Báo cáo Nghiên cứu khoa học Intensive in-Pond raceway production of marine finfish (card vie 062-04)

Ministry of Agriculture & Rural Development Project Progress Report Project title: INTENSIVE IN-POND RACEWAY PRODUCTION OF MARINE FINFISH (CARD VIE 062/04) MILESTONE 2& 4 REPORT Two milestone reports are combined in one for ease in understanding of raceway technology and application of potential users Michael Burke (QDPI&F, Australia) Tung Hoang (Nha Trang University, Vietnam) 12/2006 PART 1 Design and performance of floating raceways used to nurse fingerlings of marine finfish in Central Vietnam 1 Design and performance of floating raceways used to nurse fingerlings of marine finfish in Central Vietnam Tung Hoang1*, Phuong T. Luu1, Khanh K. Huynh2, Quyen Q.T. Banh1, Mao D. Nguyen1, Michael Burke3 1 International Center for Training and Research, Nha Trang University, Vietnam 2 Khanh Hoa Fisheries Promotion Center, Vietnam 3 Department of Primary Industries & Fisheries, Bribie Island Aquaculture Research Centre, Bribie Island, Queensland, Australia 1. INTRODUCTION The development of mariculture in Vietnam requires large number of marine fish fingerlings for stocking. In recent years, small seeds of high-value fish such as grouper (Epinephelus spp.), cobia (Rachycentron canadum), barramundi (Lates calcarifer) and other species are produced in hatcheries, meeting part of the increasing demand by fish farmers. Not only quantity, but also body size of fingerlings is limited. Marine finfish are mostly cultured in cages in Vietnam. Stocking, therefore, requires fingerlings larger than 80÷100 mm in total length. In hatcheries, the production of large fingerling is costly and apparently constrained by limited nursing tank area. Poor survival and difficult husbandry are recorded also with nursing in ponds (Le Xan 2005). Floating raceways have been recently trialled successfully for freshwater fish farming in USA, Australia and Germany. Despite of their relatively high capital and running costs, the use of floating raceways has a number of advantages including (i) high stocking density and less predation; (ii) effective feeding and disease management; (iii) easy to handle and fewer labor required; (iv) taking advantage of natural food in ponds. In Vietnam, Nha Trang University (the former University of Fisheries) designed a floating raceway and trialled this system in 2005 – 2006 through the CARD VIE 062/04 project “Intensive in-pond raceway production of marine finfish” coordinated by the Ministry of Agriculture and Rural Development of Vietnam. This current report presents the working principles of floating raceways; guidelines for installation and operation of the version SMART–1 for nursing marine finfish fingerlings; experimental results on barramundi (Lates calcarifer) covering both financial assessment and dynamics of raceways. Some initial results on snapper (Lutjanus argentimacus), red drum and red tilapia (Oreochromis sp.) are also discussed. Target species for coming trials are cobia and grouper. 2 2. DESIGN OF FLOATING RACEWAY 2.1 Operational principles Operational principles of floating raceway (FR) is relatively simple. FR can be made of different materials and looks like a long, narrow tank that float itself or supported by floating structure. Water in reservoir pond is continuously pumped into one end and discharged at the other end of the raceway through a system of airlifts, powered by central air compressor or blower. This helps reduce power costs and increase dissolved oxygen concentration. Fish are nursed or grown in raceways at high densities, fed with formulated feed. In addition, plankton in reservoir pond is an important supplementary feed source for small fish. To keep fish from escaping, a screen is installed at the outlet of raceways. Net is also used to cover the raceway’s surface to protect fish from predation. Floating raceways should be designed to maintain high exchange rate, enable waste collection and create a quiet area for feeding. In case chemical treatment is needed, raceways become ‘close’ tanks when the airlift operation is ceased and its outlet is blocked. Depending on biological requirement of the cultured species, floating raceways can be put in relatively deep pond containing either fresh, brackish or marine water. Reservoirs have enormous potentiality for the application of this farming system. However, electricity is required for operation of air compressor or blower. 2.2 Pond The rectangular reservoir pond is 2000 m2 (Fig. 1). Pond should be built on impermeable soil or lined with plastic. Pond bank is 1.5 slope and 1.8 – 2.0 m wide, making it convenient for daily management and harvesting. Pond bottom should be flat and inclines to outlets. The higher water level in pond, the better it is. Minimum water depth is 1.6 ÷ 1.7 m. Conversely, in case of low water levels, the airlift system will take up wastes and mud from pond bottom into raceways. The reservoir pond is partitioned by a plastic wall placed in the middle of the pond, directing water to flow around with the aid of a 2-hp paddle-wheel. 2.3 Floating raceways Floating raceways version SMART-01 are small in size, used to nurse marine finfish from small sizes to fingerlings. These are made of fiberglass – the most appropriate material in Vietnam which is durable, weather proof and easy to clean or move around. Despite its higher cost than other simple materials, fiberglass raceways have demonstrated a worthy investment. SMART-1 has a trapezoid-shape (3.5m3 volume, 3.5×0.8×1.0m), 30o 3 slopped at both heads (Fig. 2). One head of the raceway is connected with an airlift system. The other is attached with a screen to avoid fish escape and predators. At the inlet side of the raceway, a panel is put to drive water downwards. Overpass Floating raceways Sluice Air pipeline Air compressor Wall Aerator 1.8 – 2 m 1.8 m Bank Wall b Figure 1: Pond and in-pond floating raceways 2.4 Airlifts The airlift s ncludes four PVC ∅90-mm pipes. Each pipe is 100 cm long, attached togethe raceway. This fra side of this fram Air flow is contr on the lower side push water up. capacity” of the a 2.5 Air comp Water is pum upon the numbe six floating racew ystem ir by a rectangular frame made me also has a function of bringin e is connected with an air compr olled by a plastic valve. Four sma of the supporting frame, one for The distance from water surfac irlifts is dependent upon the pow ressor ped into the raceway by an air c r of airlifts and desired flow rate ays with a total of 24 airlifts) use 4of PVC ∅21-mm pipes, fixed into the g air into the airlifts (Fig. 3). The upper essor or a blower by a soft plastic pipe. ll holes (3.0 mm in diameter) are drilled each airlift, allowing air to flow in and e to these holes is 80 cm. “Pumping er of air compressor or blower used. ompressor whose capacity is dependent . The SMART-01 system (comprises of s an ANLET BSR-40 air compressor (3 HP or 2.2 KW; Made in Japan). The amount of compressed air is 66 m3 per hour. While operating, each airlift can pump about 86÷87 L of water per minute. 