WWW.WAS.ORG • WORLD AQUACULTURE • DECEMBER 2015 35 marine flatfish inhabiting estuarine and continental shelf waters of the south Atlantic and Gulf coasts of the US (NCDMF 2009b). Declining natural populations and wide temperature and salinity tolerances make southern flounder a versatile candidate for intensive aquaculture. Technology for commercial scale production of southern flounder embryos and for rearing larvae through juvenile stages is available (Daniels and Watanabe 2003, Watanabe et al. 2001, 2006, Alam et al. 2009, 2011). Juveniles have been grown to market size in intensive RAS in freshwater and seawater using commercial diets. The goal is to accelerate the development of the nascent marine fish culture industry in North Carolina by developing a key input component to commercial production—a nutritious, cost-effective, environmentally-friendly practical feed for commercial production of black sea bass and southern flounder raised in intensive RAS. Specific objectives were to 1) test the most promising diets from previous laboratory studies in pilot, commercial-scale RAS, 2) compare the grow-out performance to market size of hatchery-reared southern flounder and black sea bass fed diets in which soybean meal replaces 30 percent (southern flounder) and 50 percent (black sea bass) of dietary fishmeal and 3) transfer technology to commercial growers, using their facilities. Diet Formulation Based on previous laboratory studies at UNCW, a control, highfishmeal diet and two cost-effective, optimized diets containing 45 percent crude protein and 11 percent crude lipid were formulated. The level of fishmeal incorporation was reduced in test diets by substituting soybean meal for fishmeal (Table 1). The control diet (diet 1) contained 50 percent fishmeal. Diet 2 was formulated for southern flounder and 30 percent of the fishmeal was replaced with solvent-extracted soybean meal. Diet 3 was formulated for black sea bass and 50 percent of the fishmeal was replaced with solvent-extracted soybean meal. Poultry meal (11 percent) was included in all three diets. All other ingredients were included to meet the nutrient requirements of black sea bass and southern flounder (Alam et al. 2011, 2012) (Table 1). Slow-sinking, extruded diets (8 mm pellet size) were prepared by a collaborating feed manufacturer (Carolina Feeds, Ayden, NC) and supplied to collaborating fish farms. (CONTINUED ON PAGE 36) TABLE 1. Composition of diets (g/100 g). Percent FM protein replacement: Control Southern flounder Black sea bass Ingredients Diet 1 - 0% Diet 2 - 30% Diet 3 - 50% Menhaden fish meal 60.0 42.0 30.0 Solvent-extracted soybean meal 0.0 22.5 37.5 Poultry meal 11.0 11.0 11.0 Wheat middlings 7.5 7.5 7.5 Ground corn 10.4 4.4 0.4 Fish oil 5.5 7.0 8.0 Binders 1.5 1.5 1.5 Mineral premix 1.9 1.9 1.9 DiCal phosphate 0.1 0.1 0.1 Vitamin premix 2.0 2.0 2.0 Stay-C 0.1 0.1 0.1 Total 100.0 100.0 100.0 Proximate composition (% dry basis) Protein 44.5 45.3 44.4 Lipid 11.8 10.6 11.3 FIGURE 2. Southern flounder at Blue Ocean Farms, Jacksonville, NC. The goal is to accelerate the development of the nascent marine fish culture industry in North Carolina by developing a key input component to commercial production—a nutritious, costeffective, environmentally-friendly practical feed for commercial production of black sea bass and southern flounder raised in intensive RAS.
RkJQdWJsaXNoZXIy MjExNDY=