Developing and integrating sustainable aquaculture in degraded agricultural areas using low salinity groundwater from shallow aquifers relies on production strategies for growth and survival of salt-tolerant freshwater species and estuarine/marine species. Species have been selected for research and development based on sound technology already existing for culture of these species in ‘natural’ freshwater, estuarine or coastal environment and/or an existing industry for seedstock production.
Degraded agricultural land is a problem common to both India and Australia. Large-scale irrigated agriculture, practiced in semi-arid and arid areas can create water-logging and salinity. Rising groundwater tables, both of high quality (freshwater) and low quality (saline) contribute to and are causal factors in water-logging and salinity. In India approximately 8.7 million hectares of land is salt affected, in Australia 2.5 million hectares. Management options severely constrict agricultural output on what is already marginal land. In Australia one management method is pumping rising saline groundwater out of shallow aquifers into large ponds, allowing evaporation to remove the water. These schemes are, however, expensive and non-productive for outputs. In India land ownership issues and cost have impeded the adoption of this approach.
The use of aquaculture in saline ponds offers a potential solution and incentive to utilise such schemes. Demand for seafood is rising worldwide, increasing pressures on fisheries. Many are in danger of being overfished, with declining catch levels. Long-term overfishing can also result in the collapse of fisheries. To alleviate these pressures aquaculture is being seen as a viable alternative, including as a potential means of delivering outputs and profitability in rehabilitating saline lands.
Project research began formally in July 2004. In India, major progress was made with larval rearing of the Giant Freshwater Prawn (GFP), Macrobrachium rosenbergii, in saline groundwater at the Central Institute of Fisheries Education (CIFE) Rohtak Centre in the State of Haryana. Saline groundwater (12 ppt) pumped directly from the ground is not suitable for larval rearing of GFP as all larvae died within 5 days after hatching. Analysis of the ionic composition of the inland saline groundwater (ISG) showed that concentrations of potassium and magnesium were much lower and calcium was much higher than those found in the same salinity coastal seawater (CS). Methods were developed to alter the concentration of these ions in ISG to approximate CS concentrations and GFP larvae survived and grew through all 11 larval stages and successfully metamorphosed into post larvae. This represents the first account of successful post larval production of GFP in ISG. A small-scale commercial GFP hatchery will be constructed at the Rohtak Centre to continue replicated experiments and also to produce post larval seed for supply to local growout farms, which are developing in Haryana. Research into development of growout technology of GFP in ISG did not commence as the Spring/Summer growing season was missed due to delays in starting the project.
In Australia, an experiment was completed to (1) evaluate the performance of rainbow trout in plastic-lined ponds at the ISARC (2) provide production data to allow bio-economic modelling (3) obtain feedback on market acceptance of harvested trout. Approximately 9000 rainbow trout smolt (39g average weight) were stocked into 5, 500m2 ponds filled with 25 ppt ISG at the Inland Saline Aquaculture Research Centre (ISARC) in early May 2004. Trout grew and survived extremely well following stocking until mid July when fish in several ponds stopped feeding and started dying. Poor water quality, especially high concentrations of suspended organic matter due to inadequate exchange of new ISG was the causative factor. Prevailing drought conditions had limited the saline groundwater pumping. Measures to alleviate the problem included routine harvest of surviving fish and transfer to new ponds filled with clean saline groundwater, and the installation of a new pipeline and diesel pump by Murray Irrigation Limited to provide saline groundwater directly from the subsurface drainage scheme. Following adoption of the new pond management procedures trout continued to grow well and fish stopped dying. Approximately 500 kg of fresh and smoked trout were sold by November 2004 through retail outlets in the local community and market acceptance was high.
In summer 2003/04 an experiment was conducted to determine the effect of greenhouse covers on growth and survival of black tiger prawns, P. monodon. Two, 500m2 ponds were covered with a cheap, inflatable greenhouse cover and two ponds were left uncovered. Fifteen day old post larval prawns were stocked into each pond (50 prawns/m2) filled with saline groundwater (20 ppt; fortified with 80-100% K+ as in same salinity seawater) and ponds were managed similarly to coastal ponds. The greenhouses were effective at increasing average pond water temperature but excessively hot air could not be easily vented on hot days. This caused pond water temperatures to exceed 35oC and all prawns died in both greenhouse-covered ponds within 3 weeks of stocking. After 112 days, prawns in ambient ponds were small (4.3 g) with survival of 64.6% and did not reach market-size before ambient pond temperatures were too cold for growth. A floating solar cover greenhouse cover was laid directly onto the water surface of one pond with prawns stocked from the ambient treatment ponds. Pond water temperature was increased from 20-23oC to 25-30.3oC during March to late April 2004. After 59 days, prawns had grown significantly and were harvested with an average weight of 19 g. These results demonstrate that floating solar covers are effective at increasing pond water temperatures and that prawns grew in covered ponds at rates similar to that in coastal ponds. This needs further replicated research to determine if long-term management of floating covers is feasible and if cheap, effective covers can be designed.
