Inland Saline Aquaculture Research Centre - Wakool
Rainbow trout fingerlings. Rainbow trout have emerged from trials as one of the best performing species in inland aquaculture
Inland saline aquaculture is a new area of aquaculture research and development in Australia. It involves culture of various species of marine, euryhaline, diadromous or freshwater-salt tolerant juveniles in saline groundwater from inland locations. Expansion of coastal aquaculture is limited by a shortage of suitable sites with the necessary water quality, depth and proximity to land-based infrastructure, high land cost or environmental value, conflict with coastal land uses including tourism and real or perceived environmental concerns. Saline groundwater is abundant in Australia and other arid parts of the world and there is growing interest in developing commercial inland saline aquaculture.
Salinity and inland aquaculture
NSW DPI is involved in a collaborative research program with Murray Irrigation near Wakool, NSW to develop an inland saline aquaculture industry. Salinity affects more then 2.5 million hectares of Australia’s interior and it is estimated that this area will increase fourfold within 40 years. In 2002, the Inland Saline Aquaculture Research Centre (ISARC) was established to evaluate the potential of various species of salt tolerant finfish and crustacean species for inland saline aquaculture. The facility includes 6 small plastic-lined ponds, an experimental tank system and a temperature controlled room. Fresh and saline waters of different salinity are available. ISARC is located at the Wakool-Tullakool Sub-Surface Drainage Scheme (WTSSDS), the largest evaporation scheme in Australia disposing of 35,000ML of saline water each year. The scheme comprises of 60 bore pumps and 1600ha of evaporation ponds for salt interception and disposal. It is estimated that the scheme has helped return 50,000 hectares of unproductive salt-degraded land back to productive farming.
Adding potash counteracts a potassium deficiency found in saline ground water
Research at ISARC indicated that the inland saline ground water from the WTSSDS had 95% less potassium than marine water and as such was not initially suitable for survival and growth of marine species. This research has been supported by ACIAR (Australian Centre for International Agricultural Research) and the FRDC/DAFF project through the National Aquaculture Council on coordinating inland saline aquaculture research in Australia. A method was developed to counteract the deficiency by adding potash to the water. Initial small-scale experiments demonstrated marine species survived and grew in fortified inland saline groundwater at similar growth rates reported for the species in marine water. Potassium addition is not required for silver perch and rainbow trout as they grew well in raw inland saline groundwater.
Pilot-scale commercial production
Recently, pilot-scale commercial production of black tiger prawns, snapper, mulloway and rainbow trout has been completed. The research facility has also evaluated silver perch, brown trout, Atlantic salmon, kuruma prawns and Sydney rock oysters. These species were selected for research as they all have established culture technology, a closed lifecycle, access to juveniles, are high value and are tolerant of various levels of salinity.
Wakool has 1600ha of evaporation ponds
Cool winters and fluctuating daily water temperatures limited the growth of snapper and black tiger prawns. However, mulloway grew well in the summer. Rainbow trout (Oncorhynchus mykiss) have emerged from trials at ISARC as one of the best performing species. Rainbow trout is one of the most popular aquaculture species with world production exceeding 500,000 tonne/year. In Australia, 2000 tonne/year of rainbow trout is produced from land based freshwater farms with an additional 490 tonne/year from seacages in Tasmania. Rainbow trout are cultured in both freshwater and seawater, have a fast rate of growth and are robust osmoregulators.
Rainbow trout
Rainbow trout have been reared to market size over 4 consecutive seasons during 2004, 2005, 2006 and 2007. Approximately 1700kg of Rainbow trout have been sold fresh and smoked through local butchers, cafes and supermarkets averaging 600g per fish. The product was very popular with consumers as it had a fresh, salty flavour. Saline rainbow trout were sold for a premium price of several dollars per kg more than freshwater trout as they were found to be a superior product.
The performance of Rainbow trout in inland saline groundwater is impressive. A market size of 600g was reached after only 3-6 months with a food conversion ratio of 1.1:1. The fish display good growth in all ranges of salinity trialed, including fish as small as 10g which grew well in salinities of up to 14ppt. The fish displayed strong appetite and high levels of feed intake. Rainbow trout had very high levels of survival while remaining tolerant of high density, handling and fluctuating salinity. The best method of production was semi-intensive flow-through pond culture.
NSW DPI in partnership
Commercialisation of this rainbow trout research is imminent. In a Seafood CRC project, with partners Lonsec Ltd and Aquatic Solutions Australia Enterprises, a commercial inland saline rainbow trout farm is to be constructed near the Wakool Tullakool Sub-Surface Drainage Scheme in 2008. The farm plan and financial models have been established using data from rainbow trout grown at ISARC.
Future directions
If successful, it is planned to incorporate similar farms in other Sub-Surface Drainage Schemes and salt affected areas. Further research is planned to establish the most efficient way to utilise groundwater on-farm including investigating recycling and remediation of the water supply. Projects in other states have also found species and water sources that are suitable for inland saline aquaculture. Several consultancies have been published regarding investment, marketing and promotion.