oyster aquaculture

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