Short-term bioassays and an eight month growout trial in tanks demonstrated that mulloway, Argyrosomus japonicus, require fortification of potassium in ISG (13-35 ppt) from ISARC to provide 50-100% of the same concentration as that found in same salinity seawater. Once this was done, mulloway survived and grew in ISG as well as in CS. A long-term growout experiment is planned for 2005/06 to determine the performance of mulloway in ponds covered with floating solar covers.
Project research in Australia began formally in July 2004 but was delayed until November 2004 in India. In India, major progress was made with larval rearing of the Giant Freshwater Prawn (GFP), Macrobrachium rosenbergii, in saline groundwater at the Central Institute of Fisheries Education (CIFE) Rohtak Centre in the State of Haryana. Saline groundwater (12 ppt) pumped directly from the ground is not suitable for larval rearing of GFP as all larvae died within 5 days after hatching. Analysis of the ionic composition of the inland saline groundwater (ISG) showed that concentrations of potassium and magnesium were much lower and calcium was much higher than those found in the same salinity coastal seawater (CS). Methods were developed to alter the concentration of these ions in ISG to approximate CS concentrations and GFP larvae survived and grew through all 11 larval stages and successfully metamorphosed into post larvae. This represents the first account of successful post larval production of GFP in ISG. A small-scale commercial GFP hatchery is under construction at the Rohtak Centre to continue replicated experiments and also to produce post larval seed for supply to local growout farms, which are developing in Haryana. Research into development of growout technology of GFP in ISG did not commence as the Spring/Summer of 2005 growing season was missed due to delays in starting the project and severe waterlogging of the research site after the monsoon. Waterlogging prevented the construction of experiment greenhouses and evaporation ponds for disposal of saline groundwater.
In Australia, two experiments in successive winters of 2004/05 (reported earlier) and 2005/06 have been completed to (1) evaluate the performance of rainbow trout in plastic-lined ponds at the ISARC (2) provide production data to allow bio-economic modelling (3) obtain feedback on market acceptance of harvested trout.
Results demonstrate that the saline water pumped directly from the ground at ISARC is suitable for production of rainbow trout and that air and water temperatures are suitable (cool) for approximately 7 months/yr for optimal growth of trout. Harvesting of market-size (300g+) trout commenced in September 2005, 4 months after stocking and continued until December 2005. Approximately 500 kg of fresh trout was sold through retail outlets in the local community of Deniliquin, Barham, Finley and Wakool with excellent market acceptance.
In summer 2004/05 an experiment was conducted to determine the effect of greenhouse covers on growth and survival of kuruma prawns, P. japonicus. Six, 2000-L tanks were filled with potassium fortified saline groundwater (35ppt) and each tank was stocked with 150 post-larval prawns (0.1 g average weight). Three tanks were covered with a polysheet and three tanks remained open to ambient environmental conditions. Prawns were fed and managed according to normal pond culture methods. After 131 days, prawns grown in the covered tanks were 7.3 g and twice the weight of prawns grown in uncovered tanks (3.8g). Water temperatures in the covered tanks were 2-5 oC warmer on average than that in uncovered tanks and was the likely factor contributing to increased growth in covered tanks.
An experiment to evaluate the performance of juvenile mulloway in ponds covered with floating solar covers was initiated in May 2005 however a severe storm soon after stocking destroyed the covers in two ponds. The experiment was terminated while the floating covers were repaired. Mulloway held in uncovered, ambient ponds during winter did not grow but survival was high. The experiment was restarted in November 2005 and will continue until December 2006.
