36 DECEMBER 2015 • WORLD AQUACULTURE • WWW.WAS.ORG Production Facilities and Feeding Trial Protocols Collaborating fish farms were production facilities for black sea bass (Aqua Plantations, Wilmington, NC) and southern flounder (Blue Ocean Farms, Jacksonville, NC). At each farm, four 4.61-m diameter tanks (16.7-m3) were used for experiments. At each facility, each dietary treatment was assigned to two replicate tanks. Production tanks were part of a RAS that included particle traps, microparticulate filter, low-space bioreactor, UV sterilizer, oxygen saturator cone and heat pump. At Aqua Plantations, juvenile black sea bass were produced at the UNCW Aquaculture Facility from photothermally conditioned broodstock and induced to spawn using established procedures (Watanabe 2011). Southern flounder juveniles at Blue Ocean Farms were sourced from a private hatchery (Carolina Flounder, Wallace, NC), where juveniles were raised from eggs supplied by the UNCW Aquaculture Facility at Wrightsville Beach. Adult flounder broodstock were photothermally conditioned and induced to spawn at UNCW using established procedures (Watanabe et al. 2006). To begin the feeding trial at each farm, initial fish weights and lengths were measured in a sample of 150 fish from each tank. Approximately 150 fish in each tank at each facility were then sampled monthly to determine growth rate (Figs. 3 and 4). Fish were fed twice daily as much as they could consume (without wastage) in about 10-20 min. The daily ration was adjusted according to this observation and recorded. The feeding protocol was provided to each farmer at the start of the feeding trial to ensure that administration of feed, rearing conditions, water quality, monitoring of growth performance and mortalities, and collection of data were standardized among facilities. A standardized data sheet was distributed to each farm to monitor and record salinity, pH, dissolved oxygen, ammonia and nitrite concentrations. The amount of feed administered to each tank and the observed mortalities were recorded daily. Feed consumption was calculated as a percentage of tank biomass consumed per day for the duration of the rearing period. Feed conversion ratio (FCR) was calculated as the total biomass gain during the rearing period (not adjusted for biomass lost from mortality) divided by the total feed administered during that period. Black Sea Bass Grow-out at Aqua Plantations Black sea bass were stocked at approximately 1,200 fish per tank. Fish were fed test diets (diets 1 and 3) in duplicate tanks for TABLE 2. Production performance of black sea bass and southern flounder fed a high fishmeal diet (Diet 1) and test diets in which some fishmeal was substituted by soybean meal (Diets 2 and 3). Black sea bass Diet 1 Diet 3 Initial weight (g) 145 145 Final weight (g) 440 463 Survival (%) 82 95 Feed consumption (% body weight/d) 0.53 0.62 FCR 1.45 1.58 Southern flounder Diet 1 Diet 2 Trial 1 Initial weight (g) 255 255 Final weight (g) 437 433 Survival (%) 76 61 Feed consumption (% body weight/d) 0.33 0.28 FCR 1.82 1.40 Trial 2 Initial weight (g) 202 202 Final weight (g) 423 393 Survival (%) 64 66 Feed consumption (% body weight/d) 0.32 0.28 FCR 1.45 1.40 FIGURE 3. Sampling black sea bass at Aqua Plantations, Wilmington, NC. FIGURE 4. Sampling southern flounder at Blue Ocean Farms, Jacksonville, NC.
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