Prawns (aquaculture)

25.05.17

Prawn (or shrimp) is the name given to the ten-legged, swimming crustacean (shellfish) from the Pandalus and Panaeus genus. Prawns are eaten all over the world and are consistently ranked in the top ten favourite Australian seafoods. They are commercially fished (wild caught) as well as farmed in Australia.

Prawn farming started in Australia in the 1980s with most farms located on flat land adjacent to sea water sources, such as tidal rivers or creeks. Farms extend from northern New South Wales to far north Queensland but 95% of production takes place in Queensland.

Overview

Prawn farming is a high-risk, capital-intensive industry that is site-specific and requires technical expertise. Mostly, prawns are sold from the farm as a cooked product, so an investment in processing infrastructure is necessary, in addition to production infrastructure.

Global concern about sustainable fisheries, combined with a strong consumer demand for seafood, has seen aquaculture industries expand around the world. However in Australia, the combination of high capital costs and lengthy approval processes for new developments has limited the growth of prawn aquaculture.

Cheaper imports had a major impact on the prawn farming industry during the 1990s, however prices for domestic prawns have subsequently improved, as imported prawns tend to fill a different market segment—lower price and size product.

Historically, Australian prawn aquaculture was based on three native species but the dominant aquaculture species is black tiger prawn.

The peak body for prawn aquaculture is Australian Prawn Farmers Association.

Facts and figures

  • Prawns are a popular seafood in Australia and consumer demand is high
  • Prawn farming started in Australia in the 1980s and currently contributes 15–20% of total prawn production — the remainder is wild caught
  • Prawn farming is a high-risk, capital-intensive industry that is site-specific and requires technical expertise
  • Environmental approvals and other regulatory requirements can make establishment of a prawn farm a costly and time-consuming process

Production status

Australian seafood production is dominated by wild catch. While the proportion of aquaculture is small, it is increasing as consumers become concerned about the sustainability of global fish stocks.

Most production (95%) is in tropical and subtropical Queensland, with the remaining production undertaken in northern New South Wales.

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Map of current and potential growing regions

Uses

Prawns are eaten as a fresh food and can be served hot or cold. To prepare prawns, the head, shell (exoskeleton) and digestive tract are removed, leaving pale flesh that has a moist, medium–firm flesh when cooked.

Prawns are widely eaten around the world and are a key ingredient of many iconic dishes, like gumbo, paella and sushi. They can be mixed with starch (normally tapioca flour) and then deep-fried to create prawn crackers or chips, a popular snack food in Asian cuisines.

Prawns are high in protein, carbohydrate-free, low in fat and high in omega 3 and 6 polyunsaturated fatty acids, better known as “good” fats. They are also an excellent source of vitamins and minerals including iodine, iron, zinc, niacin and vitamin B.

Shellfish, and prawns in particular, are one of the most common causes of allergies in adults. People with severe allergies may carry a shot of adrenaline to administer in case of an allergic reaction, however shellfish allergies can only be managed through an exclusion diet.

Production Requirements

Growing regions

Potential locations for prawn farms are rare, due to the specific requirements needed. While most northern coastal areas of Australia are suitable for prawn farming, many are populated residential areas making environmental approvals difficult. Coastal areas remote from residential areas may lack the necessary infrastructure (like roads or reliable power), or are too far from markets, to make farming viable.

Prawn farming has been trialled unsuccessfully in the Northern Territory and it is thought appropriate farm sites exist in the north of Western Australia between Geraldton and Kununurra where some investment has taken place.

However, prawns are only farmed commercially in northern New South Wales (around Yamba) and in clusters along the entire Queensland coast at Gold Coast, Bundaberg, Mackay, Townsville and Cairns. Ninety-five per cent of Australian farmed prawn production takes place in Queensland.

Climate

Before establishing an aquaculture enterprise, potential operators need to understand the relationship between air temperature and water temperature in their region. Temperature will have an impact on the growth rates of prawns and therefore the number of harvests in any one year.

