A pilot evaluation of aquaculture integration with irrigated farming systems

Abstract

Proc. Aust. Soc. Anim. Prod. 1996 Vol. 21 A PILOT EVALUATION OF AQUACULTURE INTEGRATION WITH IRRIGATED FARMING SYSTEMS L.J. MCKINNON, G.J. GOOLEY and R.J. GASIOR Victorian Fisheries Research Institute, Snobs Creek, Private Bag 20, Alexandra, Vic. 3714 With a global emphasis on ecologically sustainable development of natural resources, it is logical to integrate, where possible, appropriate farming practices to enhance productivity. The production of silver perch Bidyanus bidyanus under semi-intensive culture conditions was evaluated as part of an integrated agriculture/aquaculture research project in the Goulburn-Murray Irrigation District (GMID) of Victoria. The study aimed to demonstrate the integration of aquaculture into existing irrigated farming systems during a normal irrigation season and to adapt and develop appropriate husbandry and production methodologies to enable viable, cost-effective commercial fish production in such systems. Silver perch were grown in 3 experimental integrated systems, viz: channel ranch cages (floating cages in an irrigation supply channel), storage cages (floating cages in an on-farm storage) and groundwater tanks (floating cages in above-ground, PVC lined tanks). Cages were 1.0m3 volume and were constructed of polyurethane mesh ( 144mm2). A fourth system, an 'industry standard', consisted of purpose-built, earthen fish ponds at a local commercial fish farm. All cages were stocked with hatchery-bred, 'advanced young-ofthe-year' silver perch (mean weight 18.3 + 1.4g; mean length 110.1 & 2Smm) in November (channel, groundwater and fish farm sites) and December (storage site; mean weight 9.7 2 0.2g; mean length 9 1.6 + 1.6mm), and were harvested in April 1995. Fish were hand-fed once daily with commercially available feed. Primary experimental fish husbandry variables for each experimental culture system included high and low stocking (60 and 40 fish/cage respectively) and high and low feeding rates (6 and 4% bodyweight/day respectively), each replicated 3 times and tested concurrently in all combinations. Random subsamples were collected at the commencement of the experiments and at monthly intervals to determine growth. All live fish were counted at the completion of the trials to estimate survival. Table 1. Final weight, survival and daily growth of silver perch by site , During the trials, optimal temperature conditions (20-25 OC) existed for no more than about half (three months) of the total test period. However in the latter part of the season, when water temperatures began to decline, growth rates were maintained in all systems. This suggests that other parameters such as feed type and water quality are also equally important determinants to growth, and that under more optimal conditions, growth rates may be significantly enhanced and viable integrated production of silver perch achieved in the GMID. We thank the Rural Industries Research and Development Corporation for its funding contribution to this research. 392