All key project activities were successfully completed during the reporting period. In India, research focused on refinement of techniques for larval rearing and growout of giant freshwater prawns (GFP) in low salinity groundwater (SG). In addition, large-scale, pilot-commercial production of GFP post-larvae (PL) was done using laboratory grade potassium to fortify the SG. A total of 200,000 PL were produced after broodstock prawns were successfully held in indoor tanks during winter and induced to spawn by March. The PL were sold to government and commercial growout farms in Mizoram, Madhya Pradesh, Bihar and Himachal Pradesh. This is the first large-scale production of GFP post-larvae using SG.
Replicated larval and growout experiments included:
1. An experiment designed to determine the minimum concentration of potassium needed in SG for successful culture of GFP larvae. PL reared in saline groundwater (12ppt) which was fortified with 80% of the concentration in equivalent salinity seawater grew and survived at similar rates to those cultured in water fortified at 100% concentration, thus reducing the cost of fortification of SG for larval rearing by 20%.
2. An experiment designed to determine the effects of potassium concentration (0, 70 and 100%) in 7ppt SG and stocking density (30 and 45 PL/m2) of PL. After 30 days all PL grown in raw (no potassium added) SG died but PL held in 70 and 100% fortified SG had average survival of 88.3 and 85.8%. Growth was slightly reduced when stocking density was 45 PL/m2.
3. An experiment designed to determine the effects of salinity (5 and 10 ppt) and potassium fortification (0 and 100%) on growth and survival of PL. After 45 days, survival of PL in raw SG was 11.6% compared with 96.6% for PL held in 100% SG. In 10 ppt SG without potassium addition, all PL died however 33.3% of PL’s survived in SG which was fortified with potassium.
4. A field experiment designed to evaluate nursery production of nursery production of PL in raw, low salinity (4 ppt) SG. Two cement ponds (0.045 ha) were stocked with 267,000 PL and cultured using standard techniques for 45 days. PL grew well with mean survival of 61%.
5. A field experiment designed to evaluate nursery production of PL in 7-9 ppt SG at three different stocking densities (SD; 250,000, 350,000 and 500,000 PL/ha) in 200m2 ponds (2 ponds per treatment). After 45 days survival in each SD was 30, 22.6 and 10.5%, respectively. This experiment will be repeated in 2007 to evaluate performance of PL in ponds filled with potassium fortified SG (7-9 ppt)
6. A field experiment designed to evaluate performance of GFP grown out in concrete ponds (0.045 ha) filled with unfortified, low salinity (3-4 ppt) SG. Three ponds were each stocked with 58,900 PL45 and cultured for 3 months. Survival after 3 months ranged from 61-90.2% and production averaged 1266 kg/ha, which is approximately 20% greater than standard freshwater pond production of GFP in India.
7. A field experiment designed to evaluate performance of GFP grown out in earthen ponds (0.1 ha; 2 ponds) in high saline SG (7-9 ppt). After 3 months survival was 20% (163kg) and 0%. This experiment will be repeated in 2007 using potassium fortified SG.
8. A field experiment designed to evaluate performance of GFP grown out in earthen ponds filled with moderately saline, raw SG (7-9 ppt) in polyculture with Indian major carp. Two ponds were each stocked with 50,000 PL/ha and 10,000 carp/ha and cultured for 3 months. After 90 days survival of prawns was25 and 32% but all fish had died. This experiment will be repeated in 2007 with potassium fortified SG
9. An experiment designed to evaluate survival and maturation of broodstock GFP held during winter in earthen ponds and covered with a polyhouse. This experiment was started in December 2006 and will continue through winter in 2007.
In Australia, research focused on evaluation of solar sheet covers for temperature manipulation of ponds and repeated evaluation of growout of rainbow trout in plastic-lined ponds during winter.
Replicated experiments included:
1. An experiment designed to determine the efficacy of floating solar covers on performance of mulloway in plastic-lined ponds (500 m2). Two ponds were covered and two ponds were kept uncovered an each pond was stocked with 500 juvenile mulloway. Water quality data was collected daily to information on temperature, DO, CO2, pH, salinity. After 5 months, ponds were harvested. The solar covers increased water temperature in winter by approximately 1.5oC and in summer by 3.0oC compared with ambient ponds. Mulloway were also 20% larger in solar covered ponds, thus indicating that solar covers are useful in increasing pond temperatures. However, floating solar covers were expensive, difficult to maintain (i.e. biofouling, blew away with wind) and hard to operate (e.g. access to fish for feeding and sampling was difficult).
