HARWICH — There is a proposal in the works to restore oyster beds in the Herring River that could also serve to improve estuary's health.
The oyster reef proposal would be a cooperative venture between the town's natural resources department and the conservation commission.
Oysters have become a recognized source of filtration for the ability to process carbon, nitrogen and phosphorus at high rates, byproducts of human habitation that have an adverse impact on the marine environment. Oyster reefs are being used along the East Coast to filter pollutants to assist in mitigating eutrophication of coastal waters and to enhance fisheries.
The conservation commission has been talking for several months about establishing an oyster reef in the river. Chairman Brad Chase, who is a senior biologist with the state division of marine fisheries, has established a draft proposal for the reefs.
“Oysters are considered to be the keystone species for the health of estuaries on the East Coast due to their substrate building capacity and ability to each filter up to 20 gallons of water per day. The river continues to support wild, native oysters; however, the population has declined from past conditions when dense oyster beds were present in the deeper channels,” the draft proposal reads.
The cause of the decline is uncertain, although water quality degradation due to nutrient loading is a suspected factor. The Herring River watershed has an abundance of nitrogen in need of removal to protect the marine environment.
The project involves a small-scale pilot program that will provide monitored feedback after three years. The project goal is to use natural materials to restore oyster bed habitat and improve seed stock. Chase emphasized to his commission last week that unlike many oyster bed applications, this project seeks to enhance bed reefs with natural recruitment as the primary goal rather than harvest.
The secondary goal of the project is to improve habitat diversity and ecological benefits to other aquatic species and potential contributions to water quality improvements through enhanced filtering and nutrient removal.
“If region-wide efforts to reduce human nutrient loading in the Cape's rivers and estuaries are successful, ultimately this project could improve harvest potential,” according to the document.
The plan is to pack oyster shells with spat attached into a natural fiber mesh and place them in intertidal bays under the Route 28 and Lower County Road bridges and at the pilings at the shellfish hatchery operated by Aquacultural Research Corporation along the edge of the river.
The mesh rolls will be approximately 18 inches in diameter, 20 inches high and seven feet long. Pilings furthest away from the navigation channel will be used so as not to interfere with boaters. The substrata in these areas are exposed on average low tides. Two of the rolls will be placed in each bay at the two bridges and put four at the shellfish hatchery.
There is also a plan to place eight oyster bed rolls in subtidal waters, four about 50 feet downstream from the Route 28 bridge in a deep channel site and another four off the shellfish hatchery site away from the main navigation channel. The estimated cost of the project is less than $1,000. The commission had earlier suggested using fines levied against the owner of the former fishhouse, now the shellfish hatchery, for noncompliance during the reconstruction of the building.
Monitoring and reporting will be done for three years following deployment, including checking the stability of the rolls, random sampling of oyster density and measuring of shell length. From the data growth and survival rates will be estimated. Monitoring of the intertidal beds can be done at low tide, but the subtidal beds will require scuba diving, according to the plan.
The document points out the Herring River has a conditionally approved shellfish classification which can be permitted for the planting of shellfish seed. The project requires a special project permit from the state division of marine fisheries, which also requires approval from the local shellfish constable. The project will also need approval from the conservation commission and the harbormaster and may need approval from the Army Corps of Engineers and the state department of environmental protection.
Chase said the proposal has been reviewed by the appropriate town departments and the permitting process will begin soon, working with Natural Resources Director Heinz Proft and Conservation Administrator Amy Usowski. The next step will be filing a notice of intent with the conservation commission and seeking the special permit from the division of marine fisheries. Chase said some of the permits could take up to a year to be issued.