3.5 m 3.7 m 0.9m 0.6m 0.25m 2.5m Outlet Airlifts Inner side Outer side Hole to set airlift Groove to install baffleGroove to install screen Outlet a Figure 2: Structure of SMART-01 b Air Incoming water Coming-out water Air vent Figure 3: Structure of airlift system In order to ensu fficient dissolved oxygen and well prepare technical failure, two air compressors are used in turn. Each operates for 12 hours per day. The air line that connects the air compressor and the airlift system is designed to end as a rectangular loop around the su rting pontoon. This helps equalize the amount and pressure of compressed air at all positions in the system, allowing all the a operate at the same rate. 5irliftsd forre suppo 2.6 Supporting pontoon A pontoon is used to support the floating raceways. This system was constructed using 6×12 cm blocks of wood and 200-L HDPE drums. These materials are locally available and often used to make spiny rock lobster cages. The pontoon is rectangular in shape (510 × 750 cm) and is divided into six chambers. The width of each chamber is 95 cm, enabling convenience while lifting or lowering the floating raceways. Side walkway was made around the pontoon for daily management and husbandry practices (Fig. 4). The SMART- 01 system uses 17 HDPE drums arranged equally to support the pontoon, sufficiently enabling the attached raceways always float on the water surface when technicians are feeding the fish or cleaning the raceways. Six raceways are hung on the raft by Ø14 mm bolts (450 mm long). This helps keep the raceways emerged 5÷10 from the water surface Nonetheless, as the raceways are attached to the pontoon, their floatability is dependent upon the pontoon’s floatability. a’c c’ 6 1 2 1 b b’ 3 cross section topdown a 6 6 5 3 4 outflow side Inflow side Figure 4: Structure of floating raft supporting raceways Notes: 1: Floating raceways 2: Float 3: Airlifts 4: Outlet Screen 5: Bolds hanging raceways 6: Air supply 2.7 Installation and operation Firstly, the supporting pontoon is assembled and put into the reservoir pond. PVC and soft plastic pipes were then used to connect the air compressor with the raceways. When using PVC pipes, it is better to put them underground to prevent damage caused by UV ray and heat of sunshine. As the air coming off the compressor is very hot, the first segment of the pipe that attaches to the compressor must be heat-resistant or made of zinc, and is about 6 six meters long. Next, the raceways, airlifts and regulating valves are installed. The compressor ANLET BSR 40 is capable of operating six raceways and one separate air outlet for emergency use or when additional aeration in raceways is needed, e.g. during therapeutic treatment or harvesting. The top baffle, once installed will direct incoming flows downwards and velocity of surface current is nearly zero. This helps create a quiet area for feeding behind the baffle. In addition, the downwards flow will push faeces and uneaten feed toward the end of raceways. Part of this waste will overflow through the raceway’s outlet. The rest is accumulated at the end of the raceways and will be daily siphoned out. The newest system SMART-02 has a waste trap for ease in maintenance. Key environmental parameters such as salinity, pH, NH4-N, total dissolved solids (TDS) and temperature are equivalent between the raceways and the reservoir pond. Therefore, good control of water quality in pond will ensure good nursing environment in raceways. Thanks to the airlifts, dissolved oxygen levels of water in raceways well meet fish’s requirement. However, regular attention should be paid to the aeration system because, by any means, if this system ceases (e.g. due to no power or technical problems), fish mortality due to lack of oxygen is extremely high. When nursing species that need natural foods, fertilizers should be used to promote plankton growth in the reservoir pond. During operation, the aeration system must be regularly checked. As density of fingerlings in raceways is very high, any problem related to air loss is a danger to fish. Two air compressors should be used in turn to prolong longevity and minimize damages because of overwork. In geographical areas where electricity is not reliable, it is advisable to prepare a petrol-operated generator . Farmers can adjust the amount of air and number of airlift to control water exchange rate as well as velocity of current in raceways that best suit the cultured species. The airlifts will underperform if being bio-fouled. Thus, this system must be cleaned periodically. Cleaning raceways can be conducted easily by using brushing along the inner sides and bottom of raceways. However, when nursing species which is sensitive to turbulence like barramundi, it had better not clean raceways daily. 3. EVALUATING PERFORMANCE OF SMART-01 ON BARRAMUNDI 3.1 Experimental method Barramundi fingerlings (15÷20 mm total length) were locally produced and transported to the trial site at Ninh Loc, Khanh Hoa which is belong to the Khanh Hoa 7 Fisheries Extension Center. Stocking density was 10,000 fish per raceway or 3.3 fish/L. Two trials were conducted; each used three raceways. The raceways were chlorinated at 100 ppm before used. The total length and body weight of fish are determined after two- day acclimation. Fish were fed with INVE and Grobest pellet (granular size 800÷1200 µm; crude protein content 42÷56%). The former feed was used for younger stages in hatchery. In the first trial, fish were fed with INVE during the first week and then weaned to Grobest. In the second trial, fish were fed merely with Grobest pellet to reduce feed cost. The amount of feed is about 2÷18% of body weight depending on development stages and actual consumption. Fish were fed every hour 06:00 to 18:00. Feeding load was adjusted in the next feeding based on actual consumption of the current feeding. Key environmental parameters such as pH, dissolved oxygen (DO) and temperature were monitored daily at 08:00 and 14:00, both in raceways and in the reservoir pond. Other factors include total dissolved solids (TDS), total ammonium (NH3-N) and salinity were measured every five days; total suspended solid every 7 days. Sampling plankton at inlet and outlet of raceways, and in the reservoir pond was also conducted weekly to observe changes in species composition and evaluate “filtration efficiency” of the raceways. Artificial dye and small buoys were used to study the dynamics of water in the raceways. Every five days, 50 fish from each raceway were randomly collected. Total length and body weight were measured and recorded. Fish health was also assessed by visual examination. The survival rate was determined at the end of the experiments. The first trial lasted for three weeks and the second trial lasted for 5 weeks. The total length of the nursed fish was 60÷80 mm and 80÷100 mm, respectively at the end of the first and second trials. Survival, growth and size variation of nursed fish; profit margin and profit per unit of investment were used for overall assessment. 