Marimepear culturel

7/30/2019 Marimepear culturel

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Represented By-:

Hariom vermaAQC-04/11


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Pearls are among the oldest and most universal of germs.

These were probably the first germs to adorn mankindand need no polishing or faceting to reveal their beauty.They were valued above all germsuntil diamond gainedtop status in the early 19 th century.Besides

adornment,pearls and their shells can be ground tocalcium carbonate tablets for pregnancies, weak bodies;toothcavities, stomach acid and allergies. Tiny or flawedpearl unfit for jewelry are also used in medicines,cosmetics and tooth past.


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Pearl oysters of the genus Pinctada are widely distributedin the worldThe gold/silver-lip pearl oyster P. maxima occurs along thenorth coast of Australia, Burma . P. margaritifera is widelydistributed in the Persian Gulf, Red Sea, Sudan, Papua NewGuinea, Australia, French Polynesia, Indonesia, Andamanand Nicobar Islands, Southwestern part of the IndianOcean, Japan and the Pacific Ocean . The pearl oyster P.

fucata is distributed in the Red Sea, Persian Gulf, India,China, Korea, Japan, Venezuela and Western Pacific Ocean

In the southwest coast of India at Vizhinjam, Kerala coast,large numbers of spat of P. fucata have been collected frommussel culture ropes


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Though Pinctada fucata P. maxima . P.

margaritifera are available in Indian coast P.fucata is common in the production of fine pearls. Hencethis species is paid much attention in the culture andartificial pearl production .The oyster belonging to

P.fucata are foundatteched with byssus to hardsubstrata (pars) such as corals, rocks, etc. in the areaof gulf of mannar. Though this species is stenohaline.it can tolerate short term salinity fluctuation and isfound to survive in a salinity as low as 7 ppt . Beingfilter feeder it mainly feed phytoplankton andoccasionally on bivalve eggs shelled larvae, copepods, crustacean appendages


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P.Fucata has life span of 5-6 years and get maximum sizeof 10cm.

Spawning- this sp. Attains maturity when it is young (25-30).Two peaks in spawning during jul. to Aug. and Nov. toDec. coinciding with south west and northeast monsoonhave been recorded in P.fucata.

Development- the eggs and sperms shed in the seawater by thefemale and male are fertilized externally and fertilized eggsin a period of about 24hrs. Pass several stages viz. morula,gastrula, trochophor and straight hinge, stage beforereaching a typical molluscan veliger. Free swimminglarvae set as spats when they are 0.3mm in size.


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Laboratory breeding in P.fucata - for laboratorybreeding of P.fucata rip male and female oysters areplaced in glass throughout of 10 L. capacity orfiberglass tank of 100 L. containing filtered seawaterand subjected to aeration .As the water turns milky onspawning as in the case of edible oysters. The parent

oysters removed. The fertilized eggs settle at thebottom of the containers. After removing the supernantwater containing unfertilized eggs, debris, etc, freshseawater is added for about five time followed by

decanting every time until the fertilized eggs onlyremain in vessel


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Larval Rearing-After about 4 hrs of fertilization, the swimming morulastage appears and is transferred with the help of polythene

tube to larval rearing vessels(10L. Glass jars or 10,50,40mfiber glass tanks)containing filtered seawater. Theseawater is to be changed almost daily in these vessels.However aeration is not required in these rearing vesselsuntil the spats start setting. At this stage the larvae are fedwith flagellates such as Isochrysis galbana.After about 20 hrs of fertilization, the straight hingstage(D-shaped shell of veliger or Prodissoconch-I)whichis transparent ,granulated and with globulated velumappears .This larva has a size range of 70 60m.-

100

85m.which is reached in 9days of development.When the larva grows to a size of 100 100m, its shellbecomes rounded and body become globular. A distinctumbo, mantle folds and equal right and left valves developwhen the larva is 135 130m.


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On the 15 th day of fertilization, the larva which is210 190mbecome deeply pigmented and developseye spot, foot primordium and ctenidial ridge. By 20 th day the functional foot and gill filament appear and thelarva has a size of 230 200m.In this stage the velumis pushed to the anterior side and the velar crowngradually begins to shrink in size Further the larva nowswims with velum, crawls eith foot and starts settlingon the substratum by 22 nd day. When the larva becomesplantigrade stage (250 240m).


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The latter stage is characterized by the absence of velum and the presence of labial pulps, additionalgill filaments and 3new shell strongly sculpturedwith irregularly rectangular or oval markings whichis beginning of the formation of adult or dissoconch. By 24 th day theplantigrade stage turns into an

young spat(330

300m) with hinge line anteriorauricles and notch. During the formation of differentstages in the rearing vessels, the larvae are fed with

Isochrysis galbana at the rate of 10,000-

25,000cell/day/larva


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In the natural pearl formation, if any of the foregein

substance, like sand particles, blood cells ,brokencell of tissue or bacteria, enters accidentially in to theoyster body the epithelial cell of mantle form a sacwhich secretes nacre over the substance layer after

layer and in the course of time the natural pearl isfound. When the pearl are formed in the mantle orany soft tissue of the oysters they are said to be freepearl Such free pearls are rarely round as theygenerally depend on the shape of foreign substanceenter.


