Post on 24-Feb-2016
description
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.