WWW.WAS.ORG • WORLD AQUACULTURE • DECEMBER 2015 37 10 months. Ranges of water quality parameters during grow-out were: temperature 22.0-23.0 C, pH 6.6-7.7, salinity 32.8-35.3 g/L, dissolved oxygen 6.4-10.9 mg/L, ammonia 0.08-0.62 mg/L and nitrite 0.01-0.11 mg/L. Growth, feed consumption and FCR of black sea bass fed the two diets were similar (Fig. 5, Table 2). Mean survival of fish fed diet 1 was somewhat less than that of fish fed diet 3. Mortalities observed during this study were related primarily to mechanical problems, including pump intake cavitation causing nitrogen supersaturation, or to excessive dissolved oxygen levels that were periodically encountered in the pressurized recirculating system. Feed conversion does not account for biomass lost through mortality and are therefore conservative. Feed consumption and FCR were comparable to those reported for wild-caught black sea bass raised from subadult (311-326 g) to large market sizes (873-1,051 g) over 221 days on commercially prepared diets with different crude protein (44.0-53.9 percent) and crude lipid (11.415.1 percent) levels (Copeland et al. 2002). FCR in the present study, however, was higher than those achieved (1.12-1.19) with hatchery-raised black sea bass raised from advanced fingerling (27 g) to large marketable stages (682 g) over 570 days on commercially prepared diet with significantly higher protein (55 percent) and lipid (18 percent) levels than those used in the present study (Watanabe 2011). The 10-month feeding trial conducted under pilot, commercial-scale conditions demonstrated that a diet replacing 50 percent of fishmeal with soybean meal (diet 3) did not decrease growth performance, feed utilization and survival of black sea bass compared to a high fishmeal diet (diet 1). This is consistent with laboratory findings that black sea bass juveniles are able to use efficiently diets that replaced up to 58 percent fishmeal protein with soybean meal protein (Alam et al. 2012). Black sea bass can be raised on a high soybean meal-based diet under commercial-scale rearing conditions over an extended time period from advanced juvenile (~145 g) to market size (>450 g) without a diminution of performance compared to fish fed a high fishmealbased control diet. (CONTINUED ON PAGE 38) TABLE 3. Initial and final whole-body proximate compositions of black sea bass (% wet weight basis) fed a high fishmeal-based (control) diet (D1) and a high soybean meal-based diet (D3). Data are means ± SD (N = 3). Diets Moisture Protein Lipid Ash Initial D1 61.4 ± 1.2 16.0 ± 0.6 16.2 ± 0.2 4.9 ± 0.2 D3 63.2 ± 1.5 16.4 ± 0.3 13.7 ± 0.2 5.3 ± 0.1 Final (after 10 months) D1 58.4 ± 1.7 15.7 ± 0.2 19.1 ± 1.2 4.6 ± 0.6 D3 57.4 ± 0.3 15.8 ± 0.3 17.9 ± 0.7 4.3 ± 0.4 TABLE 4. Initial and final whole-body proximate composition of southern flounder (% wet weight basis) fed a high fishmeal-based (control) diet (D1) and a high soybean meal-based diet (D2) in Trials 1 and 2. Data are means ± SD (N = 3). Diets Moisture Protein Lipid Ash D1 69.4 18.5 ± 0.4 9.4 ± 0.2 3.7 ± 0.7 D2 72.0 16.4 ±1.0 7.0 ± 0.0 4.0 ± 0.4 Initial (Trial 2) Diets D1 72.0 15.6 ± 0.5 6.4 ± 0.1 4.0 ± 0.2 D2 72.1 16.6 ± 0.8 6.0 ± 0.2 3.9 ± 0.1 Final (after 10 months, Trial 1) Diets D1 68.1 ± 0.2 20.0 ± 0.6 7.2 ± 0.2 4.1 ± 0.1 D2 67.6 ± 0.3 18.4 ± 0.6 7.7 ± 0.0 3.9 ± 0.5 Final (after 7 months, Trial 2) Diets D1 67.6 ± 0.3 19.0 ± 0.2 8.6 ± 0.2 4.1 ± 0.6 D2 66.3 ± 0.3 19.1 ± 0.9 9.2 ± 0.4 3.6 ± 0.6
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