Prawn farms require temperatures above 25°C during the production season and the water temperature should not fall below 22°C.

Australian prawn farms located south of Townsville in Queensland are usually limited to one crop a year due to the colder winters. Farms at higher latitudes may produce two crops by stocking ponds in winter, typically aiming for a harvest around Christmas when prices are higher and restocking in January.

Housing

Prawns are housed in earthen ponds in a layout that allows water to flow in from a natural sea water source, such as tidal rivers or creeks, through the ponds before being processed through an effluent treatment system and draining back to the natural source.

Ponds are generally a square or rectangle shape, with sloping walls and rounded edges to maximise water movement. Pond walls are often lined with a polyethylene black liner to protect against erosion. Ponds can vary in size from 500m2 to 2ha, but tend to average around 1ha in size.

Delivery of water to the ponds is undertaken by an aqueduct system that uses gravity and pumps to move water from a storage reservoir around the ponds.

To grow prawns successfully, expertise in pond ecology, biology and water quality dynamics is required. Prawns must have clean water and they are highly sensitive to any changes in water quality. This makes the management of ponds the most critical aspect of prawn farming.

The optimum location for a prawn farm is on flat land that is less than 1km from access to estuarine or marine (sea) water. At this close proximity to water, elevation of the land becomes important and an understanding of the location’s highest astronomical tide (HAT) will be required. The farm elevation should be more than 1m above the HAT to ensure ponds can still be drained for harvest during high tide, but less than 10m above the HAT to minimise the energy costs of pumping water through the farm ponds.

The farm site should also have access to mains electricity (three-phase) and good roads that make transporting produce easy.

To ensure the necessary water quality, the site should have access to an unpolluted water supply, with an optimum salinity range of 15 to 36 parts per thousand (ppt). It is important to understand the impacts of seasonal events, like rainfall and evaporation, on salinity noting that salinity should not be less than 1ppt or greater than 40ppt (which is the average salinity level for seawater).

The optimum range for pH of the water source is 7.5 to 8.5. The pH of estuarine waters can be affected by local soil factors. Also ensure water sources are not polluted by industry, urban areas, agricultural activities or water treatment facilities.

Ensuring adequate volumes of water is also important to prawn health. Determine whether sufficient daily volumes of water will be available to supply a prawn farm in any location.

Soil type is another important consideration in the establishment of a prawn farm. Soils will need to have adequate clay content to create a water seal to reduce the loss of water by seepage, low organic matter content and a pH of 5.5–8.5. It is recommended that soil sampling be undertaken to determine the site’s suitability for pond construction. In particular, understanding the load bearing capacity, permeability and presence of contaminants, is important.

Ponds should be filled with water to a depth of 1m, 21 days before prawns are added. This allows for the establishment of a healthy and stable bloom of algae and other plankton that makes up a large proportion of the larval prawn’s diet.

After the prawns are harvested, it is recommended that the pond is drained and dried out for a minimum of two weeks. This allows for the removal of any decomposed organic material and enables soil remediation if necessary. Some farmers till the soil at the bottom of the pond to breakdown any organic residues and nutrients. It also exposes more surface area to sunlight, which will kill any algal spores or fish eggs. Heavy rollers may then be used to compact the soil.

The Australian prawn farming manual includes detailed information about pond establishment.

Feed requirements

Larval prawns (about 1cm in length) feed on phytoplankton and zooplankton that has been cultivated in the pond water, prior to stocking.

Post-larvae prawns (15–20 days old) are stocked in nursery or grow out ponds and fed a commercial prawn diet until the prawns are ready for harvest at 4–6 months old.

Most farmed prawns are fed diets of commercial aquaculture pellets, which include all the nutrients needed for healthy stock.

