PEARL OYSTERSCaitlin Marsh

Taxonomy Genus: Pinctada

Includes most of the pearls found in fashion. Pinctada maxima

South Sea pearls

Pinctada fucata Akoya pearls (classic)

Pinctada margartifera Tahitian peals (black)

Economic Importance Billion dollar retail industry

Sold all over the world Price depends on rarity and quality

$50 Pair of freshwater pearl earings to $100,000 strand of South Sea pearls.

Life Cycle

Reproduction in Captivity Thermal stimulation induces spawning.

Breeded from healthiest looking oysters. Larvae are allowed to float freely in the

water under controlled conditions until they are a few weeks old.

Once the larvae develop into baby oysters they are moved to a “nursery” area.

Remain in nursery for about 1-2 years, until they are large enough to be grafted.

Grafting A nucleus/grain (usually mother of pearl)

is inserted with a piece of donor mantle tissue into the pearl pocket.

If it is rejected then can create deformed “Keshis”

Number of times an oyster can be seeded depends on species.

Growing Raft Culturing

Appropriate for sheltered bays Long-line culture method

Cages are hung from horizontal ropes or chains connected to floats.

Oysters are threaded at onto a small thread or rope that is hung from a raft.

Good for open ocean environments On-bottom culture

Can only be used in areas of granite or coral sand composition of the sea bottom.

Harvest Akoya pearls are harvested after 8

months – 2 years. All other pearls are harvested after 2 – 6

years. Harvesting is done in the winter months,

when the pearl luster is highest. An x-ray can be used to determine pearl

size before harvest. Harvested pearls are then cleaned,

polished, and treated.

Extensive Aquaculture Most food is supplied by filtering water

wherever they’re located. In larval and nursery stage, fed with

microalgae and algae. Most labor is devoted to grafting and

insuring good pearl growth.

Water Chemistry Temperature

20 – 25C Salinity

Prefer higher salinities, but tolerate wide range.

Bottom Gravelly Avoid sandy or muddy bottoms, reduce pearl

quality. Depth

Optimum depth at ~ 15m

Advantages Disadvantages

Almost 100% of new pearls come from aquaculture

Almost any size, color, luminosity, shape, etc.

Largely extensive.

Limited production of more expensive pearls.

Time consuming In competition with

imitation pearls. Can be effected by

weather or natural disasters.