Review of Some Recent Developments in Sustainable Shrimp Farming Practices in Texas, Arizona, and Florida

FAU Institutional Repository http://purl.fcla.edu/fau/fauir

This paper was submitted by the faculty of FAU’s Harbor Branch Oceanographic Institute.

Notice: © 2002 The Haworth Press, Inc. This manuscript is an author version with the final publication available and may be cited as: Samocha, T. M., Hamper, L., Emberson, C. R., Davis, A. D., McIntosh, D., Lawrence, A. L., & Van Wyk, P. M. (2002). Review of some recent developments in sustainable shrimp farming practices in Texas, Arizona, and Florida. Journal of Applied Aquaculture, 12(1), 1-42. doi: 10.1300/J028v12n01_01

Tzachi M. Samocha Louis Hamper Craig R. Emberson Allen D. Davis Dennis McIntosh Addison L. Lawrence Peter M. Van Wyk

ABSTRACT. The world shrimp-farming industry is currently experiencing major crop losses due to disease outbreaks, which are often associated with environmental degradation. Such losses can be minimized through the adaptation of technologies that enhance biosecurity and environmental control. Current technologies suggest that a shrimp yield as high as 10 kg/m2/crop can be achieved in indoor, super-intensive, closed- recirculation systems in which environmental parameters are controlled. Nevertheless, high construction and operating costs make the financial

Tzachi M. Samocha, Texas Agricultural Experiment Station, Shrimp Mariculture Research Facility, 4301 Waldron Road, Corpus Christi, TX 78418. Louis Hamper, Arroyo Aquaculture Association, Route 2, Box 1040, Rio Hondo, Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 TX 78583. Craig R. Emberson, Wood Brothers Farms, 77 Biltmore Estates, Phoenix, AZ 85016. Allen D. Davis, Auburn University, Department of Fisheries and Allied Aqua- culture, Auburn, AL 36849. Dennis McIntosh, University of Arizona, Tucson, AZ 85705. Addison L. Lawrence, Texas Agricultural Experiment Station, Shrimp Mariculture Research Laboratory, 1300 Port Street, Port Aransas, TX 78383. Peter M. Van Wyk, Harbor Branch Oceanographic Institution, 5600 Highway US 1, Fort Pierce, FL 34946. Journal of Applied Aquaculture, Vol. 12(1) 2002  2002 by The Haworth Press, Inc. All rights reserved. 1 2 JOURNAL OF APPLIED AQUACULTURE

viability of these systems questionable. Production of shrimp with reduced water exchange in outdoor ponds is another promising method to minimize monetary losses and environmental degradation. Data from commercial shrimp farms in south Texas suggest that significant reduction in water exchange and nutrient release is feasible with no impact on production when an adequate level of aeration is provided. Researchers of the Texas Agricultural Experiment Station, Corpus Christi, Texas, are currently testing other potential management tools for intensification of outdoor pond productions. These trials demonstrated the feasibility of producing a yield of almost 0.9 kg/m2 of marketable size shrimp with no water exchange. Inland production of shrimp in low-salinity ground water can provide another potential solution to disease and environmental problems, as production is conducted in isolated areas away from other host species and where effluent water can be used for crop irrigation. Re- cent studies with this water showed that high-density nursery and grow- out of Pacific white shrimp, Litopenaeus vannamei, are feasible, with excellent survival and yield. [Article copies available for a fee from The Haworth Document Delivery Service: 1-800-342-9678. E-mail address: Website:  2002 by The Haworth Press, Inc. All rights reserved.]

KEYWORDS. Pacific white shrimp, Litopenaeus vannamei, closed- recirculation system, culture

INTRODUCTION

Viral disease outbreaks in farm-raised shrimp have resulted in severe crop losses all over the world. In some cases, these losses have been associated with shrimp farming intensification and receiving-stream deg- Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 radation. When virulent pathogens are found in wild populations and in natural waters, disease control in cultured stocks becomes difficult and sometimes very costly. Farmers and researchers are interested in developing cost-effective shrimp production methods to reduce the risk of these disease outbreaks. Aquaculture, by definition, uses resources from, and interacts with the environment. Many aquaculture operations generate metabolic waste products (e.g., feces, ammonia, uneaten food, etc.) that are being released into receiving waters. Consequently, some cases of environmental degradation in coastal areas have been documented in Europe, Southeast Asia, and Latin America due to intensive aquaculture activi- Samocha et al. 3

ties (Phillips et al. 1993). In most cases, the organic particulate waste will accumulate on the seabed in the immediate vicinity of the farm, while the soluble waste will eventually end up in the receiving waters. Organic enrichment of the benthic ecosystem may result in formation of anoxic conditions. Under extreme cases, reduction in macro fauna biomass, abundance, and species composition may also follow (Barg 1992). In semi-intensive and intensive pond systems, it is not uncommon to exchange 40% of the pond volume daily. For example, old shrimp production practices in Taiwan required up to 43 m3 of water for every 1 kg of shrimp produced (Chien et al. 1989). Hopkins and Villalon (1992) found only small correlation between estimated water usage per unit weight of product and shrimp production rates. Often on large farms, water exchange is based on a set schedule, with occasional emergency flushes (Macia 1983), rather than as an ongoing response to changing pond conditions. Water exchange rates are seldom based on well-con- ceived nutrient and algal population monitoring. Often, pond-flushing removes phytoplankton, nitrifying bacteria, and natural productivity that could have otherwise benefited the pond water quality and the cultured organism. Hopkins et al. (1993) studied the effect of water exchange rates on production, water quality, effluent characteristics, and nitrogen budgets of intensive shrimp ponds. They reported that reducing typical water exchange is feasible without negatively affecting shrimp survival or growth, thereby decreasing economic costs and potential negative environmental impact. Furthermore, Hopkins et al. (1995a, 1995b) stated that high shrimp yield was achieved without water exchange (7,000 kg/ha/crop). To avoid nutrient release during harvest, they suggest storing the water for reuse with subsequent crops. Although the efficiencies of water recycling systems are still far from perfect, more and more shrimp producers are incorporating this tech- Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 nology on their farms. One of the main reasons for this increased activ- ity is the farmer’s effort to reduce the risk of losing their crops due to viral disease outbreaks. A good example is the recent White Spot Syn- drome Virus (WSSV) disease that affected shrimp production in the Far East. Several organisms (especially crustaceans such as crabs, copepods, Artemia, etc.) have been found to be potential carriers of this virus. To minimize the risk of introducing these carriers into the culture systems, water is treated before stocking. This water is recirculated within the farm and every effort is made to avoid bringing new, untreated water until harvest. Unlike farmers in the Far East, the initial driving force for the Texas shrimp farmers to use the closed recirculating system was 4 JOURNAL OF APPLIED AQUACULTURE

their need to meet effluent water quality standards set by regulatory agencies. Furthermore, effluent waters from coastal shrimp farms have created a serious growth-limiting factor for the shrimp farming industry in Texas. It is particularly true for Texas coastal areas, in which the discharge is going into bays and estuaries behind barrier islands that have limited water exchange with the Gulf of Mexico. This paper reviews management practices used by producers and researchers in Texas, Ari- zona, and Florida to reduce both water usage and pollution from shrimp production operation.

INDOOR SUPER-INTENSIVE SHRIMP PRODUCTION TECHNOLOGY

Current technology advancement suggests that a high shrimp yield can be achieved in indoor, super-intensive, closed-recirculation production systems with “zero water exchange.” These systems can serve as an alternative to conventional pond culture, in which environmental regu- lations and user conflicts of coastal land and water sources can be ad- dressed more effectively. The University of Texas at Austin, Marine Science Institute, Fisheries and Mariculture Laboratory, has employed water reuse systems for over 20 years for both research and intensive production of fish and shrimp. Arnold et al. (1990) and Reid and Arnold (1992) provide a general description of the basic recirculating system used for shrimp production. In these prototypes, post-larvae are stocked directly into a raceway type culture tank. Airlift pumps and a biological filter, made of vertical filter plates, served to maintain adequate water quality in the culture chamber. Davis and Arnold (1998) have recently published a paper with detailed description of this system along with several alterations of procedures and system design to increase the effi- Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 ciency of waste removal, minimize labor requirements, and maximize biomass loading. The following is a brief description of the culture systems that have been used for intensive culture of the Atlantic white shrimp, Litopenaeus setiferus, and the Pacific white shrimp, L. vannamei. Unlike the prototype, a separation is made between the nursery and the grow-out phases. Nursery is conducted in 10-m3 circular tanks. Culture water is circulated via a settling box with foam fractionation into a biological filter and a secondary settling area before the final return into the tank. In- stead of vertical filter plates, the biological filter is composed of polypropylene packing material (1.6 cm Flexrings®, Aquatic Ecosystems, Samocha et al. 5

Apopka, Florida1). Grow-out production trials are conducted in three sizes of raceways (with 25, 35, and 72 m3 of operational water). The 25-m3 and 35-m3 systems each consists of three separate components: a fiberglass raceway; a fiberglass reinforced plywood filter box housing a rotating micro-screen filter; and a fiberglass filter box divided into four equal compartments, consisting of a foam fractionation/settling chamber, two biological filter compartments, and a secondary settling chamber/ozone reactor. For each system, the effluent water from the culture chamber is discharged into a micro-screen barrel. Suspended solids are collected on the rotating screen and washed into a catch basin for discharge. The filtered water is then air-lifted out of the rotating micro-screen filter box into two foam fractionators. The water passes through a settling chamber, two reverse-flow biological filter chambers, and a secondary settling chamber/ozone reactor. After treatment, the water is pumped back into the culture chamber. Aeration to the raceway (via ten porous plastic diffusers and airlift pumps) is provided by a re- generative blower. The biological filter consists of two chambers, each containing 0.9 m3 of 5.8-cm Lanpac® polypropylene packing material (Lantec Products Inc., Agoura Hills, California1) and supplemental aeration. Filtered water entering the secondary settling chamber is treated with ozone (5.6-11.3 L/hour or 2-4 SCFH). Ozone is produced with a corona discharge ozone generator (Innovative Water Technologies Cor- poration, San Antonio, Texas) with oxygen feed. Ozone and oxygen are injected via venturi aspirators powered by a 1/10 horsepower (HP) sub- mersible pump. When needed, a second pump that is equipped with two oxygen-fed venturi aspirators and a screened intake achieves an increase in dissolved oxygen level in the culture tanks. The 72-m3 system, has a similar design but the culture system and filters are constructed out of wood with a liner. In this system, effluent water leaving the raceway can be directed through two micro screens or Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 directly into the settling basin. All water, either from the micro-screens or directly from the raceway, enters a common settling chamber. Water entering the settling chamber is exposed to a stream of ozone, which is introduced to facilitate flocculation of particulate material. Suspended solids that have settled are discharged through a drain line running along the bottom of the settling chamber or by manual siphoning. The settled water is then airlifted into each of three parallel biological filters. Water exits each filter box and enters a common foam fractionation/ ozone reactor chamber. Ozone is introduced into the reactor via three

1. Use of trade or manufacturer’s name does not imply endorsement. 6 JOURNAL OF APPLIED AQUACULTURE

venturi aspirators. Treated water then travels via a common 15.2-cm PVC pipe into the retention chamber for degassing and final settling. Treated water is air-lifted into the top of the culture chamber at a rate of 720 L/minute. A summary of selected water quality parameters measured in the nursery and the grow-out trials can be found in Table 1. Table 2 provides a summary of nursery and grow-out production trials with the Pacific white shrimp and the Atlantic white shrimp over a six-year period (Davis and Arnold 1998). The nursery studies suggest that the nursery system has supported a yield as high as 2.8 kg/m3 when used with the Pacific white shrimp. High survival rates were obtained for both species. Survival rates in the grow-out trials were lower than those obtained in the nursery. Nevertheless, these trials showed that the raceway-system could support biomass loads of 5.7 kg/m3 when used for the production of live bait Atlantic white shrimp. When used with the Pacific white shrimp, the system supported a yield of 9 kg/m3 of marketable size and 11.23 kg/m3 of juvenile shrimp (Table 2). Their results suggest that the system can be operated with either 10-15% or with as low as 0.2% daily water replacement. To optimize loading of the culture system, Davis and Arnold (1998) suggest using a three-phase system with nursery, post-nursery and grow-out. Harbor Branch Oceanographic Institution (HBOI), Fort Pierce, FL USA has been working for the last three years to develop a commer-

TABLE 1. Summary of water quality parameters for the major phases of production (adapted from Davis and Arnold 1998).

