50 MARCH 2022 • WORLD AQUACULTURE • WWW.WA S .ORG captured with a cast net, sedated with clove oil, then weighed and counted in groups. Individual length and weight of a second sample of 25 fish was used to determine Fulton condition factor (K). Fish were harvested in late June after 117 d of culture. At harvest, total weight by raceways and treatment was obtained and subsamples of fish were taken to determine average weight. For economic analysis, sales price and variable and fixed costs were determined. Fish Culture Performance The growth rate of red tilapia fed the two 32-percent protein diets was very similar (2.5 g/d for diet A and 2.7 g/d for diet B). Specific growth rate decreased from 3.4 percent/d in the beginning of the culture period to 2.2 percent/d at harvest. The final weight of fish fed diet B was 358 g and of fish fed diet Awas 332 g, meeting the objective of producing fish between 270-340 g. Condition factor of fish at harvest raised on the two diets was similar (2.2). The total biomass harvested from each raceway was similar for the two diets (1246 kg for diet A and 1274 kg for diet B), as well as maximum biomass density (86 kg/m3 for diet A and 88 kg/m3 for diet B). The FCR of red tilapia fed with diet A (1.36) was more efficient than with diet B (1.46). Traditional pond fish culture with red tilapia in Honduras usually requires six months, with a production of 8-10 t/crop (16-20 t/ha per yr) with aeration. Multiplying this yield by 20 raceways indicates that the yield would be 25.2 t in 4,225 m2 (59.6 t/ha per crop). According with the prevailing climate, specifically water temperature, it is possible to produce two crops in a year, equivalent to 119 t/ha. Water Quality Temperature and dissolved oxygen were measured daily in the early morning and late afternoon. Water quality in the open pond was the same as that of water running through the fish raceways. The total alkalinity and hardness of the source water is 12-15 mg/L as CaCO3. After adding dolomitic limestone, total alkalinity was increased to FIGURE 3. The floating In-Pond Raceway System at Mission UpReach, Honduras. FIGURE 4. Sampling fish from the IPRS at Mission UpReach to determine culture performance. TABLE 1. Summary of red tilapia production performance in an In-Pond Raceway System in a 4225-m2 pond, comparing two commercial 32-percent protein diets, Mission UpReach, Honduras. A B Av e ra g e Culture period (d) 117 117 117 Initial weight (g) 37 39 38 Final weight (g) 332 358 345 Initial biomass (kg) 157 166 162 Final biomass (kg) 1246 1274 1260 Initial biomass density (kg/m3) 10 11 11 Final biomass density (kg/m3) 86 88 87 Growth (g/day) 2.50 2.70 2.60 Specific growth rate (%/d) 2.17 2.15 2.16 Fulton condition factor (K) 2.20 2.20 2.20 Survival (%) 89 85 87 FCR 1.36 1.46 1.41 Production (t/ha per harvest) 59.6 Production (t/ha per yr) 119.3
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