Đề tài Development of in-Pond floating raceway technology for intensive farming of marine finfish

Collaboration for Agriculture and Rural Development (CARD) Program 72 DEVELOPMENT OF IN-POND FLOATING RACEWAY TECHNOLOGY FOR INTENSIVE FARMING OF MARINE FINFISH Project title: Intensive in-pond floating raceway production of marine finfish Project code: CARD 062/04 VIE Author: Hoang Tung, School of Biotechnology, International University, Vietnam National University Ho Chi Minh City, Email: htung@hcmiu.edu.vn Project Implementing organisations: Vietnamese organisation: Nha Trang University, Khanh Hoa Vietnamese Project Team Leader: Dr. Hoang Tung Australian Organisation: Queensland Department of Primary Industries & Fisheries Australian Personnel: Mr Michael Burke SUMMARY CARD project 062/04 VIE entitled ‘Intensive in-pond floating raceway production of marine finfish’ was conducted from August 2005 through August 2007 aiming to develop the larval rearing and nursery capacity of marine finfish production in Vietnam through the use of accessible, cost effective and environmentally sustainable technologies. After two year of implementation, both components of the project are all successful, achieving the expected outputs, including trial of in pond floating raceways with systems management, water quality management and waste remediation to grow-out marine finfish to market size; and capacity building for Nha Trang University. The final production trial at BIARC (Australian component) was to evaluate the suitability of raceways for extended grow-out of fish to 1.5 kg that confirmed fish husbandry (feeding, monitoring, harvesting) is easily managed in raceways either as a nursery system, as an intermediate grow-out system, or as an on-growing system. At the same time, research into water remediation strategies was also completed. Bio-flock technology was found to be the most promising technology to progress towards zero water discharge under Australian conditions. For the Vietnamese component the trial on zero-discharge system and trials on cobia and groupers were all conducted successfully. Growth performance and survival of the Malaba grouper in the floating raceways were outperformed that in any other nursing system. Mortality was, however, still high with cobia due to parasite infection in previous nursing stage. Dissemination of technology to farmers has been conducted various manners, including organization of workshops and exhibition booth, scientific publications, oral presentations at national and international conferences, temporary provision of floating raceways to local farmers for testing, provision of free-of-charge consultation for interested companies or individuals, incorporation of project outcomes into lecture notes for graduate and undergraduate aquaculture programs at Nha Trang University and production of a technical guideline and movie clip. These activities have brought the project results to the users. 1. Introduction According to FAO (2009) Vietnam ranks No.3 worldwide in term of aquaculture production. Thus, Vietnam should further develop its aquaculture industry to meet the increasing seafood demand of both domestic and export markets, and to improve the economics of coastal communities. Recent evaluation showed that the production of farmed marine fish reached only 5% of the target of 20,000 metric tons by 2010 set by the government for the 2001-2010 national aquaculture development program (Dr Phạm Anh Tuấn, personal communication). The shortage of CARD 062/04 VIE – In-pond floating raceways 73 quality fingerlings at large sizes has been considered as one of the major barriers for marine fish farming in Vietnam, not to mention significant reduction of purchasing power due to the recent global economy crisis. During 2000-2005 many projects were conducted on the development of technologies for artificial propagation of high-value marine fish species such as barramundi (Lates calcarifer), groupers (Epinephelus spp.) and cobia (Rachycentron canadum), resulting in some remarkable successes (Le Xan 2005, Nguyen Van Su 2005). As a result the production of marine fish fingerlings increased significantly, meeting partially the demand of local fish farmers. Fingerling size was, however, not large enough for direct stocking for grow-out in sea cages or coastal ponds. Low survival in the early stages of farming was typically reported. Advanced nursing of fish fingerlings to 10 to 12 cm total body length in indoor facilities is costly and cannot produce huge numbers of fish due to limitations of both nursing area and capital investment. Meanwhile, advanced nursing of fish in earthen ponds was not effective and associated with many difficulties in feeding, husbandry and health management. To address these constraints our CARD project 062/04 VIE entitled ‘Intensive in-pond floating raceway production of marine