3.2 Operation of raceways and capacity of water exchange Flow rate from the reservoir pond to raceways is about 350 L/min. The use of artificial dye to estimate exchange rate revealed that water in raceways is completely exchanged every 15 mins (Fig. 1). This ensures relatively similar water quality between the in the reservoir pond and the raceways, except for DO and TSS (Table 1&2). DO of water in the raceways is always over 4.0 mg/L and higher than that in the reservoir pond through effective operation of the airlifts. TSS in raceway is higher than in pond due to accumulated faeces of fish and uneaten feed. 8 When operating without the top baffle, the average velocity of surface current is 35 cm/s. When the top baffle is used, the water flows downwards and aside with the bottom of the raceway. This forms a quiet area behind the top baffle for feeding and keep feed pellets in the raceway. Furthermore, suspended solids are brought out the raceway into pond more easily. Larger waste is accumulated at the end of raceway, making it easy for daily cleaning. Examination of the plankton samples showed that the diversity was similar between the raceways and in the reservoir pond. However, plankton biomass in raceway is higher than in pond (Table 1), demonstrating its plankton capturing efficiency. hút 2 - 3 phút 5 - 6 phút 7 - 8 phút 11 - 13 phút 15 - 20 phút T? ư?c Lư?i ch?nscreen? ng nâng nAirlifts m ch?nplate 0 p0 min Figure 5: Water exchange rates between raceways and pond (gray area indicates water mixed with artificial dye) Table 1 : Water quality in raceway and pond during the first trial. Data in the same rows with different superscripts are statically different (P < 0.05) Factors Pond Raceway 3 Raceway 4 Raceway 5 DO (ppm) Morning 3.95 ± 0.16a 4.55 ± 0.14b 4.54 ± 0.14b 4.60 ± 0.13b Afternoon 5.55 ± 0.17a 5.60 ± 0.16a 5.61 ± 0.17a 5.67 ± 0.16a Temperature (oC) Morning Afternoon pH Morning Afternoon Salinity (ppt) 31.6 ± 0.16a 31.6 ± 0.16a 31.6 ± 0.16a 31.6 ± 0.16a 33.4 ± 0.25a 33.3 ± 0.25a 33.3 ± 0.25a 33.3 ± 0.25a 7.6 ± 0.02a 7.6 ± 0.01a 7.6 ± 0.02a 7.6 ± 0.02a 7.6 ± 0.02a 7.6 ± 0.02a 7.6 ± 0.02a 7.6 ± 0.02a 22 ± 0.12a 22 ± 0.12a 22 ± 0.12a 22 ± 0.1a 9 Table 2 : Water quality in raceway and pond during the second trial. Data in the same rows with different superscripts are statically different (P < 0.05) Factors Pond Raceway 1 Raceway 2 Raceway 3 DO (ppm) Morning 5.85 ± 0.09a 5.86 ± 0.09a 5.80 ± 0.12a 5,80 ± 0,10a Afternoon 11.02 ± 0.24a 8.05 ± 0.20b 8.09 ± 0.21b 8,22 ± 0,21b Temperature (oC) Morning 30.2 ± 0.10a 30.1 ± 0.10a 30.1 ± 0.10a 30.1 ± 0,10a Afternoon 32.6 ± 0.30a 31.1 ± 0.20b 31.1 ± 0.20b 31.1 ± 0.20b pH Morning 8.1 ± 0.01a 8.0 ± 0.02a 8.0 ± 0.02a 8.0 ± 0.02a Afternoon 8.4 ± 0.01a 8.3 ± 0.02b 8.3 ± 0.02b 8.3 ± 0.02b Salinity (ppt) 29 ± 0.30a 29 ± 0.30a 29 ± 0.30a 29 ± 0.30a TSS (ppm) 63.8 ± 8.93a 111.1 ± 19.77b 92.5 ± 14.88a 92.4 ± 13.33a TDS (ppm) 1309 ± 48.9a 1357 ± 57.5a 1334 ± 59.1a 1321 ± 71.0a NH4+ (ppm) 0.13 ± 0.01a 0.13 ± 0.01a 0.13 ± 0.01a 0.13 ± 0.01a Outflow water top baffle Screen Airlifts beh mor fish the ± 0 Coe tota with imp from Inflow water Figure 6: Dynamic of flows in pond 3.3 Growth rate of f Nursed barramundi in raceways grew fast. They fed avior while feeding and did not eat in the dark. Feeding ning and late afternoon. Stomach examination of the nu larger than 20 mm in total length hardly used zooplankto first trial, the average body weight and total length (± S.E .05 cm, respectively after 15 days of nursing. Surv fficient of variation was 23.8 ± 0.83 % in term of weigh l length. Estimated food conversion ratio (FCR) is 0.83 ± nursing barramundi in earthen ponds or concrete tank rovements. Another separate experiment showed that growth and s 20 mm to 80 mm are not different when fed with INVE 10ish actively, showed aggressive was most active in the early rsed barramundi showed that n (Luu The Phuong 2006). In .) was 2.36 ± 0.07 g and 5.13 ival rate was 81.9 ± 1.0%. t and 11.7 ± 0.28 % in term of 0.01 (Table 3). In comparison s, these results are significant urvival of barramundi nursed or Grobest pellets (Table 4). Nevertheless, the cost for Grobest pellet is only 1/5 of INVE pellets. The aim to reduce feed cost, however, was not successful in the second trial where Grobest pellets were merely used. As the fish got used to INVE feed in the hatcheries, they were not interested in Grobest pellets. Furthermore, water quality was lower than that for the first trial. Pond water had been kept for 10 months and salinity was higher (Table 3). Fish were infected with copepod parasites Caligus. Consequently, hydroperoxide (H2O2) at 150 ppm was used to treat fish in raceways for 20 – 30 mins. Although relatively effective, it was one of the reasons for slow growth and lower survival of fish in the second trial. The overall performance of the second trial was, therefore, inferior than the first one. As a result, fish growth was not high for the second trial. Specific growth rate of weight and length of fish are 4.66 ± 0.05 %/day and 1.44 ± 0.03 %/day in the first and the second trials, respectively. At the end of the trial, the average total length was 10.03 ± 0.23 cm; average body weight was 16.36 ± 1.28 g. Average survival rate of fish was 53.43 ± 1.39%, not as high as in the first one. However, duration of this batch is three times as long as the first one. Average rate of graded population of body weight is much higher than the trial I (109.23 ± 3.36 %). Feed conversion rate (FCR) of the trial 2 is 2.8 ± 0.15. Table 3: Performance of nursed barramundi Trial I (15 days) Norms Raceway 3 Raceway 4 Raceway 5 Average L2 (cm) 5.05 ± 0.09 5.22 ± 0.08 5.12 ± 0.09 5.13 ± 0.05 W2 (g) 2.4 ± 0.12 2.24 ± 0.09 2.5 ± 0.14 2.36 ± 0.07 SRGL (%/day) 3.37 ± 2.21 3.81 ± 2.35 3.59 ± 2.06 3.59 ± 0.13 SRGW (%/day) 9.34 ± 3.08 9.04 ± 3.67 9.40 ± 3.11 9.26 ± 0.11 Survival (%) 80 82.7 83.1 81.93 ± 0.97 CVW (%) 24.80 ± 8.04 22.15 ± 4.46 24.46 ± 9.05 23.8 ± .83 CVL (%) 11.21 ± 1.38 11.71 ± 0.91 12.19 ± 1.34 11.7 ± 0.28 FCR 0.83 0.81 0.85 0.83 ± 0.01 Trial II (45 days) Norms Raceway 1 Raceway 2 Raceway 3 Average L2 (cm) 9.65 ± 0.16 10.00 ± 0.16 10.45 ± 0.21 10.03 ± 0.23 SRGL (%/day) 1.40 ± 0.30 1.43 ± 0.29 1.50 ± 0.25 1.44 ± 0.03 W2 (g) 14.38 ± 0.82 15.95 ± 0.84 18.75 ± 1.46 16.36 ± 1.28 SRGW (%/day) 4.56 ± 0.78 4.66 ± 0.72 4.75 ± 0.67 4.66 ± 0.05 Survival (%) 51.1 55.9 53.3 53.43 ± 1.39 CVW (%) 105.27 ± 26.21 106.50 ± 26.27 115.92 ± 33.05 109.23 ± 3.36 CVL (%) 11.02 ± 0.94 10.70 ± 1.10 10.21 ± 1.01 10.64 ± 0.24 FCR 