Species System Temp. (°C) DO (mg/L) pH TAN (mg/L) NO3 (mg/L) Salinity (ppt) Litopenaeus setiferus Nursery 27.7 5.5 7.7 0.17 0.17 28.3 (6/93) 35 m3 28.1 6.5 7.5 0.30 0.74 31.0 L. setiferus (8/93) Nursery 27.2 5.3 7.5 0.32 0.30 33.2 Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 25 m3 24.7 7.0 7.5 0.18 0.12 29.2 L. vannamei (6/94) Nursery 28.0 6.0 7.6 0.38 0.31 22.6 25 m3 27.5 6.8 7.4 0.41 0.43 31.8 25 m3 27.7 7.0 7.4 0.37 0.60 31.6 35 m3 26.1 6.2 7.6 0.36 0.30 29.3 L. vannamei (6/95) Nursery 29.5 6.1 7.5 0.76 0.31 29.5 25 m3 29.5 6.7 7.4 0.66 0.98 33.1 72 m3 27.5 6.4 7.5 0.54 0.79 28.0 L. vannamei (2/96) Nursery 24.0 6.4 7.6 1.16 0.51 31.3 72 m3 28.9 5.6 7.5 0.50 1.48 23.9 Samocha et al. 7

TABLE 2. Summary of shrimp production under various culture conditions at the University of Texas Marine Science Institute, Port Aransas, Texas (adapted from Davis and Arnold 1998).

Species System Stocking Daya Mean Harvest EFCE Survival shrimp/m3 weight (g)b (kg/m3)c (%)d (%) Litopenaeus setiferus (6/93) Nursery 2,100 28 0.18 0.36 85.1 96.9 35 m3 582 99/111 5.2/6.4 3.41 49.4 99.0 L. setiferus (8/93) Nursery 5,000 32 0.14 0.63 69.5 87.0 25 m3 1,739 120 4.3 5.70 56.9 76.4 L. vannamei (6/94) Nursery 6,000 34 0.45 2.29 110.6 84.8 25 m3 1,018e 161 16.1 6.51 25.4 44.8f 25 m3 1,018e 161 17.7 9.00 35.9 56.4f 35 m3 165 161 19.5 2.90 36.0 89.8 L. vannamei (6/95) Nursery 8,300 31 0.37 2.85 96.2 96.0 25 m3 3,189 77 3.46 11.23 81.2 87.8 72 m3 902 172 12.7 8.95 24.3 78.3 L. vannamei (2/96) Nursery 8,200 21 0.16 1.22 94.1 92.4 72 m3 700 175 15.6 7.26 29.6 66.7 a All shrimp were received as PL8-15. Day denotes the number of days from receipt of the population and indicates the culture day that the population was moved or harvested. b Mean weight at harvest of at least 30 individuals, towel dried and weighed individually. c Kg shrimp harvested per cubic meter of culture water. d Estimated feed conversion efficiency (EFCE) = biomass gain/total feed offered ϫ 100. e At day-90 a portion of the shrimp (2,896) having a mean weight of 8.6 g were transferred to the 35 m3. f Shrimp jumping out of the culture system was estimated to result in 11.8% mortality.

cially viable freshwater recirculating system for the production of Pa- cific white shrimp in greenhouses (Van Wyk 1999a, 1999b). Scarpa and Vaughan (1998) demonstrated that Pacific white shrimp can be successfully acclimated to freshwater, provided that the water has a minimum of 300 mg/L of chloride ion, and 150 mg/L as CaCO3 of total

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 hardness. Water with chloride levels this low is generally classified as freshwater and can be used to irrigate most crops. The significance of this is that the ability of Pacific white shrimp to grow and thrive in hard, freshwater means that shrimp can be produced on cheaper, non-coastal agricultural land. There are many locations in Florida where freshwater wells meet these minimum requirements for culturing Pacific white shrimp, including at Harbor Branch. The well water used in the HBOI greenhouse production systems has a salinity of approximately 0.5 ppt Ϫ (300 mg Cl /L) and a total hardness of 400 mg/L as CaCO3. Salinities in the HBOI production trials averaged 0.7 ppt, chloride concentrations Ϫ averaged 400 mg Cl /L, and total hardness and alkalinity as CaCO3 av- 8 JOURNAL OF APPLIED AQUACULTURE

eraged 400 mg/L and 150 mg/L, respectively. The salinity of the water in the culture systems (0.7 ppt, 400 mg ClϪ/L) was slightly higher than that of the well water. This was due to the periodic addition of small amounts of seawater to the system to replace calcium, magnesium, and trace minerals that were depleted as a result of uptake by the biological components of the system. The objective of the researchers at HBOI has been to develop a cost-effective indoor, freshwater recirculating production system capable of growing shrimp at moderately high densities (up to 150 shrimp/m2). These densities are significantly lower than the densities (> 600 shrimp/ m2) that have been achieved for Pacific white shrimp in more sophisti- cated recirculating systems (Davis and Arnold 1998). However, the profitability of a system is not strictly a function of carrying capacity. The systems with the greatest profit-making potential will be those that utilize capital, labor, energy, and other inputs most efficiently (Van Wyk in press). The focus of the HBOI research effort has been on developing relatively inexpensive indoor production systems that make efficient use of space, energy, and labor. In 1998, HBOI set up two prototype greenhouses measuring 9.2 m ϫ 29.2 m. Each greenhouse encloses two 70.7-m3 (4.4 m ϫ 26.8 m ϫ 0.60 m) culture tanks, which occupy 90% of the area enclosed by the greenhouses. The two culture tanks share a common interior wall. A catwalk mounted on top of the interior wall provides access to the entire length of the culture tanks. The culture tanks consist of a wooden frame supporting a black 30-mil high-density polyethylene liner. The tanks are set up in a “racetrack” configuration with a central baffle and drain outlets at opposite ends of the baffle (Figure 1). The water in the tank flows in an elongated oval pattern, with a semi-circular flow pivoting about the drain outlets at either end of the central baffle. This flow pattern gener- ates centrifugal forces as the water circles the drain, concentrating the Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 suspended solid wastes in the area around the drain outlets. The drain outlets are connected to a common drainage pipe, which carries water from the culture tanks to the filtration system. These culture systems feature a low-head filtration consisting of an upflow static-bed bead filter for solids removal and an aerated submerged-bed biofilter. The solids filter, designed and built at HBOI, consists of cylindro-conical sump (1.22 m diameter ϫ 1.22 m deep, 1,200-liter capacity), filled with 0.5 m3 of positively buoyant Kaldnes® biofilter media (Water Management Technologies, Baton Rouge, Louisiana). Solids-laden water from the culture tank enters the solids filter from below. As the water flows up through the filter bed, suspended solids con- Bed

Bed

Biofilter

Filter

Submerged

Solids

Submerged

Pump

Spray Bar

60% systems at Harbor Branch Oceanographic Institute.

Central Baffle

Final Growout

Central Baffle

Single-Phase Production System

Three-Phase Production System

30% Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010

Intermediate

10%

Nursery FIGURE 1. Layout for single-phase and three-phase production

9 10 JOURNAL OF APPLIED AQUACULTURE

tact and adhere to the sticky surfaces of the filter media. Filtered water exits the solids filter at the top of the filter bed through a slotted pipe. Head loss through the solids filter is less than 5 cm. The solids filter is backwashed every three days. Approximately 2,000 liters, or about 3% of the system volume, is discharged during each backwash operation. Total water exchange rates average about 1% of the system volume per day. Nitrogenous wastes are removed by an aerated, submerged-bed biofilter. Water flows by gravity from the solids filter to the biofilter. The biofilter consists of a 2,700-liter rectangular polyethylene tank (1.22 m ϫ 1.83 m ϫ 1.22 m) filled with 1 m3 Kaldnes® biofilter media (effective specific surface area = 492 m3/m2). The biofilter media is tumbled by air bubbles introduced through a grid of 10 medium pore airstones (1 cubic feet per minute, CFM, airflow per airstone). Total ammonia nitrogen levels averaged 0.25 mg NH3-N/L (S.D. = 0.46 mg NH3-N/L) in three production trials carried out in 1998, while nitrite Ϫ Ϫ levels averaged 0.56 mg NO2 -N/L (S.D. = 1.15 mg NO2 -N/L) (Table 3). The water in the culture tanks is circulated through the filtration system once every 2.5 hours. At a flow rate of 500 LPM, there is less than 10 cm of total head loss through the solids filter and biofilter. Water flows by gravity through the filter system, and is pumped back to the culture tanks by a low-head 3/4 horsepower (HP) centrifugal pump. The water returning to the culture tanks is introduced through spray bars, which span the raceways. The sprays bars aerate and de-gas the water as it is returned to the culture tank. In addition, the spray bars generate a circulating flow of water within the culture tank. The circulation of wa-

TABLE 3. Summary of daily water quality parameters of three freshwater recirculating production systems stocked with Pacific white shrimp at Harbor

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 Branch Oceanographic Institute in 1998.

Water Quality Parameter Value±SD Salinity (ppt) 0.7±0.5

Total hardness (mg/L as CaCO3) 390±145

Total alkalinity (mg/L as CaCO3) 132±8.4 Dissolved oxygen (mg/L) 6.9±0.9 Temperature (ºC) 27.2±1.8 pH 7.82±0.45

Total ammonia nitrogen (mg NH3-N/L) 0.25±0.46

Nitrite (mg NO2-N/L) 0.56±1.15 Samocha et al. 11

ter within the tank is important because it suspends the solid wastes in the water column and facilitates the transport of solid wastes to the drains. Aeration for the two greenhouses is supplied by a 2.5-HP regenera- tive blower. The blower provides 0.16 CFM of air per kilogram of antic- ipated shrimp biomass. The air diffusers serve both to aerate the water and to help keep solid wastes suspended in the water column. During the 1998 production trials, dissolved oxygen levels averaged 6.97±0.87 mg/L, and rarely dropped below 5 mg/L. The effluent from the shrimp production operation is discharged into a series of three, 0.11 ha, retention ponds at Harbor Branch. All effluent from the facility discharges into a corner of the first pond in the series. Overflow pipes pass through the levees separating each of the three ponds. Nitrogenous wastes are removed from the water by algae and aquatic plants. Evaporation and seepage account for all of the water loss from the retention ponds. There is zero discharge of effluent from the retention ponds to surface waters. During the nursery phase, shrimp were fed specially formulated diets (Bonney, Laramore, and Hopkins, Inc., Ft. Pierce, Florida) with 50% and 45% crude protein levels and elevated levels of calcium, phosphorus, potassium, vitamin C, and other vitamins and minerals. Shrimp in the grow-out phase were fed a commercial diet with 35% protein and 2.5% squid meal (Rangen, Inc., Angleton, Texas). Feed was offered ad libitum four times a day. Feed conversion ratios (FCR) are summarized in Table 4. A focus of the research performed at HBOI has been to compare the productivity and economics of single-phase and three-phase production systems. The two shrimp greenhouses at HBOI were set up in two different configurations (Figure 1). In one greenhouse, the culture tanks

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 were set up as non-partitioned single-phase culture tanks, while in the other, a raceway was partitioned into a nursery, an intermediate, and a final grow-out section. In the three-phase system, the shrimp spend 50-60 days in each phase of the grow-out. The area assigned to each section was calculated so that the shrimp would reach a density of approximately 2.5 kg/m2 at the end of each culture phase. The nursery section occupied approximately 10% of the culture area, while the intermediate and final grow-out sections occupied 30% and 60% of the culture area, respectively. Shrimp were transferred from one section into another by draining the volume of one section into the next through 10-cm bulk- head fittings that pass through the partitions between sections. Trans- 12 JOURNAL OF APPLIED AQUACULTURE

TABLE 4. Summary of the results obtained in production trials carried out at Harbor Branch Oceanographic Institution comparing single-phase and three- phase production systems.