finfish’ was conducted between 2005-2007. The project was financially and technically supported by the Collaboration for Agriculture and Development Program (CARD), Bribie Island Aquaculture Research Center – QDPI&F (Australia), Nha Trang University (Khanh Hoa, Vietnam), Grobest Imei Vietnam, and Khanh Hoa Fisheries Promotion Center. The CARD VIE062/04 project adopted the operational principles of in-pond floating raceway which have been successfully tested in the USA (Masser & Lazur, 1997), Germany (Gottschalk et al. 2005) and Australia (Collins & Hoang Tung, unpublished) in order to (i) design and construct in-pond floating raceways using local materials, (ii) conduct farming/nursing trials on high value species and (iii) develop and introduce the established technology to the local aquaculture industries. In-pond floating raceways are basically similar to elongated rectangular tanks which can be made of different materials such as aluminium, molded plastic or wooden frame and HDPE plastic sheet. They are either self-floating or supported by a pontoon installed in the reservoir pond. Water is continuously circulated through the raceway by airlifts. This type of pumping has been considered as an effective means for moving water when pumping head is low. In addition, incoming water is enriched with oxygen in the airlifts. Together with high water exchange rate it allows high densities of farmed fish in the raceway, e.g. 70 - 100 kg/m3. In-pond floating raceway is also convenient for the farmers to handle and manage. Observation on feeding, health and behavior of the farmed fish, grading and harvesting are all easily conducted as fish are concentrated in a small volume of water. Thus, labor cost can be reduced by 50%. Predation is effectively excluded since the inlet, outlet and surface of the raceway are covered with net. If treatments are needed for the farmed fish, farmers can turn the raceway into a ‘close’ tank by temporarily ceasing the operation of airlifts and blocking the outlet. Thank to this remarkable advantage, prophylactic treatment for fish is highly effective and economical. Previous trials in the USA, Germany and Australia also showed that feed efficiency of fish cultured in floating raceways is significantly improved compared with other farming systems. Feed cost and waste from the system are reduced by approximately 30%. Generally, floating raceways have many advantage over the traditional nursing systems and should be introduced extensively. However, the application of this technology is limited by unreliable electricity supply and high electricity cost in the developing countries. Thus, the focus of our CARD VIE062/04 was different for Australia and Vietnam. The Australian component aimed to develop grow-out technology using in-pond floating raceways to improve overall management and reduce labor cost. The Vietnamese component focused on advanced nursing of marine finfish fingerling in order to meet the urgent demand for large fingerlings and to overcome the limitations of high capital Hoang Tung 74 investment and high operation costs by fast turn-over rate that is usually achievable in fingerling production. After two years of implementation (August 2005 - August 2007) both components of the project are all successful, achieving the expected outputs, including capacity building for Nha Trang University. This report presents the obtained results of the project with more emphasis on the SMART floating raceway system and the advanced nursing technology developed by the Vietnam component. 2. Research contents and methods The CARD project 062/04 VIE ‘Intensive in- pond floating raceway production of marine fish’ is considered as an R&D project rather than a pure research one with the following specific activities 2.1 Design in-pond floating raceway for grow-out of marine finfish in Australia, trial operation and evaluation Mulloway (Argyrosomus japonicus) and whiting (Sillago ciliata) were used as the model species for trials in Australia from 2005 – 2006. Based on the biology of these species and production targets, two types of floating raceways were designed and constructed: 3.6 m3 for nursing grow-out of whiting to the size of 60 g/individual and 20 m3 for grow-out of Mulloway to the size of 2,000 g/individual. Six raceways were made by wooden frame and 2- mm HDPE canvas. The raceways were placed in a grow-out pond of 1600 m2 (40*40 m), 2 m deep and lined with 2-mm HDPE. The duration of trials was up to 18 months. Ridley’s Aqua-Feed Native Fish Diet (low sinking, granular size of 1 - 3 mm and 4 - 6 mm) was used to culture whiting. Mulloway were fed with the floating and sinking Ridley’s Aqua-Feed Barramundi Diet feed with granule size of 4 – 10 mm. Feeding rate was adjusted daily depending on the recorded actual consumption by fish, weather condition and water quality. Regular recording of the important data on water quality, feeding amount, growth rate and survival was conducted to evaluate the efficiency of system (see the milestone reports 2 & 4, Burke & Tung 2006 for more details). 