Pearl culture

Most scientific studies on oyster resources, biology and farming have been carried out in the twentieth century. New approaches to our understanding of the intricate pattern of the oyster behaviour in respect of feeding, reproduction, larval development and disease control have enabled scientists to plan and undertake highly successful oyster farming in recent years. This is not only the situation in advanced countries but has become a distinct possibility in India. Scientists of the Central Marine Fisheries Research Institute have achieved remarkable success by carrying out extensive investigations relating to the breeding and farming of the edible oyster during the past one decade. In addition to the evaluation of the potentialities of natural resources in several zones of Indian coastal waters, estuaries and backwaters, suitable technologies for oyster farming and hatchery production of oyster seed have been developed by the CMFRI. It would only be a matter of time before commercial farming of the edible oyster takes place in the country

Pearl and Chank Fisheries - A New Outlook in Survey and Fishing

The Gulf of Mannar and the Palk Bay Zones of the east coast of the Madras state, particularly the area from Rameshwaram to Manapad, are of very great fishing importance as far as the pearl and chank fisheries are concerned. The submarine plateau of the inshore areas of the sea here affords excellent habitat for the growth of the shell fish, Xnrcvs pyrum (Linn.) (the sacred chank) and Pivcunla jucaia (Gould) (the pearl oyster). Chank fishing and pearl fishing in this zone had been conducted from time immemorial under the control of the State. All along the stretch of the sea-bottom, extensive, flat rocky patches occur at a distance of 8-12 miles from the shore within 7-12 fathoms, separated from one another and surrounded by equally extensive patches of fine sandy areas at the same or slightly deeper zones. Whereas the chanks prefer fine and soft sandy areas called locally 'Poochi-manal' or 'pirals' as their abode, the oysters are sedentary and are attached to hard rocky substrata called'Pa ar'. Occasionally tfe one is found in the natural habitat of the other. There are more than 65 well known'Paars' (rocky sea-bottom) and lesser in number of good chank grounds in the Gulf of Mannar known to fisherman by their depth and location fixed by land bearings. The sea bottrm on Palk Bay side is not rocky, at the same time less shallow also. The chanks rrowing in this zone are classified as 'Patti' variety which is priced less than the 'Jadhi' variety fished from Rameshwaram to Tiruchendur. The differentiation between these two lie in the latter being elongate, elegantly formed, comparatively narrower and with well balanced spire whereas the former is with a short spire. The Tirunelveli and Ramanathapuram chanks now constitute the bulk to meet the demand from Bengal for chank bangle industry

Oyster culture- Status and prospects

Most scientific studies on oyster resources, biology and farming have been carried out in the twentieth century. New approaches to our understanding of the intricate pattern of the oyster behaviour in respect of feeding, reproduction, larval development and disease control have enabled scientists to plan and undertake highly successful oyster farming in recent years. This is not only the situation in advanced countries but has become a distinct possibility in India. Scientists of the Central Marine Fisheries Research Institute have achieved remarkable success by carrying out extensive investigations relating to the breeding and farming of the edible oyster during the past one decade. In addition to the evaluation of the potentialities of natural resources in several zones of Indian coastal waters, estuaries and backwaters, suitable technologies for oyster farming and hatchery production of oyster seed have been developed by the CMFRI. It would only be a matter of time before commercial farming of the edible oyster takes place in the country

Underwater ecological observations in the Gulf of Mannar, off Tuticorin-II. The Occurrence of the Synaptid Chondrocloea along with the Massive Sponge, Petrosia

In this paper an interesting instance of association between a sponge and a synaptid, which was observed during the course of our underwater dives with SCUBA is recorded. The rocky patches of the sea bottom off Tuticorin exhibited certain sharacteristic fauna depending on the depth and locality. For instance, the shorepvard rocky floor in the 10-13 metre range was characterized by, amongst other things, the small and medium sized sponges firmly attached to the substratum and Ivas conspicuous by the absence of the massive sponge of the genus Petrosla

