Virginia Tech Marine Aquaculture Research Flourishes

     Blacksburg, VA -- The Aquaculture Center at Virginia Tech has just received 2500+ juvenile summer flounder (Paralichthys dentatus) from the Virginia Seafood Agricultural Research and Extension Center (VSAREC) in Hampton, VA. The fish will be used in a research project funded by the National Marine Aquaculture Initiative of Sea Grant. For this collaborative effort, approximately 30,000 summer flounder eggs spawned at the University of Rhode Island were shipped to the VSAREC, hatched and reared using a unique greenwater culture system developed and refined by Michael Schwarz and researchers at the Hampton Seafood Center. This protocol resulted in 60-day post-hatch survival rates in excess of 90%. The high survival rate is remarkable, because during this time period, larval flounder must be fed a succession of live feeds, be weaned to dry feeds, and undergo substantial metamorphic changes. Prior to metamorphosis, flounder larvae resemble the larvae of other fishes more closely than adult flounder, with a symmetrical body shape and eyes on both sides of their head. Approximately 30 days post-hatch, larval flounder undergo metamorphosis and their eyes gradually migrate to the left side of the head and their body takes on a flattened appearance as they transform from a free-swimming stage to a benthic lifestyle, events which are normally associated with high mortality rates. The high survival rate with summer flounder larvae at the VSAREC is exceptional and has resulted in the availability of sufficient flounder juveniles to perform three simultaneous feeding trials. In addition, several hundred metamorphosed flounder were returned to URI to conduct pigmentation studies, and over 5,000 juvenile flounder were sent to Harbor Branch Oceanographic Institute to foster collaborative flatfish research. Research work at the VSAREC has also included larval rearing of southern flounder (Paralichthys lethostigma) eggs with similar results. These advances in the larviculture of Paralichthys sp. eggs and larvae are the direct result of innovative systems design and larval rearing techniques that have been perfected by Michael Schwarz and the researchers at the VSAREC. Information on these production protocols will be presented at the World Aquaculture Society’s Aquaculture America 2003 meeting in Louisville, KY.

Left: Michael Schwarz (right) and David Mowry separate southern flounder by size for a growout trial to be conducted at VSU with Dr. Craig Kasper and Dr. Scott Newton. Right: Schwarz and Mowry sample tanks for an oxidizer study.

     The flounder juveniles at the VT Aquaculture Center will be used in two separate studies investigating the basic nutritional requirements of the species. The research will be directed by Dr. Steven Craig, Head of Aquaculture Nutrition, and Dr. Ewen McLean, Director of the Virginia Tech Aquaculture Center. The two studies will determine dietary lipid levels that promote optimal weight gain and body composition in summer flounder. The third study is presently beginning in Hampton under the supervision of Michael Schwarz and David Mowry, and will investigate optimal protein levels that support maximal weight gain in summer flounder. These studies will be conducted for a minimum of eight weeks in new state-of-the-art nutrition research systems that have recently been installed at the Aquaculture Center and at the VSAREC. The new systems represent the latest in biofiltration and recirculation technologies and are among some of the finest systems available for nutritional research in the country. Under the direction of Drs. McLean and Craig, extensive renovations at the Aquaculture Center have been underway for the last ten months. These renovations will culminate with the addition of over 150 experimental units of varying capacities and designs. When completed, the Center will have invested over $250K in new equipment, recirculating systems, laboratories, a workshop, and a new graduate study room. These funds have been acquired with extramural funding, internal Virginia Tech funding and startup funds from Drs. McLean and Craig.
     Basic nutrition work is also underway focusing on southern flounder reared at the VSAREC. Collaboration between main campus and the VSAREC is ongoing and the future looks extremely bright as new marine species are being investigated in addition to the work already underway with summer and southern flounder. Other species under investigation are yellow perch, tilapia, and cobia. Cobia (Rachycentron canadum), a relatively new candidate species, offers great promise in the emerging aquaculture industry, and is currently being cultured at the VSAREC. The cobia at the VSAREC will be incorporated into a nutrition study for dietary lipid optimization. Another cobia production cycle is scheduled at the VSAREC in October to provide additional fish for experimentation, with the overall goal of enhancing economic viability of cobia culture for application in the aquaculture industry.