Researchers Reel in Ways to Aid Fishing Industry

Fishing has been part of North Carolina culture for centuries, with indigenous tribes and then generations of coastal residents relying on the fruits of the sea for their food and their livelihoods. Commercial fishing is now a $255 million industry in North Carolina, and recreational fishing adds millions more to the state economy each year. NC State researchers are finding ways to ensure fishing remains a thriving industry and that the seafood brought to dock and sold at supermarkets and restaurants is safe to eat.

Protecting against overfishing and depleted fish stocks is one of Dr. Jeffrey Buckel's primary goals as an associate professor of biology at NC State's Center for Marine Sciences and Technology (CMAST) in Morehead City. Buckel tracks the number of juveniles in various species and studies how fast fish grow and how different species interact. "The production of juveniles is highly, highly variable, and that's what makes management of stocks difficult," he says. The so-called "recruitment" of striped bass, for example, has been reduced for almost a decade in Albemarle Sound. To track fish and help determine natural and fishing-related mortality rates, he catches fish and tags them with either streamers or electronic devices that emit an individualized ping as they enter or leave coastal estuaries.

Buckel's research team also works with the state Division of Marine Fisheries to identify strategic locations for protection under the Coastal Habitat Protection Plan. His group has related the abundance of fish to various factors that determine a healthy habitat, such as the amount of submerged aquatic vegetation in an area and upstream land use patterns. "A single marine fish may lay millions of eggs a year, but more than 99.9 percent don't survive to become juveniles," he says. "Changing the survival rate by even a fraction of a percent could make the difference between an average year and a banner year-class."

"We need to better identify control measures and provide consumers with a greater margin of food safety related to fish consumption."

Farm-raised fish can help fill the gaps for consumers when wild stocks are experiencing below-average years, says Dr. Tom Losordo, a professor and extension specialist in the Department of Biological and Agricultural Engineering. An aquaculture expert, Losordo has developed a fresh-water system for raising fish, but he says some species cannot be adapted to live in fresh water. So, he opened the Marine Aquaculture Research Center last year on land in Carteret County donated by I.J. Won, a former NC State professor. He designed a pump system to pull water from a salt creek during high tide and cleanse it of silt, and his team is developing constructed wetlands to remove nutrients from water that has circulated through the fish tanks before it is returned to the creek. "There are thousands of acres of land with salt creeks," Losordo says. "If we can manage the engineering, we can open up many coastal areas to aquaculture with no environmental impact." Dr. Marc Turano, a researcher and extension specialist with North Carolina Sea Grant, has already used the facility to demonstrate that farmed fish can be fed soy-based diets without affecting their growth.

For North Carolina shrimpers, the challenge is more distribution than engineering. Dr. Robert Handfield, the Bank of America University Distinguished Professor of Supply Chain Management in the Department of Business Management, studied the industry to find the best way for shrimp fishermen to compete with a flood of imports from Southeast Asia. Some supermarket chains and restaurants told Handfield they have no market for fresh North Carolina shrimp—and other seafood branded as "Carteret Catch" to emphasize its local origin and freshness—because seafood distributors have plenty of imported shrimp to offer at lower prices. There is year-round demand for frozen shrimp, he says, but the shrimpers here don't have any facilities to handle that. Handfield suggested that they follow the example of shrimpers in Maine and form a co-op to build a cold-storage distribution facility and jointly market their product. "They need to look at where the markets are nationwide," he says. "Once they find niches, they have to have the coordination to promote their product."

Dr. David Green is working to ensure the seafood that winds up on people's plates is safe to eat. A professor of seafood safety and extension specialist at CMAST, he studies bacteria in fish, such as tuna and mahi-mahi, to get a better understanding of how they form histamines. Such bacteria are responsible for more than a third of the cases of seafood-related food poisoning in the U.S. Certain bacteria can grow and produce histamine when fish aren't adequately chilled after being caught and kept chilled through the entire distribution chain to consumers. "A whole host of spoilage bacteria exist in the marine environment," Green says. "We need to better identify control measures and provide consumers with a greater margin of food safety related to fish consumption." Detecting the bacteria has been troublesome for public health officials. Traditional culture methods often produce false positives, Green says, while some molecular techniques don't pick up certain strains of bacteria because they have unique mechanisms for producing histamines. His research team is developing an assay that targets specific enzymes in histamine-producing bacteria to improve detection and better correlate the presence of bacteria with histamine levels. Preliminary results have shown promise, but the tool needs further refinement and validation. "The success of the fishing industry is important to us," Green says, "but our primary mission is to protect the public from contamination of our food supply."

 

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Dr. Jeffrey Buckel tags a fish to track indicators of recruitment variability in marine and estuarine fishes.

Dr. David Green is developing a method to identify bacteria in fish that represent more than a third of seafood-related food poisoning in the U.S.

Commercial fishing is a $255 million industry in North Carolina, involving nearly 4,500 people who catch, harvest and/or sell seafood.