Parameter Single-Phase Three-Phase Percentage of culture area harvested (%) 100 60 Survival (%) 77±14 61±12 Feed conversion ratio (FCR) 1.59±0.24 1.74±0.11 Harvest density (shrimp/m2 of area harvested) 153±38 128±21 Days to harvest 180 180 Average shrimp weight (g) 14.1±2.6 15.9±3.05 Growth (g/week) 0.55±0.10 0.62±0.12 Yield (kg/m2/crop) per area harvested 2.07±0.40 2.00±0.35 Yield (kg/m2/crop) per total area 2.07±0.40 1.20±0.21 Crops/yr 2 6 Yield (kg/m2/yr) per total area 4.14±0.80 7.20±1.26

fer-related mortality was minimized by the elimination of handling of shrimp during transfers. The nursery, intermediate and final grow-out sections of the culture tank were set up in a stairstep configuration, with approximately 15 cm of elevation difference between adjacent sections. A series of paired production trials were carried out in which single-phase and three-phase culture systems were stocked simultaneously with high health postlarvae that had been acclimated to freshwater. The tanks were stocked at an average density of 206 postlarvae/m2 of final grow-out area. In the three-phase tanks, this resulted in an average nursery density of 1,236 postlarvae/m2. The shrimp were harvested after 180 days in all trials. The results of these trials are summarized in Table 4. Survival in the three-phase systems (61%) was significantly lower Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 than in the single-phase systems (77%). This was primarily due to an increased frequency of cannibalism in the nursery and intermediate phases. This problem was more severe in systems that were very shallow (30 cm deep) in the nursery sections. This problem has been largely over- come by using deeper nursery tanks (50 cm deep) and artificial substrates. Growth rates were slightly higher in the three-phase systems (0.62 g/week) than in the single-phase systems (0.55 g/week), but the difference was not statistically significant. Harvest densities per unit area of final grow-out area were nearly identical, averaging 2.00 kg/m2 in the single-phase systems and 2.07 kg/m2 in the three-phase systems. The final grow-out area occupies only 60% of the total production area Samocha et al. 13

of a three-phase system, so the harvest density per unit of total production area is only 1.22 kg/m2. However, six crops per year can be harvested from the three-phase system, compared to only two crops per year for the single-phase system. The annual productivity of the three- phase system was 7.2 kg/m2 of production area, versus only 4.00 kg/m2 for the single-phase system. These results demonstrated that the annual productivity of greenhouse production systems could be increased by 70-80% by adopting a three-phase production strategy. This gain in productivity was obtained with little additional capital or operating cost. An economic analysis was performed to examine the economic feasibility of a twelve-greenhouse hypothetical commercial facility using a three-phase production strategy (Van Wyk 1999c). This analysis used production data and cost information obtained from the prototype facility described above. The analysis assumed a stocking density of 221 PL/m2 of final grow-out area and a harvest density of 135 shrimp/m2 (61% survival). The analysis assumed that 180 days were required to grow an 18-g shrimp. The cost of production for this hypothetical commercial enterprise was $4.28/lb of whole shrimp. This cost of production is high when compared to the cost of production of shrimp in semi-intensive pond production systems. The capital requirements for building indoor recirculating production systems are high relative to their productivity. In addition, the energy costs and labor requirements are much higher than are typical for typical pond production operations. The challenge for shrimp recirculating system designers is to increase system productivity while reducing capital, energy and labor costs. Because of this fact, shrimp produced in recirculating production systems cannot compete directly with foreign-produced shrimp on the wholesale frozen tail market. Rather, these shrimp must be direct-mar- keted to restaurants and specialty seafood markets as premium fresh

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 product in order to bring a higher price. Based on the assumptions of the economic model (Van Wyk 1999c), these shrimp would have to be sold at a price of $6.00/lb in order to earn an internal rate of return of 26%. This was the minimum rate of return that the project would have to earn to justify the risk of the investment. A sensitivity analysis showed that if the survival could be improved from 61% to 70% and the time required for grow-out could be reduced from 180 days to 150 days, the cost of production could be reduced from $4.27/lb to $3.32/lb (Van Wyk 1999c). These goals appear to be achievable with only slight modifications in system design and operation. 14 JOURNAL OF APPLIED AQUACULTURE

Recent observations at HBOI suggest that survival rates in raceway nursery systems may be improved by deploying artificial substrates. Artificial substrates may also allow stocking densities to be substan- tially increased with little or no decline in growth or survival rates (Pe- terson and Griffith 1999). During the production trials reported in Table 4, the HBOI greenhouses were covered by a 95% shade cloth to limit algal growth in order to prevent diurnal fluctuations of dissolved oxygen and pH. While the shade cloth effectively stabilized water quality, it appears that it also slowed shrimp growth rates by lowering water temperatures and inhib- iting algae growth. In a recent uncontrolled production trial at HBOI, the average weekly growth rate of shrimp grown in an unshaded raceway averaged 1.1 g/week (VanWyk, unpublished data). This was nearly double the average growth rates of the shrimp grown in shaded raceways in the 1998 trials. Other observations at HBOI indicated that water temperatures in unshaded raceways average 3.2°C higher than in the shaded raceways (Collins, pers. comm.). The low light levels in the shaded greenhouses may also have affected growth rates by suppress- ing the growth of algae in the raceways. Very little algal growth was observed in the shaded raceways. In contrast, dense blooms of green algae were typical in subsequent crops grown in unshaded raceways. Moss (2000) demonstrated that shrimp growth is enhanced by the presence of microalgae in the water. In conclusion, the intensive water reuse systems have many desirable attributes. They allow freedom from site limitations, improved environmental control, increased product quality and availability, and facilitate the control of stock and effluent management (Rijn and Shilo 1989; Lee 1993). Another reason for the strong interest in indoor recirculating systems is the high degree of biosecurity these systems provide (Ogle and

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 Lotz 1998; Leung and Moss 1999). Nevertheless, businesses based on this technology will only be profitable if project planners design their facilities so that resources such as space, labor, and management are uti- lized as efficiently as possible. Facilities will need to take full advantage of economies to scale wherever possible, and adopt production strategies that maximize productivity per unit inputs of capital and labor (Van Wyk in press). This can be accomplished either by designing ultra-intensive systems capable of supporting extremely high standing crops (Davis and Arnold 1998), or by adopting a three-phase production strategy (Van Wyk in press). Although the economic viability of recirculating production systems for bait or food shrimp has yet to be proven, the Samocha et al. 15

consistent results, low water usage, and ease of waste management are encouraging and warrant further economic and marketing evaluations.

BIOSECURE SHRIMP NURSERY TECHNOLOGY

Researchers of the Texas Agricultural Experiment Station, Shrimp Mariculture Research Facility in Corpus Christi, Texas, have evaluated a variety of management strategies for intensive shrimp production. Re- cent studies have been designed to develop a biosecure shrimp production nursery and to develop grow-out practices that lower the risk of viral disease outbreaks in cultured stocks while reducing the potential negative impact from shrimp farm effluent waters on receiving streams. The nursery studies were conducted in greenhouse-enclosed raceways, each with a bottom area of 68.5 m2 and an operating volume of 45 m3. Sturmer et al. (1992) and Samocha et al. (1993) provide a detailed description of the system. Figure 2 provides a schematic description of this system. Every raceway is equipped with a rapid sand filter and a center partition positioned over a 5.1 cm PVC pipe. Spray nozzles are attached to this pipe to enhance water circulation near the raceway’s bottom. Eighteen, 5.1-cm airlift pumps, grouped into six banks, are positioned on both sides of the center partition to enhance water column circulation. In addition to the aeration provided by the airlift pumps, three 1-m long air diffusers provide supplemental aeration and a venturi injector operated by the same pump used for running the sand filter (Figure 2). Nursery trials have been conducted with three native shrimp species (the Atlantic white shrimp; the Atlantic brown shrimp, Far- fantepenaeus aztecus; and the Atlantic pink shrimp, F. duorarum) and with the exotic species the Pacific white shrimp. The following is a short summary of studies with the Pacific white shrimp and the Atlantic Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 brown shrimp, which were conducted with reduced water discharge. All shrimp were fed a 45% protein diet with 10% squid meal (“45/10” Rangen, Inc., Buhl, Idaho) supplemented for about two weeks with newly hatched Artemia nauplii and with a 50% protein diet (“PL Redi-Reserve” Zeigler Bros., Inc., Gardners, Pennsylvania). Diet was offered four times a day while daily rations were adjusted based on growth and feed consumption. To reduce the risk of introduction of pathogens with the incoming water, after adjustment of salinity, culture water was treated with liquid chlorine solution (10 ppm active chlorine initial-concentration). Raceways were stocked with post-larvae only when no chlorine residue could be detected in the culture water. Trials 2.5 m

7.6 cm air pipe

Valve

5.1 cm Airlift pumps Agricultural Experiment Station, Shrimp Mariculture

Current

27.3 m

5.1 cm air supply line

5.1 cm Water return pipe

Center partition

2.54 cm

20.3 cm Filter pipe

Airdiffusers

Venturi injector Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010

20.3 cm Filter pipe

15.2 cm Outlet

Sand filter

Pump

Multiport valve FIGURE 2. Planer view ofResearch the Facility, nursery Corpus raceway Christi, used Texas. by the Texas

16 Samocha et al. 17

were conducted with/without inoculation of the water with the diatom Chaetoceros muelleri. Throughout the nursery trials, only small volumes of freshwater or chlorinated seawater were used to compensate for evaporation, leaking and losses due to sand filter backwash. Table 5 provides a summary of selected water quality parameters for these nursery trials. The water quality data indicate that under the conditions tested, post-larvae of the Pacific white shrimp can tolerate a total ammonia nitrogen level as high as 10.4 mg/L without adverse effects on survival. A summary of the nursery production trials with the Pacific white shrimp and the brown shrimp is provided in Table 6. Feed conversion ratio (FCR) values in all of the nursery trials were below 1. These studies demonstrate that a yield of 1.48 kg/m2 or 2.23 kg/m3 with good survival can be achieved when post-larvae of the Pacific white shrimp were stocked at a density of about 2,000 PL/m2 under reduced water discharge. Furthermore, Cohen et al. (2001), in a more recent study in this nursery system, reported 100% survival of Pacific white shrimp under similar stocking density (2,200 PL/m2 or 3,300 PL/m3). The mean weights of the juveniles harvested after seven weeks varied between 1.1 and 1.2 g with excellent yield (4.1-4.2 kg/m3), low FCR (< 1) and very limited water renewal (1.1%/d).

