A report on window pane oyster fishery in Tuticorin bay

The window pane oyster (Placenta placenta) are fished regularly for pearls and shells from Kakinada Bay of Andhra Pradesh and Okhamandal Coast of Gulf of Kutch

Pearl culture

Pearl culture gives the highest gross income for unit area among aquaculture systems. The techniques developed by CMFRI to suit Indian condition have attracted the entrepreneurs to enter into the venture of pearl culture. The rate of return works out to more than 50%. The recent line of research on the onshore pearl oyster farming and pearl culture, can easily revolutionize the concept and this can be profitably taken up in the east and west coasts of India where prawn farming was successfully conducted. In this paper the cost of seed production and economics of pearl production is dealt with The possibilities of taking up production of seed of desired qualities through selective breeding, manipulation of conditions in the onshore tanks culture are counted as priorities. Black pearl production and farming and pearl culture in the natural beds are the other priorities

Larval and juvenile rearing of black-lip pearl oyster, Pinctada margaritifera (Linnaeus)

The black-lip pearl oyster, Pinctada margaritifera (Linnaeus), has been cultured in the experimental shellfish hatchery at Tuticorin, India. The flagellates Isochrysis galbana and Pavlova lutheri were used independently as larval food at a concentration of 5 cells/μl up to day 5 and the ration was doubled thereafter until spat setting. The initial larval density was 1/ml. Straighthinge veliger stage (75×60 μm) was reached in 20 h, umbo stage (140×130 μm) on day 12, pediveliger (220×210 μm) on day 20 and plantigrade (260×240 μm) on day 23, and spat of 350×300 μm appeared on day 28. I. galbana promoted faster growth and early spat setting as compared to P. lutheri. The modal component of the larval population showed an average growth of 10.98 μm/day. A total of 6.3% of the initial larval population metamorphosed as spat. Juveniles cultured in the laboratory showed a growth rate of 0.09 mm/day. On transplantation to the culture raft in the farm, growth rate increased to 0.4 mm/day. The juveniles suffered heavy mortality after 4 months. It remains to be tested whether P. margaritifera juveniles would have a greater chance of survival in oceanic island conditions, as the natural distribution of the species in India is confined to the Andaman and Nicobar Islands

Marine pearl production

Pearls are harvested manually. Oysters are opened and pearls are squeezed out. In case 9,500 reuse, the pearls are removed carefully by opening the pearl- sac through the gonad without damaging it. The harvested pearls are washed in distilled water polished in refined salt and again washed in distilled wate

Pearl production in relation to the graft tissue in the pearl oyster Pinctada fucata (Gould)

This reports the results of study on which region of the mantle gives good quality pearls and also higher production rate. The mantle tissue from 4 areas namely anterior (a),posterior (b), middle (c), and central (d)regions were used. This study showed that the middle region of mantle when used as graft tissue resulted in not only high percentage of pearl formation (50.28%) but also, the marketable pearls (A, B and C - groups) accounted for 77.53% of the total pearls produced

Manual on Pearl Oyster Seed Production, Farming and Pearl Culture

The Central Marine Fisheries Research Institute has developed expertise on various marine fisheries and mariculture technologies over the past several years. Based on this expertise the Institute has been offering regular training courses to officials from State Governments, Universities, ICAR Institutes, Krishi Vigyan Kendras, training institutions, industry and progressive farmers on subjects like marine prawn hatchery, prawn farming, pearl oyster hatchery, pearl oyster culture, pearl culture, edible oyster hatchery, edible oyster farming, seaweed culture and utilisation, SCUBA diving, estimation of marine fish production and stock assessment. The Trainers' Training Centre (TTC) of the CMFRI, Cochin, established in the year 1983, has so far conducted 83 such trainings for 590 personnel from the various maritime states including Pondicherry, Lakshadweep and the Andaman & Nicobar Islands

The pearl oysters

An account of the pearl oyster resources with a brief note on biology, collection methods, seed production and conservation and management in the Indian subcontinent is dealt with in this paper. Both in the Gulf of Kutch and the Gulf of Mannar, the population does not show improvement. Conservation and management of this important resource in the light of the present R&D carried out by the CMFRI is discussed. Enhancement of the wild stock through the production of genetically improved seed in the hatchery and ranching them to selected beds and close monitoring of the physico-chemical and biological factors over a period of time is suggested. Farming of oysters on the natural beds can enhance the pearl quality and may form a breeding reserve

Settlement and growth of barnacle and associated fouling organisms in pearl culture farm in the Gulf of Mannar

The settlement of fouling organisms on the pearl oysters, pearl oyster shells and wooden test panels was compared. The barnacle Bedanus amphitrite variegatus was the major fouling organism observed and the polychaete Polydora ciliata and the sponge (Cliona vasiifica) were the main boring organisms. Theintensity of settlement at different depths and the period of abundance of these organisms were studied.The successive settlement and fast growth of barnacles resulted in heavy loading on the oysters within a short period. The fouling load and the rate of growth of barnacles were higher on the shells than on live oysters. The settlement was more at the top rows of the sandwich-type frame ne

Embryonic and early larval development of pearl oyster Pinctada fucata (Gould)

Hatchery production of seed is of great importance in aquaculture, particularly in situations where availability of natural seed is undependable. Besides, the system provides advantages of selective breeding keeping in view the genetic factors. Commercial hatcheries already sustain large-scale production of edible oysters in several countrie

Biofouling, boring and predation of pearl oyster

During the course of the experiments in pearl culture since 1972 in the Gulf of Mannar, several problems were encoimtered in the farm due to biofouling, boring and predation of oyster stocks. An account of fouling and boring organisms in the farm at Veppalodai was given by Alagarswami and Chellam (1976). Nishii (1961) and Nishii et al. (1961) indicated some relationship between the frequency of cleaning and growth of pearls in the Japanese waters. Wada (1973) reported that animals and seaweeds setting on the oysters and baskets inhibited the growth not only of the oysters but also of the pearls. The occurrence of polychaete and sponge borers on the pearl oyster Pinctada fucata and their control measures were given by Velayudhan (1983)