presentation by karen jensen marine aquaculture 2013
TRANSCRIPT
Common Saltwater Species Family Penaeidae
Whiteleg shrimpPenaeus vannamei
Giant tiger prawnPenaeus
monodon
Economic importance World production of captured and farmed shrimp is ~6
million tons 25-30% of worldwide saltwater shrimp production is in
ponds Texas produces the most of any state- 8 million lbs in
2001 Florida has the largest hatcheries
Penaeus vannamei aquaculture has boomed in recent years 2011: 2,877,542 tons produced Market price decreasing, 3-3.5 USD/kg in 2005 Main suppliers to US: Thailand, Ecuador, India, China,
Vietnam Penaeus monodon
2011: 662,453 tons produced Market price in Japan: 9-14 USD/kg in 2004
Life cycle• After hatching • 6 nauplius
stages• Attracted
to light, feeds on yolk
• 3 zoea stages• 3 mysis
stages• Postlarvae are
carried to the protection of estuaries
• Development through larval stages takes ~3 weeks
• Juveniles and adults migrate offshore and mature in the ocean• Also spawn offshore
• Females grow faster and larger
Reproduction in captivity• Many hatcheries
collect gravid females from the sea to spawn in captivity• No control of
genetics, disease tolerance
• Captive maturation can be done• Large tank at low
density: 5-7 shrimp per meter
• Constant conditions- temp, pH, light, good nutrition- are important for maturation
• Eyestalk ablation in females
• After spawning, the female releases eggs into the water, fertilizing them by simultaneously rupturing the spermatophore • 150,000-200,000 eggs per
spawn (P. vannamei)• 500,000-750,000 eggs/spawn
(P. monodon)
Production methods Hatcheries
Eggs hatch within 24 hours After hatching, nauplii are stocked into V or U-shaped
tanks ~3 weeks to reach postlarval stage
Nurseries Smaller ponds or intensive raceways act as an
intermediate between hatchery and grow-out size Not always used
Most US prawn farms are semi-intensive or intensive ponds Must make up for land costs, short growing season Extensive ponds common in South/Central America, where
land is cheaper Ponds stocked in April/May
Stocked at post-larval stage, <1/2 inch
Harvest Harvest in October when temps drop and
growth slow Potentially 3 crops per year in a warm climate-
not in US Drains are invaluable in shrimp ponds Gently sloping ponds with drains allow shrimp
to concentrate in a catchbasin
Feeding Ponds are fertilized prior to stocking
Stimulates phytoplankton and zooplankton production
Artificial supplemental food still necessary Lower protein needed for P. vannamei: 18-35% 36-42% for P. monodon, more carnivorous
Protozoea can be fed diatoms Mysid stages can be fed Artemia nauplii Broodstock fed squid,
mussels, and cockles
Water Chemistry Parameters
pH 7-9 DO 5-15 ppm Temperature 26-29 ˚C 5-35 ppt salinity 100-500 ppm hardness (Ca2+
concentration) Lower may reduce calcified shell Higher may produce encrustations on the
shells Hardness increased by addition of calcium
in the form of agricultural gypsum
Marine Shrimp Aquaculture
Advantages Disadvantages
Very popular food item in the US, Japan, and increasingly in EU
Fast-growing (~6 months)
FCR 2:1 or lower Some natural food
supplied Disease-resistant
strains are being produced
Pond must be near brackish water source Mangrove ecosystems used
in pond construction (improving)
Few hatcheries produce post-larval shrimp Must have pristine water
quality
Higher densities usually required to make a profit, increases risk