Date post: | 29-Nov-2014 |
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Oyster AquacultureMelissa Long
Taxonomy
Pacific OysterCrassostrea gigas
Eastern Oyster Crassostrea virginica
Sydney Rock Oyster Saccostrea glomerata
European Flat Oyster Ostea edulis
Market Price: $3/ 1lb of meat
Market locations:
•United States
•China
•Korea
•Japan
•France
Countries:
•United States
•China
•Japan
•France
Economic Importance:
Oyster aquaculture has provided a business for harvesting oysters as FOOD source for many countries
Life Cycle and Larval Stages• Fertilized egg develops into a:
– planktonic trochophore larvae (free swimming)
– Then develops into veliger larval stage (swimming)
– Then develops into pediveliger larval stage (swim and crawl)
• May spend about 2 weeks in larval stage
before they metamorphose by settling
into a “spat”
• Once the oyster finds the appropriate
habitat it uses cement secreted from a
gland in the foot to attach permanently
Reproduction in Captivity• Some oysters are protantrous hermaphrodites
– Start out life as a male and most will change into a female
• Oysters may be placed in separate containers for selective breeding– Eggs and sperm can be collected and distributed to the
containers
• Or males and females may be left together to mass fertilize
• Sperm triggers females to release millions of eggs
Production Methods:
Hatchery:Adults: induced to spawn
Larvae: fed algae until they are ready to set• Once larvae is ready to set, it is placed
in upwellers that contain crushed shells
Nursery:Spats are placed in nurseries to grow and
harden
Production Methods
Growout:Where oysters can grow to maturity
• Cultch set oysters are grown:– On the bottom in reefs– On ropes suspended off the bottom– Extensive culture
• Single oysters are grown:– In bags that are attached to racks with several layers– Extensive culture
Feeds and Feeding
• Oysters feed on naturally occurring phytoplankton and detritus
• No feed input
Water Chemistry/ Environmental Requirements
For optimal growth and induce spawning:
• Water temperature: 25-30 ºC
• Salinity: 10-22 ppt
Advantages
• Oysters clean the water, remove nitrogen, accelerate denitrification, enhance water clarity
• No feed input
• Nutritional value for humans:– Highest concentration of zinc of any food– Very high in vitamin B12, iron, selenium, phosphorus,
and magnesium
• Tastes great!
Disadvantages
• Fouling organisms – (such as parasites)
– Compete for space and food– Restrict water movement and transportation of food
• Predators – (such as crabs and oyster drills)
– Must expose oyster to air to avoid predation
Even though a pearl oyster is different…
Resources
http://www.bayoyster.com/farming.html
http://www.mrc.state.va.us/Shellfish_Aquaculture.shtm
http://www.chesapeakebay.net/fieldguide/critter/eastern_oyster
http://www.nap.edu/openbook.php?record_id=10796&page=100