“ZERO WATER EXCHANGE” POND TECHNOLOGY Other studies at the TAES facility have evaluated the feasibility of producing marketable size Pacific white shrimp under “zero water ex-

TABLE 5. Summary of selected water quality parameters (mean±standard deviation) for nursery production trials with Pacific white shrimp in raceways un-

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 der reduced water discharge at the Texas Agricultural Experiment Station, Corpus Christi, Texas. RW = raceway

RW ID DO (mg/L) Temperature (°C) pH Salinity NH4 (date) a.m. p.m. a.m. p.m. a.m. p.m. (ppt) (mg/L) R1 (6-7/98) 7.3±0.6 7.1±0.6 27.9±0.4 29.3±0.4 8.1±0.4 8.3±0.3 20±1.2 0-4.2 R2 (6-7/98) 6.8±0.5 7.2±0.7 27.9±0.3 29.3±0.4 8.0±0.3 8.2±0.3 21±1.4 0-10.4 R3 (6-7/98) 6.6±0.5 7.3±0.7 28.5±0.4 29.9±0.4 8.1±0.3 8.3±0.3 20±1.1 0-7.8 R1 (4-5/99) 7.2±0.4 7.2±0.6 26.9±1.4 28.6±1.6 7.9±0.3 8.0±0.3 16±2.8 0-3.0 R2 (4-5/99) 7.0±0.5 7.3±0.6 27.0±1.2 28.2±1.4 7.8±0.3 8.1±0.2 16±2.7 0-3.0 R4 (4-5/99) 6.9±1.4 7.0±1.2 28.5±0.2 29.2±1.3 7.8±0.4 8.0±0.4 16±1.2 0-5.2 18 JOURNAL OF APPLIED AQUACULTURE

TABLE 6. Summary of shrimp nursery production trials in raceways under reduced water discharge at the Texas Agricultural Experiment Station, Corpus Christi, Texas. RW = raceway

a b c RW ID (date) Species WtTi PL Density Days WtTf Survival Yield (kg) FCR Water d (mg) (/m2) (/m3) (g) (%) (/m2) (/m3) usage R1 (6-7/98) Litopenaeus 1 1,000 1,370 35 0.70 86.8 0.61 0.83 0.61 0.3 vannamei R2 (6-7/98) L. vannamei 1 1,000 1,370 35 0.58 99.7 0.58 0.79 0.65 0.4 R3 (6-7/98) L. vannamei 1 1,000 1,370 35 0.42 111.1 0.47 0. 64 0.68 0.7 R1 (4-5/99) L. vannamei 1 1,460 2,220 42 0.54 82.1 0.64 0.98 0.68 1.1 R2 (4-5/99) L. vannamei 1 1,460 2,220 42 0.60 59.2 0.52 0.79 0.97 1.3 R4 (4-5/99) L. vannamei 1 2,020 3,070 48 0.81 89.9 1.48 2.23 0.92 4.7 R1 (3-4/99) Farfantepenaeus 1 3,390 5,150 15 0.067 75 0.17 0.26 0.52 0.8 aztecus R2 (3-4/99) F. aztecus 1 3,390 5,150 15 0.054 84 0.15 0.23 0.57 0.8 R1 (5/99) F. aztecus 1 3,240 4,940 34 0.27 100 0.87 1.33 0.8 0.8 R2 (5/99) F. aztecus 1 3,240 4,930 34 0.23 100 0.75 1.14 0.8 0.8 R6 (5/99) F. aztecus 1 3,240 4,940 34 0.27 100 0.87 1.33 0.8 0.8 a Mean weight at stocking. b Nursery duration in days. c Mean weight at harvest. d Percent of the total volume of culture water added daily.

change.” These trials were also designed to evaluate the effect of two low-protein diets and a commercial bacterial supplement on selected water quality parameters and shrimp performance. The studies were conducted in outdoor tanks and in HDPE-lined ponds. The following is a short summary of study conducted in the outdoor tank system. Eigh- teen 10.5-m2 round tanks (3.66 m ϫ 1 m) were provided with a 15 cm of sandy clay loam soil. Tanks were positioned under a shade (73% light reduction) to avoid water heating in excess of optimal limits for shrimp. Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 Prior to stocking, tanks were filled with water from a nearby saline la- goon to an average water depth of 65 cm (6.8 m3/tank) and salinity was adjusted to 15 ppt using municipal freshwater. Aeration was provided to each tank with ten air stones (5.3±1.6 L/minute/stone), fed by a regener- ative air blower. Municipal freshwater was added periodically to avoid an increase in salinity due to evaporation. All tanks were stocked with Pacific white shrimp juveniles (average weight of 1.69±0.58 g) at a density of 40/m2. Tanks were randomly assigned into three treatments of six tanks each. Shrimp in the first treatment (21%) were offered a 21% protein feed. Shrimp in the second treatment (21%+) were offered the Samocha et al. 19

same 21% protein diet but culture water was enriched with a bacterial inocula (Bacillus sp., BioStart® Advanced Microbial Systems, Inc., Shakopee, Minnesota). This bacterial inocula was applied five times/week. The manufacturer’s instructions for brewing and applying the bacteria were followed. Shrimp in the third treatment (31%) were offered a 31% protein diet. Shrimp in all treatments were fed twice a day, receiving 50% of the ration in the morning and 50% in the afternoon. The ration was adjusted weekly, based on weight sampling of one tank from each treatment. The combined average weight of the three treatments was used to determine the weekly ration. Both diets were produced by a commercial feed mill (Rangen, Inc., Buhl, Idaho). Selected water quality parameters were measured daily (dissolved oxygen, temperature, salinity, pH, and secchi disk reading) while total ammonia nitrogen, nitrite-nitrogen, nitrate-nitrogen, total phosphorus, reactive phosphorus, five-day carbonaceous biochemical oxygen demand, chemical oxygen demand, total suspended solids, and volatile suspended solids were monitored weekly. The study was terminated after 94 days, at which time the shrimp were harvested manually and individually weighed. This information was used to calculate mean final weight, survival, and FCR. Repeated measures of analysis of variance (ANOVA) was used to compare data associated with daily and weekly water quality of the three treatment sets. Survival, mean final weights, and FCR were ana- lyzed using the one-way ANOVA. Percent survival data were arcsine transformed prior to conducting the analysis. Tukey’s HSD was used to determine which treatments were statistically significantly different. The same significance level (P = 0.05) was used for all tests. No statistically significant differences were found in the daily water quality parameters among treatments (Table 7). Table 8 summarizes the weekly changes in water quality for each treatment. Among the weekly water quality parameters, total phosphorous and reactive phosphorous Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 levels in the 21%+ treatment were significantly higher than the 31% treatment. No statistically significant differences were found in weekly water quality between the 31% and the 21% treatments (Table 8). Fur- thermore, the regular application of the bacterial inocula did not significantly improve the water quality in the treated tanks. It is interesting that even though there were significant differences among the treatments in survival, mean final weight, and FCR (Table 9), there were very few statistically significant differences in the water quality parameters measured. Survival was high in all treatments, ranging between 91% and 93% in the 21% treatments and 96% in the 31% treatment. The difference in survival between the 21% and the 31% treatment was sig- 20 JOURNAL OF APPLIED AQUACULTURE

TABLE 7. Summary of daily water quality parameters (mean±standard deviation) in a 94-day study with Pacific white shrimp in outdoor tanks with “zero water exchange” under stocking density of 40 shrimp/m2 when fed diets with 21% and 31% protein and treated with bacterial supplement.

Dissolved Oxygen (mg/L) Temperature (°C) pH Salinity Secchi disk

a.m. p.m. a.m. p.m. a.m. p.m. (ppt) (cm)

6.7±0.8 6.8±0.7 27.4±1.9 28.7±2.1 7.7±0.3 8.1±0.3 14.5±2.2 13.8±7.6

TABLE 8. Summary statistics of weekly water quality parameters (mean±standard deviation) in a 94-day study with Pacific white shrimp in outdoor tanks with “zero water exchange” under stocking density of 40 shrimp/m2 when fed diets with 21% and 31% protein and treated with bacterial supplement.

Parameter Treatment Mean±SD Maximum Minimum

Ammonia (mg/L) 21% 0.4±0.72a 3.9 0.0 21%+ 0.4±0.89a 4.7 0.0 31% 0.4±0.66a 3.9 0.0 Nitrite (mg/L) 21% 0.5±0.92a 6.2 0.0 21%+ 0.6±0.92a 4.2 0.0 31% 0.8±1.05a 4.3 0.0 Nitrate (mg/L) 21% 0.1±0.29ab 1.3 0.0 21%+ 0.1±0.25a 1.6 0.0 31% 0.3±0.60b 3.0 0.0

cBOD5 (mg/L) 21% 7.1±4.82a 23.6 0.4 21%+ 6.6±4.30a 21.6 0.2 31% 6.1±3.32a 13.6 1.1 Chemical oxygen demand (mg/L) 21% 443±86a 1,010 321 21%+ 470±110a 767 244 31% 510±131a 646 281 Reactive phosphorus (mg/L) 21% 2.0±2.11ab 8.4 0.0

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 21%+ 2.5±2.52a 8.6 0.0 31% 1.5±1.74b 7.5 0.0 Total phosphorus (mg/L) 21% 4.7±4.76ab 28.6 0.1 21%+ 4.8±4.22a 14.2 0.2 31% 3.9±3.72b 14.8 0.1 Total suspended solids (mg/L) 21% 257±187a 648 9 21%+ 264±212a 1,097 17 31% 330±298a 1,147 2 Volatile suspended solids (mg/L) 21% 80±49a 200 Ϫ12 21%+ 86±48a 217 1 31% 89±55a 254 Ϫ93 a Note–Treatment means sharing the same letter are not statistically significantly different (P > 0.05) using Tukey’s HSD method. Samocha et al. 21

TABLE 9. Summary statistics of survival, mean final weight (mean±standard deviation) and FCR of Pacific white shrimp in 94-day trial in outdoor tanks with “zero water exchange” under stocking density of 40 shrimp/m2 when fed diets with 21% and 31% protein and treated with bacterial supplement.

