Oyster Aquaculture Melissa Long. Taxonomy Pacific Oyster Crassostrea gigas Eastern Oyster...

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