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4. Production Systems and Growth 4.1 Background The physical and operational issues faced when developing aquaculture in non-specific water bodies are often significantly different from those encountered when using specifically designed aquaculture ponds. Net cages are the most common form of culture in large reservoirs. However, extensive stocking of fingerling in reservoirs is also common where a managed fishery approach is used to harvest the stock. In Australia most aquaculture is undertaken on an intensive basis. Net cages are used in the barramundi industry, especially in the fingerling and juvenile phases, to help separate size classes, improve general husbandry practices, reduce bird predation and manage cannibalism in carnivorous species such as barramundi. Ring tanks are typically high walled structures which when full can be as deep as 7 m. Net cages can potentially operate effectively within this type of water infrastructure if water levels are maintained. Another option for intensive production is raceway culture. Floating raceway systems have been shown to be more cost effective than cage operations as they can operate at higher densities within a much smaller area with less labour (Yoo, Masser & Hawcroft, 1995 and Masser & Lazur, 1997). At Loch Eaton both net cage and floating raceway systems were used at different times of the farms development. The objective of this study was to monitor the farms use of these systems to determine which best suit the ring tank environment. This monitoring included assessing the growth, survival and food conversion rate (FCR) in both cages and raceways. A third objective was to assess the viability of extensive stocking of ring tanks might play in the development of aquaculture in cotton farm water storages. 4.2 Materials and Methods 4.2.1 Production Systems Three types of production system were employed in this study. Net cages were the first production system to be used on-farm and were established prior to commencement of this study. The second system, a floating raceway system, was in development during this study but by midway through the exercise it was the main production system used. The use of extensive stocking was also investigated in this study but this was not a major focus of the study. 4.2.1.1 Cages Small 8 m 3 cages (Fig 4.2.1) were used for both silver perch and Murray cod juveniles while larger 100 m 3 cages were used for silver perch juveniles and adults (Fig 4.2.2). All cages were covered in bird netting to reduce predation. Silver perch fingerlings supplied by commercial hatcheries were either stocked into a series of 10 t HDPE tanks or stocked directly into cages within the ring tank. The 8 m 3 cages used for fingerlings were a 5 mm knotless mesh while two sizes of mesh, a 10 mm and 20 mm, were used for the larger 100 m 3 nets. Fish in tanks were stocked at a rate averaging less than 5 kg/m 3 . Water to the tanks was supplied on a flow through basis at ambient temperatures following degassing in a 20 m 3 header tank. Fingerlings were stocked into net cages at an initial rate averaging 1,000 fish/m 3 but not exceeding 1,375 fish/m 3 . Fish were graded and restocked as dictated by growth and stocking strategies. 4.2.1.2 Raceways The initial plastic raceways were fabricated from HDPE sheets and rotomoulded boxes welded together to form 7 and 14 m 3 raceways supported by plastic floats (Figs 4.2.3 and 4.2.4). The rotomoulded raceway was developed by Paul McVeigh in conjunction with Total Aquaculture Management Company (TAMCO) (Fig 4.2.5). 18
Figure 4.2.1 Net cages 8m 3 used for silver perch and Murray cod fingerlings and juveniles Figure 4.2.2 Net cages 100m 3 used for silver perch grow out 19
Page 1: Integrated Agri-Aquaculture Demonst
Page 4 and 5: © 2009 Rural Industries Research a
Page 6 and 7: Acknowledgments The authors would l
Page 8 and 9: Contents Foreword .................
Page 10 and 11: Table 4.3.11 Table 4.3.12 Table 4.3
Page 12 and 13: Executive Summary What the report i
Page 14 and 15: crop. This is much higher than simp
Page 16 and 17: documented such waters types as bei
Page 18 and 19: 2. Demonstration Farm 2.1 Backgroun
Page 20 and 21: Figure 2.2.3 Net cages used for sil
Page 22 and 23: 3. Water Use and Quality 3.1 Backgr
Page 24 and 25: inland Australia with high levels o
Page 26 and 27: Table 3.3.3 Average monthly afterno
Page 28 and 29: 169 165 161 157 153 149 145 141 137
Page 30 and 31: In February 2001, enough water was
Page 34 and 35: Figure 4.2.3 The first 7m 3 floatin
Page 36 and 37: Figure 4.2.7 Uplift, baffle board a
Page 38 and 39: float to prevent drowning of air br
Page 40 and 41: Figure 4.2.13 Raceway push gate gra
Page 42 and 43: Table 4.3.1 Number and volume of ne
Page 44 and 45: Table 4.3.3 The length of culture p
Page 46 and 47: Stock retention was also high in th
Page 48 and 49: Table 4.3.10 The length of culture
Page 50 and 51: 4.3.5 Disease Detection and Treatme
Page 52 and 53: The average rate of growth for silv
Page 54 and 55: R E Figure 4.4.1 Existing (E) and r
Page 56 and 57: 5. Pesticide Monitoring and Residue
Page 58 and 59: 5.2.1.1 Pesticide Application and U
Page 60 and 61: prior to the commencement of the tr
Page 62 and 63: 5.4.2 Pesticide Bio-concentration a
Page 64 and 65: 0.4 0.35 0.3 0.25 ug/L 0.2 0.15 0.1
Page 66 and 67: There were no detections of endosul
Page 68 and 69: While further expansion of the inte
Page 70 and 71: 7. General Discussion The integrati
Page 72 and 73: Appendix Floating Raceway Technolog
Page 74 and 75: Why Raceways? McVeigh Brothers P/L
Page 76: Alternative but Adaptable System Mc
Page 79 and 80: Water Flow (eddy) Flow (cm/sec) 35
Page 81 and 82: End gates - changeable 67
Page 83 and 84:
35 g average fish - 3200 each 120 g
Page 85 and 86:
Paul McVeigh Mark Fantin Doug Young
Page 87 and 88:
Das, B., Sharif, Y., Khan, K., Das,
Page 89 and 90:
Müller , J.F., S Duquesne, Jack. N
Page 91:
Integrated Agri-Aquaculture Demonst
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