DNET: A communications facility for distributed heterogeneous computing

This document describes DNET, a heterogeneous data communications networking facility. DNET allows programs operating on hosts on dissimilar networks to communicate with one another without concern for computer hardware, network protocol, or operating system differences. The overall DNET network is defined as the collection of host machines/networks on which the DNET software is operating. Each underlying network is considered a DNET 'domain'. Data communications service is provided between any two processes on any two hosts on any of the networks (domains) that may be reached via DNET. DNET provides protocol transparent, reliable, streaming data transmission between hosts (restricted, initially to DECnet and TCP/IP networks). DNET also provides variable length datagram service with optional return receipts

Oyster farming

Large quantities of the edible oyster, Crassostrea madrasensis (Fig. 1) growing wildly in most of the tidal creeks and estuarine regions along the east coast of India, are allowed to perish un-exploring the great strides made in this venture by developed nations. The Central Marine Fisheries Research Institute focused its attention in developing systems for the culture of edible bivalves, identifying edible oyster farming and mussel farming as priority areas for Research and Development. Evaluation of the resources potential, identification of suitable water spread and areas for culture, evolving proper techniques to collect required seed for farming, introducing an appropriate method of farming and establishing a model farm formed the broad objectives of the project initiated in 1975 on edible oyster culture. By employing suitable method for spat collection and providing better growing conditions for the seed so collected it appeared distinctly possible to raise large number of oysters achieving faster growth rate and better meat yield. Weighing the pros and cons of the different systems of oyster culture followed in other countries and bearing in mind the local conditions, it was decided to experiment with the 'rack' system of culture

Ill Edible Bivalves; Clams and others

Clams belonging to a number of species and a fevi' other edible bivalves occur in appreciable quantities in different parts of the Indian coasts and support subsistence fisheries. Thousands of square kilometres of our coastal seas, backwaters and estuaries form ideal habitat for the growth of these bivalves and many among the poorer classes of the coastal population use them as food although it should be admitted that a vast majority of other fish-eating population of our country have not developed a liking for these shellfish. The flesh of clams being rich in glycogen, protein and health giving minerals is highly nutritious

Chank resources of India

The sacred chank Xancus pyrum (Linn.) is a commercialJy important gastropod fished in large numbeis along the coasts of all but a few of the maritime states of India. Fishing is carried out mainly by skin diving, although hand-picking and net fishing are also prevalent here and there. The fishery provides a good source of living to nearly 1,000 divers in the Madras State in addition to those engaged in the same profession along the Gujarat and Kerala coasts. The main market for these chanks is West Bengal where chank bangle industry is flourishing. Investigation conducted by means of SCUBA by the authors have brought to light good concentration of chank population suitable for commercial exploitation, over vast stretches in the Palk Bay and Gulf of Mannar. The statistics of annual chank landings, yield from area to area, account of the chank fishery in important centres, details of the diving method and the extent of the chank grounds are recorded. Possibilities for exploiting unfished areas and suggestions for increasing the fishing tempo are discussed in detail. In this context SCUBA diving for chanks has proved very advantageous and is recommended keeping in view the economic aspect of the divers as well as judicious exploitation of the stock

Scuba diving investigations and training

During the past 35 years underwater technology, engineering, bio-medicine, saturation diving and automation had developed tremendously to enable man to forge to very great depths in to the oceans and stay there for extensive periods. It was possible to experience a three dimensional space, diving with selfcontained underwater breathing apparatus(SCUBA). The CMFRI acquired modern equipments to promote this discipline of scientific work enabled the scientists to facilitated collection of useful data on the pearl oysters and chank, in the study of the ecological features of the sea bed of Tuticorin and estimation of the density of chank and oyster population in different localities investigated. One such assignment was the survey of Andamans and Nicobar Islands for assessing potentialities of these areas for mariculture purposes. Another contribution by the diving scientists team was the detailed survey of 20 islands in the Gulf of Mannar during 1978-80 and exploration of the fringing coral reefs and adjacent areas . In order to promote 'SCUBA' diving for scientific and exploratory purposes and for exploitation of marine resources the Institute conducts training programmes for scientists and technical personnel and this consists of theory classes in Snorkeling, Diving equipment, Diving ,Aqua lung, Deep dive, Skin diver and marine life, Model gadgets in diving and practical classes