2. Rainbow trout were stocked into 4, 500m2 ponds and operated on flow-through basis with raw SG (15-35 ppt) on a pilot-commercial basis Trout reached market size within 3 months and harvesting continued for a further 3 months. Trout were sold fresh to 4 outlets on the local markets (Deniliquin, Finley, Wakool, Barham) and consumer acceptance was extremely high.
3. A small-scale experiment designed to evaluate the performance of rainbow trout in a raceway system during winter-spring 2006. A total of 103 rainbow trout (123 g) were stocked into each of 2 x 2000L tanks. Each tank was fed with raw groundwater from the delivery pipeline, with a 100% turnover every 15min. The fish grew from 123g to 455g with 83% survival after 5 months. The water was high in CO2 (>45mg/L) and has a pH of 6.9-7.1. Salinity was mostly 10-18ppt. Unfortunately all fish died following a power failure which resulted in groundwater salinity increasing rapidly from 10-18 ppt to 45 ppt.
The project in India has focussed on development of technology for hatchery and growout production of giant freshwater prawn, Macrobrachium rosenbergii, in shallow water table, saline groundwater (4-10ppt). Excellent progress has been made towards achieving project objectives and the last 12 months has largely concentrated on validation studies of technology developed in the first two years of the project.
Major achievements include:
Identification of ionic imbalances in raw saline groundwater (low K+, high Ca2+ & Mg2+) compared with seawater
Development of a cheap, efficient method to ameliorate the chemical imbalances and make the saline groundwater suitable for Macrobrachium larval rearing
Reliably produced 100’s of thousands of post-larval (PL) Macrobrachium per annum
Sale of juvenile Macrobrachium to local and interstate commercial and research facilities
Increas in the hatchery capacity at the Rohtak Centre by extending the existing hatchery using ACIAR funds. CIFE subsequently constructed another commercial hatchery/laboratory for production of Macrobrachium and fish seed
Construction and evaluation of polyhouses over ponds for winter maintenance of brooder Macrobrachium
Successful maturation of brooder Macrobrachium during winter in polyhouse-covered ponds and produced viable eggs and larvae at the beginning of the Spring/Summer growing season.
Successful maintenance of juvenile Macrobrachium in polyhouses during winter with 90% survival. This will allow early stocking of ponds with advanced prawns
Determination of optimal salinity and ionic fortification protocols of saline groundwater for nursery production of juvenile Macrobrachium
Evaluation of growth and survival of Macrobrachium in commercial-scale ponds filled with saline groundwater from 4-10 ppt. Production in saline groundwater of 4 ppt was approximately 1200 kg/ha which is greater than commonly produced in coastal, freshwater ponds
Identification of the need to evaluate methods to reduce moult entrapment syndrome in hatchery production
Identification of the need to further evaluate and develop technology for polyculture of carp and Macrobrachium
Following the success of the ACIAR project ICAR/CIFE have recognised inland saline aquaculture as a niche area of research and significant funding has been provided through several sources including (1) ICAR Mega Seed Project. A new hatchery at Rohtak Centre has been constructed to produce seed prawns and several marine fish species (2) National Agricultural Innovation Project, NAIP, to construct new experiment and commercial ponds at the Rohtak Centre for production of prawn and fish species.
Approval to extend the project for 6 months in India was granted to complete some summer trials which were investigating broodstock management and hatchery production.
In Australia, all project activities were successfully completed by June 2007. The final growout experiment with mulloway was completed and in excess of 1000, 1kg mulloway were sold on the local market (Deniliquin, Finley, Barham and Wakool) at $10/kg farm-gate. Consumer demand and acceptance was high as the mulloway was an excellent quality. Mulloway grown in saline groundwater at the Inland Saline Aquaculture Research Centre grew well with Food conversion of 1.6:1 when water temperatures were >16oC. However, extended winters resulted in slow growth. It is unlikely that production of mulloway in ponds in saline groundwater in southern Australia will be economically viable.
The final evaluation of production of rainbow trout in raceways using saline groundwater was completed and confirmed the technical and economic viability of this activity. Commercialisation of this activity is now underway with the formation of a consortium including an agribusiness R&D group, commercial freshwater trout farmers, saline groundwater managers and the Seafood CRC, which has developed a business plan and funding to construct a commercial demonstration farm has been approved. The farm will be capable of producing 200t trout/year and will be a showcase for inland saline trout farming in anticipation that the technology will be transferred and adopted at other inland saline sites.