Posts Tagged ‘shellfish’

Zebra Mussels Discovered Near Baltimore

Wednesday, August 26th, 2015

The Maryland Department of Natural Resources (DNR) recently confirmed the presence of zebra mussels (Dreissena polymporha) in tributaries of the upper Western Shore near Middle River in Baltimore County.

On August 17, 2015, a waterman alerted DNR Biologist Brenda Davis of small zebra mussels fouling their crab gear off the Gunpowder, Bush and Middle Rivers. The next day, DNR Fisheries Habitat and Ecosystem Program biologists found numerous mussels in aquatic vegetation while trawling Middle River.

Past monitoring suggested that zebra mussels had not spread beyond the Susquehanna Flats. However, heavy rainfall in the late spring has led to lower than average salinity in the upper and middle Chesapeake Bay, potentially allowing zebra mussels to spread into habitat where they would normally not survive.

It is not yet known if zebra mussels will persist in these upper Chesapeake Bay tributaries as salinity levels increase around the Baltimore area.

For more information on zebra mussels is available at, including a fact sheet and reporting form.

DNR asks citizens to report any suspected sightings to

source: Maryland Department of Natural Resources

Chesapeake Bay Zebra Mussels

Friday, May 1st, 2015

Biologists from the Maryland Department of Natural Resources (DNR) recently found a significant increase in this harmful invasive during their most recent zebra mussel monitoring effort in the upper Chesapeake Bay.

Every fall for the last three years, DNR has inspected marker buoys and anchors as they are brought aboard the Department’s buoy-tending vessel, the A.V. Sandusky, for winter storage. This past fall, there were approximately 35 times more attached mussels and colonized anchors compared to the year prior.

Also during this time, two alert watermen submitted specimens of zebra mussels that had colonized their fishing gear on the Susquehanna Flats. Citizen sightings – such as zebra mussel larvae entering water system intakes, and adults attaching to infrastructure – help DNR assess trends in the population.

According to DNR, mariners who use the lower Susquehanna River and upper Bay can help prevent the spread of zebra mussels to other Maryland waters by taking these precautions:

– Remove all aquatic plants and mud from boats, motors and trailers; and put the debris in trash containers.

– Drain river water from boat motors, bilges, live wells, bait buckets and coolers before leaving to prevent these aquatic hitchhikers from riding along.

– Dispose of unused live bait on shore, far from the river or Bay or in trash containers.

– Rinse boats, motors, trailers, live wells, bait buckets, coolers and scuba gear with high pressure or hot water between trips to different water bodies.

– Dry everything at least two days, and preferably five days, between outings.

– Limit boating from place to place – particularly between the Susquehanna and upper Bay to other water bodies in Maryland – where zebra mussels haven’t invaded.

DNR also asks that people who live, recreate and work on the water report any suspected sightings to or 410-260-8604. More information is available at

In Maryland, zebra mussels are currently restricted to the lower Susquehanna River and upper Chesapeake Bay.

source: Maryland Department of Natural Resources

2015 Harris Creek Oyster Sanctuary Construction

Tuesday, February 10th, 2015

The U.S. Army Corps of Engineers and partners resumed oyster restoration in Harris Creek, Jan. 13, 2015. The project is part of the Maryland and Virginia statewide oyster restoration program, as laid out by the Corps’ Native Oyster Restoration Master Plan that identifies the most suitable tributaries throughout the Chesapeake Bay for large-scale oyster restoration based on physical and biological conditions.

New construction in Harris Creek consists of placing 57 acres of reef in water 6 to 9 feet deep (mean lower low water, MLLW). Similar work in the Tred Avon River is also scheduled to begin this winter, and efforts may occur simultaneously. In the Tred Avon, 24 acres of reef will be placed in water 9 to 20 feet deep (MLLW).