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The suitabilities of site and techniques for the culture of mother pearl oyster are more or less similar to that of edible oyster as similar raft and long line and cages areused.

Pearl Production- It involves two phases vize.laboratoryphase and farm phase .

Laboratory Phase-This involve the conditioning of grown oysters andimplementation of nucleus along with graft tissue.

Suitable oysters are selected and cleaned from foulerfollowed by placing them in a glass trough containingfiltered seawater to which some menthol crystals aresprinkled. After about 1hour, the oysters are taken out of the vessel.


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Graft Tissue Preparation-An oyster is shucked and sacrificed for this purpose.

The mantle is cut ,cleaned and trimmed. It is placed onsoft wooden piece and fractioned into pieces 3 2mm.The pieces are finally seared with a weak eosinsolution to avoid deterioration of tissue

Nucleus-The nuclei used for implantation in the oysters for theproduction of pearls are spherical beads of 2-8mm andmade from either chank or freshwater mussel shells

.


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Surgery-It involves the implantation of the graft tissue and the

nucleus inside the body of the oyster with the help of small stainless vice ,lancelet, vacuum cupped needles,etc. The actual process is as follows. The selected andconditioned oysters are first mounted on a stand with

their valves slightly open to faciliate surgery. Now withthe help of lancer needle an incisions made at the baseof foot. Then a canal is cut through the gonad below theepithelium without damaging the stomach or intestine

up to selected site of implantation.


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For the implntation of nucleus, the site is invariablyclose to the intestinal loop. On the other hand forinserting 2nuclei. The area nearer to thehepatopancrease is selected and for multiplenuclei(8nuclei) the area between intestine andhepatopancreas. This is followed by the implantationof nucleus in contact with the outer epithelium of thegraft tissue. After the operation is over the oyster areremoved from the stand and kept in seawater troughunder aeration for some time until the oyster become

active .


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The implanted oyster are subjected to farm phase whichinvolves suspension of frame net or cage containing theimplanted and convalescent oyster from raft or longline. The frame net are more suitable for phase as thecrowding of oyster is avoided in these .Further it is also

easy to follow performance of individual oyster inframe nets. The outer epithelium of the implantedmantle graft tissue grows over the nucleus during thisphase and forms a pearl sac in period of about one

week. Subsequently, the pearl sac starts secreting thelustrous nacre over the nucleus layer after layer information of pearl.


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The harvesting period of the farm grown pearl oysterfor their pearls depend on the size of pearls required .Itis known that a period of about 3-20 month is requiredfor the production of pearl of 3-8mm in diameter.Processing of Pearls-To clear spots and make the pearl whiter, they may be

bleached in hydrogen peroxide Japanese using amixture of medicinal dye colour the pearls as pink,silver , creamy, yellow ,green, blue or black. Soaking of pearls in a solution of mercinochrome may retain thecolour for about 5 year.


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TRAINING PROGRAMMES The Central Marine Fisheries Research Institute is thenerve centre of pearl culture technology in India. Inaccordance with the policy of the Indian Council of

Agricultural Research on transfer of technology, theabove technologies developed by the Central MarineFisheries Research Institute have been disseminatedthrough training courses offered to candidates

sponsored by different governments, universities andother agencies. The aim of the training programmeshas been to extend the technical know-how to end-users.


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The Central Marine Fisheries Research Institute, after

developing the technology indigenously, has adoptedan open policy of imparting the technology throughtraining courses, not only to Indian citizens but also toforeign technicians who are sponsored by their

respective Governments.Long-term training course- A long-term trainingcourse of six months duration was conducted once in1976 77 by the CMFRI for managerial and supervisory

personnel. This was a comprehensive course whichdealt with pearl oyster resources, oyster biology,mother oyster culture, pearl collection and farmmanagement. Nine trainees from maritime states of India participated in that programme.


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Short-term training course- The above long-termcourse has been replaced by a short term course of 4 6weeks duration. Four such programmes were conductedbetween 1977 and 1986, in which 25 personnel weretrained. The content was developed for technicians. Thecourse is more popular among the interestedorganizations.Training programme in pearl oyster hatchery- This isa 4-week course. This is useful not only to thoseconcerned with pearl culture, but also to the molluscans

aqua culturists who wish to raise marine bivalve stocksin hatchery. The course curriculum includesinfrastructure facilities needed for a hatchery, biology of pearl oyster,


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controlled maturation and spawning, micro algal foodproduction, larval rearing, larval feeding, water qualitymanagement, disease control, spat settlement, spatcollection and juvenile rearing.Training for mariculture students- An intensive one-week training on the techniques of pearl culture and

pearl oyster hatchery is given to each batch of studentsof M.Sc. and Ph.D. courses in mariculture under thepost-graduate teaching programme in mariculture of CMFRI every year.

Marimepear culturel

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