SHELL FISH CULTURE

UNIT -3

TOPIC- BIOLOGY OF “ Penaeus vannamei”

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Biology of Penaeus vannamei

SCIENTIFIC CLASSIFICATION

Kingdom : Animalia

Phylum : Arthropoda

Subphylum : Crustacea

Class : Malacostraca

Order : Decapoda

Suborder : Dendrobranchiata

Family : Penaeidae

Genus : Litopenaeus

Species : L.vanamei

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INTRODUCTION:

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• Whiteleg shrimp also known as Pacific white shrimp or King prawn, is a variety of prawn of the eastern Pacific Ocean commonly caught or farmed for food.

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DESCRIPTION:

• L. vannamei grows to a maximum length of 230 mm with a carapace length of 90 mm.
• Adults live in the ocean, at depths to 72 m, juveniles live in estuaries.
• In India, the L.vannamei culture has grown significantly from 2009 in Andhra pradesh both in area and production.

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DISTRIBUTION & HABITAT :

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• Whiteleg shrimp are native to the eastern Pacific Ocean, from the Mexican state of Sonora to as far south as northern Peru.

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• It is restricted to areas where the watertemperatures remain above 20 °C (68 °F) throughout the year.

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• Penaeus vannamei live in tropical marine habitats.

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• Adults live and spawn in the open ocean, while postlarvae migrate inshore to spend their juvenile, adolescent and sub-adult stages in coastal estuaries, lagoons or mangrove areas.

Males becomes mature from 20 g

Females becomes mature from 28 g.

• P. vannamei weighing 30–45 g will spawn 100 000–250 000 eggs of approximately 0.22 mm in diameter.

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LIFE CYCLE OF Liptopenaeus vannamai:

1. Spawner

2. Roe

3. Nauplius – 6 stages

4. Zoea – 3 stages

5. Mysis – 3 stages

6. Post larvae

7. Fry

8. Adult

Migration of L.vannamei

FEEDING HABITS:

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• L.Vannamei are carnivorous feeds on small crustaceans, amphypoda, and polychaeta.

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• Nauplii do not feed, but live on their yolk reserves.

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• The next larval stages protozoea, mysis and early postlarvae respectively remain planktonic for some time, eat phytoplankton and zooplankton, and are carried towards the shore by tidal currents.

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• The postlarvae (PL) change their planktonic habit about 5 days after moulting into PL, move inshore and begin feeding on benthic detritus, worms, bivalves and crustaceans.

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MORPHOLOGICAL CHARACTERISTICS:

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• Abdomen enclosed by 6segments.
• There are 5pairs of swimming legs which are attached to the 1 segment to 5 segment.
• The 6 and 5^th segment swimming legs changing its form into a tail fan(uropod).
• The tail fan that tapered at the edges is called telson.
• Internal organs that can be observed are the gut (intestine)
• which leads to form anus located at 6^th segment.

Male reproductive organ – petasma

Female reproductive organ - Thelycum

Lateral view of L.vanameii showing important parts

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SEED SUPPLY

• Captured wild seeds were used in extensive pond culture of Penaeus vannamei until the late 1990s.

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• Domestication and genetic selection programmes then provided more consistent supplies of high quality, disease free and/or resistant PL, which were cultured in hatcheries.

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BROOD STOCK

• Brood stock are stocked in maturation tanks in dark rooms supplied with clean, filtered seawater.

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• Feeds consist of a mixture of fresh and formulated broodstock feeds.

Female Broodstock

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• One eyestalk from each female is ablated, leading to repeated maturation and spawning.

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• Females of 8–10 months of age reproduce effectively, while males peak at >10 months.

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• Spawning rates of 5–15 percent/night are achieved, depending upon broodstock source.

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• Females are either spawned in communal or individual tanks.

Maturation Tank

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• The following afternoon, the healthy nauplii are attracted by light, collected and rinsed with seawater.
• They are then disinfected with iodine and/or formalin, rinsed again, counted and transferred to holding tanks or directly to larval rearing tanks.

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HATCHERY MANAGEMENT:

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• Hatching occurs about 16 hours after spawning and fertilization.
• Nauplii are stocked into flat, or preferably 'V' or 'U' shaped tanks with a volume of 4–100 m³, made from concrete, fibreglass or other plastic lined material.

• The larvae are either cultured to PL10–12 in a single larval rearing tank, or
• harvested at PL4–5 and transferred to flat-bottomed raceways/tanks and
• reared to PL10–30.

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• Survival rates to PL10–12 should average >60 percent.

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NURSERY MANAGEMENT

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• Most farming operations for L.vannamei do not use nurseries, but
• transport PL10 –PL12 at reduced temperature either in plastic bags or
• oxygenated transportation tanks to the pond and introduce them directly.

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ON GROWING TECHNIQUES

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• Ongrowing techniques can be sub-divided into four main categories:

a. Extensive Method:

1. Add postlarvae at minimal tide –mangroves,ponds.

2. No water pump/aeration.

3. It takes about 4 – 6 months to become sub-adult.

b. Intensive Method :

1. Add postlarvae to small earth ponds.

2. Heavily aerated , recirculating ,use liners to enchance water quality, feed daily.

3. Use bacterial floc system to diminish feed.

Extensive Method

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HARVESTING TECHNIQUES:

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• Extensive and semi-intensive ponds are harvested by draining the pond at low tide through a bag net installed in the outlet sluice gate.

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• If the tide does not allow harvesting, the water can be pumped out.

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• In some larger farms, harvesting machines pump shrimp and water up to the pond bank where they are dewatered.

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• Intensive ponds may be harvested similarly and small 2–6 man seine nets are dragged around the pond to corral shrimp to the side of the pond from where they are removed by cast or dip net or perforated buckets.
• In super-intensive systems, the shrimp are simply harvested with large scoop nets when required for processing.

Harvesting

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Over view of L. vannamei

ENVIROMENTAL REQUIREMENTS IN CULTURE :

1. Salinity:

Tolerate wide fluctuation, 5 – 40ppt ( Higher salinity may retard growth).

2. Temperature:

Rate of chemical and biological reactions is said to double every 10○c increase in temperature.

3. PH:

Below 5 retards growth – can add lime to neutralize.

4. Alkalinity :

PH levels must be below 9.5 ( retards shrimp growth ).

5. Ammonia :

0.45mg/L can reduce growth by 50%.

6. Dissolved oxygen:

Above 5ppm, exchange water improve aeration, avoid trees, larger ponds allow more o2 diffusion.

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THANK YOU