Mud crab, also known as manglar crabs, are widespread in the temperate, subtropical and warm temperate estuaries and coasts of the world. There are four species of clay crab are the focus of both aquaculture production and commercial fishing throughout its distribution. They are among the most valuable crab species in the world. Most of their commercial production goes directly to the market.
Clay crab is an important secondary crop in shrimp farming systems or traditional fish in some of the coastal states and territories of the Union and is increasingly popular thanks to the quality of their meat and its large size.
In India, mud crabs have come to prominence in the 1980s with the start of live crab export to Southeast Asian countries, which has created a renewed interest in exploitation as well as in the production of crab Of clay through aquaculture.
Between six, two species of clay crabs, called Escila Serrate and Scylla tranquebarica. They are found in the coastal seas, estuaries, coastal lagoons and mangroves of all the maritime states. In addition to the coves and bays of the Andaman and Nicobar Islands. Both species coexist in the sea near the coast, as well as in the brackish waters of the interior, as they prefer the muddy or sandy bottom.
The great demand of the market for clay crabs:
Scylla Serrata, commonly known as the clay crab or green crab. This crab has an immense market demand worldwide, especially in Southeast Asian countries. This delicacy is considered as one of the tastiest of all crab species. It is often sold live in many international markets. India generates foreign currency in the amount of US $ 18 million from the export of live crab, caught in the low coastal strips of the country.
Therefore, the natural stocks of mud crab in the country are under constant pressure from the fishing.
Among the edible species, Scylla Serrata is popular because of its size, meat quality, high price and export potential. The ability of the fast-growing clay crab. Its suitability for cultivation in the brackish water areas makes it attractive to develop clay crab cultivation. Fattening programs in India to meet the growing demand for export and market internal.
A community based on crabs, which is fattened in cages, was first implemented in the State of Tamil Nadu in 2006 for livelihood purposes for women of fishermen. This has proven to be a great success, not only in terms of generating additional income to the family through the self-help groups but also in raising awareness among fishermen, about the value of marine resources and the need Conservation and sustainable use.
Clay crab breeding is traditionally small-scale and family-owned enterprises in India. The earthen ponds are the most used. Although, with simple modifications, the marine shrimp ponds are used for the fattening of the mud crab in some areas. The size of the ponds ranges from 0.3 to 0.5 hectares with a water depth of between 0.8 and 1.5 meters.
They have different structures, although the network fences are more often used, although concrete or coated ponds are also used. All are made to prevent leaks. The most commonly used systems are semi-intensive enclosures, often built in intertidal zones, which use mostly bamboo. The population density ranges from one to five crabs per square meter.
Feeding of Mud Crab:
You must provide enough food to get better growth and avoid cannibalism. Although crabs can use natural diets, supplemental foods such as small fish, animal by-products, cheap mollusks and seafood formulated for marine shrimp are used to feed mud crabs.
Feed rates are generally between 3-10% of the biomass, with a decrease in feed ratio as they mature. The growing period for juvenile fattening to achieve market size is generally between five to eight months and survival is between 30-70 percent. The fattening period is normally 20 days. The mud crab fattening takes place in the states of Andhra Pradesh, Tamil Nadu, Kerala, Karnataka, Orissa and West Bengal.
Crabs are harvested after their shell hardens and before the next molt. Harvesting can be effective in tidal ponds, allowing water to pass through the sluice to the pond at high tide. As the water begins to enter, the crabs are rinsed and tend to swim against the ingress of water and congregate near the floodgate.
The crabs are caught with the help of nets and/or with manual harvesting at the lowest levels of low tide. The harvest is preferably done in the morning or at night.
Clay crabs are very popular throughout the Indo-Pacific region, especially in countries where they occur naturally. They stay alive out of water for long periods of time (more than 1 week if kept moist) and are traditionally marketed live. However, they are also sold frozen to the recent market for soft-shell crab. Although the price may vary considerably from one country to another. Mud crabs are generally an item of very high value in local markets.
The export possibilities of live mud crabs have generated good opportunities for crab cultivation. The export market for live crab, mainly to Southeast Asian countries, is steadily increasing. The crab is about to be the next potential sea product on the world market and will join marine crustaceans, shrimp, and lobsters.
Scylla Serrata is in great demand in the domestic market. It sold at a good price compared to other crab species. Large and medium-sized crabs larger than 14 cm wide and weighing more than 400gm are harvested exclusively for export in the West Bengal, Orissa, Andhra Pradesh, Tamil Nadu, Kerala, Karnataka, Goa, Maharashtra and Gujarat.
Clay crab breeding is becoming a popular practice in coastal districts of India; Due to the good demand and best price of the clay crab in the international market. The mud crab has become a good export commodity as well as a large livelihood for the poor coastal communities of India.
Although clay crab is an important secondary crop in shrimp farming systems or traditional fish in some coastal states. The state’s coast has yet to wake up and assess its potential. Mud-crab fattening, which is non-existent there, can provide employment opportunities for fishermen as an alternative livelihood in addition to promoting crab fishing.