Research Advances the Next Wave of Aquaculture
Small pondside tanks may be key for a more sustainable future for the aquaculture industry. This innovative approach could help conserve water and maximize the use of earthen ponds in raising striped bass.
“Our goal is to help promote and expand the hybrid striped bass and striped bass aquaculture industry in the state of North Carolina and nationwide,” says NC State University Associate Professor Benjamin Reading.
Part of StriperHub — a program funded by the National Oceanic and Atmospheric Administration, Sea Grant, and the U.S. Department of Agriculture’s National Institute of Food and Agriculture — this project, led by Reading at the Pamlico Aquaculture Field Lab (PAFL) in Aurora, North Carolina, aims to make striped bass aquaculture more efficient. This initiative is the first of its kind for this species.
Traditionally, striped bass have been reared in indoor tanks or expansive outdoor earthen ponds. Both practices have their shortcomings. Indoor tanks utilize expensive recirculating aquaculture systems (RAS) that filter and reuse water. Alternatively, quarter-acre outdoor earthen ponds require a lot of land and labor.
“The concept of pondside tanks was developed as a way to bridge the gap between intensive indoor rearing systems and outdoor earthen pond-based aquaculture,” explains Erimi Kendrick, a graduate student in the Department of Applied Ecology who is working on the project for her master’s thesis in biology.
To implement their idea, Reading and his team installed several small tanks along the perimeter of an earthen pond at the PAFL. Connected by pipes, the tanks and the pond support each other in a continuous cycle. After fertilizing the central pond, fish waste water continues to feed plankton blooms, which are then pumped into the small pondside tanks to feed striped bass fry as they grow.
“The nitrogen cycle is naturally occurring in our ponds rather than having to install physical infrastructure like filters in RAS,” Reading explains. Nitrate from fish waste in the water sustains zooplankton, serving as a nutrient source.
“The first trial of experiments with the pondside tanks informed us that the amount of fish reared per gallon of water used was higher than in earthen ponds,” Kendrick says. “If pondside tanks are successful, then farmers could dedicate less land and smaller bodies of water to serve as a food reservoir, using the pond to primarily cultivate zooplankton rather than as a direct rearing environment. By placing tanks around a single pond instead of maintaining multiple large ponds for stocking fry, farmers could still rear fish while maximizing space and conserving water.”
Another drawback of outdoor earthen ponds is that extracting bass fry early in their development is difficult. “Once fry are stocked directly into large earthen ponds, they have to remain there until they reach the fingerling stage,” Kendrick says.
Fry face higher mortality rates due to handling stress and injury. They also may simply be too small to be caught effectively by seine nets. Small pondside tanks keep fry accessible at a young age and may appeal to farmers who prefer young fry for stocking.
In addition to advancing aquaculture practices, Reading is mentoring the next generation of fisheries and aquaculture professionals. After earning her bachelor’s degree in fisheries, wildlife, and conservation biology at NC State, Kendrick joined Reading’s lab as a graduate student after being inspired by his course Applied Ecology 441- Biology of Fishes.
“If you had talked to me two years ago, I would never have imagined myself working on an aquaculture project,” Kendrick says. “Prior to taking Dr. Reading’s class, I never considered aquaculture as a career path or even realized how important it was to fisheries science. However, his course introduced me to the critical role that aquaculture plays in both fisheries science and conservation.
“The aspect of aquaculture that interests me the most is its potential for species conservation, particularly for non-game fish with threatened populations. While a good bit of fisheries science focuses on managing popular sport and commercial species, I have also been drawn to lesser-known but ecologically important fish that receive less attention.”
As a first-year graduate student, Kendrick is already contributing to the field of aquaculture. From her research on pondside tanks, she created a developmental staging chart for striped bass. Prior to using pondside tanks, this was not possible because it was difficult to extract young fry from earthen ponds.
Kendrick hopes the development chart can help farmers, biologists and others interested in the early developmental stages of striped bass by providing a resource for tracking key morphological milestones like yolk sac absorption, mouth formation and swim bladder inflation. This developmental staging chart could also be used for other fish species that are reared in aquaculture environments to help reduce mortality rates.
“One thing that everyone should know about fisheries and aquaculture is that they are inseparable from the health of our ecosystems and the sustainability of our food systems,” Kendrick shares. “Fisheries science is important in maintaining the balance of aquatic ecosystems and protecting biodiversity. Similarly, aquaculture is more than just fish farming; when practiced sustainably, it can alleviate pressure on wild populations, restore endangered species and be a reliable protein source to meet the demands of a growing global population.”
