Workers with Stevens Towing Co. use excavators to offload marl from a barge into the Swan Island Oyster Sanctuary July 10, following N.C. Division of Marine Fisheries specifications for the project, which is part of an overall strategy to restore oyster populations in North Carolina. Video: Jennifer Allen
BEAUFORT – Two excavators moving in a noisy but graceful dance Wednesday chipped away at the tons of limestone marl piled on a 250-foot-long by 52-feet-wide barge, offloading the oyster bed base material at the Swan Island Oyster Sanctuary, where work is wrapping up this week on the three-year restoration project where the Neuse River and Pamlico Sound meet.
As he stood at the back of the tugboat watching the two excavators scoop up piles of rock from the dredge platform to place in the sound, Will Hollowell, operations manager for Stevens Towing Co. North Carolina’s office in Morehead City, described how the crew members operating the excavators strategically place the rock.
Hollowell oversees the contractors who have been working to build the 40-acre Swan Island Oyster Sanctuary, a three-year project of the North Carolina Department of Environmental Quality’s Division of Marine Fisheries and the North Carolina Coastal Federation and one of the 15 sanctuaries in the Pamlico Sound making up the Sen. Jean Preston Oyster Sanctuary Network, which was built to promote oyster growth and named after the longtime state lawmaker who represented Carteret County before her death in 2013.
As contractors, Stevens Towing Co.’s role in the project is to operate the tugboats and barges and to deploy the material using guidelines set by division.
The work has taken place mostly during spring and summer 2017, 2018 and this year. Over the past three years, the dredge has made in total 70 trips to the site, carrying more than 1,000 tons of rock each trip.
The project used, overall, nearly 80,000 tons of material, with the first phase in 2017 using 30,600 tons of marl and the second phase in 2018 using 25,000 tons of granite and 25,000 tons of marl this year.
Hollowell said that the barge is loaded with about 1,200 tons of material per trip at the division’s South River facility. The crew coordinates with the division on where to place the rock, and once the dredge gets to the site, excavators and loaders begin deploying rock, or moving it from the barge into the sound.
While waiting Wednesday at the division’s South River facility boat ramp before heading to the Swan Island Oyster Sanctuary work site, Cameron Luck, oyster sanctuary biologist with the division, gestured to the mountains of granite and marl. He said the piles of marl are being used to build the ridges for oysters to colonize and that there was only about 1,500 to 2,000 tons left to be deployed of the 25,000 tons used this year.
Erin Fleckenstein, coastal scientist in the federation’s Wanchese office and project manager for the restoration project, said all the material should be in place as soon as Saturday.
“Swan Island Sanctuary, when it’s concluded, will be about 40 acres of total oyster reef made up of both limestone marl and granite, providing the substrate for other oysters to land on, grow up and create a new reef structure,” said Fleckenstein to the small gathering at South River before embarking on the boat ride to the sanctuary.
Fleckenstein, holding a map of the Sen. Jean Preston Oyster Sanctuary Network, explained that the network is part of an overall strategy to restore the oyster populations in North Carolina. “There’s 15 sanctuaries placed throughout Pamlico Sound and the idea is that it will serve as a safety net or insurance policy for our oyster population.”
The 15 reefs total between 250 and 275 acres of oyster sanctuary, and research is showing that these reefs support 27 times more adult oysters than the other reef types in the waterways.
“The research is also showing that their footprint is only 6 percent of all the oyster reefs but contributing to 30 percent of the oyster population in the sound,” Fleckenstein said. “Small footprint, big impact is the take-home message.”
The ridges making up the sanctuary vary in height but leave plenty of room for boat traffic above. “I think the maximum is about 4 feet tall, so there is still plenty of clearance for navigation across these reefs, which is a requirement from Army Corps of Engineers for navigation purposes,” she explained after handing out a reef map the division created. Higher ridges are shown in and cooler colors represent the lower ridges.
Oysters in the sanctuaries are not open to harvest but do support numerous finfish species, and the reefs are open to hook and line fishing.
The reefs help build up oyster populations by providing a sanctuary for adult oysters, that are then able to spawn and seed other nearby reefs that may be harvested, including the cultch-planted reefs that division is also instrumental in building, Fleckenstein said.
Cultch are shells and rock strategically placed to enhance shellfish habitat in potentially productive shellfish areas. These sites are open to oyster harvest when the oysters on them reach legal size, or about 3 inches, according to the division.
Because of the success of the sanctuaries in general, she continued, a comprehensive survey of oyster populations in Pamlico Sound was recently performed. The survey looked at the oyster sanctuaries, cultch-planted reefs, subtidal and inner-tidal natural reefs and fished reefs.
“Data is showing that these sanctuaries are very successful and a good strategy to continue pursuing.” Fleckenstein said.
She explained that the division invests a great deal of time and effort in determining where to place sanctuaries to ensure they’re feeding the other harvested reefs and ensuring that they’re creating an interconnected network that serves as an insurance policy for maintaining the state’s oyster population.
The division also works with restoration researchers to plan future sanctuaries for the network, Fleckenstein said. There are four potential reef locations being explored for the next sanctuary and the division is collecting information on the sites’ bottom type, water quality and salinity, and to make sure they’re suitable for a sanctuary.
Luck said during the tour that division researchers are using what is called a habitat suitability model, which takes into account the different factors that drive a healthy oyster sanctuary. In addition to water quality, the researchers look at where the larvae from other sanctuaries comes from and to try and understand how currents and wind affect larvae movement in the system.
Once areas that are most suitable are pinpointed, Luck continued, the division will look to make sure reef construction is not going to impede boat traffic.
They’ll then go assess the site and study the bottom composition to find out if the rocks and material that we’re going to deploy won’t move. “Are they going to stay in the site for many years to come? That’s the point,” Luck said. “And then we also want to make sure that by applying all this, the sanctuary is going to grow oysters.”
The three-year Swan Island Oyster Sanctuary project was funded with more than $3 million in state appropriations and nearly $3.3 million in grant funds from National Oceanic and Atmospheric Administration’s community-based restoration program, with additional funding from Grady White Boats and federation members.
Fleckenstein added that Swan Island Oyster Sanctuary “has been a great partnership between the Division of Marine Fisheries, North Carolina Coastal Federation and contractor Stevens Towing to bring some additional resources from the federal government through the NOAA community-based restoration program to match state appropriations to build these reefs.”
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