Seed production of Holothuria fuscogilva and Thelenota ananas which are found to be distributed in 30 to 40 m. depth can be taken up in the first instance. These two species of sea cucumbers have good economic value.
The breeding season for the above two species is from December to March in the Maldives. Therefore, the seed production experiments can be taken up during this period.
The two rooms constructed at Gamu Island by the Oceanographic Society of Maldives can be converted into a mini sea cucumber hatchery with suitable modifications.
Always brood stock has to be maintained in the hatchery in brood stock tanks in healthy condition for thermal stimulation whenever required.
The larger room constructed by the project can be used as a wet laboratory for larval rearing. A small portion of this laboratory is set apart for the examination of larvae, preparation of algal extract etc.
The smaller room can be partitioned and the toilet should be shifted outside. This would allow space for stock culture and for mass culture. The temperature in this room should be maintained at 20–22°C for the optimum growth of micro-algale.
The basic plan for the hatchery is given in Fig. 1. The sea water can be drawn directly from the sea by PVC pipe (90 mm. diameter) by gravitation to a well sunk near the shore.
At Gamu Island, fresh water is available at a depth of 1 m. Therefore before sinking the well near the shore, the salinity of the sub-soil water has to be tested. During the high tide, sea water flows into the well by gravitation.
If the water in the well becomes less saline due to fresh water influx, then the sea water can be directly pumped to the sedimentation tank. For the development of the sea cucumber larvae, the salinity of the sea water used should be around 33 to 35 ppt.
The filter bed is used as a biological filter. Inside the filter bed at the bottom gravel in the middle coal and at the top river, sand is provided to a thickness of 30 to 45 cm. The river sand has to be changed once in 15 days and the filter bed has to be cleaned with bleaching powder once in three months.
Despite the biological filter and the UV filter if bacteria are found in the sea water leading to heavy mortality of the larvae, then de-chlorinated sea water has to be used. Chlorination up to 6 ppm. will kill all the pathogens.
A proper drainage has to be arranged in the hatchery to remove the waste water. The water so removed should be let out at the other end.
A separate store room may be constructed to keep all the diving and other equipment of the laboratory.
All the pipes used in the hatchery should be made of PVC material and no metal pipes should be used to avoid corrosion,
The two small rooms already constructed a little away from the main building can be used as compressor room and generator room.
The Consultant is in touch with the Director of Oceanographic Society, the Director of Fisheries and other officials of Maldives regarding the seed production of sea cucumbers to provide any required advice on culture techniques of commercial tropical sea cucumbers.
The Consultant has already provided a sample of lsochrysis galbana which is the chief feed used for rearing sea cucumber larvae. The larvae of sea cucumbers are known to feed well on this microalgal. The growth is good and also the mortality rate is low when fed on this food. This culture is now maintained in a refrigerator at the Marine Research Section in Male. The isolation method for the micro-algae and the Conway or Walne's medium used in the stock culture are also given in Section 4.
The Consultant has already supplied twenty-one publications on taxonomy, anatomy, biology, ecology, hatchery and culture of commercial tropical sea cucumbers (Appendix I). He will continue to publish papers.
Subject to the clearance by the Government of India, the consultant will be available for further missions as provided for in the work plan.
