mud crab farming tarang shah

WEL-COME

Mud Crab Farming in India

Presented by- Tarang Kumar Shah M.F.Sc(Aquaculture)

CREDIT SEMINAR ON

a) 1.Introduction

• Mud Crab is also known as “ Mangrove Crab”. • Scylla serrata and Scylla tranquebarica are the common mud crabs

occurring in the estuarine and mangrove areas along the coast of India.• Scylla serrata is commonly called as “Red crab” and it prefers to live

in low saline waters.• Scylla tranquebarica the “Green crab” lives in high saline waters.• Mud Crab farming is widely practiced in Thailand, Taiwan, Malaysia,

Singapore and Indonesia.

Item/Year  2003-04

 2004-05

 2005-06

 2006-07

 2007-08

 2008-09

 2009-10

 2010-11

 2011-12

Live Crab (MT)

 1599

 1749

 2022

 1909

 1918

 2230

 2863

 2963

 3054

FrozenOther (MT)

 4781

 5152

 4797

 4285

 4066

 4758

 4505

 3251

 2848

Total Crab (MT)

 6380

 6901

 6819

 6194

 5984

 6988

 7368

 6214

 5902

World Mud Crab Production

India Mud Crab Production

2.Distribution in India

• Two species mud crab(Scylla Serrata and Scylla tranquebarica ) occur along the Indian Coasts.

• Mainly distributed in Andhra Pradesh, Tamil Nadu and Kerala.

3.Taxonomic Classification

Scientific classification

Scylla SerrataScylla tranquebarica

Kingdom: Animalia

Phylum Arthropoda

Subphylum: Crustacea

Class: Malacostraca

Order: Decapoda

Family: Portunidae

Genus: Scylla

Species Serrata,

tranquebarica

Scientific Name: Scylla SerrataCommon Name: Red Mud Crab

Scientific Name: S. tranquebaricaCommon Name: Green Mud Crab

4. Identifying Characters 

 Character Scylla serrata

 Scylla tranquebarica

 Size

 Smaller Size

 Larger size

 First sexual maturity

 83mm

 120mm

 Weight

 0.5 to 0.75 kg

 2.5 kg

Colour of upper surface of body

(carapace)

greenish brown to ferrugenous brown light to dark green

 Polygonal markings

  No Polygonal markings

limbs

 Present Polygonal markings

all limbs

 Number of Spines

 One spines on the outer margin of

wrist of chelipeds

 Two spines on the outer

margin of wrist of chelipeds

5. Habitat and feeding Habits

• Mud Crab are found both in the seas and estuarine system.• The Mature female mud crabs emigrate to inshore seas for

hatching of the larvae.• Mud crabs in their megalope stage (post larva) migrate into the

estuaries, coastal lagoons and backwaters.• Mud crabs are nocturnal feeder feeding mainly on bottom

dwelling, slow moving animals such as bivalve, small crabs and dead decayed animal matter.

6. Reproduction

• The sex are separate and there is distinct sexual dimorphism.• The size at first sexual maturity is 120mm (carapace width) for larger species

(Scylla tranquebarica) and 83 mm (carapace width) for Scylla serrata.• The early maturing ovary is bright orange whereas in mature ready to spawn

female it is deep yellow. • Mud crab is able to breed throughout the year.• The peak spawning periods of the mud crab

Kerala coast is from September-February. Tamil Nadu coast from September-April Andhra Pradesh coast from Oct.-Feb. & May-June.

Life cycle of mud crab

B) Farming Techniques of Mud Crab

1. Site selection for Mud crab Culture

• Site selection is an important process in farming as it decides the success or failure of the mud crab farming.

• Silt - clay, clay loam or clayey soil is ideal for both mud crab framing.• Clear seawater with high plankton production is ideal for mud crabs. • No new farms to be established within 200 meter from high tide line.• Water of good quality should be adequate all year round, coming directly

from the sea or river. The following range are required such as.Category Range

Water temperature 23-32·cWater Salinity 15-30 ppt

DO concentration >4pH 8.0-8.5

Water depth (cm) >80

Cont…..

2. Seed collection

• For culture purpose crab seed are mainly collected from natural resources.

• Juvenile crabs can be collected from estuaries, lakes, backwaters, creeks, mangroves and salt water lagoons.

• Juvenile crab can be collected by using bamboo traps, lift nets or scissor nets.

Hatchery production of Mud crab

• A hatchery has been set up at the Central Marine Fisheries Research Institute, Kochi for the commercial production of crab seed.