Parameter Treatment Mean±SD Maximum Minimum Survival (%) 21%+ 91±4a 95 83 21% 93±5ab 98 87 31% 96±2b 99 93 Mean final weight (g) 21% 12.17±0.28a 12.53 11.80 21%+ 11.69±0.63a 12.79 10.93 31% 14.04±0.58b 14.86 13.25 FCR 21% 2.15±0.11a 2.31 1.99 2 1%+ 2.19±0.11a 2.10 2.39 31% 1.75±0.07 1.85 1.66 a Treatment means sharing the same letter are not statistically significantly different (P > 0.05) using Tukey’s HSD method.

nificant. However, no significant differences were found between the 21%+ and the 21% or 31% treatments. Mean final weight was lowest in the 21%+ treatment (11.7 g) and highest in the 31% treatment (14.0 g). The 21% treatment had a mean final weight of 12.2 g. Significant differences were found between the 31% treatment and both the 21% and 21%+ treatments. No significant difference was found in mean final weights between the 21% and 21%+ treatments. The FCR for the 31% treatment (1.75) was significantly lower than either the 21% treatment (2.15) or the 21%+ treatment (2.19). There were no significant differences in FCR when comparing the 21% and the 21%+ treatments. In a more recent study that was conducted in the same tank-system, juveniles (0.68 g) of the same species were stocked at higher density Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 (50/m2) in six 10.5 m2 tanks and were raised with no water exchange. Shrimp in three tanks were offered a 30% protein diet, while shrimp in the other three tanks were offered a diet with 40% protein. As in the first study, the diets used were commercial shrimp diet produced by Rangen, Inc. Shrimp were fed a fixed ration four times a day at approximately 08:00, 11:00, 13:00 and 16:00. Rations of the 40% protein diet were fed on an equal nitrogen basis (e.g., daily ration was 75% of the ration provided to the shrimp which were fed the diet with 30% protein). The measured daily and weekly water quality parameters were similar to those mentioned previously. Preliminary analyses suggest no statistically significant differences in daily and weekly water quality between 22 JOURNAL OF APPLIED AQUACULTURE

treatments. Table 10 summarizes the information collected in this study. These studies suggest that the Pacific white shrimp can be cultured at high densities with no water discharge with good survival and growth. A similar study was conducted to evaluate the effect of “zero discharge” on shrimp performance in two 1,700-m2 HDPE-lined ponds. Shrimp (average weight of 0.64 g) were stocked at the same density (40/m2) tested in the tanks with soil substrate. Ponds’ aeration was provided by paddlewheel aerators (6 HP/pond). Prior to stocking, culture water was treated with chlorine as described earlier. Shrimp in two ponds were fed commercially available diets containing 21% and 31% protein (Rangen, Inc., Buhl, Idaho). Municipal freshwater was used to maintain salinity at 20 ppt. A third similarly sized pond was stocked (30/m2) with juvenile shrimp (3.49 g) seven weeks after the stocking of the other two ponds. These shrimp came from the same population stocked into the other two ponds. Shrimp were fed a 45% protein diet (Rangen “45/10”). The daily and weekly water quality parameters monitored in this study were identical to those described for the tanks with the soil substrates. Diet was offered four times a day, seven days a week. Daily ration were adjusted based on shrimp growth and feed consumption. Water releases from the ponds throughout the production cy- cle was minimal (e.g., less than 0.6%/day). These discharges were needed due to heavy rains. Table 11 summarizes the mean values of the daily water quality parameters found in the three ponds. Few differences were found between ponds. Table 12 shows the weekly changes in water quality parameters in the ponds offered the 21%, 31%, and 45% protein diets. Slightly higher ammonia, nitrite and nitrate levels were found in the 31% protein treatment than the 21% protein treatment. Ammonia levels in the pond that was offered the 45% protein diet were lower than in the other two Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 ponds. The smaller amount of diet and the shorter operating period are

TABLE 10. Results from a high-density (50 shrimp/m2) outdoor tank study with Pacific white shrimp under no water exchange when offered commercial shrimp diets with 30% and 40% protein.

Mean Shrimp Size (g) Duration Survival Growth Treatment FCR Stocking Harvest (days) (%) (g/week) 30% 0.5 17.97 111 94.5 1.15 2.44 40% 0.5 19.34 111 92.4 1.24 1.72 Samocha et al. 23

the main reasons for these differences. The pond with the high protein diet was harvested after 48 days while the other two ponds were harvested after 100 days. Table 13 summarizes the average initial and harvest sizes, survival, weekly growth rates and FCR values for the shrimp in the three ponds. Shrimp survival and mean average weight in the 31% protein diet were higher than in the lower protein diet (86.0% vs. 81.4% and 20.2 g vs. 16.1 g). A slightly better FCR was observed in the pond that was offered the 31% protein diet (1.75 vs. 1.86). The shrimp mean weight after 50 days in the pond that was offered the 45% protein

TABLE 11. Daily mean values for dissolved oxygen, temperature, pH, and salinity for three ponds stocked with Pacific white shrimp and fed one of three diets with different protein levels.

Mean Temp. (°C) DO (mg/L) pH Treatment Salinity (ppt) a.m. p.m. a.m. p.m. a.m. p.m. 21% (40/m2) 27.7 30.1 6.4 8.8 8.0 8.4 18.6 31% (40/m2) 27.8 30.0 6.4 9.1 8.1 8.4 19.1 45% (30/m2) 26.7 28.5 6.9 10.7 8.0 8.6 22.6

TABLE 12. Water quality parameter in a pond under no water discharge stocked with Pacific white shrimp (40 shrimp/m2) and fed diets with 21%, 31%, and 45% protein levels.

cBOD5 COD NH4 NO2 NO3 TP RP TSS VSS Diet (mg/L) 21% 18±12 757±504 0.9±1.2 0.1±0.1 0.7±0.7 5.0±4.0 2.0±2.0 91±49 80±63 31% 15±9 817±314 1.3±1.8 0.5±0.9 0.9±0.7 3.9±3.5 1.9±1.7 84±71 85±67 45% 10±5 922±348 0.2±0.2 0.1±0.0 0.8±0.5 6.3±2.3 1.6±1.2 77±69 54±21 Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010

TABLE 13. Mean initial and harvest weights, trial duration, growth, and FCR of Pacific white shrimp stocked at 40 and 30 shrimp/m2 and fed three diets with different protein levels under no water discharge.

Mean Shrimp Size (g) Duration Survival Growth Treatment FCR Stocking Harvest (days) (%) (g/week) 21% (40/m2) 0.64 16.1 100 86.0 1.1 1.86 31% (40/m2) 0.64 20.2 100 81.4 1.4 1.75 45% (30/m2) 3.49 16.8 48 96.1 1.9 1.00 24 JOURNAL OF APPLIED AQUACULTURE

diet was 16.8 g. Excellent survival (96.1%) and FCR (1:1) value were obtained in this pond. This study shows that the Pacific white shrimp can be cultured to marketable size at high stocking density (40/m2) with no water exchange with good survival and yields using a diet with 31% protein level. The low FCR (1:1) and the good water quality obtained when the shrimp were stocked at lower density (30/m2) and fed a 45% protein diet suggest that additional studies are needed to determine the optimal feed to be used under “zero water exchange” strategy.

INLAND POND SHRIMP PRODUCTION TECHNOLOGY

Inland production of shrimp in low-salinity water can provide another alternative to disease and environment problems. This technology is currently being implemented by commercial shrimp producers in Ar- izona, Florida and Texas. Smith and Lawrence (1990) documented one of the first attempts to raise the Pacific white shrimp in saline ground water. These authors reported successful culture (86.7% survival) of juveniles (1.2 g) to marketable size (19.9 g) in 120 days in inland ponds stocked at a density of about 25 juveniles/m2 using saline (28.3 ppt) ground water. A preliminary test in the early nineties by researchers from the Texas A&M University System demonstrated the ability to successfully grow shrimp in west Texas using low salinity (11 ppt) ground water. Follow- ing this test, two small farms (one with 14 ha and the other with 20 ha) were built in 1994 and 1995. One of the major differences between these farms and the farms along the Texas coast is the short growing season of mid-May through mid-September. Although there are other shrimp production operations in this area, this summary will focus on the information received from the Regal Farm. The farm has fourteen Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 rectangular 1.45-ha earthen ponds with an average depth of 1.2 m. Each pond is provided with paddlewheel- and aspirator-type aerators (8.3-12.5 HP/ha). Ponds are generally stocked with “high health” eight-day-old (PL 8) at a density of about 40 PL/m2. Pond bottoms are disked three to four time after harvest. Due to the low salinity, dragonflies can sometimes create a problem. After filling, ponds are fertilized with cotton- seed meal, nitrogen, and phosphorus sources. Diet (35% to 38% protein) is offered up to three times a day using an air blower. Rations are adjusted based on weekly growth samples. Feed trays are used (1 per pond) mainly for health evaluation and for monitoring growth during the early stocking phase. For the first few months ponds are maintained Samocha et al. 25

with limited exchange. About 5% daily water exchange is employed to- wards the harvest. Shrimp are harvested by a fish pump. FCR is generally 2:1 with a typical survival of 65% and an average yield of about 4,500 kg/ha of 17.5 to 21 g average shrimp size. All effluent is kept on the property and is used to create a lush natural area that becomes a part-year wetland. Thus far, this farm has shown only one year of profitability (Mr. Morris, Regal Farms, pers. comm.). The one crop per year limits the revenue for the invested capital compared to tropical climates. The overall expenses are higher than for most other shrimp farming areas of the world. Nonetheless, it is believed that economic viability is possible, even if not yet demonstrated. The area presents these special problems:

• A short growing season of four months (mid-May through mid- September). Some years, stocking at the first of May has been successful, but major losses have occurred as well. Therefore, to minimize risk, ponds’ stocking has to take place in mid-May. Another option is to stock the PL mid to late-March in greenhouse-enclosed nursery systems. These systems not only extend the growing season, but also enable production of two shrimp crops a year. At this time, risk management and economics don’t give a clear advantage to any of the three solutions. • Midsummer daytime air temperatures of 43°C are not uncommon in the area. These high temperatures can negatively affect oxygen solubility and shrimp growth. Due to the evaporative cooling effect generated by paddlewheel aerators, a greater use of these types of aerators rather than the aspirator-type aerators should help lower water temperatures. • Limited water availability and high pumping costs. A dropping water table is now a major concern. In past years, under maximum Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 pumping of all wells, the water table dropped from a static depth of 6-9 m in the early season to 18-27 m late in the season. This drop was attributed to higher demand by a nearby cotton farmer. • Exposure to pesticides due to proximity to agricultural lands. On both sides of the farm, there are cotton fields participating in the boll weevil eradication program that relies on the heavy use of malathion. • Biosecurity and sustainability issues have arisen: several new op- erators in the area either have already done so or intend to violate both good husbandry practices and the applicable regulatory standards. This will place the whole region in jeopardy for importing 26 JOURNAL OF APPLIED AQUACULTURE

viral diseases and degrading water quality of the aquifer. It is obvi- ous that this area will not be able to support high-density shrimp farming, but it certainly should be able to provide important diver- sification for the area.

Samocha et al. (1998, 1999a, 1999b) provide a short summary of the studies conducted in an intensive nursery system using low-salinity geothermal water in Arizona. Preliminary data suggest that the Pacific white shrimp can be raised in low salinity water without negative effects on growth and survival. The following is a short summary of nursery and grow-out studies conducted in raceways of a shrimp farm located in the Sonora Desert, Arizona. These studies were conducted in greenhouse-enclosed, concrete raceways of the Wood Brothers Farm, Gila Bend, Arizona. Design of these raceways was similar to the one presented in Figure 2. Each raceway had a bottom area of 97.5 m2 with an operational water volume of 147.6 m3, and a center partition extended 2 m from the end-walls. Raceways were built with 1% bottom slope and 0.3-m-deep settling basin at the deep end. Water depth of the raceway at the deep end was 1.8 m and 1.2 m in the shallow end. A PVC filter-pipe (30.5 cm in diameter), at the center of the settling basin, served for water exchange and pump-driven water circulation. A 30.5-cm PVC return line delivered water from the settling basin into a concrete reservoir at the shallow-end of the raceway. A 3-HP pump delivered water from this sump back into the raceway, with an optional loop directing the water via a rapid sand-filter and/or a venturi injector. Water was forced into the raceway by a PVC spray-pipe (5.1 cm in diameter) and/or a bottom PVC pipe (7.6 cm) manifold with spray nozzles. Three banks of four airlift pumps (7.6 cm in diameter), were positioned on each side of the center partition to provide a counterclockwise current. Supplemental aeration was provided Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 by six 3-m-long air diffusers positioned along the sidewalls. A flat-lay- ing polypropylene heat exchanger supported by solar energy and/or a gas-fired boiler was used to increase culture water temperature when needed. Table 14 provides a summary of the ion composition analysis of water samples taken from the two geothermal wells of the farm. Although several nursery trials were conducted in these raceways, results are summarized for one trial only. In this trial two raceways (Raceway 3 and 4) were filled to about 10% capacity one day before the scheduled stocking and salinity was adjusted to 17 ppt with artificial sea salt (Marine Enterprises Int., Baltimore, Maryland). Raceway water was fertilized with urea (46-0-0), triple superphosphate (0-45-0), and Samocha et al. 27

TABLE 14. Ion composition of the two geothermal wells at the Wood Brothers Farm, Gila Bend, Arizona.