2.5 3 2.9 2.8 ± 0.15 W2, L2: Body weight and total length of fish at the end of the trial SRGL: Specific growth rate of total length of fish SRGW: Specific growth rate of body weight of fish 11 CVW (%): Coefficient of variation of weight CVL (%): Coefficient of variation of total length Table 4: Performance of barramundi nursed with three different diets: INVE, Grobest and trash fish after 42-days. Data in the same row with different superscript are statistically different (P<0.05) Norms INVE Grobest Trash fish L2 (mm) 7.69 ± 0.91a 7.44 ± 0.94a 6.92 ± 1.07b W2 (g) 5.55 ±2.1 5.00 ±1.99 4.33 ± 1.64 SRGL (%/day) 0.013 ± 0.002 0.012 ± 0.001 0.012 ± 0.001 SRGW (%/day) 0.039 ± 0.01 0.038 ± 0,01 0.037 ± 0.001 Survival (%) 98.0 ± 0.63a 82.3 ± 1,63b 74.1 ± 1.63c Observed dead fish (%) 1.16 ±1.09 6.23 ±2.83 10.72 ±2.83 CVW2 (%) 34.0 ± 7.1 39.0 ± 5.3 38.5 ± 1.9 CVL2 (%) 11.1 ± 1.3 12.8 ± 1.0 15.2 ± 0.7 FCR 0.87 0.90 4.85 3.4 Economic analysis Operation cost for the first and the second trials was VND 28,802,500 and VND 37,040,000. At harvest, current price was VND 2,500/fish for the first trial and VND 3,000 /fish for the second trial. Thus, calculated profit for the trial was VND 32,947,500 and for the second trial was VND 10,960,000. Profit rates of the two trials was 1.14 and 0.30, respectively (Table 5&6). Table 5: Economic analysis for the first trial (15 days; currency: VND) Item Unit Quantity Cost price Total Seed cost fish 30,000 800 24,000,000 Feed cost kg 35 17,000 595,000 Labor cost month 0.5 1,000,000 500,000 Depreciation of fixed assets month 0.5 970,000 485,000 Fuel cost (diesel) L 5 4,500 22,500 Electricity cost (air machines) KW 800 1,500 1,200,000 Other costs 2,000,000 Total costs 28,802,500 Total income fish 24,700 2,500 61,750,000 Profit 32,947,500 Profitable rate (Profit/Total costs) 1.14 12 Table 6: Economic analysis for the second trial (45 days; currency: VND) Item Unit Quantity Cost price Total Seed cost Fish 30,000 800 24,000,000 Feed cost Kg 120 17,000 2,040,000 Labor cost month 1.5 1,000,000 1,500,000 Depreciation of fixed assets month 1.5 970,000 1,455,000 Fuel cost (diesel) L 10 4,500 45,000 Electricity cost (air machines, paddle-wheel) KW 4,000 1,500 6,000,000 Other costs 2,000,000 Total costs 37,040,000 Total income Fish 16,000 3,000 48,000,000 Profit 10,960,000 Profitable rate (Profit/Total costs) 0.30 The profitable rate of the second trial was low because of fish disease and long duration (i.e. higher electricity cost). Therefore, the nursery environment must be well control to shorten duration and reduce production costs. 4. LIMITATION OF SMART-01 AND SOLUTION The two trials have revealed a number of limitations in design of SMART-01. As the raceways are attached on the pontoon, their mobility is limited and their floatability is completely dependent upon that of the pontoon. When many people step on the pontoon, the efficiency of the airlifts are severely affected as the openings where the air is released are pushed deeper. Further, it is difficult to clean the airlifts. Although accumulated wastes (at the end of the raceway) can be siphoned easily, SMART-01 does not have a waste collector. These disadvantages will be improved in SMART-02, an improved version of SMART-01. This newly-designed raceway is made of fiberglass; 6.0 m3 in volume; self- float and equipped with a small air compressor. The airlifts of SMART-02 are designed to float independently off raceways, easy to assemble and clean. Water intake is from the surface. Therefore, SMART-02 can be put in ponds that are shallower. Fish and waste on the pond bottom are kept away from the intake water. Both the inlet and outlet of the raceway are redesigned for better performance and ease in management. ACKNOWLEDGEMENT This report uses results of the Project “Intensive in-pond raceway production of marine finfish’ CARD VIE 062/04 funded by CARD (Collaboration for Agriculture Research & 13 Development) program through Ministry of Agriculture and Rural Development of Vietnam. The research team would like to thank the sponsor, Nha Trang University, Institute for Ship Building and Equipment, Khanh Hoa Fisheries Promotion Center, a number of students of Nha Trang University (Mr. Luu The Phuong, Mr. Nguyen Van Quyen, Mr. Dam Thanh Ngoc, Ms. Tran Thi Nhat Huong and Mr. Nguyen Phi Thang) and the following faculty members: Dr . Nguyen Huu Dung, Dr. Nguyen Thi Hoa, Mr. Phan Van Ut, Mr. Bui Ba Trung, Dr. Hoang Bich Mai and Ms. Mai Thi Bich Hanh for their valuable help during the implementation of the project. REFERENCES Dam T. Ngoc (2006) Effect of some types of feed on growth, survival and size variation of barramundi (Lates calcarifer Bloch 1790). Thesis. Nha Trang University. (In Vietnamese). Lai D. L. Binh (2006) Procedure of nursing barramundi fingerlings from 1 – 45 days after hatching and determining effect of densities of nursed fingerling on growth, survival and size variation. Thesis. Nha Trang University. (In Vietnamese). Le Xan (2005) Results of research on reproduction and culture some species of marine and brackish fish in Vietnam in recent years, orienting for coming researches. In: Proceedings of the Conference on research and application science and technology in aquaculture. Agriculture Publishing House, Ho Chi Minh city, pp. 541-549. (In Vietnamese). Luu T. Phuong (2006) Application float raceways to nurse barramundi (Lates calcarifer Bloch, 1790) from 2 – 8 cm total length. Master thesis. University of Agriculture 1, Ha Noi. (In Vietnamese). Nguyen V. Su (2005) Developing tendency of marine fish reproduction technology. Tap chi Thuy san 3: pp. 28-29. (In Vietnamese). Tran T. N. Huong (2006) Evaluating the plankton exchange efficiency between reservoir pond and floating raceways at Ninh Loc, Ninh Hoa, Khanh Hoa. Thesis. Nha Trang University. (In Vietnamese). Kunvankij P. (1986) Biology and culture of seabass (Lates calcarifer Bloch, 1790). NACA Training Manual Series No. 3. Lee C.S. (2003) Biotechnological advances in finfish hatchery production: a review. Aquaculture 227: pp. 439 – 458. 14 PART 2 In-Pond Raceway Technology for Marine Finfish Nursery Production and Grow-Out Developed and Tested – Australian Component 15 In-Pond Raceway Technology for Marine Finfish Nursery Production and Grow-Out Developed and Tested – Australian Component M.J. Burke1, B. Chilton1, L. Dutney1, B. Russell1, A. Collins2 and T. Hoang3 1Department of Primary Industries and Fisheries, Bribie Island Aquaculture Research Centre, Bribie Island, Queensland, Australia. 2Department of Premier and Cabinet, International Collaborations, Brisbane, Queensland, Australia. 