2.2 Design in-pond floating raceway for advanced nursing of marine finfish in Vietnam, trial operation and evaluation The component conducted in Vietnam focused on advanced nursing of marine finfish fingerlings from 2 – 4 cm to 10 – 15 cm body length. Abandoned shrimp ponds due to virulent diseases along the central coast of Vietnam were targeted. Fiberglass was selected as the material to build floating raceway. This material makes the raceway light, solid and more durable thus enhancing its mobility, convenience for transportation and installation, ease in cleaning. The raceways are named SMART, an abbreviation of Sustainable Mariculture Technology. Based on the biology of the model species; requirement for water exchange rate and waste discharge, hydraulic dynamic principles and the results of previous studies the CARD VIE062/04 has designed and tested a system consisted to six SMART-1 raceways 3-m3 working volume each in the first year (2005– 2006). The tested species included red tilapia (Oreochromis sp.), barramundi (Lates calcarifer) and mangrove jack (Lutjanus argentimacus). The SMART-1 raceways were attached on a pontoon constructed with wooden frame and 200-L plastic drums. All were placed in a reservoir pond of 2000 m2, 1.7 m deep. The duration of each trial was about three to four weeks (Lu The Phuong 2006). Water in the pond was circulated by portioning the pond with plastic sheet in the middle and using a 2-hp paddle wheel. No water exchange was conducted during eleven months of different trials. Water quality, feed amount, growth rate and survival of fish were periodically monitored for evaluation (for more details see Burke & Tung 2006). Based on the analysis of SMART-1 performance, the second version SMART-2 (6 m3, self-floating) was designed, manufactured and tested in the second year of the project. This was to improve productivity up to commercial scale. In the second year more trials on nursing barramundi (Lates calcarifer), Malaba grouper (Epinephelus malabaricus) and cobia (Rachycentron canadum) were conducted simultaneously with the trial on zero-exchange water system (for more details Burke et al. 2007). CARD 062/04 VIE – In-pond floating raceways 75 2.3 Investigate on the potential of building the zero-exchange in-pond floating raceway system for nursing marine finfish The trials were conducted at Bribie Island Aquaculture Research Centre in Australia and at Khanh Hoa Fisheries Promotion Center in Vietnam during the second year of the project. In Australia fish were cultured in floating raceways placed in a reservoir pond. Discharged water was treated by biofloc technology and seaweed. In Vietnam marine fish fingerlings were nursed in SMART floating raceways placed in a reservoir pond stocked with giant tiger prawn (Penaeus monodon) and red tilapia (Oreochromis sp.). No water exchange was conducted during the trial period (for more details see Burke et al. 2007). 2.4 Dissemination of technology to farmers The dissemination of research outcomes and technology was conducted in various manners, including organization of workshops and exhibition booth, scientific publications, oral presentations at national and international conferences, temporary provision of floating raceways to local farmers for testing, provision of free-of-charge consultation for interested companies or individuals, incorporation of project outcomes into lecture notes for graduate and undergraduate aquaculture programs at Nha Trang University and production of a technical guideline and movie clip. 2.5 Capacity building for Vietnamese staff This activity was conducted by sending one junior lecturer to Australia for short-term training, supporting and supervising two MSc students, organizing relevant seminars for staff of the Faculty of Aquaculture – Nha Trang University and Khanh Hoa Fisheries Promotion Center and get them involved in project activities where appropriate. 3. Research results and discussions 3.1 Design in-pond floating raceway for grow-out of marine finfish in Australia, trial operation and evaluation The structure of floating raceway used in BIARC is relatively simple (see Burke & Tung 2006). The supporting frame is made by waterproof treated wood and is floated by 200- L plastic drums. The body of the raceway is made of 2 mm thick HDPE, hung on the pontoon by rust-proof pins. The airlift system installed for the 20m3 grow-out raceway consists of eighteen Ø90-mm PVC pipes that results in a pumping rate of more than 1500 L/min. It takes circa 13 minutes to completely exchange the raceways with new water. For the nursing raceways the airlift system consists of four Ø90-mm PVC pipes. Pumping rate is 350 L/min or 14.5 minutes to complete 