The Virginia scientist who conducts the annual survey of underwater grasses in the Chesapeake says this year’s aerial photography continues to show extensive damage to Maryland grass beds that appear to be the result of fishing activities.
Bob Orth, a professor of biological sciences at the Virginia Institute of Marine Science, said in a letter to Maryland Depart-ment of Natural Resources Secretary Sarah Taylor-Rogers that some previously dense grass beds were being “reduced to scattered, small pockets.”
In the letter, Orth said the state needed to be “more proactive” in protecting beds of submerged aquatic vegetation, or SAV, which are recognized as one of the Bay’s most important resources. The beds help to improve water quality and provide food and habitat for waterfowl, blue crabs and other species.
Orth said the photographs show scarring in several areas of the Eastern Bay, the Wye River and the lower Miles River. The scars appear more extensive than when they were first observed in 1997, he said.
Much of the scarring is apparently caused by hydraulic clam rigs disrupting the bottom in search of clams. The rigs not only rip up grass beds, but also leave long, dense plumes of sediment, sometimes more than a mile long, which may have the potential to smother remaining grasses, Orth said in his letter.
In addition, he said a new pattern of scarring was visible this year, which appeared to be the result of two heavy crab scrapes being pulled side-by-side through the grass beds.
In 1998, the Maryland General Assembly passed a law banning clam dredging in all existing grass beds in the Chesapeake and coastal bays after Orth and other scientists raised concerns about the damage to grass beds. The law was passed over the objection of watermen, who have already have other fisheries restricted over the years.
Robert Magnien, who heads the DNR’s Tidewater Ecosystem Assessment Division, said the law was “something that we are trying to implement in a fair and timely manner. The DNR is very concerned about and destruction to SAV beds and has spearheaded nutrient reduction programs and Bay grass plantings to bring this important resource back.”
Each year, the state identifies grass beds from Orth’s aerial photos and then closes those areas. But the final mapping of bed locations are not available until up to two years after they are photographed and thus don’t always match up with where new beds are located. Magnien said the state was trying to shorten the lag time between the photos and actions to close the beds.
“There’s still, admittedly, quite a bit of work to do, but we’ve made a major step in the direction of halting some of these situations where the beds were completely unprotected,” Magnien said. “Most of the scarring of beds appears to have occurred before the current law was implemented.
“But there are still significant details that need to be worked out in how we draw the lines and try to satisfy the interests of preserving SAV, as well as allowing some clamming activities in those areas where people are making their livelihoods,” he said.
Orth also expressed concern that dredging near grass beds could hinder the return of grass beds into those areas. In 1998, Virginia set aside as permanent grass sanctuaries areas that were being dredged by commercial clammers. Virginia also established buffer zones around the beds and, in his letter, Orth said Maryland should also consider buffers.
“Given the value of SAV beds as the prime nursery area for the blue crab, the last viable and significant fishery in Chesapeake Bay, and one that is possibly endangered, the protection of this habitat should be an absolute priority by your state,” Orth wrote.
Orth has been conducting aerial surveys of grass beds in the Bay since the mid-1980s to track SAV trends. Grasses today cover only about a tenth of the 600,000 acres they are though to have occupied decades ago.