
The Chesapeake Bay has more than 11,600 miles of shoreline. Evidence of its changing tides can be observed along much of the region, whether it is a high water mark on a dock piling, a line of seaweed on a beach or a shorebird pulling shellfish from the mud of a temporarily exposed flat.
In some watershed cities—like Annapolis, Maryland—the difference between high and low tides is about one foot. In others—like Norfolk, Virginia—this difference can reach up to three feet. We have built our roads, homes and buildings around the regular movement of this water. But as sea levels rise, land subsides and natural barriers to coastal flooding are lost, our coastal cities will face more impactful high-tide flooding that occurs regardless of heavy winds or rain.
High-tide flooding has also been called sunny-day, shallow coastal or nuisance flooding. The National Oceanic and Atmospheric Administration (NOAA) records a high-tide flood when one of its local tide gauges measures a water level above the local threshold for minor impacts. While the depth and extent of high-tide floods can vary, the nuisances that result are far from minor: disrupted transportation, degraded stormwater management systems, flooded roads, homes and businesses, and strained maintenance budgets.
Rates of high-tide flooding on all coasts are rising. In a June 2016 report on the state of high-tide nuisance flooding in the United States, NOAA researchers attribute increasing flood frequencies to local sea level rise—which itself is attributed to the melting of ice on land as the air warms and the expansion of seawater as oceans warm—and local land subsidence, or the settling or sinking of land. Indeed, according to the report, “annual flood rates have increased locally by two or three times or more as compared to the rate experienced 20 years ago.”
Of the 28 local long-term tide gauges operated by NOAA, four are in the Chesapeake Bay watershed. Together, these four cities—Annapolis and Baltimore in Maryland, Norfolk in Virginia and the District of Columbia—experienced a total of 128 high-tide flood days in 2015, with Baltimore and Norfolk experiencing local totals just two days and one day below the highest historical record. These floods were likely exacerbated by El Niño, which affected winds and storm tracks along the mid-Atlantic and West coasts.
The 2016 outlook for each of these four cities is lower than the number of flood days the cities observed in 2015: 15 flood days are expected to occur in 2016 in Baltimore, 47 in Annapolis, 33 in Washington, D.C., and 8 in Norfolk. However, NOAA expects future outlooks to underestimate flood days because of the increasingly “nonlinear response” flood frequencies will have to sea level rise. Furthermore, the agency’s high-tide flood outlook does not account for flooding compounded by local rainfall, and precipitation in the watershed is expected to increase in response to climate change.
While we cannot reverse the effects of climate change that have already been observed in the region—which include warming temperatures, rising sea levels and more extreme weather events, as well as coastal flooding, eroding shorelines and changes in the abundance and migration patterns of wildlife—we can enhance our resiliency against them. To build resiliency against high-tide flooding, for example, cities have relied on flood barriers to block rising water, drafted ambitious plans to raise low-lying streets and constructed new facilities higher off the ground.
Through the Chesapeake Bay Watershed Agreement, the Chesapeake Bay Program has committed to increasing the resiliency of the region’s communities, living resources and wildlife habitats to the adverse impacts of changing environmental conditions. Learn about our work to monitor and assess the trends and impacts of climate change and to pursue, design and construct restoration and protection projects that will enhance the resiliency of our ecosystem.