CMFRI has succeeded in the laboratory breeding of sea cucumbers,

top shell, great clam and the blood clam, through temperature

manipulation, for the first time in India at the

Shellfish Hatchery Laboratory at Tuticorin Research Centre

CMFRI, Kochi

CMFRI Digital Repository

Advances in Sea Farming The Central Marine Fisheries Research Institute, Cochin has achieved more breakthroughs in the field of seafarming. The Institute which has developed a number of techniques for cul-ture of commercially important marine animals has also been concentrating on sea ranch-ing programmes for replenish-ing the natural fishery resources. The research efforts in this di-rection have culminated in the success, for the first time in In-dia, of laboratory breeding of sea cucumbers, top shell, great clam and the blood clam. The beche-c'e-mer prepared from sea cucumber earns a fo-reign exchange of about Rs. 20 lakhs annually. The major mar-kets for this product are Singa-pore and Hongkong. In India this commercially important re-source is restricted to the Gulf of Mannar and Palk Bay region and there are evidences of over exploitation of the single species (Holothuria scabra) contribut-ing to the fishery. Dr D. B. James, Shri M. E. Rajapandian and Dr C. P. Gopinathan, Scientists and Shri B. K. Baskar, Senior Research Fellow of the Institute, developed the techni-que for laboratory breeding of this animal by temperature ma-nipulations. This achievement can pave way for large-scale cul-ture of the sea cucumbers for further development of the in-dustry and breeding of much larger and more valuable species occurring in the Lakshadweep islands for sea ranching and ex-port. Large s p e c i m e n s of Holothuria (Metriatyla) scabra (300-350 mm in length and 500-600 g) were brought to the laboratory in the last week of January, and they were acclamatised to the laboratory conditions. The specimens were induced to spawn in the labo-ratory by slightly raising the SEA CUCUMBER (Holothuria) A. Blastular stage; B. Auricularia stage; C. Pentactula stage CMFRI has succeeded in the laboratory breeding of sea cucumbers, top shell, great clam and the blood clam, through temperature manipulation, for the first time in India at the Shellfish Hatchery Laboratory at Tuticorin Research Centre. 3 TOP SHELL (Trochus radiatus) Top — 3 month-old shells Bottom Left: Late trochophore — 3 hours after ferti-lization (250 H) Right: Typical veliger — 4 hours after fertilization (300 V-) temperature of seawater. First the male spawned and this sti-mulated the females to release eggs. One female released near-ly one million eggs. After ferti-lisation the eggs transformed, undergoing several changes into a stage known as auricularia on the second day. The eggs were sperical, white and were visible to the naked eye and they were floating. The auricularia trans-formed into another stage known as doliolaria. Doliolaria is parrel-shaped with five bands and with two tentacles project-ing out. They move fast in the anterior direction. The posterior portion is slightly tapering. On each side there are five round structures with distinct opening at the posterior end. There are five groups of hair-like struc-tures on either side. The larvae are fed on micro-algal cultures maintained at the Research Cen-tre. On the thirteenth day some of the doliolaria transformed into pentactula stage. The body of pentactula is tubular with five tentacles at the anterior ehd and one short stumpy tubefoot at the posterior end. Tlie colour is greenish-brown. Trie tentacles have a web in bet-ween them. Later one more tubefoot developes and they be-come elongated. The tentacles and tubefeet develop small cal-careous particles known as spi-cules. These give rigidity to the body. The pentactula have the habit of moving to the edge of the tank and remaining just be-low the surface of the water. They settle down to the bottom of the tank as miniature holer thurians. They are fed with algal powder mixed with sand or mud. The top shell (Trochus nilo-ticus) is in great demand in shell craft industry. To establish techniques for breeding and lar-val rearing methods of this group of. animals, experiments were conducted at the Shellfish Hatchery Laboratory of the Institute wi th the candidate spe-cies Trochus radiatus. The ful-ly matured animals kept in clean filtered seawater spawned and hatched out and developed into young animals. These animals attained full growth within three months. Isochrysis and soft agal fila-ments were given as feed. S/Shri K. Ramdoss and S. Ma-hadevan, Scientists and T. Rajan, Technical Assistant achieved this success. Based on these results commercially important species of top shells available in Anda-man and Lakshadweep regions could also be bred using the same technique. 3 GREAT CLAM — Meretrix meretrix Top: Adult clams; Bottom Left: Straight stage; 2 days old Bottom Right: Spat 22 days (461 V-) L. BLOOD CLAM — Anadara granosa : spat — 27th day (417 V-); fltf• Umbo — 10th day (155V-) Clams which play a very im-portant role in coastal rural eco-nomy belong to the group of animals which are suitable for farming. Clam is an efficient con-verter of primary production into food suitable for human consumption, thus contributing to low cost nutritious food ma-terial. The shell, rich in cal-cium carbonate is used in lime, cement, fertilizer, sugar and shell craft industries and as a feed for prawn and poultry. I't also has a place in the export market and clam meat worth Rs. 1 crore is being exported annualy to Japan. The present breakthro-ugh obtained in the laboratory breeding by temperature mani-pulation and production of seed of the great clam (Meretrix meretrix) and blood clam (An-adara granosa) would help in transplanting seed in suitable areas where a production of 40 tonnes per hactare can be ob-tained in a period of six months. This success was achieved by a team of scientists consisting of Dr K. A. Narasimham, Shri P. Muthiah and Dr C. P. Gopina-than. There is scope for taking up clam farming on a large scale in the coastal and brackish-water areas of the country for increasing production and em-ployment opportunities. A well established shell fish hatchery laboratory having run-ning water and algal culture faci-lities with proper i l lumination, temperature control and dust-free atmosphere have contribut-ed remarkably for achieving suc-cess in the induced breeding techniques. 

Advances in sea farming

http://eprints.cmfri.org.in/6564/1/Advances_in_sea_farming.pdf

Advances in sea farming

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