Parameter Well 1 Well 2 (ppm) Fe 0.22 0.4 Zn < 0.01 < 0.01 Sulfate-S 115 230 Phosphate-P 0.01 0.05 Pb 0.25 0.29 Br 0.66 2 TOC < 1.0 < 1.0 Ca 124 250 Mg 8.5 22 Na 627 820 K 11 14 Carbonate 0 0 Bicarbonate 153.7 248.4 Cl 796 985

NH4-N 0.3 1.1

NO2 < 0.02 < 0.02

NO3 7.7 22.3 Total N 8.2 23.4 pH 7.6 7.3 Total soluble salts 1,843.6 2,591.8 Ca+Mg hard. (meq/L) 20.8 33.6

sodium silicate to provide a final nutrient concentration of 10, 1, and 1 mg/L for the N, P, and Si, respectively. In addition, each raceway was inoculated with mono-culture of the diatom Chaetoceros muelleri at an

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 initial cell concentration of 50,000 cells/ml. “High Health” PL 8 of the Pacific white shrimp were received from a commercial hatchery in Texas (Harlingen Shrimp Farms). Mortality due to shipping stress was estimated at 1.9% and 2.9% for Raceway 3 and 4, respectively. Stocking densities of live PLs in these raceways were 19,200 PL/m2 (12,700 PL/m3) and 20,400 PL/m2 (13,500 PL/m3), respectively, with PL mean weight of 0.0025 g. Dissolved oxygen, temperature, pH, and salinity in the raceways were monitored twice daily. Ammonia, nitrite, and nitrate were monitored three times a week using Hach DR 2010 procedures (Hach Company, Loveland, Colorado). Algal cell-counts were taken every other day starting about seven days after stocking. Shrimp were 28 JOURNAL OF APPLIED AQUACULTURE

fed a 45% protein dry diet (“45/10,” Rangen, Inc., Buhl, Idaho) that was supplemented for the first eight days with newly hatched Artemia nauplii. Diet was distributed five times a day. Rations varied between 4.5% and 11% of the total estimated shrimp biomass in the raceways. Shrimp growth was monitored three times/week from a group sample. Shrimp biomass at harvest was recorded after water was allowed to drain for 20 seconds. Percent survivals and average weekly growth rates were calculated from the harvested biomass and the shrimp mean weight as determined from group weight samples. Individual weight samples were also taken during the harvest from each raceway. An In- dependent T-Test with significant level of P = 0.05 was used to determine differences in water quality and mean weights between raceways. Individual weight records were used for the statistical test. Raceway water salinities were reduced gradually (over a 28-day period) from the initial 17 ppt to 2 ppt. New water was added to both raceways with no water discharge until day 12 of the study. The raceways’ daily water exchange was increased from 10% on day twelve to 84% starting on day 25th of the study. Good algal density was noticed in both raceways on the fourth day after stocking with algal density reaching 167,000 and 375,000-cells/ml for Raceways 3 and 4, respectively. No statistically significant differences (P > 0.05) were found in water quality parameters between the two raceways. The mean values of these water quality parameters are summarized in Tables 15 and 16. Differences in mean weights at harvest were not statistically different. The calculated FCR values for both raceways were low with 0.7 and 0.71 for Raceway 3 and 4, respectively (Table 17). Shrimp survival in both raceways was high (100%) with yields of 2.34 and 2.10 kg/m2 for Raceways 3 and Race- way 4, respectively. These results suggest that nursery of the Pacific white shrimp can be conducted at low-salinity ground water with excellent survival and yields. Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 In addition to the nursery trials, another grow-out trial was conducted in four raceways. Raceways were stocked with two-month-old juve-

TABLE 15. Summary of daily water quality parameters in raceway water during a nursery trial with Pacific white shrimp in low salinity geothermal water.

DO (mg/L) Temp. (°C) pH Culture Tank a.m. p.m. a.m. p.m. a.m. p.m. Raceway 3 5.86±0.32 6.52±0.97 24.66±1.42 26.41±1.02 7.71±0.40 8.00±0.43 Raceway 4 6.01±0.26 6.69±0.97 24.28±1.34 25.93±1.12 7.75±0.39 8.09±0.38 Samocha et al. 29

TABLE 16. Ammonia, nitrite, nitrate, and algal density in raceway water during a nursery trial with Pacific white shrimp in low-salinity geothermal water.

ϫ 6 Culture Tank NH4 (mg/L) NO2 (mg/L) NO3 (mg/L) Algae (cell/mL 10 ) Raceway 3 0.779±0.499 0.376±0.283 11.93±2.20 260,600±154,300 Raceway 4 0.610±0.426 0.340±0.249 11.49±1.78 327,700±174,400

TABLE 17. Summary of stocking and harvest information from a nursery trial with Pacific white shrimp using low salinity geothermal water.

Stocking Duration Harvest Culture Tank Survival (%) FCR shrimp/m2 shrimp/m3 Size (g) (days) Mean Wt. (g) kg/m2 kg/m3 Raceway 3 19,200 12,700 0.0025 34 0.103±0.078a 2.34 1.54 100 0.70 Raceway 4 20,400 13,500 0.0025 35 0.091±0.069b 2.10 1.39 100 0.71 a Mean weights with different letter within a column are significantly different at P = 0.05.

niles (0.5 g) at a density of 74, 93, 107, or 346/m2. Temperature, dissolved oxygen, and pH were monitored twice daily; ammonia, nitrite and nitrate at least twice weekly. Shrimp were fed four times/day a commercial diets (Rangen, Inc., Buhl, Idaho) with either 40% or 45% protein. Daily rations were adjusted based on weekly shrimp growth. Table 18 summarizes the minimum and maximum range of selected water quality parameters in the four raceways along with the daily water usage. Differences among raceways were small; however, the daily water discharge from the high-density raceway was much higher. Information concerning shrimp survival, FCR, and yields in this study is presented in Table 19. Survival in the high-density raceway was much higher than in the low-density raceways. Although the mean average weight of the Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 shrimp at harvest for the high-density was the lowest among the raceways, the yield was almost four times higher. FCR value for this raceway was a little lower than the other three raceways. This study showed that juvenile shrimp could be raised to marketable-size in 107 days with good survival and excellent yield (4.39 kg/m2), using low-salinity geothermal water. A relatively high volume of water was used to maintain the high yield in the high-density raceway. However, since effluent water was used for crop irrigation, no effort was made to conserve water. In addition to the nursery and grow-out studies in raceways, other production trials were carried out in fourteen rectangular earthen ponds of the farm. Emberson et al. (1999) provide a short summary of this 30 JOURNAL OF APPLIED AQUACULTURE

TABLE 18. Minimum/maximum values of selected water quality parameters in a grow-out trial of Pacific white shrimp in raceways using low salinity geothermal water.

Density Temp. (°C) pH DO NH4 NO2 NO3 Water Discharge (shrimp/m2) (% total (mg/L) volume/day) 74 24.7-31.3 6.8-9.1 4.2-9.2 0.0-0.36 0.08-0.5 6.4-12.8 21 93 23.7-30.9 6.8-9.1 4.9-10.6 0.0-0.34 0.08-0.4 6.6-12.8 21 107 24.0-31.5 6.7-9.0 5.1-10.5 0.0-0.60 0.1-0.6 7.4-11.3 21 346 24.5-30.9 6.6-8.8 4.5-9.7 0.0-0.79 0.05-0.6 7.2-13.6 133

TABLE 19. Summary of stocking and harvest information from a grow-out trial with Pacific white shrimp using low-salinity geothermal water.

Stocking Duration Harvest Culture Tank Survival (%) FCR shrimp/m2 shrimp/m3 Size (g) (days) Mean Wt. (g) kg/m2 kg/m3 Raceway 1 74 49 0.5 107 19.53 1.00 0.67 69.4 2.66 Raceway 2 93 61 0.5 94 17.26 1.16 0.76 72.1 2.37 Raceway 3 107 71 0.5 107 18.66 1.18 0.78 59.2 3.22 Raceway 4 346 228 0.5 107 14.72 4.39 2.89 86.1 2.11

study. The pond size varied between 0.11 and 1.06 ha with an average water depth of 1.6 m. Water was provided from four low-salinity (1.6-2.6 ppt) geothermal (25°C) wells. Aeration was provided by double-bladed paddlewheel aerators (2-HP each) or by air diffuser system. An average of 20.4 HP/ha of aeration was used in the large ponds and 13 HP/ha in the small ponds. Compressed air was supplied (24 h/day) by three air blowers (100 HP total) that delivered air at a rate of 28.3 3 Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 m /min (1,000 CFM). Air was distributed via three 5.1-cm floating tubes with outlets positioned 8 to 10-m apart; each outlet had 4 air stones (7.8 L/air stone). All paddlewheel-aerated ponds were provided with one air supply line. Table 20 summarizes the experimental design of this study. Ponds were fertilized before stocking with a liquid ammo- nium phosphate (33-5-0) until a rich algal bloom has developed. Tem- perature, dissolved oxygen, and salinity were monitored twice daily; secchi disc readings were taken in the afternoon; ammonia and algal counts were measured weekly. Daily rations were adjusted based on shrimp growth and water quality. Shrimp were fed a 40% protein diet (“40/5” Rangen, Inc., Buhl, Idaho) for 14 weeks and a 25-30% protein Samocha et al. 31

TABLE 20. Experimental design for production of Pacific white shrimp in earthen ponds at Wood Brothers Farm, Gila Bend, Arizona (AD = Airdiffuser, PW = Paddlewheel aerators).

Pond Group ID Parameter ABCD Total # of ponds 3443 Pond size (ha) 0.75 0.74-0.96 0.82-1.06 0.11-0.18 Density (juvenile/m2) 34-37 61-70 40-52 71, 90, 109 Shrimp size (g) 0.4 0.18-0.22 0.11-0.22 0.12 Aeration (HP/ha) AD (14.7) PW (15-27) AD (17.3-20.3) AD (26.7-43) AD (6.7-9.9) PW (11-18)

diet for 6 weeks (Zeigler Bros., Inc., Gardners, Pennsylvania). Shrimp in one pond were fed a combination of the two diets with 30% diet replacement by wheat flour. Diet was distributed twice a day (0800 and 1900) using an air-powered feeder mounted on a flatbed truck. Due to setup limitations, up to 50% of aeration generating capacity was lost in the air diffuser aerated ponds, as only half of the 4 air stones per outlet were operating at full capacity. A heavy clogging of the air stones with bryozoans (up to 0.3 m thick) was noticed during the last two months before harvest. All ponds were affected by Haemocytic En- teritis disease outbreak; severity varied among ponds. Water temperature of the paddlewheel-aerated ponds was 1°C lower than the ponds aerated with air diffusers. Many dragonfly nymphs were noticed in Group C ponds (ponds that were provided with air diffuser aeration only) a few days after stocking. The average daily farm exchange rates by month were as follows: May 5.3%; June 6.0%; July 10%; August 16.7%; and September 8.3%. No significant differences (P > 0.05) were

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 found in water quality parameters among the four groups. Table 21 provides a monthly summary of the water quality data collected from the ponds in Group A. As no significant differences were found among ponds in water quality, these data are provided only to characterize the culture water in this study. The mean-morning pond water temperature in the early season was lower than 25°C required for adequate shrimp growth. The mean afternoon water temperature during July was above 32°C. Good algal blooms were found in all four months. This may ex- plain the low ammonia levels in these ponds (below 0.2 mg/L). It is interesting to see that the mean afternoon pH levels in the ponds were below 9.3 even under the high algal bloom conditions. Table 22 32 JOURNAL OF APPLIED AQUACULTURE

TABLE 21. Monthly summary of selected water quality parameters in earthen ponds (Group A) stocked with Pacific white shrimp in Wood Brothers Farm, Gila Bend, Arizona.

