Upload
jade-villareal
View
283
Download
19
Tags:
Embed Size (px)
DESCRIPTION
Oyster aquaculture
Citation preview
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