• Seeds are available in commercial scale in RGCA.(Rajiv Gandhi Centre for Aquaculture)

3. Culture Method

Pond Culture

Pond culture in mangrove area

Pen culture in pond

Pen culture in mangrove area

Cage culture (Suspended or Fixed type)

a) Pond Culture

• The pond size depends on the production type.Pond size of 0.5 to 2 hectares is most suitable for crab culture.

• Small sized ponds are very suitable for crab farming.• Sandy soils with a mixture of 50% clay are ideal for culture of these

crabs. • The maximum stocking density should be 1 crab/m2.

• Young crabs are raised and grown for a certain period of 5 to 6 months till they reach marketing size and weight.

• A water inlet system and an outlet system to drain out water during water exchange should be constructed as in the case of shrimps.

• In addition, about 1000 numbers of stone wire, pipes of 6 inch diameter and 1.5 feet length etc. should be kept at the bottom of the pond throughout the dike.

Cont….

b) Pond culture in mangrove area

• The ponds could be constructed as described above around the mangrove plants.

• Maximum pond area of 100 m2 is suitable for this type of culture.• A canal of 1 m wide and 0.5 m deep.• In which water will be available even during low tide should be dug

around the edge of the pond.• Polythene nettings could be used to prevent the escape of the

crabs.• Feeding depends on the availability of organisms namely low-value

fishes, mangrove snails, clams, mussels etc.

Pond culture in mangrove area

c) Pen culture in pond

•  Crab Culture can also be done in pens.• Pens size of 4 X 4 X 2.5 m could be made inside the ponds using

bamboo strips.• Bamboo strips are driven 1-1.5 m deep into the soil to prevent the

escape of the crabs by burrowing. • The pens could be made nearer to the dykes for easy stocking and

monitoring.

d) Pen culture in mangrove area

• The pens could be constructed using the locally available bamboo splits or

arecanut logs or cane.

• These strips should be driven 1-1.5 m deep into the soil to keep the crabs

inside and the potential predators outside.

• Mangrove trees in the Centre of the pen provide shade for the crabs.• The crab could be fed once a day during high tide with low-cost fishes, mussels,

clams, snails etc. • The crabs could be selectively harvested after they reach 400 g or more.• This system is eco-friendly, survival rate of only 47 to 50 % could be expected.• The crabs could be harvested after 4–7 months.

Cont…

e) Cage culture (Suspended or Fixed type)

• Cage Design:-• Crab fattening can be carried out in Cell-type Cane Cages of 1

m (L) X 1 m (W) X 20 cm (H) size.• Cages can be partitioned into nine equal compartments.

• Crab fattening can also be done in floating net cages, bamboo cages in shallow estuarine waterway.

• 3 m X 2 m X 1 m (3 m long, 2 m wide and 1 m height) is ideal cage size for crab fattening.

Cont…

• One crab should be placed in each compartment of the cages. • In this method of fattening, higher number of crabs can be fattened in a

square meter area, i.e. 9 crabs/m2. • Different types of feeds such as trash fish, mussel, chicken waste, clams etc.

can be given to the crabs.

Stocking and feeding in cages

Marketing

Marketing:- Generally the mud crabs are sold in live condition. The first pair of largest legs (chelate legs) of each live crab are firmly tied up

with the body by jute/nylon thread . The basket packed crabs are transported from remote fishing villages to the

major cities by road or rail. The mud crab are sold through the middlemen to retailers. Export:- The live mud crab export from India has started in 1987-88 . Exported mostly to South east-Asian countries. The live crabs are packed in perforated carton boxes lined with thermocol

sheets and air-lifted from Chennai and Kolkata.

C) Economic

 Culture method

 Crab culture

 Crab Fattening

Species Scylla Serrata S. tranquebarica

Scylla Serrata S.tranquebarica

Culture periods(days) 120 38Expenditure(Rs.)(seed,feed,pond

preparation,labour)43,860 56,200

Production(tonnes)0.78 0.56

Income(Rs.) 1,57,200 1,22,850

Net profit/crop (Rs.) 1,13,340 66,650

References

• Allan, G. and Fielder, D. 2004. Mud crab aquaculture in Southeast Asia. Proceedings

of the ACIAR Crab Aquaculture Workshop.28–29 April 2003.

• Angel,C.A(1992).Report of the seminar on mud crab culture and trade. Bay of Bengal

programme BOBP/REP/51,246pp.

• Blackshaw, A. (Eds.), Mud Crab Aquaculture and Biology, ACIAR Proceedings No.78.

Canberra, Australia, pp. 14-20.

• FAO (2013) Fisheries and Aquaculture Department, Statistics and Information Service

Fish Stat J: Universal software for fishery statistical time series. FAO. Rome.

Thank You