Uat Polyculture

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Assessment of Pacific white shrimp (Litopenaeus vannamei) Growth in a Polyculture System with Red tilapia (Oreochromis mossambicus × O. niloticus) in a Recirculating System

I assessed Polyculture of Pacific white shrimp (Litopenaeus vannamei) and Red tilapia (Oreochromis mossambicus × O. niloticus) through a preliminary study in the facilities of the ERL. The experiment was conducted in 2007,over five weeks using unreplicated treatments. The shrimp used in this experiment were weighed and placed in mesh baskets placed within plastic pools containing 300 L of saline water at 5 ppt. The fish were placed in aquariums with 40 L of water capacity. Each one was equipped with an air stone and an individual thermometer float. Aquariums were placed over the plastic pools on a wood stand. Fishwere distributed in three aquariums, placing four fish with a total weight of 40 g in the first, eight fish with 80 g in the second and twelve fish with 120 g in the third aquarium. Fish were fed at 6% of body weight with commercial fish feeds of 35% protein. Shrimp were weighed and placed in the baskets with five shrimp per basket. The average initial weight of each shrimp per basket was 1.37 gin the first plastic pool, 1.25 g at the second, and 1.40 g at the third. All of the shrimp were fed with commercial pellets at 10 % of their body weight. The final mean weight of shrimp at the middle fish density was 11.1±0.88 g followed by shrimp at high fish density 10.5±0.83 g and low density 9.7±0.87 g, respectively. The average final weight of fish, were 25.5±0.59 g, 28.6±0.59 g and27.7±0.72 g, respectively.
A formal analysis of variation could not be performed due to lack of replicates. Therefore coefficients of variation were calculated indicating little variation among treatments. This preliminary experiment showed that fish did not adversely affect shrimp growth.
The experiment was conducted over 5 weeks with no fish or shrimp mortalities during the experimental period(Figure 1).

Figure 1. Photograph of the experimental systems of the preliminary study (ERL).

Test of animals
Juvenile Pacific white shrimp (L. vannamei) were obtained from Shrimp Improvement Systems, Inc. in Miami, FL. Red tilapia is a hybrid line from existing stocks at the facilities of the ERL, from hybrid crosses (O. aureus x O. mossambicus, and O. aureus x O. urolepis hornorum) whereas, thetilapia (O. niloticus) is an improved line that comes from existing stocks at the facilities of the ERL, with original stocks from Auburn University, Auburn, AL.
To test the productivity of tilapia (O. niloticus x O. mossambicus) and shrimp (L. vannamei), three treatments (3 pools and 3 aquariums), were set (Table 1). Shrimp were stocked in baskets at a density of 5 individuals per basket and 4baskets into each pool, whereas tilapia were stocked at densities of 4, 8 and 12 fish/aquarium, Treatments One, Two and Three, respectively.

Table 1. Shrimp and tilapia stocking density in the experiment cultured for 35 days at different fish densities

Treatment | Shrimp/pool | Baskets/pool | Shrimp/basket | Tilapia/aquarium | Shrimp: tilapia ratio |
T1 | 20 | 4 | 5 | 4 (low density) |5/1 |
T2 | 20 | 4 | 5 | 8 (mid density) | 2.5/1 |
T3 | 20 | 4 | 5 | 12 (high density) | 1.66/1 |

Each aquarium was 45 cm L ×30 cm W ×30 cm H (40L capacity).
Each pool was 124 cm D x 25 cm H (300L capacity).

Feed and feeding
Shrimp and fish were fed once a day for 5 weeks, using commercial pellets (made by Rangen Company, Buhl, ID and Ace Hi Feed from Star-Milling fromPerris, CA, respectively). Feed adjustments were made according to shrimp and fish weights once a week. Feed was distributed into baskets as well as into aquariums. Feeding rate for fish and shrimp was 6 % and 10% of their body weight per day, respectively.
Measuring and monitoring...
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