100% water exchange. The air compressor system is operated automatically by a Center Management System (CMS) that can control temperature, pressure and air flow. The standard pressure is maintained at 36 Kpa. Automatic feeding machines are used. Fig. 1. Floating raceway 20 m3 for grow-out marine finfish in Australia and the harvested whiting Trial on grow-out of whiting was successful at a density of 70 kg/m3 (see Burke & Tung 2006). After 9.5 months the farmed fish reached 88.9 g from 5.5 g at stocking. Standing biomass increased from 26 kg/m3 to 70 kg/m3 in nearly eleven weeks. Food conversion ratio was estimated at 1.8. The harvested whiting were well accepted by customers when placed in local supermarkets. Retail price for whiting as whole or fillet was $ 10/kg and $ 24/kg, respectively. Trial on Mulloway showed that this species can be reared at densities up to 100 kg/m3 or two metric tons per a 20 m3 raceway. Standing biomass increased from 15 kg to 100 kg/m3 in eleven months of culture. Fish weight was 500 g/individual and 1000 g/individual Hoang Tung 76 after 9 months and 14 months, respectively. FCR was 1.6 on average. More importantly, the trials demonstrated that husbandry (feeding, observation, grading, health care) and harvesting in raceway were highly convenient for all culture stages from nursing to grow-out. 3.2 Design in-pond floating raceway for advanced nursing of marine finfish in Vietnam, trial operation and evaluation The raceways were designed and tested successfully with two versions SMART-1 and SMART-2. They were placed in a 2000-m2 reservoir pond. The pond was partitioned by a plastic wall right in the middle of the pond. This helped directing water to flow around the pond with the aid of a 2-hp paddle wheel (Figure 2). Detailed design of the system is presented in the Milestone of the project 2&4 (Burke & Tung 2006) and in the publications of Phuong (2006), Tung et al. (2007). The operational volume of SMART-1 is 3 m3 (Figure 2). Water flow through the raceway is circa of 350 L/min, equivalent to 700% water exchange in one hour. SMART-1 design helped circulate water within the raceway as expected, facilitating waste collection and allowing high densities of nursed fish (up to 80 kg/m3 at harvest). Fig. 2. System arrangement Fig. 3. SMART-1 floating raceway A few drawbacks were, however, identified with the design of SMART-1 version. The raceways were attached to the supporting pontoon thus reducing its mobility and making cleaning difficult. The buoyancy of the pontoon remarkably depended on the numbers of workers working on it, causing negative impact on efficiency of the airlift system. There was no waste collector for SMART-1 although the accumulated wastes at the end of the raceway could be easily siphoned out once a day (Burke & Tung 2006; Tung et al. 2007). These drawbacks were well addressed in the second version SMART-2 (Hoang Tung & Khanh 2008). The operational volume of SMART-2 is six m3, double that of SMART-1. It is self-floating, i.e. requires no supporting structure. Its light weight (400 kg) allows easy transportation and installation. The raceway could be put immediately in operation after placing in a reservoir pond (Figure 4). The airlift system can be easily installed and removed for cleaning. Surface water of the reservoir pond is used to exchange with the raceway rather from lower layers as for SMART-1. Hence, SMART-2 can be placed in relatively shallow ponds, i.e. with water depths between 100 and 120 cm, without no contamination of the dirt from the pond bottom. SMART-2 also has a simple waste collector at the end of the raceway, making it more convenient and effective in cleaning than SMART-1. Fig. 4. Floating raceway version SMART-2 Paddle wheel Partitioned wall Floating raceways Monk Air compressorsAir line Walkway CARD 062/04 VIE – In-pond floating raceways 77 The nursing trials using SMART-1 and SMART-2 floating raceways both obtained good results. In addition a protocol of using Grobest shrimp pellets manually coated with vitamin mix and squid oil was successfully developed and applied. This improved profitability significantly while ensuring the quality of nursed fish. If applied properly the nursing protocols recommended by Tung et al. (2009) can result in 85%, 90-95%, 60% survival after 40-45 days of nursing for barramundi, grouper and cobia, respectively. In addition, production cost is significantly lower than that for advanced nursing in tanks, ponds or cages (Tung et al. 2008). Table 2. Fingerling size and production cost of marine fish nursed in SMART floating raceway (at the market price in 2008) Barramundi Malaba grouper Cobia Harvest size (mm long) 100 120 200 Production cost (VND) 1551 7391 9596 Market price (VND) 7000 16000 20000 Profit return 2.82 1.16 1.08 3.3 Investigation on the potential of developing a zero-exchange system for growing/nursing marin