Rock solid: Oysters abound on restored reefs in Harris Creek, survey finds
Densest clumps of shellfish found clinging to granite stones put in Choptank tributary; watermen continue to question project's cost
You may not be able to get blood from a stone, but it appears you can get a lot of oysters.
Biologists checking reefs restored in 2013 in Maryland’s Harris Creek found the vast majority crowded with oysters, according to a new report. And those reefs built by piling granite rocks on the creek’s bottom had four times as many oysters clinging to them, on average, as did any of the other reefs that had been treated.
The report, released this week by the National Oceanic and Atmospheric Administration, provides further evidence that the controversial effort to restore oysters in Harris Creek is meeting advocates’ expectations, at least for the time being.
Of 30 reefs surveyed last fall, all but one had at least the minimum hoped-for density of oysters growing on them, while 80 percent reached or surpassed the restoration goal of hosting 50 or more bivalves per square meter, the NOAA report said. Densities among reefs varied, but those built with stone bases had the most by far, averaging more than 200 oysters per square meter.
“You’re looking at densities there that the Maryland part of the Bay has not seen since there have been oyster harvests,” said Donald Boesch, president of the University of Maryland Center for Environmental Science. He called it a “spectacular demonstration” of the viability of using alternative materials to enhance reefs when oyster shells are not available.
Harris Creek, a tidal offshoot of the Choptank River, was one of the first areas selected for large-scale restoration in Maryland, and work was finished there in 2015. Restoration is under way on two other Maryland rivers, the Tred Avon and Little Choptank, as well as in the Lafayette, Piankatank and Lynnhaven rivers in Virginia. The 2014 Chesapeake Bay Watershed Agreement calls for rebuilding oyster populations in 10 tributaries by 2025.
Harris Creek is the largest project so far. About 2 billion hatchery-spawned baby oysters were planted on 350 acres’ worth of reefs in Harris Creek, an area covering roughly 8 percent of the tributary’s bottom.
“Restoration at this scale just hasn’t happened before,” noted Sean Corson, acting head of NOAA’s Chesapeake Bay office.
Corson said that monitoring done by NOAA and other partners in the Harris Creek project offer preliminary evidence the experiment is working. The results reported this week echo findings by NOAA last year that all of the initial batch of reefs built in the creek, which had been seeded in 2012, had the minimum density of shellfish established by scientists. Half of those reefs had met or exceeded the higher target level of 50 bivalves per square meter.
“If your goal is to restore oysters in Harris Creek, it has been very successful,” Corson said.
But watermen and their supporters remain skeptical. They opposed Harris Creek’s designation as an oyster sanctuary in 2010, which deprived them of a once-productive harvest area. They insist that the restoration work there, which cost $26 million, has been a costly boondoggle, and they have questioned reports of abundant oyster growth on the rebuilt reefs.
They did so again Monday night, when the latest NOAA monitoring results were presented at a meeting of the state’s Oyster Advisory Commission.
Robert T. Brown, president of the Maryland Watermen’s Association, said he and other oyster harvesters feel officials have hyped the benefits of oyster sanctuaries and of restoration projects like the one in Harris Creek.
“We were sold a bill of goods when these sanctuaries went in,” he said, contending that proponents had predicted that the restored reefs would produce enough oyster larvae to repopulate nearby waters. But he noted that Talbot County watermen saw no increase in spat settling on a reef just outside the Harris Creek sanctuary that they’d replenished with shell in hopes of benefiting from the restoration.
Others, though, pointed out that free-floating oyster larvae can drift tens or even hundreds of miles from where they were spawned before settling to the bottom. There is no easy way to tell where a particular oyster was spawned.
Still, watermen and supporters on the oyster commission demanded further information about the NOAA report — particularly on the productivity of the granite reefs, which have been a focus of complaints.