3Nha Trang University, International Centre for Research and Training, NHATRANG City , Vietnam Correspondence: Michael Burke, Bribie Island Aquaculture Research Centre, PO Box 2066 Bribie Island, Queensland, 4507 Australia. michael.burke@dpi.qld.gov.au Introduction Aquaculture plays an important role in the development of Vietnam’s economy and has been widely considered as an effective means for poverty alleviation by the FAO. The country aims to produce 2 million tons of aquaculture products, mainly with marine species, by 2010. This ambitious target has been supported by a great amount of financial and technical assistance from the Ministry of Fisheries and several international agencies including CARD. In Australia, aquaculture has been the fastest growing primary production sector over the last five years with increasing interest in species like barramundi, yellowtail kingfish, and more recently grouper and cobia. Nonetheless, growth of the marine finfish industry in both countries has been constrained by the absence of cheap, robust production technologies that alleviate the negative environmental impacts associated with marine aquaculture. In Vietnam, marine fish are farmed mainly in small sea cages and partly in coastal ponds with wild-caught fingerlings. In Queensland the traditional sea cage approach to marine fish farming is also viewed as damaging to coral reefs and other sensitive aquatic habitats. Intense scrutiny of sea-cage operations indicates these are limited prospects for marine fish farming in Queensland’s inshore waters. New sustainable yet profitable land based production methods must be employed in order to return value from the ongoing effort into marine finfish production. This need is heightened considering that prawn farmers are seeking alternative cropping opportunities in the wake of global oversupply and the impact of cheap imports on Australian prawn markets. Currently, no cost effective commercial systems are available for the intensive production of marine finfish in closed ‘zero discharge’ systems. Tank based marine recirculation facilities are cost prohibitive and 16 would fail to take advantage of Queensland’s favourable climate and existing pond aquaculture infrastructure. This CARD project will address the aforementioned issues by developing a new and more sustainable farming system for coastal areas with also potential for application to inland waters. The developing system combines the innovative design of floating raceways (FRs) with the concept of bioremediation. FRs, either made of plastic or cheap materials, have been trialled successfully in Japan, Australia and US. They function as flow through culture units that exchanges water at a rapid constant rate, thus enabling intensive stocking rates (up to 100 kg/m3) at low capital and operational cost. In comparison to net cages, FR’s return lower FCR, produce less waste (up to 30%) and require almost half the labour. Further, a combination of FR’s and bioremediating secondary crops could result in a closed/semi-closed system that would help remedy environmental impacts of marine aquaculture. A special feature of this developing system is its high applicability to small- scale farms using existing infrastructure with no major change in pond design. This project is expected to help boosting production of marine fish fingerlings and better use the existing shrimp ponds, of these many are abandoned, in coastal areas. These fit nicely into the CARD’s framework and aims, i.e. promoting productive technology addressing social, environmental and human resource development issues. Figure 1. In-Pond Floating Raceway in Grow-Out Pond/Reservoir at BIARC. 17 This project aims to develop the larval rearing and nursery capacity of marine finfish growers in Vietnam that is accessible, cost effective and environmentally sustainable. Through the targeted use of in pond floating raceways (FR) this project will assistance farmers develop their own intensive but durable and technically manageable larval rearing capacity. This capacity will be used to improve fingerling supply to the industry which is currently both costly and limited. In addition, advanced nursery capacity will also be developed using the same principles. Grow out of finfish in raceways to market size will also be investigated in this project in conjunction with Australian researchers. Researchers from the Queensland DPI&F will provide expertise in systems management, water quality management and waste remediation. Species proposed for study include grouper, cobia and barramundi. All activities will be conducted using ‘zero discharge’ principles where there is no net discharge of effluent. Information form these activities will be used to train staff from the UoF, its students, industry and other relevant stakeholders. Active involvement and contribution of different stakeholders will make this research highly relevant and applicable to the local aquaculture industries. During 2005/06 at the Bribie Island Aquaculture Research Centre (BIARC), grow-out trials for both mulloway (Argyrosomus japonicus) and the sand whiting (Sillago ciliata) have run for over 18 months with both species reaching an acceptable market size within this time. Two different sized raceways were used (Fig.3) – Nursery Raceways (whiting) with a working volume of 3,600 litres and Grow-Out Raceways (mulloway) with a working volume of 20,000 litres. Both were assessed for their capacity to produce market sized fish but with the two different species having large differences in both market size and growth rate. Whiting in the Australian market can be seen at premium prices from 60 grams onwards. The mulloway trial, of which fish have now reached over 1 kg, will continue to grow fish for a further 6 months into their premium price/size category of 2 - 2.5 kg. Materials and Methods In-Pond Floating Raceways Floating raceways at BIARC are simply constructed with treated hardwood floating platforms supported by 200 litre sealed plastic chemical storage drums (Fig.1 & 2). The raceway itself is constructed of 2mm high density polyethylene (HDPE) secured, and 18 essentially suspended from, the floating platform and end gates affixed to allow water both in and out through oyster mesh ‘windows’ but having the capability to retaining fish and even plankton if desired. Mesh size of these ‘windows’ varies according to species and life stage. The mesh ‘windows’ sit and slide in aluminium window frames (Fig.4) that are secured with 316 stainless steel screws and C-cup washers to the two end walls. The end walls are secured to the longitudinal section of the raceway by butting the two HDPE sheets together perpendicularly and securing (again with 316 stainless steel screws and C- cup washers) both to a 20 mm x 20 mm strip of compressed recycled plastic cut to the appropriate length (Fig.4) . More detailed construction information is contained in the Plan and Isometric drawings below (Fig.7&8). Figure 2. Raceway floating platform construction Airlifts and Air Supply A bank of eighteen PVC Ø90 mm pipes supplies air and water to each of the 20,000 litre grow-out raceways