Work includes constructing 1-foot reefs using rock and mixed-shell materials. Constructed reefs will be made of: 1) rock only, (3 to 6 inches in size); 2) combination of rock and mixed shell; or 3) mixed shell only (2 to 3 inches in diameter). The shell comes from processing plants in the mid-Atlantic region and is permitted to be imported and placed in the river. The rock is quarried in Havre de Grace, Md.

Construction is anticipated to end spring 2015. The reefs will be monitored to assess the restoration progress. The State of Maryland has planted more than a billion oysters in the Harris Creek Sanctuary since 2011.

source: U.S. Army Corps of Engineers

Maryland 2013 Fall Oyster Survey

Wednesday, May 14th, 2014

Results of Maryland’s 2013 Fall Oyster Survey indicate populations are continuing to increase. The oyster population has more than doubled since 2010, reaching its highest point since this type of monitoring began in 1985.

The upswing was driven by high oyster survival over the past few years as well as strong reproduction in 2010 and 2012. As a result, oyster harvests have increased, with watermen quickly reaching their daily catch limits during the early part of the season.

“Preliminary harvest reports for the past season have already surpassed 400,000 bushels – with a dockside value in excess of $13 million – the highest in at least 15 years,” said DNR Secretary Joe Gill. “Coupled with the survey results, we have reason to be cautiously optimistic a sustainable oyster population can once again play a vital role in the Bay’s ecosystem and Maryland’s economy.”

In one of the longest running such programs in the world, Maryland has monitored the status of the State’s oyster population through annual field surveys since 1939. The surveys track relative oyster population abundance, reproduction, disease and annual mortality rates, and offer a window into future population levels.

According to the survey, at 92 percent, oyster samples revealed the highest survival rate (the number of oysters found alive in a sample), since 1985 when these measurements began. The Maryland Oyster Biomass Index, a measure of the oyster population, was also the highest since 1985. Oyster reproduction was slightly above the 29-year midpoint, but was largely confined to the lower portion of the Bay.

Oyster diseases remain at relatively low levels. Dermo was below the long-term average for the eleventh consecutive year, with levels similar to 2012, but, continues to be widely distributed throughout Maryland waters. MSX increased slightly from the record-low levels of 2011 and 2012, but remains well below the long-term average.

The survey shows that natural mortality rates within oyster sanctuaries were similar to adjacent harvest areas.

source: Maryland Department of Natural Resources

2014 Blue Crab Winter Dredge Survey

Wednesday, May 7th, 2014

The 2014 Blue Crab Winter Dredge Survey results indicate that female blue crab populations in the Chesapeake Bay have declined below minimum levels, according to the Maryland Department of Natural Resources. The abundance of spawning-age females was estimated to be 69 million, below the minimum safe level of 70 million.

While the crabbing harvest remained at a safe level for the sixth consecutive year, and juvenile crabs increased 78 percent from 2013’s record low, the total abundance of crabs — which include juveniles, and adult males and females – has returned to pre-2008 levels of approximately 300 million.

The results illustrate the inherent variability of the Blue Crab population and the ever-present complexities of managing this dynamic fishery. There are a suite of environmental factors that could be contributing to the low crab abundance, including the unusually cold winter, coastal currents, weather patterns and natural predators.

The long cold winter appears to be one cause of the low abundance level. Low water temperatures resulted in one of the worst cold-kill events since the start of the survey in 1990, causing the death of an estimated 28 percent of adult crabs in Maryland.

The decline in spawning age females will be the biggest factor in determining new management actions by Maryland, Virginia and the Potomac River Fisheries Commission to increase reproductive potential in 2014 and 2015.

DNR and the Virginia Institute of Marine Science have conducted the primary assessment of the Bay’s Blue Crab population annually since 1990. The survey employs crab dredges to sample Blue Crabs at 1,500 sites throughout the Chesapeake Bay from December through March.

The Chesapeake Bay Stock Assessment Committee, supported by NOAA’s Chesapeake Bay Office, is reviewing the data; their 2014 Blue Crab Advisory Report is expected to be released in early summer.

Complete survey results are available at

Maryland Department of Natural Resources

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