S.C. Sea Grant Consortium

2020-2022 Sustainable Fisheries and Aquaculture Research Projects

Developing a sex-linked DNA marker for cobia (Rachycentron canadum) using next generation sequencing technology for use in stock enhancement, aquaculture efforts, and stock assessments

Tanya L. Darden, Michael R. Denson, and Matt J. Walker, S.C. Department of Natural Resources

Cobia is a popular recreational fishery, and the species gathers in large numbers in high-salinity estuaries on the Atlantic coast and the Gulf of Mexico to spawn, including Port Royal Sound in South Carolina. Heavy fishing pressure in inshore waters has reduced the population in the past two decades, prompting harvest restrictions and seasonal closures of the fishery.

S.C. Department of Natural Resources grows hatchery broodstock for a cobia stock enhancement program.

This project aims to improve the success of stock enhancement by determining the sex ratio of wild populations through a non-lethal and minimally invasive identification tool. The research goal is to use next generation sequencing to develop a sex-linked DNA marker for cobia and use that information to assess the genetic health and hatchery contribution to cobia in South Carolina.

Modeling optimal responsible stocking strategies for spotted seatrout

Tanya L. Darden and Michael R. Denson, S.C. Department of Natural Resources

Spotted seatrout (Cynoscion nebulosus) populations are vulnerable to catastrophic winter kills at least once a decade. Enhancing the wild spotted seatrout population with hatchery-raised stocks after those catastrophic kills requires a balance to ensure the ideal genetic diversity and population size for long-term species adaptability.  

Hatchery managers have few established protocols for determining appropriate stocking numbers or evaluating the potential risks of stocking on the genetic health of the wild population. Researchers will compare stocking strategies at multiple population abundance levels to determine the best practices for spotted seatrout conservation efforts.

Evaluating shellfish pond potential to produce a compatible crop of marine fish, tripletail (Lobotes surinamensis)

Jason Broach and Michael R. Denson, S.C. Department of Natural Resources

Tripletail, a fast-growing fish species found in tropical and subtropical oceans, is popular for its firm meat and mild flavor. Restaurants in the southeastern United States have reported a large demand for tripletail that isn’t being met by U.S. commercial fisheries, which sets up the potential for a strong aquaculture product.

The few attempts at tripletail aquaculture in the southeastern United States so far have been unsuccessful. Researchers plan to try new methods in recirculating aquaculture systems using fish food with hormones designed to induce spawning. They also will examine the effectiveness of synthetic, waterborne hormonal pheromones to improve spawning.

Utilizing local Charleston, South Carolina craft brewery by-products to fill nutritional gaps in sustainable fish feeds for juvenile red drum, Sciaenops ocellatus

Aaron M. Watson, Fabio Casu, and Michael R. Denson, S.C. Department of Natural Resources

This project will evaluate the feasibility of utilizing dried spent brewer’s grains, a by-product of the brewing process, for use in feeds for fish aquaculture. Most craft breweries in coastal South Carolina now donate their by-product to farmers for cattle or pork feed, but the growth in the number of breweries means there’s more by-product than those farmers can use. A new use for the by-product would keep it out of landfills and offer local aquaculture operations a locally sourced, cost-effective alternative to fishmeal.

Researchers will determine if spent grains contain sufficient nutritional content to be utilized as an ingredient in fish feed formulations, is digestible for juvenile red drum, and can be incorporated into feed without negative consequences to fish growth or health. Three local breweries, Tradesman Brewing Co., LowTide Brewing, and Holy City Brewing, have agreed to assist and collaborate on this project.