#Oyster spat collector manual#
The Pearl Oyster Farming and Pearl Culture Manual in India (Central Marine Fisheries Research Institute at Tuticorin, India, published February 1981), stated that when inducing spawning chemically "A pH value of 9.0 in the case of Tris buffer and 9.5 in NaOH gives 78.6% and 68.4% of spawning, respectively."įurther, they say, "Injection of 0.2 ml of N/10 ammonium hydroxide (NH4)H) solution into the aductor muscle of the pearl oyster results in 48% spawning." The pH media can be prepared using Tris buffer or Sodium hydroxide pellets. These include different concentrations of hydrogen peroxide either in normal seawater or alkaline seawater (pH 9.1). Other than the thermal method of spawning stimulation, chemical methods can be used to induce spawning. The numbers of shell being cleaned are generally large, so there is no problem with obtaining sufficient eggs for stocking into the hatching tanks. Large quantities of good quality eggs can be obtained by this method because shells which have been hanging on chaplets and longlines generally are in good condition and release gametes readily upon handling. Cleaning of these shells can be combined with their use as broodstock for a planned spawning in the hatchery. Although the farmer must be careful not to have excessive handling of these seeded shell, it is normal in most places that cleaning of these shell is carried out on a regular basis to reduce fouling organisms growing on the outside of the shell. This allows time for the shell to acclimate to the lagoon condition and for gametogenesis to proceed toward ripe gametes.Īnother very suitable source of broodstock are seeded shell which are already hanging on longlines. They should remain on the longline at least 4-6 months before they may be used during a spawning for the hatchery. If the shell looks suitable for broodstock use, the shell should be drilled in the appropriate place and hung on chaplets from a longline or they may be placed into 8-pocket panel nets and suspended from a longline. Freshly collected shell which are potential broodstock should be assessed for DVM (Dorso-Ventral Measurement) size and shape of the shell. Broodstock Pinctada margaritifera may be obtained from shell that have settled on collectors set in the lagoons of atolls or in some cases from wildstock shell. It is the intent of Dr Braley that the start-up and training stage of this new hatchery and nursery will be greatly facilitated by the information contained in a manual which is prepared for each hatchery.Ĭentral to larval culture is the availability of good quality broodstock.
The hatchery/nursery staff must exhibit these qualities in their work. Good observation and thoroughness are necessary to fine-tune the initiating protocol. In the end, the protocol for the given hatchery will be the most efficient possible for that hatchery. This development of the specific protocol for a hatchery will take place as the start-up begins and as spat are produced. Aquasearch works on-site with the technicians to assure the technical knowledge has been successfully transferred.Įvery hatchery and nursery has site specific conditions which require fine-tuning of the initiating protocol used at the facility. Rick Braley has prepared plans to setup a blacklip pearl oyster hatchery and nursery at Fakareva Atoll, Tuamuotu, French Polynesia and redesigned and setup an existing hatchery in Penrhyn Atoll, Cook islands as well as trained staff to operate the two facilites. This is the road to proper animal husbandry.ĭr. The hatchery and nursery will give the farmer a predictable supply of spat and will allow greater manipulation of genetic traits. Likewise, the thought of controlling some desirable characteristics of the pearl oysters has resulted in the setup of hatchery and nursery facilities. As the industry has expanded the need for a more predictable source of the spat has emerged. The pearl oyster industry traditionally relied upon spat collection in the field to supply its needs for farm requirements. Excerpts from a Blacklip Pearl Oyster Culture Manual of Dr.
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