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Mud crabs, also known as

mangrove crabs, occur

widely in estuaries and

along tropical, subtropical

and warm temperate

coasts in the world.

There are four species

of mud crab (Family:

 Portunidae), Scylla serrata,

S. tranquebarica, S. paramamosain and S. olivacea that are the

focus of both commercial sheries and aquaculture production

throughout their distribution. They are among the most valuable

crab species in the world, with the bulk of their commercial

production sent live to market.Mud crab constitutes an important secondary crop in the

traditional prawn or sh culture systems in some of the coastal

states & Union Territories and has become increasingly popular

by virtue of its meat quality and large size.

In India, the mud crabs have come into prominence in the early

eighties with the commencement of live crab export to the South

East Asian countries which has created a renewed interest in the

exploitation as well as in the production of mud crabs through

aquaculture see Table 1.

Among six, two species of mud crabs, namely Scylla serrate

and Scylla tranquebarica are found in the inshore seas, estuaries,

backwaters, coastal lakes and mangrove swamps of all maritime

states on the main land and the creeks and bays of Andaman and

Nicobar Islands. Both the species co-exist in the inshore sea as wellas in the inland brackish waters preferring muddy or sandy bottom.

The immense market demand for mud crab

Scylla serrata, commonly known as the mud crab or green crab,

has an immense market demand all over the world, particularly in

MUD CRAB

FARMING

IN INDIA

by Dr B Laxmappa, Fisheries Development

Ofcer, Telangana, India

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South East Asian countries. This seafood delicacy is considered

as one of the tastiest of all crab species. This is often sold in live,

in many international markets. India earns foreign exchange to

the tune of 18 million US $ by exporting live mud crab captured

from the low-lying coastal belts across the country.

Therefore, natural stocks of mud crab in the country are under

constant pressure from shing.

Culture practices

 Among the edible species, Scylla serrata, is

popular because of its size, meat quality, high

price and export potential. The ability of

mud crab to grow fast and its suitability

for culture in brackish water and

estuarine areas make it attractive to

develop mud crab culture/fattening

programmes in India to meet

the increasing demand for

export and domestic market.

A community-based crab

fattening in cages project

was implemented rsttime in Tamil Nadu state in

2006 for alternative livelihood

purposes especially for the sher women.

This has proved to be a great success not

only in terms of generating extra income

to the family through the Self Help Groups

(SHG) but also in creating an awareness

among sher folk about the value of marine

resources and the need for conservation and

sustainable utilisation.

There are two basic forms land-based mud crab

culture practices - fattening of crabs with low esh content/

water crabs and grow-out of juveniles to market size. The most

common culture systems for mud crab growout are pond culture

and mangrove culture.

Mud crab farming is traditionally a small-scale, family-run

business in India. Earthen ponds are commonly used in pond

culture. With simple modications, existing marine shrimp

ponds utilised for mud crab growout in some areas. The size, of

the ponds are generally between 0.3 and 0.5 hectare with a water

depth between 0.8 and 1.5 metres.

Various structures, most often simple net fences, but sometimes

also concrete or lined pond banks, are constructed to prevent

escapes. The more commonly used system is semi-intensive

enclosures, often constructed in intertidal zones using easily

harvested bamboo. The stocking density is generally between one

and ve crabs per square meter.

Feeding

Care is taken to provide sufcient food for better growth and

also to avoid cannibalism. Although crabs can utilise natural

diets, supplementary feeds like trash sh, animal offal, cheap

mollusks and sometimes formulated feeds for marine shrimp, are

used to feed mud crabs.

Feeding rates are generally between three and ten percent

of biomass, with a decreasing feeding ratio as they mature.

The culture period for growout from juvenile to market size isgenerally ve to eight months, and survivals of 30-70 percent are

commonly achieved. The duration of fattening is normally 20

days. Fattening of mud crab is popularly undertaken in the states

of Andhra Pradesh, Tamil Nadu, Kerala, Karnataka, Orissa and

West Bengal.

Harvesting

The crabs are harvested after the shell hardens and before the

next moulting. The harvesting can be effectively done in tide-fed

ponds by letting in water through the sluice into the pond during

high tide. As the water starts ushing in, the mud crabs tend to

swim against the incoming water and congregate near the sluice

gate.

The crabs can be caught with the help of a scoop nets and

also by hand picking at the lowest low tide levels. Harvesting

preferably in the early morning hours or evening.

Marketing

Mud crabs are popular throughout the Indo-Pacic region,

particularly in countries where they occur naturally. They remain

alive out of water for considerable periods of time (more than

1 week when kept moist) after capture and are traditionally

marketed alive. However, they are also sold as a frozen for

the newly emerging soft-shell crab market. Although the price

may vary substantially from country to country, mud crabs are

generally a high-priced seafood item in local markets.

The scope for live mud crabs export has opened up good

opportunities for crab farming/fattening. Export market of

live crab especially to South East Asian countries is picking

up steadily. Kerala is a major supplier to the export trade and

Chennai is the main centre of live mud crab exports to Singapore

and Malaysian markets. Crab is poised to be the next potential

sea food in the world market among the marine crustaceans nextto shrimp and lobsters.

The export as well as domestic market of crab is met through

crab landings from the natural collection / harvest from the sea

as also from the brackish water areas. Frozen crab meat and live

crabs are exported from India to south East Asian countries.

