Best Presentation in india for mud crab

2. CREDIT SEMINAR ON

3. 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.

4. 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
Frozen
Other (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

5. 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.

6. 3.Taxonomic Classification
Scientific classification
Scylla Serrata
Scylla tranquebarica
Kingdom: Animalia
Phylum Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Portunidae
Genus: Scylla
Species Serrata,
tranquebarica
Scientific Name: Scylla Serrata
Common Name: Red Mud Crab
Scientific Name: S. tranquebarica
Common Name: Green Mud Crab

7. 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

8. 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.

9. 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.

11. B) Farming Techniques of Mud Crab
1. Site selection for Mud crab Culture

12. • 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·c
Water Salinity 15-30 ppt
DO concentration >4
pH 8.0-8.5
Water depth (cm) >80
Cont…..

13. 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.

14. 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)

15. 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)

16. 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.

17. • 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….

18. 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.

20. 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.

21. 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.

22. • 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…

23. e) Cage culture (Suspended or Fixed type)
• 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.

24. • 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…

25. • 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.

26. 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.

27. C) Economic
Culture method Crab culture Crab Fattening
Species Scylla Serrata
S. tranquebarica
Scylla Serrata
S.tranquebarica
Culture periods(days) 120 38
Expenditure(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

28. 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.