Temp. (°C) DO (mg/L) Secchi Algae (ϫ105) pH NH Month disk 4 p.m. (mg/L) a.m. p.m. a.m. p.m. min (cm) min. max. May 23.4 26.2 8.8 11.5 7.7 8.9 67 0.04 1.3 3.0 June 25.2 28.0 6.1 10.8 5.8 9.3 65 0.12 0.4 1.0 July 30.0 32.3 4.2 10.5 4.0 8.7 47 0.19 0.5 1.4 August 29.6 31.5 4.7 12.0 4.5 9.1 40 0.03 0.6 2.2 September 28.4 30.0 5.1 10.1 5.0 9.3 44 0.11 N/A N/A

TABLE 22. Mean production data for Pacific white shrimp in earthen outdoor ponds at the Wood Brothers Farm, Gila Bend, Arizona.

Pond Group ID Farm’s Parameter ABCDAverage Density (shrimp/m2) 34-37 61-70 40-52 72-109 58 Average final weight (g) 18.0-19.5 17.7-20.5 15.8-27.7 20.7-22.6 19.8 Yield (ton/ha) 4.0-5.1 3.4-6.8 3.0-5.5 6.7-12.4 4.6 Biomass at harvest (kg/m2) 0.40-0.51 0.4-0.7 0.3-0.6 0.7-1.2 0.53 Growth (g/week) 1.1-1.5 0.9-1.0 0.8-1.1 0.9-1.1 1.0 Survival (%) 62-75 27-55 34-57 42-53 46 FCR 1.3-2.2 2.0-3.8 2.1-2.8 2.4-2.6 2.4 Aeration type AD* PW**+AD AD PW+AD * Aeration by air diffusers ** Aeration by paddlewheel aerators

summarizes the production results from the four groups of ponds. The

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 highest group average survival (69.6%) and growth rate (1.34 g/week) was obtained in Group A (ponds stocked at the lowest densities that were aerated by air diffusers). The mean FCR value (1.79) for these ponds was the lowest among all other groups. The highest yield (5.5 ton/ha = 4,850 lb/ac) in the diffuser-aerated ponds was achieved in the pond with the highest aeration rate (20.3 HP/ha) that was stocked at 49 shrimp/m2. The highest yield (6.8 ton/ha = 6,000 lb/ac) in the paddlewheel-aerated ponds was achieved in the pond with the highest aeration rate (27 HP/ha) that was stocked at 70 shrimp/m2. The highest yield on the farm (12.4 ton/ha = 10,930/ac) was achieved in 0.11-ha pond stocked at 109 shrimp/m2 with 61 HP/ha of aeration (PW-18 HP/ha, Samocha et al. 33

AD-53 HP/ha) and about 30% water exchange/day. It is interesting to note that a high yield (9.6 ton/ha = 8,470 lb/ac) was obtained in another 0.11 ha pond stocked at 90 shrimp/m2 with the same aeration regimens when 30% of the diet was replaced by wheat flour, with only 5% water exchange/day. A cost-breakdown for direct farm operating costs showed that pumping cost accounted for 7% of the estimated total operating costs. Since all effluent water from the farm was re-used for agricultural crop irrigation, the actual pumping cost was much lower. The nursery and grow-out studies suggest that the Pacific white shrimp can be raised to marketable-size at high densities in raceways and earthen ponds using low-salinity geothermal water. Unlike coastal producers that often use contaminated water that result in disease outbreaks, inland shrimp farming using non-polluted ground water can help reduce this risk. Furthermore, when water salinity is low, effluent water from these facilities can be used for crop irrigation, negating potential negative environmental impact from effluent water.

OUTDOOR SHRIMP POND PRODUCTION TECHNOLOGY WITH REDUCED WATER USAGE

In south Texas, much progress has been achieved with outdoor pond production systems operated with reduced, or with no, water discharge. In most cases, these systems employ heavy aeration to maintain adequate dissolved oxygen levels. Significant reductions in water usage, nutrient, and pollutant releases were achieved when these farms started to use sedimentation basins, water recirculation, lower stocking densities, low-protein diets, and high aeration rates. The following is a brief description of one of the farms (Arroyo Aquaculture Association Farm, Rio Hondo, Texas) along with a short summary of the farm’s past and Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 current management practices. The Arroyo Aquaculture Association (AAA) farm is located on the far southeast region of Texas, near Arroyo City along the Gulf of Mex- ico. The farm pumps its water from a nearby creek (Arroyo Colorado) into two distribution canals that feed the ponds by gravity. Out of 85 two-ha earthen ponds at the farm, only ten ponds are not being used. Each pond is equipped with twelve to eighteen 2-HP paddlewheel aerators. Typical production management during the early 1990s included: high stocking densities (50 PL/m2) of the production ponds with the Pa- cific white shrimp, use of high-protein diets (40-45%), heavy water exchange (up to 380,000 m3/day with about 10%/day water discharge), 34 JOURNAL OF APPLIED AQUACULTURE

high fertilization rate, and minimal aeration. The effluent waters generated by this and other shrimp farms had created a serious growth-limiting factor for the emerging Texas shrimp farming industry. It was particularly true for Texas coastal areas, in which the discharge is going into bays and estuaries behind barrier islands that have limited water exchange with the Gulf of Mexico. Farms were required to limit their volume of discharges and to meet certain effluent water quality standards. Under these conditions, the farmers were looking for cost-effective methods to improve effluent water quality and reduce the nutrient releases to receiving water. In early 1994, researchers from TAES and Texas A&M Univer- sity-Kingsville, together with the farmers, launched an intensive sampling program to characterize the farm’s effluent water quality. Preliminary testing was also carried out to identify potential methods to minimize pollutant releases to receiving waters. Lopez (1996) and Samocha and Lawrence (1997) provided a detailed summary of the data collected in this study. The study showed that dissolved oxygen, ammonia, and total suspended solids (TSS) levels were in most cases above the limit set by the state regulatory agency. The main conclusions from these studies were: (1) drainage ditch soil erosion was one of the main sources of the high TSS levels in the farm’s effluent waters; and (2) the farm’s drainage ditch could serve as a primary settling basin to reduce TSS and to improve the water quality in the grow-out ponds. Based on the data obtained from this study, a few modifications were implemented by the farm to improve the effluent water quality. To reduce effluent TSS levels, sections of the drainage ditches with high soil erosion were lined with geotextile membrane; primary drainage ditches were deepened, widened, and partitioned to enhance settling. Drainage canals were also equipped with aeration devices to improved dissolved oxygen and enhance nitrification. Furthermore, to minimize TSS re- Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 lease, water drained from the ponds during harvest was pumped into empty ponds for initial settling. Although a trend toward reduction in water exchange was noticed throughout the years, a significant reduction was implemented after massive crop losses due to the Taura virus syndrome outbreaks in 1995. To minimize the risk of spreading patho- genic viral diseases in the state of Texas, shrimp farms are only allowed to use certified viral pathogen-free seed. After the initial Taura disease outbreak, shrimp farmers have realized that reduced water exchanges not only reduce the potential negative environmental impact from effluent waters, but also minimize the risk to their cultured stocks from contaminated incoming water. Samocha et al. 35

To reduce the introduction of competitors and disease-carrier organisms, the farm has started to filter all raw water with 250-micron screens. Further decreases in water exchange were achieved by increas- ing ponds’ aeration rates up to 18 HP/ha. A secondary pumping station was installed to pump water from the discharge canal back into the distribution canal. Discharge and distribution canals were equipped with mechanical aeration to improve water quality. For the first two months after stocking, ponds are kept under no discharge. When shrimp biomass load increases (generally 0.2 to 0.4 kg/m2) and based on water quality data, water is released from the ponds into the discharge canal system. This water is pumped back into the distribution canals and eventually returned to the ponds. Thus, the widening and deepening of the discharge canals along with installation of supplemental aeration, enable enhancement of the ponds’ effluent water quality. The improvement in water quality makes this water suitable for reuse without negative impact on the shrimp performance. Although some ponds are operated with no water release until harvest, other ponds may require up to 30% daily water release into the discharge canal system. In general, the farm’s average water recirculation rate varies between 10 and 15% of the pond volumes per day. Only limited volume of new water (1%/day) is being pumped from the river to compensate for evaporation and seepage losses. During harvest, water is pumped into empty ponds for storage. This water is released back into the river only when water quality meets the standard set by regulatory agencies. Another modification implemented by the farm to institute the “zero- discharge” management was the reduction in stocking density from the initial 50 PL/m2 to a density between 30 and 40 PL/m2. Furthermore, to improve diet utilization, the farm is currently using feed trays (2 per pond) to monitor diet consumption. In addition, diet is offered three

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 times a day using a tractor-mounted feed-blower rather than the once/day practice used in the past. Unlike past practices, fertilizers are added to the newly-filled ponds on an “as needed” basis. Under this no-discharge management, the farmers have found that the same growth and survival results can be obtained when a low-protein (30%) diet is fed rather than diets with 40 to 45% protein levels. Figure 3 shows the decrease in water usage over five-year period at the AAA Farm. Current practice requires about 2,500 L of water for the production of 1 kg of shrimp compared with about 38,000 L used during the 1994 production season. Figure 4 shows the reduction in effluent TSS from 3.5 kg for every 1 kg shrimp produced in 1994 to 0.05 kg in 36 JOURNAL OF APPLIED AQUACULTURE

FIGURE 3. Reduction in water usage (L/kg of shrimp produced) by Arroyo Aquaculture Association Farm, Arroyo City, Texas.

40,000 Liters

35,000

30,000

25,000

20,000

15,000

10,000

5,000

0 1994 1995 1996 1997 1998

FIGURE 4. Reduction in effluent total suspended solids (TSS) (kg/kg of shrimp produced) by Arroyo Aquaculture Association Farm, Arroyo City, Texas.

4.00 Kg

3.50

3.00

2.50 Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010

2.00

1.50

1.00

0.50

0.00 1994 1995 1996 1997 1998 Samocha et al. 37

FIGURE 5. Reduction in effluent ammonia levels (kg/kg of shrimp produced) by Arroyo Aquaculture Association Farm, Arroyo City, Texas.