and is capable of delivering >1500 l/min or a 100% exchange in less than 15 minutes (12.7 min). This is reduced to only four PVC Ø90 mm pipes in the nursery raceways and supples 350 l/min or a 100% exchange in 14.5 minutes (Fig.5). These calculations are based on standard pressure (36 Kpa) and delivery readings at BIARC and will fluctuate accordingly dependent on those variables and biological processes, particularly fouling of airlifts (internal) and fouling of end gates reducing the volume of water in or out. Air is supplied to the raceways by means of a Ø50 mm flexible delivery line being serviced by the research station’s air delivery system. This system comprises three aeration blowers, 2 x Wade SR 113 and 1 x Robuschi SRB. The Wade SR113 is capable of delivering 202 litres/second of air and the Robuschi SRB is capable of delivering 100 L/S of air. The system has been installed to deliver 502 L/S maximum of air 19 at any one time. The aeration blowers are individually controlled by ABB Variable Speed Drive Units which are linked to the Central Management System (CMS). 20,000 litre 20,000 litre 3,600 litre Raceway 3,600 litre Raceway 3,600 litre Raceway 3,600 litre Raceway Figure 3. Nursery and Grow-Out Ra eway Schematic. Blue line indicates air supply manifold o uplifts. Figure 4 urned out of water showing aluminium window frames for housing raceway . Raceway upt o j tyster mesh screens and a c oint. close up of end wall and longitudinal section of 20 The CMS monitors temperature, pressure and speed. The signal uses a floating control algorithm to control the VSD speeds of the blowers. Blowers control to a set point (adjustable – currently 36Kpa) and shut down at 50Kpa and instigate an alarm. The air temperature is monitored by the CMS and an alarm raised at a set point of 100°C. Reticulation water temperature has a set point of 16.6C to maintain the supply air temperature at 21.6°C. After the air is cooled it is then accepted via a system of ABS and UPVC pipe work which delivers air to the grow-out pond/reservoir and the rest of the research site. Blowers are a displacement type and not of compressed air origin. Figure 5. PVC Nursery Airlift Supply Grow-out Pond/Reservoir Construction and Management The 1600m2 (40m x 40m) grow-out pond/reservoir is lined with a 2 mm HDPE liner with central drainage (Ø150 mm) and monk gate system leading into a large harvest pit. The pond is 2.4 metres deep at the monk and 2.0 metres deep at the shallow end. Water is delivered via PVC Ø150 mm pipe and circulated and aerated using 2 x 2hp paddlewheel aerators. This circulation allows waste material from the raceway to accumulate in the centre of the pond for easier discharge and to prevent this waste material being introduced back into the raceway via the airlift system. Pond and raceway water quality is taken twice daily with a YSI multimeter measuring pH, salinity, DO, secchi depth and temperature. Critical differences in dissolved oxygen readings between the pond and raceway were the only discrepancy in water quality measures between the raceways and the grow-out pond/reservoir. Pond water exchange was regulated using daily water quality measures and on average 10%/day was exchanged. Pond management required manipulation of 21 phytoplankton blooms to acquire a secchi depth of between 30 and 60 cm using water exchange and inorganic fertilisation when required. The inorganic fertiliser consisted of urea, MAP (mono-ammonium phosphate) and potassium nitrate in varying ratios. Fish are fed twice daily to satiation by hand and then the rest of the calculated ration added to autofeeders which supply the remaining ration either during the night or very early in the morning when feeding activity is usually at it’s greatest (Fig.6). Autofeeders relied on fish surface swimming action (foraging) to activate a suspended pendulum and activate pellet release. Whiting were fed a Ridley’s Aqua-Feed Native Fish Diet (Slow Sink) 52:12 (Dust - 3 mm) and 45:10 (4 – 6 mm) and the mulloway were fed a Ridley’s Aqua-Feed Barramundi Diet (Floating and Sinking) 50:12 and 43:20 (4 - 10 mm). Feeding activity, weather conditions and water quality parameters where also used to guide experienced technicians to adjust feed inputs on a daily basis. Feeding Activity 0 1 2 3 4 5 6 10 :0 0: 01 P M 10 :2 5: 34 P M 10 :5 1: 07 P M 11 :1 6: 40 P M 11 :4 2: 13 P M 12 :0 7: 46 A M 12 :3 3: 19 A M 12 :5 8: 52 A M 1: 24 :2 5 A M 1: 49 :5 8 A M 2: 15 :3 1 A M 2: 41 :0 4 A M 3: 06 :3 7 A M 3: 32 :1 0 A M 3: 57 :4 3 A M Feeding Activity Figure 6. Example of Autofeeder Output showing peaks in feeding activity. 22 Figure 7. Plan view of raceway construction Figure 8. Isometric View of raceway construction. 23 Evaluating Performance of In-Pond Floating Raceways Sand Whiting Sand whiting juveniles were produced from hormonally induced broodstock held at BIARC. Yolk-sac larvae (200,000 or 16/l) were stocked into pre-prepared plankton ponds and when weaned, the pond was harvested and using a VAKI Bioscanner Fish Counter™ , some 17,502 juvenile whiting averaging 5.52 g where stocked into a single nursery raceway (Trial 1) on the 8th July 2005. Biomass in the raceway was 26.84 kg/m3. The whiting grew well (Graph 1) and up until harvest on the 4th October 2005 they increased in average size and biomass to 12.62 g and 51.46 kg/m3 respectively. Specific growth rate (SGR) was 0.940 and survival for this period was 86%. On the 4th October 2005, when the biomass had reached 51.46 kg/m3 the single raceway was harvested and split into two similar nursery raceways (Trial 2). This halved the biomass in each raceway to 26.5 kg/m3. From the 4th October 2005 until the 15th December 2005 (11 weeks) the raceways increased in biomass from 26 kg/m³ to 69.24 kg/m³ with a SGR of 1.391 On the 6th January 2006 when the biomass peaked at 69.24 kg/m3 and the fish were showing signs of stress and dissolved oxygen levels proved difficult to maintain above 4 ppm, the two nursery raceways were harvested and graded such that only the top 50% grade was returned to the raceways (Trial 3). This lowered the biomass to approximately 45 kg/m3. Whiting by this stage were averaging 33.12 g. The whiting continued to be grown in the 2 raceways for a further 5 months when biomass peaked at 77.65 kg/m3 and again the decision was taken due to biological considerations to reduce the biomass by splitting 3 ways instead of 2. This reduced the biomass to 55 kg/m3 (approx.). This method of growing fish by manipulating biomass/density and monitoring growth rate, feed input, general health, critical water quality parameters has given the researchers confidence to predict whiting will grow well in a nursery raceway at densities up to 70 kg/m3. The research team had hoped to produce a predictive regression analysis factoring all of these aforementioned parameters into a raceway management equation but