The crayfish farmed in New Caledonia is the “cherax quadricarinatu”, variety, more commonly known as the “redclaw”. It is a tropical freshwater crayfish which is very hardy and easy to farm.
The redclaw is a native of Australia (from North Queensland) and spends the dry period in very little water. This explains its great resistance to fluctuations in water quality. Crayfish farming is called astaciculture.
What is a crayfish ?
There are three groups of crayfish : the “Astacidae” of the Northern Hemisphere, the ”Austroastracidae” of Oceania and the “Parastacidae” of the Southern Hemisphere.
Crayfish have 5 pairs of motive legs with the first pair terminating in large powerful pincers. At the end of the tail are the swimming parts of the body. They live in freshwater and are closely related to lobster.
Crayfish are omnivores. In the wild, they feed on small living prey (zooplancton) and on decomposing plant matter. In ponds, the crayfish find 70% of their food in the water which is continually being renewed from a creek source or by pumping from a river. They receive a food supplement in the form of cereal and fish meal.
This crayfish, which was introduced into New Caledonia ten years ago, can be found on the Southern Province’s west coast and was farmed by the pioneers of continental aquaculture. They are placed in clay ponds with small surface areas (500 to 1000 m2) equipped with shelters (conglomerate, covers and tubes) both for comfort and rest during the day as crayfish are nocturnal crustaceans. The ideal temperature of the water for the reproduction and growth of this species varies between 27° and 30° and the oxygen levels are between 1.5mg/l and 3mg/l. The bottom of the ponds is covered in stones (pebbles) as crayfish like hard, clean ground. For this reason the pond is completely emptied once a year to clean it.
Its main predators in New Caledonia are the eel and fish-eating birds.
Crayfish pose no threat to New Caledonia’s fragile and unique ecosystem as the aquatic conditions of the creeks are not suited to it (clear and turbulent water).
The reproduction of farmed crayfish
In contrast to the prawn, whose reproduction is delicate and onerous, crayfish do not need a hatchery. They reproduce directly and naturally in the ponds. In fact they reproduce so well and so quickly that this vitality is one of the sensitive issues of farming them. To avoid any risk of overproduction and uncontrolled proliferation of the crustaceans, the reproductive males are put in special ponds reserved for them. The females reach reproductive age at 4 months and carry between 200 and 400 eggs at a time. They do so 4 times a year.
Then at 6 months of age they measure between 7 and 10 centimetres, and at this time the sex determination begins to separate the males from the females. They will then be placed in fattening pools. They will need to be classified by their size and by sex to obtain good growth and production results. Crayfish grow rapidly. A 10 month old crayfish can reach a weight of 120g for the males and 80g for the females.
For commercial purposes, producers classify live crayfish in three weight categories : 60.80g ; 80.100g ; +120g. After spending 24 hours in maturing ponds, the live crayfish are packed into small cages and delivered to local operators (restauranteurs, caterers, fishshops).
The “redclaw” suffers from few health problems. These crustaceans can be transported live out of water at least 72 hours.
Crayfish farms in New Caledonia
To date, thirty producers have established businesses or are in the process of doing so, investing one hundred million CFP francs for ten hectares of ponds. The producers belong to the “Association Dulçaquicole Néo-Calédonienne” which is responsible for the technical support of the farms, the marketing of the products and the development of freshwater aquaculture in New Caledonia.
Production is estimated at 10 tons per year 2004. Producers hope to satisfy the local market whose demand is estimated at 20 tons. Current production is 2.2 tons per hectare of production pools. The crayfish placed on the market by the A.D.N.C come exclusively from farms applying a guide of good farming practices guaranteeing products of perfect quality.
Bibliography
| «Article des Nouvelles Calédoniennes du 17 mai 2001» |
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| «L’écrevisse : Encyclopédie Microsoft/Encarta» |