use full mainly for fisheries course

1. Seed Production of Crab
Presented By
Shubham Sahu
AQC-05/17

2.  Interest in the farming of Scylla species has existed in
tropical Asia since the 1970s
 Mud crabs of commercial importance are S. serrata, S.
tranquebarica, S. paramamosain, S. olivacea
 Live in brackish water for growth and adults migrate to
ocean
 S. tranquebarica larger, 220mm CW (2.5kg) while S.
serrata smaller, 140mm CW (0.5-0.7kg)
 They are nocturnal feeder and omnivorous in nature
 They belong to Order – Decapoda and Family-portunidae
INTRODUCTION

5. Distribution
 Naturally Indo-Pacific region
 It is found from South Africa, around the coast of the
Indian Ocean to the Malay Archipelago, as well as from
southern Japan to south-eastern Australia, and as far
east as Fiji and Samoa.
 The species has also been introduced to Hawaii and
Florida

6. Reproductive Biology
 Sexual dimorphism between sexes
S. No. Male Female
1. Abdominal flap is slender and
triangular
Broad and Semicircular
2. Claws are larger Claws are smaller
3. Two cillia in abdomen Numbers of cillia
4. Appendages are present only on first
and second abdominal segments
Four pairs of abdominal appendages
present from second to fifth segment

7.  The size at sexual maturity is 120 mm (carapace
width) for large spp. S. tranquebarica and 83 mm
for S. serrata.
 The early maturing ovary is bright orange where as
in mature ready to spawn female it is deep yellow.
FIRST SEXUAL MATURITY

8.  Copulation takes place between a hard shelled male and a
freshly moulted, soft bodies female.
 The courtship is in initiated by a ‘premating embrace’ between
hard shelled male and hard shelled female which last for 2-3
days.
 Mating-hard shelled male with soft bodies female, male turn
the female which has undergone premating molting upside
down using his cheliped and climbs on to her ventral side.
 ventral side of female crab note the broad and semicircular
abdominal flap folded against the cephalothorax.
MATING BEHAVIOUR

9.  A berried female crab showing the orange coloured
fertilized egg mass attached to pleopods.
 Black coloured egg mass towards the end of incubation
period just before releasing the larvae.
 The female unfolds the abdomen and holds the male in
position.
 This embrace lasts for 6-8 hours during which time male
deposits the spermatophores in the seminal receptacle of
the female.
 After this the male and female separate.

11. Breeding Season
 Breed throughout the year
Peak breeding season
Sr.
No
.
Region Season Juvenile
abundance
1. Kerala coast Sept- Feb May to Oct.
2. TN coast Sept – April Dec to May
3. AP Oct – Feb Dec – April
4. Orissa Nov – Jan Mar – June (Chilka)
5. WB May – Aug Nov to Feb

12. Spawning
 The ova are extruded by the female and the same are
fertilized by the sperm stored in the spermatophores
 Fertilized ova are stored in spermatophores attached to
ovigerous setae of the abdominal appendages.
 S. tranquebarica- 2-3 million. S. serrata- 0.5-2.5 million
eggs

13. INCUBATION AND HATCHING
 The berried females carry the eggs for 2 weeks,
during which period the embryo developes in
the egg.
 The egg change the color from orange to brown.

15. LARVAL DEVELOPMNT
 The zoea larva undergoes 5 successive moults to
become the megalopa larva Thus there are 5 zoeal
stages.
 For each moult it takes 3-4 days, thus to develop a
megalopa from a zoea it takes 15-20 days.
 Megalopa develops into juvenile crab after 8-11
days.

16. Larval Stage Distinguishing Features
ZOEA 1 eyes are sessile, abdominal sigments are 5, telson is with
3+3 spines.
ZOEA 2 eyes are stalked, abdominal segments are 5,telson has 4+4
spines.
ZOEA 3 There are 5 abdominal segments
ZOEA 4 Pleopod buds appear in abdominal segments and rudiments
of 3 maxiliped and walking legs apear.
ZOEA 5 Setae are present in pleopods.telson 5+5 spines rest of
thoracic appendages develop.
MEGALOPA Carapace length is more than the width. Abdomen with 5
pair of pleopods. A pair of chelipeds and 4 pair of legs are
seen.
CRAB Carapace with 9 anterio spines on either side. First pair
of cheliped and 3 pairs of legs has paddle shaped
dactylus.

18. THANK
YOU