were unable to due to the ‘noise’ inherent in the data collected. Whiting appeared to grow equally well at all densities (low and high) up until they reached the ‘carrying capacity’ of the nursery raceways for this species. Trial 3 utilising 24 the top 50% grade had the lowest SGR and is probably demonstrative of the typical growth curve for this species of fish. Some of the larger fish were of a size to be reproductively mature. Further examination of these whiting will confirm this. Fish length, weight and routine health checks were carried out fortnightly during the trial until May 2006 (autumn) when mortalities started to appear after handling events. This mortality was subsequently put down to a secondary Flexibacter columnaris infection caused by excessive handling and the sudden drop in water temperature. Mortality ceased after handling was reduced or stopped. Fish recovered without the need for treatment. Whiting were generally well received in the whole fish (Fig.9) and fillet market. Butterflied and crumbed frozen fish retailed for more than $20/kg. Key Points: 1. Nursery raceways were successful in producing whiting in densities up to 70kg/m3. This equates to a total biomass of approximately 250 kg per unit. 2. The individual weight of whiting grown in nursery raceways increased from 5.52 g to 88.87 g in 9.5 months 3. FCR for the total nursery production was 1.8:1 4. Whiting biomass at one point increased from 26 kg/m3 to 70 kg/m3 in less than 11 weeks. 5. SGR ranged from 0.520 for Trial 3 to 1.391 for Trial 2 6. Whiting produced in nursery raceways were well received in the market and retailed whole for $10/kg and fillets up to $24/kg 25 Whiting Growth and Density 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 100.00 8/0 7/2 00 5 8/0 8/2 00 5 8/0 9/2 00 5 8/1 0/2 00 5 8/1 1/2 00 5 8/1 2/2 00 5 8/0 1/2 00 6 8/0 2/2 00 6 8/0 3/2 00 6 8/0 4/2 00 6 8/0 5/2 00 6 8/0 6/2 00 6 8/0 7/2 00 6 8/0 8/2 00 6 8/0 9/2 00 6 8/1 0/2 00 6 8/1 1/2 00 6 Time Av. Weight (gms) Density Kg/m3 Harvest Graph 1. Whiting Growth and Biomass/Density Increase for Nursery Raceways Table 1. Grow-out Pond/Reservoir Water Quality Summary G4 DO R1 DO R2 DO R5 DO R6 DO Temp pH Salinity Secchi Max 12.82 9.30 9.20 9.60 9.40 31.40 9.58 38.80 100 Min 4.32 3.70 3.20 2.80 2.10 15.30 6.65 34.20 25 Figure 9. Whiting from Nursery Raceways for sale 26 Figure 10. Diffuser being laid into the raceways for supplemental aeration. Mulloway Mulloway were spawned at a marine finfish hatchery, O’Donohue Sands in New South Wales. On the 8th February 2005 some 600,000 fertilised eggs were transported in seawater (10,000/l) via air freight to Brisbane then to BIARC by road. Mulloway eggs were acclimated and held in incubation tanks for 2 days to hatch. Approx 570,000 yolk- sac larvae were then stocked into a pre-prepared plankton pond. At harvest, the mulloway fingerlings were stocked into 30,000 l tanks whilst raceways were still being constructed. Delays due to injury of a critical staff member meant that construction deadlines were not met. In the 30,000 tanks the mulloway juveniles suffered ongoing disease issues and mortality due to Cryptocaryon irritans (White spot) as well as bacterial necrosis of tail fins. This tail erosion remained permanently disfiguring and can still be seen in market sized fish (Fig.7). These diseases were treated under veterinary supervision with formalin followed by freshwater baths and oxytetracyclene (OTC) respectively. A medicated feed 27 was also prescribed. Possible causes were handling stress, poor nutrition and high stocking densities. Finally on the 28th September that year the trials were able to commence with what were now apparently healthy fish. Grow-out raceways were used for the mulloway trials. These have a working volume of 20,000 litres. Two grow-out raceways were stocked – Raceway 5 (R5) and Raceway 6 (R6) with graded (by eye) fish. R5 was stocked with 1800 fish weighing on average 171 g. This equated to a biomass of 15.39 kg/m3. R6 was stocked with 3087 fish weighing on average 96 g. This equated to a biomass of 14.82 kg/m3 – similar to that of R5. Growth over the year was acceptable (Graph 2) and density in R6 topped 100 kg/m3. At such time DO levels were approaching critically low levels, as a result feeding activity was inhibited and there was evidence of compromised fish health. To maintain adequate DO at this time, supplemental aeration was required through a series of diffusers (Fig.10). These were simply constructed using bicycle tubes and a lathe tool to puncture up to 10,000 holes per lineal meter. Whilst it remained possible to maintain and grow mulloway at these densities the SGR dropped from 0.513 to 0.224 over this period. When the biomass/density of 90kg/m³ was obtained, growth rates stagnated, possible due to lack of feeding interest, until the density was reduced. Only supplementary aeration maintained DO levels above critical limits (4.0ppm) as the biomass approached 100kg/m³. In contrast, Raceway 5 was never allowed to exceed 80 kg/m3 and correspondingly the SGR was maintained between 0.458 and 0.644. All of the SGR figures given are for the entire grow-out season and acknowledgement needs to be given to the fact that seasonal winter temperatures in SE Qld will reduce pond water temperature to <160C. Although not capable of causing mortality for either species it does create a window of slow to no growth for a period of approximately 3 months. Key Points: 1. Grow-out raceways proved successful in producing mulloway at densities up to 100kg per cubic metre. This equates to a total of 2 tonne of fish per raceway. 2. Surface area of the production pond was 1600 m², equating to an equivalent production rate of more than 30 ton/ha or 3.125 kg/m² of pond production area. 3. Grow-out raceways produced a biomass increase from 15 to 100 kg/m³ in 11months 28 4. Mulloway were grown to market size in less than 10 months - 100g to 500g. Plate sized fish in 9 months and 170g to 1000g fillet sized fish in 14 months. 