World Aquaculture December 2018

44 DECEMBER 2018 • WORLD AQUACULTURE • WWW.WA S.ORG label instructions. The probiotic was dissolved in pond water and applied around the edges of ponds or behind an aerator that mixed the water. Each farm had a designated number of probiotic-treated ponds and control ponds (no probiotic added). There were ten probiotic- treated ponds and ten control ponds on three commercial shrimp farms that participated in the study. Greene Prairie Aquafarm (GPA) had four treatment and four control ponds. Gulf American Shrimp (GAS) and Forkland Springs (FS) each had three probiotic-treated and three control ponds in the study. Each farmmanaged probiotic- treated and control ponds according to farm-specific management protocols. Hence, feed, feed management, pond aeration, water quality management, and other factors were different for each farm in the study. Production ponds were stocked with Pacific white shrimp post- larvae (PLs) that had been transported from a hatchery in Florida and acclimated to pond water in nursery tanks located on each farm (Fig. 5). Stocking occurred in early May in ponds that had been filled with water several weeks ahead of time. The farms in west Alabama (GPA and FS) amended pond water with potassium and magnesium because the water source for these farms has low levels of these ions (Roy et al. 2010). Application of the first dose of probiotic was made 3-4 days before stocking. After stocking, shrimp were fed a commercial feed twice daily until harvest began in September. By the end of October, all ponds were harvested to prevent mortality from cold water temperatures. For the entire production cycle, starting at stocking, monthly water and shrimp (n = 10) samples were collected and evaluated for Vibrio sp. (Fig. 6). Twice during the production season, mid-cycle and just before harvest, five shrimp from each treatment and control pond were preserved and evaluated histologically for disease. In addition, PLs and harvested shrimp were evaluated for the presence of shrimp-associated viral diseases by PCR. Shrimp health evaluations were carried out by the Aquatic Animal Health Laboratory, Harbor Branch Institute, Florida Atlantic University. Water samples were collected weekly from each pond for analysis of total ammonia-nitrogen and nitrite-nitrogen. Water quality analysis was carried out in the laboratory of the Alabama Fish Farming Center near the Alabama shrimp farms or on-farm at Wood Fisheries. Early morning and late afternoon pHwere measured in situ at 60 cm depth in all study ponds once weekly at GPA. Pond water at the other two farms was periodically spot-checked for pH. For the farms in Alabama, phytoplankton (microscopic pond algae) samples were collected every other week from each pond for analysis of type and relative quantity of blue-green algae. Algae evaluation was conducted by personnel at the Alabama Fish Farming Center using a compound microscopic and Sedgwick rafter counting cell according to established techniques. All farms recorded basic information concerning each pond: LEFT, FIGURE 6. Shrimp were sampled weekly by seine or cast net throughout the trial at all three farms. MIDDLE, FIGURE 7. Shrimp production ponds were harvested at the end of the growing season. RIGHT, FIGURE 8. Pacific white shrimp produced from one of the study ponds in Alabama. TABLE 1. Total ammonia-nitrogen (TAN), nitrite-nitrogen (NO2-N), salinity, pH, and temperature in probiotic-treated ponds and control ponds on three commercial shrimp farms in Alabama and Florida, including Greene Prairie Aquafarm (GPA), Forkland Springs (FS) and Gulf American Shrimp (GAS). There were no differences between probiotic treated and control ponds (P > 0.05). Values represent the mean ± standard deviation of values. Farm TAN (mg/L) NO 2 -N (mg/L) Salinity (g/L) pH Temperature (ºC) GPA – Probiotic 0.69 ± 0.09 0.07 ± 0.01 3.0 ± 0.0 8.98 ± 0.12 29.6 ± 0.3 GPA – Control 0.61 ± 0.16 0.07 ± 0.01 2.3 ± 0.2 8.98 ± 0.15 29.7 ± 0.3 FS – Probiotic 0.96 ± 0.21 0.12 ± 0.10 4.5 ± 0.3 8.44 ± 0.20 29.0 ± 0.9 FS – Control 0.78 ± 0.19 0.17 ± 0.13 4.5 ± 0.3 8.42 ± 0.08 29.1 ± 0.8 GAS – Probiotic 0.05 ± 0.06 0.00 ± 0.00 3.9 ± 0.1 8.15 ± 0.45 29.3 ± 0.8 GAS – Control 0.07 ± 0.05 0.02 ± 0.03 3.9 ± 0.1 8.16 ± 0.44 29.3 ± 0.8