The following sections provide an overview of the two types of commercial freshwater open aquaculture systems (i.e. commercial flow-through and commercial static) addressed in this translocation protocol (Table 1).
Authorisation under the Fisheries Act 1995 is required to stock fish in these facilities and stocking must be conducted in accordance with this translocation protocol and the Guidelines for Assessing Translocations of Live Aquatic Organisms in Victoria.
Commercial flow-through systems:
Commercial flow-through systems are typically used by the salmonid aquaculture sector. The primary product of commercial flow-through systems is rainbow trout (Oncorhynchus mykiss) with lesser amounts of brown trout (Salmo trutta), Atlantic salmon (Salmo salar), chinook salmon (Oncorhynchus tshawytscha) and brook trout (Salvelinus fontinalis) for food and stocking.
A detailed description of commercial flow-through systems in Victoria is provided in the Best Practice Environmental Management Guidelines for the Salmonid Aquaculture Industry (Department of Primary industries 2006).
Commercial flow-through systems use a considerable amount of relatively clean, cool water diverted by pump or gravity from an adjacent waterway and passed through the aquaculture facility before being discharged to the waterway (Figure 1). Most commercial flow-through systems are located in upland areas of Victoria, predominantly in the Goulburn River catchment.
Victorian salmonid farms divert about 0.35 mega-litres per day (range 0.2-0.8 ML/day) for each tonne of product produced per annum. Culture units include fibreglass and concrete tanks, troughs, earthen ponds and raceways.
Settlement ponds are often used prior to discharge to trap suspended solids.
Commercial static systems:
Commercial static systems are used to produce salmonid and endemic species including Murray cod (Maccullochella peelii peelii), silver perch (Bidyanus bidyanus) and common yabby (Cherax destructor) for on-growing, food and stocking (Figure 2).
Commercial static systems usually source water from streams, irrigation channels, bores, dams, rainwater run-off non a water authority. Water is generally added to replace that lost through seepage and evaporation, used for irrigation or catch to manage water quality. Culture units
include dams, ponds and tanks that may contain suspended cages and floating raceways.
In some cases, artificial or naturally-occurring ponds, dams, lakes or reservoirs on private land may be used for non- intensive aquaculture activities, including enhanced recreational activities where a commercial entry or catch related fee is charged.
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