Aquavetplan enterprise Manual Version 0, 2015

B3.2.2 System inputs

Animals

Broodfish are caught in the wild (rivers, creeks, lagoons, etc.) and taken to hatcheries. Broodfish for aquaculture breeding programmes are generally selected from high-performance grow-out fish. Fry and fingerlings are moved from hatcheries to farms. Market-size fish come from grow-out farms.

Forage fish and crustaceans that are naturally produced in ponds may be used to feed broodfish. During conditioning periods, additional food for broodfish, including forage fish and crustaceans, is often moved from the wild and farm dams. Occasionally, additional supplementary foods, in the form of purchased seafood or bait, may be used to condition broodfish.

Birds come from natural waters or other farms and include cormorants, egrets, darters, herons and ducks.

Water

The quality of the water entering the facility influences fish health. Surface waters from rivers, creeks, runoff and irrigation canals may carry pathogens from wild fish or other farms located upstream. Small wild fish may enter via the water supply and are a potential source of pathogens.

Reservoir and effluent or settlement dams may contain small fish or escapees from ponds; these are also potential hosts of pathogens. Good management strategies will minimise risks—they may include appropriate screens, efficient harvesting and annual drying of the reservoir. Reuse of water from a ‘clean’ effluent or settlement dam will reduce the number of pathogens entering from the wild.

Underground water usually contains few or no pathogens, virtually eliminating the risk of introduction of obligate fish parasites with the source water.

Feed

Silver perch are fed artificial feed from weaning (at 4–8 weeks of age) to market size. The feed is extruded, and the main ingredients are imported fishmeal, domestic meatmeal, soybean meal and wheat. The feed is usually 35–50 per cent crude protein. The feed is trucked directly from feed mill to farm using commercial freight companies.

The feed conversion ratio is between 1.6:1 and 2:1—that is, 1.6–2 t of dry feed is used to produce each tonne of fish. Using recommended feed and feeding strategies, nutritional diseases are unlikely, although problems can occur with excessive or incorrect storage of feed in moist, hot conditions.

Personnel

Many farms are owner operated with assistants. Larger farms work seven days per week, and may have 2–10 employees, including managers, biologists and assistants. Casual workers are used for harvesting, breeding, construction and maintenance.

Other visitors to farms can include hatchery staff delivering fry and fingerlings, transportation contractors, government extension officers, scientists, aquatic animal health advisers, general visitors from other farms and interested members of the public.

Equipment

Earthen hatchery ponds may have concrete monks with wood or concrete boards; however, most grow-out ponds are drained through a standpipe. Metal mesh screens, and wire or plastic bird netting are used at some farms on outlets to prevent fish escaping. Almost all ponds have aerators. Each pond is about 0.3 ha in area and about 1 m deep.

Building equipment includes quarantine/purging tanks (fibreglass or polyethylene), PVC plumbing, pumps, filters and blowers. Laboratory equipment includes microscopes, balances, glassware and other equipment. Shed equipment includes machinery, workshops, vehicles, equipment for feed storage and other general equipment. It can also include water quality meters and a secchi disc. Nets used are seine nets (for fingerlings and larger fish), hand nets and plankton nets.

Transport tanks are fibreglass, range from 500 to 10 000 L in volume, and are transported on a truck or trailer. Most farms have backup power generators, if mains power fails.

Stores

Stores are used to house feed, spare paddlewheels, hormones for broodstock, and other chemicals (formalin, salt, anaesthetics, disinfectants, fertilisers). Antibiotics are rarely, if ever, indicated or used for silver perch.

Vehicles

Vehicles may include utilities, 4WD vehicles, tractors and four-wheel motorbikes. Earth-moving equipment may also be used.

B3.2.4 System outputs

Animals

Fry and fingerlings are moved from hatcheries to farms, usually annually in spring–summer. Fry are first moved to quarantine tanks, where they are usually treated with a daily salt bath, then stocked in ponds after several days. On many farms, fry are received into quarantine tanks, salt bathed and kept in quarantine for 1–2 weeks before being stocked in ponds. Restocking programmes will typically introduce the fish directly from the hatchery transport tanks into the wild, with prophylactic salt baths occurring at the hatchery before transport. Fish may be transported in brackish water (2–5 ppt).

Market-size fish are harvested live, and transported either live or chilled and whole to wholesalers, restaurants and fish markets. Fish are harvested using a seine net for complete or partial harvest, or the pond is drained for a complete harvest. Yields can be up to 250 000 fry from a rearing pond of 0.4 ha. Market-size fish yields may be 1 t from a 0.1-ha pond, or 5 t from a 0.5-ha pond. Market-size fish are harvested to brackish water purging tanks (to remove off flavours) for up to two weeks before being sold live, fresh, chilled or processed.

The chain of handling is as follows:

Fry are harvested.

Fry are transported in aerated fibreglass transport tanks or plastic bags, with approximately 10 kg of water and an oxygen atmosphere, to the stocking site (fish farm, public waterway or farm dam).

Fry are weaned from natural live foods onto pelleted feed.

The grow-out period (approximately 20 months) takes place.

Live fish are harvested to purging tanks.

Either live product is transported via tanker transporter to wholesalers’ tanks or restaurants, or the fish are killed, chilled and packed on ice, then transported (usually by road) to wholesalers, fish markets, restaurants or retail fish shops.

Some farms undertake limited processing in approved premises to distribute fillets.

Water

Grow-out ponds are static, with no or very limited water exchange. All effluent water is discharged into an effluent or settlement dam. No effluent water directly enters natural waterways. Most farms irrigate their settlement dam water onto adjacent pasture.

Some effluent water may leave hatcheries or farms with live fish, under monitoring by the environmental protection agency.

Parasitic diseases in ponds are usually treated in situ (with formalin, copper sulfate, potassium permanganate or trichlorfon). Diseases are readily contained on farms, when diagnosed.

Waste materials

There are very few waste materials, and these are generally buried on-site.

Vehicles and equipment

Hatchery and farm vehicles regularly move on-farm and off-farm. Nets may be shared between the smaller farms. Larger farms are self-contained in terms of equipment.

B3.2.5 Groups involved

Groups involved in the native freshwater finfish industry include:

the Victorian Warmwater Aquaculture Association

the Silver Perch Growers Association

the NSW Aquaculture Association

the South Australian Aquaculture Council

the Aquaculture Association of Queensland

the Queensland Aquaculture Industries Federation

the National Aquaculture Council

state and territory departments of agriculture and fisheries

water authorities

environmental protection agencies, and other environmental groups and agencies.

B3.2.6 Legislation and codes of practice

NSW DPI has a Silver Perch Aquaculture Policy, which sets essential and desirable criteria for the location, design and operation of farms in New South Wales. NSW DPI has recently implemented the Hatchery Quality Assurance Program across the state.¹ The NSW Silver Perch Growers Association is formulating a code of practice. The Aquaculture Association of Queensland has implemented an environmental code of practice.

Legislation relevant to aquatic animals and health is listed in Appendix 1.

B3.2.7 Occupational health

There are several health and safety issues for staff, including the following:

Pond mud is rich in bacteria and should be treated with caution, especially if the operator has skin abrasions. See Appendix 2 for information on seafood-borne disease in humans.

Significant amounts of heavy lifting can be involved in harvesting and handling fish. Caution should be taken to prevent back injuries.

Earthmoving equipment, tractors and forklifts should be operated with care after appropriate safety training.

Electrical problems are common, and qualified electricians should be used, as required.