Some of the stone-based reefs were built too high, damaging vessels that hit them and requiring remedial work. Crabbers also have complained that the rocky underwater structures have interfered with their gear; one suggested Monday night that the manmade structures have attracted so many fish that crabs have been scared away.
“I just can’t get it in my head how anyone can look at this as a good project, as a successful project,” said Ron Fithian, a Kent County commissioner and former waterman.
Others have suggested there’s another, unstated reason for watermen’s hostility to stone reefs — they hope to be able to get back into some of the state’s sanctuaries, and oysters on rocks can’t be harvested using traditional gear.
While oyster shells are widely considered the best reef material, they are in short supply, and research has found that in the right circumstances, oyster larvae will attach themselves to almost any hard surface.
But Maryland officials have yielded to watermen’s complaints, objecting to using any more granite stone on the federally-funded restoration project in the Tred Avon River. The Army Corps of Engineers is attempting to build the rest of the planned reefs there using only clam shells, but had to pause work this summer on a 10-acre portion of the restoration project planned this year because the supply ran out.
A hiatus also looms on the Little Choptank River, Maryland’s third tributary getting restoration, which is state-funded. With work more than halfway done, the Department of Natural Resources initially asked that its request for a needed federal permit be put on hold so state officials could remove any mention of possibly using so-called “alternate substrate” such as rocks or concrete, in building reefs. Now, state officials say they are looking to make even more substantial revisions, tweaking the location of planned reefs to reduce the acreage to be built in shallower water. The changes could delay work there for months, possibly even a year or more, acknowledged Chris Judy, DNR’s shellfish program manager.
Watermen and their supporters insist that Maryland wouldn’t need to use alternative reef material if the Army Corps would just let the state dredge Man-O-War Shoal, a big, old reef near the mouth of the Patapsco River with millions of bushels of fossil shells and relatively few live oysters these days. The DNR applied without success years ago for federal permission to dredge up shells, and reapplied in 2015. State officials want to remove up to 5 million bushels of shells over five years for use in replenishing reefs in waters open to commercial harvest, for helping private oyster growers and for restoring reefs in sanctuary areas.
But the state’s request for a federal permit to dredge shell from Man-O-War has drawn widespread opposition from environmentalists and recreational anglers, who say the shoal is a fish magnet and spawning area for striped bass. It’s also opposed by some commercial watermen.
The Army Corps Baltimore District has yet to decide on the dredging request. But the federal project manager for the permit recently wrote the DNR spelling out a series of conditions that would be put on the work if it is allowed. Among other things, dredging would be off limits for 7 ½ months a year to protect fish spawning in the spring and to avoid disrupting natural oyster reproduction in summer.
The DNR has until Aug. 22 to say whether it will accept the conditions. Judy, the DNR shellfish manager, said they did not seem too onerous.
But critics warn that even if dredging shell from Man-O-War is approved, it won’t be enough to meet the need. Restoration work planned in the Little Choptank alone, for instance, calls for constructing 118 acres of reefs. Building those to a height of one foot off the bottom, as done in other restoration projects, would require 4.1 million bushels of shells. That would appear to leave little for other uses, and none for reef construction in the other two tributaries that Maryland has pledged to target for large-scale oyster restoration under the Bay agreement.
“It would barely scratch the surface,” Allison Colden, fisheries scientist with the Chesapeake Bay Foundation, said of the shells the DNR wants to dredge from Man-O-War Shoal.
The cost of acquiring granite stone is roughly on par with estimates the DNR has made for dredging up the old oyster shells. But Colden, pointed out, “stone is outperforming other substrates by a wide margin.”
Colden warned that Maryland’s reluctance to use alternate materials threatens to stall or even kill the oyster restoration effort in the state.
“It’s this hump we have to get over,” she said, “if we’re going to move forward.”
- Category: Fisheries
By submitting a comment, you are consenting to these Rules of Conduct. Thank you for your civil participation. Please note: reader comments do not represent the position of Chesapeake Media Service.