Transcript Oyster Aquaculture

Oyster Aquaculture
Melissa Long
Taxonomy
Eastern Oyster
European Flat Oyster
Crassostrea virginica
Ostea edulis
Pacific Oyster
Crassostrea gigas
Sydney Rock Oyster
Saccostrea glomerata
Economic Importance:
Oyster aquaculture has provided a
business for harvesting oysters as FOOD
source for many countries
Market Price: $3/ 1lb of meat
Market locations:
•United States
•China
•Korea
•Japan
•France
Countries:
•United States
•China
•Japan
•France
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_Aquacu
lture.shtm
http://www.chesapeakebay.net/fieldguide/crit
ter/eastern_oyster
http://www.nap.edu/openbook.php?record_i
d=10796&page=100