Feeding is carried out 4–5 times per day and before each feed the farmer will check the feed trays in order to monitor prawn feeding rates, health and survival. Efficient feed management is essential in order to limit waste to maintain water quality and keep production costs down as feed represents over 30% of input costs.

The Australian Prawn Farmers Association outlines the relationship between feed and water quality in their publication Inside prawn ponds.

Breeds and breeding

Australian prawn aquaculture is based on three native species:

  • black tiger prawn – Penaeus monodon
  • banana prawn – Fenneropenaeus merguiensis
  • kuruma prawn – Penaeus japonicus.

The black tiger prawn (Penaeus monodon) is the main species farmed in Australia. It is a fast-growing tropical to subtropical species suited to warm, brackish waters. The Queensland Government has an online guide to black tiger prawn aquaculture.

The banana prawn (Fenneropenaeus merguiensis) matures to about half the size of a black tiger prawn. They have a lighter, sweeter taste than a black tiger prawn.

The kuruma prawn (Penaeus japonicus) is a subtropical species that was historically grown in Queensland and sold almost exclusively to Japan in live form. However, production has almost ceased due to higher operating and capital costs than other species. Kuruma prawns need different environments (e.g. deeper ponds) and have a longer grow out period than other prawn species and their feed is also more expensive due to higher protein levels required. The Queensland Government has an online guide to kumura prawn aquaculture.

Prawn larvae are produced in hatcheries using wild caught broodstock collected by commercial prawn fishers. These prawns known as “large spawners” are between 19cm (male) and 24cm (female) long. Each female will produce between 200,000 and 500,000 eggs, which hatch and pass through a number of larval stages until they reach the post-larvae stage. At this age (15–20 days old) they can be stocked into grow-out ponds on the farm.

Some commercial prawn farms have sophisticated genetic and selective breeding programs and are breeding their own prawns to meet a market demand.

Sourcing stock

Post-larval prawns can be sourced from a number of specialist hatcheries. Contact the relevant state fisheries department for details of local suppliers. Established prawn farms may breed their own stock and develop their own domesticated lines.

Health care & pests and diseases

Australia, mostly due to its geographic isolation but also through the banning of imports of live prawns, is free of major infectious diseases that impact prawn health. However, prawns are still vulnerable to disease, particularly under stressed conditions. Stress can be caused by environmental variables including unstable or unsuitable water qualities, high densities, too much handling, and inappropriate management regimes.

Ensuring stock densities are maintained at their optimal rate will not only reduce stress, but limit opportunities for any diseases to spread.

Overall prawn health is dependent on a thorough understanding of prawn biology and running a high quality farming operation. A high standard of care should be applied to the operation of:

  • pond preparation
  • pond filling and water preparation
  • post-larvae selection and stocking process
  • water quality management
  • pond bloom management
  • feed management
  • prawn health monitoring
  • farm record keeping
  • dealing with disease outbreaks
  • treatments and use of chemicals.

A weekly check of prawn health is recommended. Using a net in different parts of the pond to capture a representative sample of the population, farmers should check external appearance (general colour, healthy gills), gut condition (full, empty, appearance) and size.

A biosecurity program should be established for the prawn farm in order to mitigate the risk of diseases entering the farm, or spreading between ponds.

The Australian Government manages AQUAVETPLAN, the Australian Aquatic Veterinary Emergency Plan. It is a series of manuals that outline Australia’s approach to national disease preparedness and proposes the technical response and control strategies to be activated in a national aquatic animal disease emergency.

The Australian prawn farming manual contains detailed information about managing the risks of disease outbreaks.

Infrastructure Requirements

Prawn farming is capital intensive due to the large amount of infrastructure required. Investing in reliable infrastructure will contribute to the production of a high quality product.