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Scylla serrata is much in demand in the domestic market and

fetches a good price, compared to other species of crab. Medium

and large crabs of more than 14cm carapace width and weighingmore than 400g are collected exclusively for export purposes

from West Bengal, Orissa, Andhra Pradesh, Tamil Nadu, Kerala,

Karnataka, Goa, Maharashtra and Gujarat.

The rates vary for live crabs depending on its size. Live mud

crabs of 100grams to 300 grams will earn US$5 to US$7 and

those weighing more than 400 grams earn US$11. In India, live

crabs retail at IMR 300 to 350 in Bangalore and Delhi. During the

peak season from June to September the catch can go up to one to

two tons per day and it dwindles thereafter.

Role of MPEDA & RGCA

Marine Products Export Development Authority (MPEDA),

a nodal agency set up by the Government of India in 1972for the promotion of seafood exports from India. In order to

strengthen the production base of the mud crab so as to facilitate

a sustainable source of mud crab for export, Rajiv Gandhi Centre

for Aquaculture (RGCA), the research and development arm of

MPEDA, has established a mud crab (Scylla serrata) hatchery in

the state of Tamil Nadu in 2013 that regularly produces juvenile

crablets for its demonstration farm and local farmers.

This hatchery is one among very few mud crab hatcheries in the

world, Philippines, Vietnam and China being the other countries

having them. The hatchery has been regularly been producing

mud crab seed reared to crablet sizes at its demonstration farm

and supplying to farmers in the area. Crablets have also been

supplied to several research institutions like the Central Institute

of Brackish water Aquaculture (CIBA) and National Institute

of Ocean Technology (NIOT) for their farming demonstrations.

The facility has also been carrying out ranching of crablets in

estuarine and mangrove areas in Tamil Nadu from time to time

for natural stock enhancement.

Owing to the highly cannibalistic nature of the larvae of this

species, larval rearing of mud crabs is a very challenging task

and survival rates achieved are extremely low when compared to

other crustacean species and species of nsh. But, the scientists

at RGCA have achieved a breakthrough survival of 7 to 14

percent against the world average survival rates of 3 percent.

This encouraging breakthrough achieved by RGCA can open upavenues for commercialisation of mud crab hatchery technology

leading to organised mud crab aquaculture in the coastal areas of the

country especially among the weaker sections of the society giving

them an alternate livelihood option and also strengthens the production

base of mud crab for export in live and value added products. This can

Table 1: Commercially important crab species and its production source in

India.

Common

Name  Scientifc

Name

Production

source

Common size

of growth

(Carapace

width)

Green crabScylla serrata 

(Forskal, 1775)Capture &

Aquaculture13-15 cm

Green crabScylla tranquebarica 

(Fabricius, 1798)Capture &

Aquaculture20-22 cm

Red crabScylla olivacea 

(Herbst, 1796)Capture 13-15 cm

Spotted crabPortunus

sanguinolentus

(Herbst, 1783)

Capture 10-12 cm

Blue crabPortunus pelagicus

(Linnaeus,1766)Capture 10-15 cm

Cross crabCharybdis cruciata

 (Mc Neill, 1929)Capture 10-15 cm

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also result in reducing the shing pressure on the natural stocks and

thereby facilitating natural stock enhancement in the mangrove forests.

Identifying live crab exports as a potential money spinner, the

Indian seafood industry is all set to rear mangrove crabs, so as to

scale up the export of the crustacean that commands high price

in the global market, particularly in Southeast Asia. The MPEDA

has begun farming of crabs in the mangroves of Sindhudurg

district in Maharasthra state through coastal shermen. Green

mangrove crab is a much sought-after variety and fetches a price

of INR 1,000 to Rs 1,400 a kg in the world market.

At present, mud crabs are reared in farms or ponds in states like

Andhra Pradesh and Kerala. The seeds are supplied by the Rajiv

Gandhi Centre for Aquaculture in Tamil Nadu, the R&D wing

of MPEDA, which achieved a breakthrough in crab hatchery

technology with one of the highest survival rates in the world.

The seeds are farmed by the self help groups of local shermen

and then supplied to the exporters once it reaches full size in

around ten months. Live crab exports, mostly done by air from

Chennai and Mumbai, are at present pegged around INR 220

crore (2,200 million) annually and has grown only marginally

over the past few years.

Once the mangrove rearing becomes widespread, MPEDAhopes to increase it several times. To ensure steady supply of

seeds, the agency is in the process of setting up another hatchery

in Maharashtra. The crab exports have not picked up in a big way

in Maharashtra and Gujarat. Unlike in Chennai, there aren’t many

exporters in Mumbai who can share the cost of booking and

sending the consignment by air.

Conclusion

Mud crab farming is becoming very popular in the coastal

districts of India; owing to the good demand and better price

of mud crab in the international market. Mud crab has emerged

as a good potential exportable commodity as well as means of

livelihoods of the coastal poor communities in India. Though

mud crab constitutes an important secondary crop in the

traditional prawn or sh culture systems in some of the coastal

states, the state’s coast has yet to fully wake up to its potential.

The fattening of mud crab, which is non-existent there, can

provide employment opportunities for the sher folk as a meansof alternative livelihood besides promoting crab shery.

Research institutes and the Central Marine Fisheries Research

Institute (CMFRI) should create awareness among farmers

exploit the potential of crab farming in potential coastal regions

of India. The West Coast is mainly dependent on sh catch, like

Andhra Pradesh is dependent on shrimp farming. Unless there

is a crisis people will not move out of their comfort zone to try

something new.

 All references are available on request.

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