0.06 Kg

0.05

0.04

0.03

0.02

0.01

0.00 1994 1995 1996 1997 1998

1998. Figure 5 shows the reduction in total ammonia nitrogen over the years. Ammonia level decreased from almost 0.05 kg for one kg of shrimp produced in 1994 to 0.0004 kg in 1998. A similar reduction trend was noticed in the five-day carbonaceous biochemical oxygen de- mands (cBOD5). Figure 6 shows a reduction in cBOD5 from 0.18 kg for each kg of shrimp produced in 1995 to 0.01 kg in 1998. Figures 7 and 8 show the differences in selected water quality parameters between the farm’s intake water and the water in the recirculation system. As ex- Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 pected, an increase in salinity, ammonia, nitrite, and nitrated TSS and total P were observed in the recirculating system. While further modifications can help improve water quality in this system, the slight increase in salinity is unavoidable. Figure 9 shows the changes in average pond production of the farm over a five-year period. It is interesting to note that although reduction in dietary protein level and water usage was noticed for the last five years, the farm production was not affected. Aside from the decrease in pollutant-load due to lower water usage and the use of low-protein feeds, a significant improvement was noticed in the farm’s FCR value (overall reduction from 2.3 to 1.75). 38 JOURNAL OF APPLIED AQUACULTURE

FIGURE 6. Reduction in effluent cBOD5 (kg/kg of shrimp produced) by Arroyo Aquaculture Association Farm, Arroyo City, Texas.

0.20 Kg

0.18

0.16

0.14

0.12

0.10

0.08

0.06

0.04

0.02

0.00 1994 1995 1996 1997 1998

FIGURE 7. Differences in selected water quality parameters between the incoming water and the recirculating system water of the Arroyo Aquaculture As- sociation Farm, Arroyo City, Texas.

60 Intake Recirculation 50

40 Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010

Units

Salinity pH cBOD5 TSS VSS Samocha et al. 39

FIGURE 8. Differences in selected water quality parameters between the incoming water and the recirculating sytem water of the Arroyo Aquaculture As- sociation Farm, Arroyo City, Texas.

2 Intake Recirculation 1.8

1.6

1.4

1.2

mg/L 1

0.8

0.6

0.4

0.2

0 Nitrite Nitrate Ammonia Total P Reactive P

SUMMARY

The world shrimp farming industry is currently experiencing major crop losses due to disease outbreaks. In some cases, these disease outbreaks were associated with degradation of water quality in receiving Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 streams. The paper reviewed several shrimp production systems and management strategies that can be used to minimize crop losses and environmental deterioration. Based on the results from both research and commercial production facilities, it is clear that considerable improve- ments in biosecurity and sustainability can be obtained by retrofitting old facilities and incorporating new design concepts into new operations. Consequently, commercial producers are encouraged to adapt these technologies into their production systems. Based on the positive results, continued research to optimize operational parameters and develop/evaluate new technologies are warranted. 40 JOURNAL OF APPLIED AQUACULTURE

FIGURE 9. Changes in average pond production (kg) over five-year period in the Arroyo Aquaculture Association Farm, Arroyo City, Texas.

12,000 Kg

10,000

8,000

6,000

4,000

2,000

0 1994 1995 1996 1997 1998

REFERENCES

Arnold, C.R., B. Reid, and B. Brawner. 1990. High density recirculating growout systems. Pages 182-184 in Manual on Red Drum Aquaculture. Texas A&M Sea Grant College Program No. TAMU-SG-90-603. Texas A&M University. College Sta- tion, Texas. Barg, U.C. 1992. Guidelines for the Promotion of Environmental Management of Coastal Aquaculture Development. FAO Fisheries Technical Paper 328, Rome, Italy. Chien, Y.H., I.C. Liao, and C.M. Yang. 1989. The evolution of prawn growout systems Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 and their management in Taiwan. Pages 143-168 in K. Murray, ed. Aquaculture En- gineering Technologies for the Future. Hemisphere Publishing Corporation. New York, New York. Cohen, J.M., T.M. Samocha, R.L. Gandy, E.R. Jones, J.M. Fox, and A.L. Lawrence. 2001. The culture of Litopenaeus vannamei under bio-secured and zero exchange conditions. Aquaculture 2001, Book of Abstracts: 130. Davis, D.A., and C.R. Arnold. 1998. The design, management and production of a recirculating raceway system for the production of marine shrimp. Aquacultural En- gineering 17:193-211. Emberson, C.R., T.M. Samocha, and G.F. Wood. 1999. Use of ground saline water for commercial production of Litopenaeus vannamei in the Sonora Desert, Arizona, USA. World Aquaculture ’99 Book of Abstracts: 668. Samocha et al. 41

Hopkins, J.S., and J. Villalón. 1992. Synopsis of industrial panel input on shrimp pond management. Pages 138-143 in J.A. Wyban, ed. Proceedings of the Special Session on Shrimp Farming, World Aquaculture Society, Baton Rouge, Louisiana. Hopkins, J.S., R.D. Hamilton II, P.A. Sandifer, C.L. Browdy, and A.D. Stokes. 1993. Effect of water exchange rates on production, water quality, effluent characteristics and nitrogen budgets in intensive shrimp ponds. Journal of the World Aquaculture Society 24:304-320. Hopkins, J.S., P.A. Sandifer, and C.L. Browdy. 1995a. A review of water management regimes which abate the environmental impacts of shrimp farming. Pages 157-166 in C.L. Browdy and J.S. Hopkins, eds. Swimming Through Troubled Water: Pro- ceedings of the Special Session on Shrimp Farming, World Aquaculture Society, Baton Rouge, Louisiana. Hopkins, J.S., C.L. Browdy, R.D. Hamilton II, and J.A. Heffernan III. 1995b. The effect of low-rate sand filtration and modified feed management on effluent quality, pond water quality and production of intensive shrimp ponds. Estuaries 18:116-123. Lee, P.G. 1993. Computer automation for recirculating systems. Pages 61-70 in J.K. Wang, ed. Proceedings of an Aquacultural Engineering Conference, American So- ciety of Agricultural Engineers, St. Joseph, Michigan. Leung, P.S., and S.M. Moss. 1999. Economic assessment of a prototype biosecure shrimp growout facility. Pages 97-106 in R.A. Bullis and G.D. Pruder, eds. Con- trolled and Biosecure Production Systems: Evolution and Integration of Shrimp and Chicken Models. Proceedings of a Special Session. World Aquaculture Society. Sydney, Australia. Lopez, I.M. 1996. Characterization of Effluents from Three Commercial Aquaculture Facilities in South Texas. Master’s Thesis, Texas A&M University-Corpus Christi, Corpus Christi, Texas. Macia, R.P. 1983. Penaeus shrimp pond growout in Panama. Pages 169-178 in J.P. McVey, ed. CRC Handbook of Mariculture, Volume 1, Crustacean Aquaculture, CRC Press, Boca Raton, Florida. Moss, S.M. 2000. Benefits of a microbially dominated intensive shrimp production system: a review of pond water studies at the Oceanic Institute. Global Aquaculture Advocate 3(2):53-55. Ogle, J.T., and J.M. Lotz. 1998. Preliminary design of a closed, biosecure shrimp growout system. US Marine Shrimp Farming Program Biosecurity Workshop–The Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 Oceanic Institute, Makapuu Point, Hawaii. Peterson, J.J., and D.R.W. Griffith. 1999. Intensive nursery systems. Global Aqua- culture Advocate 2(6):60-61. Phillips, M.J., C.K. Lin, and M.C.M. Beveridge. 1993. Shrimp culture and the environment: lessons from the world’s most rapidly expanding warmwater aquaculture sector. Pages 171-197 in R.S.V. Pullin, H. Rosenthal and J.L. Maclean, eds. Envi- ronment and Aquaculture in Developing Countries: Proceedings of the ICLARM Conference on Environment and Third World Aquaculture Development, ICLARM, Manila, Philippines. Reid, B., and C.R. Arnold. 1992. The intensive culture of the Penaeid shrimp Penaeus vannamei Boone in a recirculating raceway system. Journal of the World Aqua- culture Society 23:146-153. 42 JOURNAL OF APPLIED AQUACULTURE

Rijn, J.V., and M. Shilo. 1989. Environmental factors in fish culture systems. Pages 163-178 in M. Shilo and S. Sarig, eds. Fish Culture in Warmer Systems: Problems and Trends. CRC Press, Boca Raton, Florida. Samocha, T.M., and A.L. Lawrence. 1997. Shrimp farms effluent water, environmental impact and potential treatment methods. Pages 33-57 in B.J. Keller, P.K. Park, J.P. McVey, K. Takayanagi and K. Hosoya, eds. Water Effluent and Quality, with Special Emphasis on Finfish and Shrimp Aquaculture. Proceedings of the 24th US-Japan Aquaculture Panel Symposium. UJNR Technical Report No. 24. Texas A&M University Sea Grant College Program, College Station, Texas. Samocha, T.M., A.L. Lawrence, and W.A. Bray. 1993. Design and Operation of an In- tensive Nursery System for Penaeid Shrimp. Pages 173-210 in J.P. McVey, ed. CRC Handbook of Mariculture. Crustacean Aquaculture. CRC Press, Boca Raton, Florida. Samocha, T.M., A.L. Lawrence, C.A. Collins, F.L. Castille, P.G. Lee, and G.F. Wood. 1998. Use of intensive nursery systems in commercial shrimp production: advan- tages and disadvantages. Proceedings of the 1st Latin American Shrimp Culture Congress and Exhibition, Panama City, Panama. Samocha, T.M., A.L. Lawrence, C.A. Collins, F.L. Castille, P.G. Lee, C.J. Davies, and G.F. Wood. 1999a. Use of greenhouse-enclosed intensive raceway system for the nursery phase of Penaeus vannamei in an inland commercial shrimp farm in Ari- zona. Aquaculture America ’99 Book of Abstracts: 167. Samocha, T.M., A.L. Lawrence, W.A. Bray, C.A. Collins, F.L. Castille, P.G. Lee, and C.J. Davies. 1999b. Production of marketable Litopenaeus vannamei in greenhouse-enclosed raceways in the Arizona desert using ground saline water. World Aquaculture ’99 Book of Abstracts: 166. Scarpa, J., and D.E. Vaughan. 1998. Culture of the marine shrimp Penaeus vannamei, in freshwater. Aquaculture ’98 Book of Abstracts: 473. Smith, L.L., and A.L. Lawrence. 1990. Feasibility of penaeid shrimp culture in inland saline groundwater-fed ponds. Texas Journal of Science 42:3-12. Sturmer, L.L., T.M. Samocha, and A.L. Lawrence. 1992. Intensification of penaeid nursery systems. Pages 323-346 in W.A. Fast and L.G. Lester, eds. Culture of Ma- rine Shrimp: Principles and Practices. Elsevier Science Publishing Company, Am- sterdam, The Netherlands. Van Wyk, P. 1999a. Farming Marine Shrimp in Freshwater Systems: An Economic Development Strategy for Florida. Pages 1-32 in Production of Marine Shrimp in

Downloaded By: [Florida Atlantic University] At: 20:22 23 July 2010 Freshwater Recirculating Aquaculture Systems. Florida Department of Agriculture and Consumer Services. Tallahassee, Florida. Van Wyk, P. 1999b. Harbor branch shrimp production systems. Pages 99-114 in Pro- duction of Marine Shrimp in Freshwater Recirculating Aquaculture Systems. Florida Department of Agriculture and Consumer Services. Tallahassee, Florida. Van Wyk, P. 1999c. Economics of shrimp culture in recirculating aquaculture systems. Pages 179-208 in Production of Marine Shrimp in Freshwater Recirculating Aqua- culture Systems. Florida Department of Agriculture and Consumer Services. Talla- hassee, Florida. Van Wyk, P.M. In Press. Designing Efficient Indoor Shrimp Production Systems: A Bioeconomic Approach in C.L. Browdy and D. Jory, eds. Proceedings of a Special Session on Sustainable Shrimp Culture. World Aquaculture Society. Baton Rouge, Louisiana.