Infrastructure required for establishing a prawn farm may include:

  • suitable land for ponds
  • machinery like a backhoe or excavator for earthworks to construct and reshape ponds (some of this work may be undertaken by contractors)
  • polyethylene black liner to line channel and possibly pond walls to prevent erosion
  • aerators (e.g. paddle or aspirator)
  • pumps to fill ponds and move water around the farm
  • inlet (mesh) screens to prevent the entry of other species into the farm
  • generators in case of a power failure (to continue running pumps)
  • jetties for easy access to ponds
  • forklift, 4WD motorbike, utility and/or small truck for use in general farm work
  • prawn feed trays
  • equipment to monitor water quality and feed rations
  • facilities for trapping (harvesting) including nets and insulated bins for storage of prawns
  • ice maker for preparation of ice for storing prawns as they are harvested
  • hoist, excavator or crane system for lifting harvested prawns
  • a vehicle for transporting the harvested prawns on-farm (keeping the harvested prawns chilled)
  • a processing facility for  grading, cooking (if required), freezing and packing
  • a cool room for storage
  • computer and software for record keeping.

Processing & Selling

A prawn takes 4–6 months to grow to a marketable size. If ponds have been monitored regularly, harvesting can be planned for when the prawns are in optimum health and at the right size and grade for the market.

There are two methods for harvesting prawns. Prawns can be harvested with traps, which select for larger prawns meaning smaller ones are able to remain in the pond where they keep growing or by draining the pond over several hours and harvesting all prawns at once by using a net on the water outlet.

Harvested prawns are kept alive in cool aerated water and should be processed within an hour of harvest. The processing of prawns involves sorting for size and quality before cooking in boiling salted water and then chilling. After they have been cooked and chilled, prawns are sorted again weighed, iced, packed, labelled and dispatched to market.

Fresh farmed prawns are packed on ice to ensure freshness and are transported to market by road or air.  Frozen farmed prawns are frozen without ice and transported to market by road or air.

Farmers have a number of options for selling their prawns. They can market the prawns themselves through a wholesale market or sell via auction, for example at the Sydney Fish Markets or, depending on the scale of the operation, create their own brand and negotiate their own contracts with large retailers. These options tend to be high risk, time consuming and have higher levels of price volatility.

Generally, farmers are contracted to supply companies that already have contracts with large supermarkets and other retailers, or they sell through an agent, which on-sells to similar larger customers.

Markets & Marketing

Prawns are a popular seafood in Australia. Cheaper imports had a major impact on the prawn farming industry during the 1990s, however prices for domestic prawns have subsequently improved, as imported prawns tend to fill a different and low-price supermarket segment.

Global concern about sustainable fisheries has seen an increase in aquaculture production since the 1980s, which has been dominated by Asia, particularly China. Asia contributes to over 90% of global aquaculture production, while the Oceania region, which includes Australia, contributed only 0.3% to global production as at 2010.

This low production base in Australia can be linked, in part, to the extensive environmental and approvals processes, which can see potential industry entrants spending large amounts of capital on the development of relevant applications which may take 10 years to process before final approval to farm.

Australian farmed prawns are consumed in the domestic market and farmers have a number of options for selling their prawns. Prawns can be sold directly to a wholesale market or sold via auction, or some produces may create their own brand and market to large retailers. The latter options tend to be high risk, time consuming and have higher levels of price volatility.

Market information (including prices) is not widely available. It is recommended that potential industry entrants speak to an agent about possible prices and fees, research wholesale prices and speak to other farmers to understand the seasonality of pricing and margins available.

Other factors affecting the price are seasonal availability, the availability of substitute products and consumer spending and preferences. A premium product will generally earn a premium price, however, there are no guarantees of this always happening. For example an oversupply will depress prices but equally, periods of low availability will see even average quality product command high prices.

It is often suggested that one of the best ways for a farmer to monitor price signals and plan production accordingly is the establishment of a good business relationship with an agent. This can add some transparency around market signals.

Risks & Regulations

Risks/challenges

The growth of the aquaculture industry globally suggests consumers are concerned about the sustainability of wild catch fisheries and the demand for farmed seafood will remain strong.

