Scientist and local fisherman work to restore oysters at the Crystal Coast

Apr 11, 2016

Credit UNC Research

There’s an environmental and economic crisis along our coast and around the world.  Oyster populations are drastically low, as compared to their numbers a century ago.  In North Carolina, oyster populations have dropped 90 percent.  But two men in Carteret County think they may have the answer to the shortage.  One is a scientist, the other is a fishermen.

It’s an unlikely partnership, since scientists and commercial fishermen haven’t traditionally had the best relationship.  Against big odds, these two have worked together for the past six years to figure out the best way to increase oyster populations in the estuarine of North Carolina’s coast.

Waters were once abundant with oysters, but now their populations have been decimated because of overharvesting and habitat destruction. 

“It’s also important to note that the environment has changed dramatically over the years.”

Dr. Neils Lindquist is a researcher at the University of North Carolina’s Institute of Marine Sciences in Morehead City.

“One of those big changes has been to allow more salt water into our estuaries, dredging inlets and building the intercostal waterway.  When you change the water and make it saltier, it’s harder for oysters because there are so many more predators and pest that love to eat oysters as much as we do.”

Credit UNC Research

Oysters are important, economically in North Carolina.  According to Dr. Lindquist, the oyster harvest over the past few years has been steady at $250 million dollars.  The industry provides local jobs and the product will be sent to seafood markets and restaurants here locally and internationally.  Oysters are also highly valued because of they clean the water.  Mollusks have the ability to filter up to 50 gallons of water each day.

“The oysters also make reefs along shorelines and they protect the shorelines from erosion so they are really important for protecting coastal properties.”

Over the past few decades, local scientists and conservationist have developed methods to restore oyster populations.  One of the more successful efforts is the creation of manmade oyster shell sills.  A pile of loose oyster shells or marl is placed in shallow water, creating a barrier that runs parallel to shore.  The rock or shell material can also be placed inside mesh bags.  Plants can be added around the sill to create a living shoreline.  The idea is that oyster larvae will attach to the substrate and you have an oyster reef.

While this is still an effective practice for oyster restoration, Dr. Lindquist called upon the local knowledge of David “Clammerhead” Cessna, a seventh generation fishermen in Down East Carteret County to improve upon traditional methods.  Together, they’ve experimented with different types of materials to get to the most effective way to restore oyster populations.

Credit UNC Research

“Imaginations took over and we came up with a new material that we’ve been testing now and it looks very promising for growing oysters and then having those oysters on a material to do a lot of different things with them.”

Their improve method for restoration bypasses marl and oyster shells and instead uses an ephemeral, plant based material to create structures for oyster larvae to attach to.  Clammerhead, who left his job in construction to return to his love of fishing, is using his building skills to create reefs.

“This new material that we created is basically a plant fiber with certain cement binders.”

The plant based reef material can be molded into different shapes and sizes, from flat square mats to long, rod shapes, pyramids, and something that he refers to as a cow patty.

Credit UNC Research

“Just a big pile of string all weaved around together with this binder on it that turned out to be a very, very productive product.”

This dynamic duo has tested new material and a variety of reef shapes behind the Institute of Marine Sciences in Morehead City.  The site is located on the busy Bogue Sound waterway which is exposed to strong southwest winds and frequent yacht wakes three to four feet high.  Dr. Lindquist says their method is showing marked improvements over traditional oyster sills. 

“We create reefs that can withstand tremendous wave and currents and we’ve had material in the water for almost 10 months now and we’ve seen it not move an inch and grow fabulous oyster populations where an oyster sill just down the beach from us has been pushed back by boat wakes and strong waves.”

There are several advantages to using this new material to build reefs over traditional methods.  If oysters fail to grow and cover the mesh bags, they eventually tear open, the shells scatter and the plastic ends up in the environment.  

Credit UNC Research

However, the new biodegradable substrate material eventually disintegrates in the water and the concrete crumbles into small pieces and becomes part of the sediment bed.

Another benefit has to do with the way the reefs are designed.  Each three dimensional structure is elevated above the bottom.  

  Since it isn’t submerged in sand, Clammerhead says oyster larvae can settle on all sides of the substrate.   This results in more oysters which means more filtration which leads to healthier waterways and a more prosperous fishing industry. 

“When you build the oyster sill out of a solid pile, then you’ve just got that surface area, nothing lives underneath it.  Nothing lives in it.  Or little to nothing.  But with our method, we usually start 6 to 12 inches above ground level, in some cases even higher to catch the intertidal zone, so that by time we start catching oyster larvae, we already got fish swimming around underneath it, we have crabs crawling through it.”

In addition to creating micro-habitats, another advantage to these rigid structures is that they can be anchored in place in intertidal areas with strong waves and currents.  Dr. Lindquist says more water movement carries more food to the reef, resulting in faster growing oysters. 

“It was typically said that it would take 18 to 24 months to grow an oyster to market size.  And that’s growing them up in the water column, in these bags that everybody assumes is the best and the fastest way to grow an oyster.”

Dr. Lindquist says they have been able to cut that time by almost half, growing market-sized, high quality oysters in only 12 to 15 months.

Credit UNC Research

  The scientist and the fishermen leased another testing site in the Newport River- an intertidal area- where a small portion of the 1.3 acres was covered with the substrate.   Their conservative estimate is that 3.6 million oysters have grown at the site, though it’s probably more like five to six million. 

That brings up another interesting point with this new method. Before the reefs were placed in that leased area, oysters didn’t exist there.  It was just sand.  These reefs can be used to create thriving oyster habitats in places where they didn’t previously exist.

Dr. Lindquist hopes the new material and the methods they’ve found for growing oysters will create opportunity for conservationists and even waterfront homeowners who want to create a living shoreline in their own backyard.

“We’re also working with the Division of Marine Fisheries and talking about ways we can use the oysters growing in our substrates to help with restoration activities and also with cultch plantings and enhancing the resources for recreational and commercial fishermen from wild oyster populations.”

Credit UNC Research

  Word about the new oyster reefs has circulated around the fishing community Down East.  Clammerhead says some his friends are interested in being a part of it.

“They see it as a way of making a decent income, a way of helping the environment, still being able to get out on the water and maintain that commercial fishing individuality.”

In the past, the relationship between scientists and commercial fishermen has been strained. But Clammerhead says this project has proven that scientists and fishermen can work together, and when they do, the results benefit everyone.