5. Average FCR in the grow out raceways was 1.6:1 Mulloway Raceway Growth and Density 0.00 20.00 40.00 60.00 80.00 100.00 120.00 28 /09 /20 05 28 /10 /20 05 30 /11 /20 05 9/0 1/2 00 6 10 /02 /20 06 15 /03 /20 06 20 /04 /20 06 24 /05 /20 06 27 /06 /20 06 19 /08 /20 06 4/1 0/2 00 6 5/1 0/2 00 6 11 /10 /20 06 18 /10 /20 06 25 /10 /20 06 30 /10 /20 06 2/1 1/2 00 6 8/1 1/2 00 6 9/1 1/2 00 6 15 /11 /20 06 18 /11 /20 06 22 /11 /20 06 25 /11 /20 06 29 /11 /20 06 6/1 2/2 00 6 8/1 2/2 00 6 12 /12 /20 06 13 /12 /20 06 15 /12 /20 06 Time Density (kg/m3) 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 Weight (kg) Kg/m3 (R5) Kg/m3 (R6) Av. Weight (R5) Av. Weight (R6) Harvest Graph 2. Mulloway Growth and Biomass/Density Increase for Grow-Out Raceways Table 2. Grow-out Pond/Reservoir Water Quality Summary G4 DO R1 DO R2 DO R5 DO R6 DO Temp pH Salinity Secchi Max 12.82 9.30 9.20 9.60 9.40 31.40 9.58 38.80 100 Min 4.32 3.70 3.20 2.80 2.10 15.30 6.65 34.20 25 Marketing Approximately 1000kg of mulloway were used for market analysis (Fig.11). The fish ranged in size from 400g through to 1.2kg, with a majority of the fish being less than 1kg. Two different market avenues were pursued. The first was retail sales to the general public by a local seafood outlet. Mulloway retailed for approximately $13/kg scaled, head on gilled and gutted fish, and approximately $16/kg for scaled, skin on fillets. The appearance and quality of fish was well received however there was continual request for larger sized fish. 29 The second marketing strategy employed the use of a wholesale fish marketer to distribute the product into restaurants through Brisbane and surrounding suburbs. Again the appearance and quality of the fish was well received. Feedback from chefs was in most cases highly complimentary. The product was deemed to be well suited the Caucasian community, having a firm white flesh with only a mild flavour. The product was generally not suited to Asian style preparation. The major restriction encountered in marketing the fish to restaurants was their size. Fish sold through the wholesaler were 500-900g in weight. These fish were sold as whole, plate sized fish. There was a general reluctance by consumers to try plate sized fish. As such there appears to be somewhat limited market for plate size fish in Brisbane. Feedback from chefs and restaurateurs was that consumers prefer fish be presented as skinless, boneless fillets. Therefore larger fish (2kg plus) would be more suitable to the local market and be more likely sustain higher production volume and may attract better prices. Increased exposure will allow recognition of the quality and suitably of mulloway to the local market. With the provision of consistent supply and fillet sized fish (2kg plus) it is believed that mulloway could maintain wholesale prices similar to that of Barramundi at $8-9/kg. Further research will be conducted to test the market acceptance of larger fillet sized fish. Figure 11. Mulloway from Grow-Out Raceways for Sale 30 Economic Analysis/Cost of Production Based on Australian conditions, our estimations of running costs, capital set up and depreciation, labour, feed inputs and operating we have determined that raceways are an economically viable alternative for grow-out production of marine finfish but like all systems there needs to be an economy of scale and regular supply to good markets. In our estimation, and based on previous experience with the barramundi industry in Australia, it is proposed that an aquaculture operation not producing 1000 kg/week for market can except lower prices, higher costs of production and lower production efficiencies. This equates to 26 grow-out raceways. This production level would establish an aquaculture operation in the market place and would demand competitive buying and selling power. Currently our best estimate for cost of production in raceways is approximately AUD$8/kg. This will improve over time and compares well with other production systems but without the large capital input. Table 3. Routine Labour Requirement for 4 x Nursery and 2 x Grow-out Raceways (Fig.3) Procedure Frequency Time (hrs/week) Water Quality/Pond Management 2 x Daily 4.25 Feeding 2 x Daily 7.5 Cleaning intake/outlet screens 2 x weekly x 8 units 4.5 Cleaning uplifts 1 x month x 8 units 2 Total Routine Labour 18.25 hrs/week for 54,400 litre raceway system (Approx AUD$6/wk/m3) One of the tangible advantages of raceway production is the lack of initial capital set up costs for ponds or recirculation operations which frequently run into the 100’s of 1000’s of $AUD for relatively small operations. Raceways are designed to be self contained production units requiring only a supply of air and a body of water (of appropriate quality) to float them in. Construction costs will also reduce as large scale production develops and raceway size is progressively made larger. This is evident from just our simple comparison of Grow-Out Raceway construction costs ($130/m3) Vs Nursery raceway construction costs ($335/m3). Labour costs will also reduce comparatively with larger system and more economy of scale. The barramundi industry in Qld currently utilises 1 FTE per 16 ton of barramundi produced. Our raceway trial utilised the equivalent of 1 31 FTE for the production of 10 ton. This is an extraordinary achievement in the first year to come close to other production systems that have been in place for many years. Grow-out Raceway Construction costs (2 x 20 m3) Material Cost (AUD$) Timber $1382.00 HDPE sheets $1723.20 PVC $509.20 Floats $240.00 Fastening materials $365.00 Transfer pump $535.00 Screening material $174.20 HDPE Plumbing $235.40 TOTAL $5164.00 or $130/m3 Nursery Raceway Construction costs (4 x 3.6 m3) 32 Material Cost (AUD$) Timber $1182.00 HDPE sheets $1723.20 PVC $278.60 Floats $240.00 Fastening materials $300.00 Transfer pump $535.00 Screening material $166.65 HDPE Plumbing $395.00 TOTAL $4820.45 or $335/m3 Conclusion and Recommendations Vietnam and Australia (more predominantly Queensland) lacks an efficient and sustainable nursery and grow-out production system that is simple and practical, cheap to set up and run and adaptable to the requirements of the species and climate in which the operation is conducted. Raceways offer a real alternative to the high capital set up and running costs of coastal pond based system and/or recirculating aquaculture systems (RAS). Our trials in Australia have demonstrated the validity of a raceway production system for fingerling and/or grow-out of a number of species and with increased efficiencies and experience, the researchers believe this type of system will surpass most other production units in terms of cost of production and flexibility (spatial and species). Further detailed economic will be conducted at the end of the trial and presented as part of the Final Report. Experience and results from these grow-out trials will enable the researchers to provide expertise in systems management, water quality management and waste remediation. All this work is directly applicable to the larval rearing and nursery focus being investigated in Vietnam by our project partners. Acknowledgements This report uses results of the Project ‘Intensive In-Pond Raceway Production of Marine Finfish’ CARD VIE 062/04 funded by CARD (Collaboration for Agriculture Research and Development) program through the Ministry of Agriculture and Rural Development of Vietnam. The research team would like to thank the Queensland Department of Primary Industries and Fisheries and our Vietnamese research colleagues ably led by Dr Tung Hoang (Director, International Centre for Research & Training, Nha Trang University) for their valuable help and support throughout this project. 33