However, risk is inherent in all agricultural industries, and aquaculture prawns are no different.

Prawn farming is a high-risk, capital-intensive industry that is site-specific and requires technical expertise. Most prawns are sold from the farm as a cooked product, so an investment in processing infrastructure will also be necessary.

The success of any aquaculture venture depends on sound initial planning. This is especially important in prawn farming, where gaining approvals can be costly and time-consuming. Potential industry entrants should develop a comprehensive business plan that identifies the goals, markets and production requirements. It is then possible to develop some forecasts and assess the financial viability of the operation.

Heightened risks for new industry entrants might include high rates of mortality as systems and housing are established, a lack of understanding of market needs resulting in poor returns and not meeting the costs of establishment and production in the early years.

Other production risks include an environmental event, like floods or drought that impact on water quality or availability, losing access to markets, price fluctuations and a pest or disease outbreak.

During harvest and processing additional staff will be required to manage the workload. These roles require a high level of proficiency and the availability of staff at critical times cannot always be guaranteed.

The Australian prawn farming manual outlines some of the risks potential industry entrants should consider.

Regulatory considerations

Establishing and operating an aquaculture enterprise requires a licence from the relevant state government authority, usually fisheries. Departments of planning, environment and local government authorities may also need to approve development applications for aquaculture enterprises.

Requirements may differ across states, so contact the relevant fisheries department for advice, but generally potential industry entrants will need to gain approval for:

  • site and species selection that minimises environmental impact
  • relevant safeguards in place to ensure that there is no nutrient input to dams or ponds
  • adequate safeguards to ensure no escape to the surrounding environment of species which are outside their natural range.

Licences are subject to conditions. More specifically, an aquaculture licence may specify:

  • the area within which the aquaculture activity is authorised
  • the species
  • type of equipment or infrastructure
  • environmental management requirements
  • translocation procedures
  • waste management requirements
  • records and reporting requirements
  • biosecurity requirements
  • other conditions.

Aquaculture operators may be required to lodge production figures with the state government and accept inspections by fisheries officers to ensure compliance with licence provisions.

Movement of live prawns may also be subject to protocols by relevant state governments.

State specific information in relation to the process of applying for an aquaculture licence is available from state government websites:

The high level of regulation required by prawn farms has resulted in the Australian industry being recognised as one of the cleanest and most environmentally sustainable in the world.

The processing of prawns on farm will require compliance with all food safety and handling laws. Detailed information on Australian standards is available from Food Standards Australia New Zealand (FSANZ).

The area used to prepare prawns will generally comprise of a cool room, stainless steel processing areas and areas for grading and packing. The processing area will need to be built and outfitted consistent with the requirements under the Australian Standard for the Construction and Fit out of Food Premises.

Publications

Publications/information

State Environmental Planning Policy No.62 – Sustainable Aquaculture NSW Department of Planning (2014)

Australian prawn farming: R&D Strategic Plan (2015-2019) Australian Prawn Farmers Association (2014)

Growing Organic Prawns – in inland saline waters RIRDC Report 2008

Guidelines for constructing and maintaining aquaculture containment structures Queensland Department of Agriculture, Fisheries and Forestry (2007)

Wastewater remediation options for prawn farms Queensland Department of Primary Industries and Fisheries (2005)

Prawn aquaculture in Western Australia: FInal ESD assessment report for prawn aquaculture WA Department of Fisheries (2009)

Other resources

Black tiger prawn aquaculture Queensland government

Kuruma prawn aquaculture Queensland government

Case Study: Black tiger prawn CSIRO

Prawns – aquaculture prospects NSW Department of Primary Industries

Image Gallery

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Prawn aquaculture ponds (source Australian Prawn Farmers Association)

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Harvesting prawns (source Australian Prawn Farmers Association)

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Harvested green prawns (source Australian Prawn Farmers Association)

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Cooked prawns ready for the consumer (source Australian Prawn Farmers Association)