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Fisheries & Aquaculture of Redclaw Crayfish (Cherax quadricarinatus)



Commercial Fishing for Redclaw Crayfish:

Map showing where Redclaw Crayfish are found in AustraliaRedclaw Crayfish are a freshwater shellfish that occur naturally in a range of different habitats to depths of 5m in rivers and streams in northern Queensland and NT. The commercial supply are farmed in culture ponds along Queensland’s east coast. They are endemic to Australia.

Redclaw have a host of biological characteristics that make them a suitable species for aquaculture. They grow quickly, breed naturally in ponds and have a simple life cycle.

In Queensland, the industry is well developed and redclaw are relatively economical to produce. Production technology is simple and redclaw can be sold as live, cooked or frozen product. Queensland redclaw is recognised both domestically and internationally as a safe and healthy product.

Although indigenous to Australia, redclaw has been exported to many other countries where commercial production has now been established. Production technologies, while still evolving, are at a stage where ‘best management practice’ methods have been identified. These technologies are relatively straightforward and the skill levels required of practitioners are not onerous.

Redclaw aquaculture has been established now for more than 25 years, and yet total production is still quite small. This is despite many projections that it would become a significant aquaculture species worldwide, and possibly a rival of the giant freshwater prawn (Macrobrachium rosenbergii).

 
Scientific Name Cherax quadricarinatus
Location Northern Australia
Season All year round.
Size 90mm carapace length and around 300g
Australian Species Code 00 704003
Taste, Texture -

 

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Exporters of Redclaw Crayfish
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Seafood Agents for Redclaw Crayfish


Redclaw Crayfish are well suited to aquaculture:

• Breeds easily, with no larval stage development.
• Potential for selective breeding; many wild population strains.
• Tolerates high stocking densities.
• Requires low protein diet, not reliant on fishmeal.
• Market position as a high value crustacean.
• Flesh texture and flavour compares favourably with other crustaceans.
• Meat recovery rate acceptable.
• Reaches commercial size in nine months grow-out.
• Survives well out of water for transport to market.
• Straightforward production technology.
• Tolerant of variations in water quality - low dissolved oxygen, wide daily pH changes, low alkalinity, temperature variations, high nutrient loads.
• Tolerates saline water up to 5 ‰ indefinitely and up to 15 ‰ for several days. This provides broad geographic potential and a means of enhancing flavour, purging and cleaning before sending to market.
• No destructive burrowing.
• Non aggressive – cannibalism not regarded as an issue.

 


Farming of Redclaw Crayfish:

Culture environment for redclaw
The natural habitat of the redclaw, the turbid billabong that is flushed during the wet season, does not provide the best environment for farming. Commercial production only occurs in purpose-built facilities rather than farm dams.

Although redclaw are able to tolerate environmental extremes, commercial growth rates can only be sustained where water quality is high.

Water temperature
One of the most important site selection parameters is temperature, and the site should maximise the period where temperatures are above 23°C.

In Queensland, redclaw grow well over a broad temperature range. Optimal growth occurs between 26oC and 29oC. Lethal limits are around 9-10oC and 34-35oC.

Water quality
Salinity levels in ponds should not regularly exceed 2 parts per thousand or growth and behaviour may be affected.

The ideal pH range for redclaw is 7-8.5. Levels below 7 may cause moulting and shell hardening problems. Low calcium levels - hardness less than 50 parts per million (ppm) - will have the same effect.

Redclaw will tolerate very low oxygen levels, which can result in poorly managed aquaculture ponds. If dissolved oxygen in the pond water drops below 1ppm, redclaw will move to the edge of the pond where oxygen levels are generally higher. In extreme cases of low oxygen, redclaw will migrate from the pond over land.

While redclaw will survive under conditions that would normally kill other species, it is desirable to have a dissolved oxygen level above 5ppm. For maximum growth and good economic returns, it is important that ponds are managed in accordance with best-practice protocols, including good water quality management.

Redclaw breeding
Breeding activity for redclaw depends on water temperature and day length, and normally occurs between September and April within their natural range. Farmers can protract breeding by providing a controlled environment in which temperature is manipulated to simulate the onset of the breeding season.

Techniques for breeding and juvenile production vary considerably between farms and regions. Generally, selected broodstock (some redclaw strains are clearly superior for cultivation over others) are placed in specially designed ponds or tanks where mating naturally occurs.

The female broods the eggs for 6-10 weeks, depending on temperature. The larger the female, the more eggs she can produce. Most females produce between 300 and 800 eggs per brood. Redclaw may produce 3-5 broods during the breeding season.

Hatchlings resemble the adult form and remain attached to the underside of the female for several weeks before progressively becoming independent of the mother.

Advanced juveniles are normally harvested at 5-10g (3-4 months old) and sorted for size and sometimes sex.

Growing and harvesting redclaw

Growout
Commercial growout is normally undertaken in earthen ponds, which usually range from 1000m˛ to 1200m˛ with sloping bottoms (1.3-1.8m deep) to facilitate drain harvesting. Similar sized juveniles are stocked in prepared ponds at 5-15 animals per square metre. The stock and pond water is carefully managed to maximise growth and animal health.

The total growout time is about 6-9 months (plus the 3-4 months spent in the juvenile production pond). Stock is often harvested progressively due to differential growth rates. Several market size grades exist from 35g to over 100g.

Shelter
Like all crustaceans, redclaw moult or shed their shell as they grow. Immediately after moulting, redclaw have soft shells and are vulnerable to predation by other crayfish in their pond.

Providing shelter increases the survival and growth potential of farmed redclaw. The best forms of shelter are mesh materials, such as onion bags or shadecloth, and short lengths of pipe. Discarded car tyres are also effective.

Feeding
Feeding is normally undertaken three times a week just before dusk to coincide with the animal's peak foraging behaviour. Some form of aeration is normally installed (usually airlift pumps) to increase the carrying capacity of the ponds.

Feeding of formulated pellets is often supplemented by a mixture of grains to provide a basic food base for the animal, although much of the nutritional requirements can be obtained from natural pond production (e.g. plankton, bacteria, protozoans). This natural production can be enhanced by organic and inorganic fertilisation, as long as ammonia (<0.05mg/L) and oxygen levels (>5.0mg/L) remain within the acceptable range.

Harvesting
Redclaw farmers use several harvesting techniques, either independently or together. These include bait trapping, drain harvesting and flow trapping. Flow trapping is the most successful technique, and utilises the animal's natural behaviour. A current of water is directed into the pond through a ramp. This solicits a response from the crayfish and they move into the current, up the ramp and into a harvest box.

In order to effectively manage the pond environment and the stock of redclaw within the pond, it is essential to drain and dry every pond at least once each year. After harvesting the best crayfish are selected as broodstock, with the majority of the production being sold. Broodstock selection ensures that individuals displaying desirable characteristics, such as fast growth rate, are able to contribute their genes to the successive generations.

 


 

See Also:
Redclaw Crayfish (Cherax quadricarinatus) Photographs and Information
Catching Redclaw Crayfish | How to fish for Red Claw Crayfish
Cooking Redclaw Crayfish | Recipes for Red Claw Crayfish
Fisheries & Aquaculture of Redclaw Crayfish (Cherax quadricarinatus)
Redclaw Crayfish (Cherax quadricarinatus) Links, Resources & Publications

 


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