Previous Page Table of Contents


7. SHRIMP CULTURE IN COASTAL PONDS


7.1 Background
7.2 Research needs
7.3 Research approach

7.1 Background

As in other regions of the world, there is a growing interest in the culture of shrimps in the coastal states of Africa also. Preliminary attempts to grow local species or to rear imported species like Penaeus japonicus have not been particularly successful. However, many countries have plans to start pilot shrimp farms. This, as well as the potentials for large-scale farming in coastal areas, accounts for the selection of this system of farming as a subject for research, even though it is accorded only a low priority in the Centre's programme of work.

The most common and promising species for culture on the West African coast would appear to be P. duorarum. On the East African coast there are more proven species like P. monodon, P. indicus and P. semisulcatus. Since the importation of these species would present several problems, which the Centre in its initial stages would find difficult to deal with, it is suggested that in the first phase, attempts be made at the Centre to develop a technology for pond culture of P. duorarum based on post larvae and juveniles collected from natural habitats. Controlled maturation, spawning and hatchery production of seed should be attempted only if the initial production experiments show promise.

As described earlier, one of the problems of coastal ponds built on mangrove soil is the acidity of the soil and consequent low pH of water. Preliminary observations seem to indicate that the bottom-living shrimps are more susceptible to such low pH. The sudden changes of salinity that may occur as a result of heavy rains, may adversely affect the survival of shrimps in coastal ponds.

7.2 Research needs

(i) Determination of salinity and pH tolerance of different life stages of P. duorarum;

(ii) study of the availability of larvae and juveniles in coastal waters, including their distribution in time and space;

(iii) methods of field identification of shrimp larvae and juveniles; their collection and transport for rearing;

(iv) methods of pond preparation and management for shrimp culture;

(v) comparative experiments in feeding shrimp larvae and juveniles with cultured food organisms and artificial feeds;

(vi) development of suitable artificial feeds for post-larvae, juveniles and adult shrimps;

(vii) rearing of the shrimp to commercial size in ponds and comparative yield trials to determine the economic viability of culturing the species;

(viii) monitoring of health and diseases in culture ponds;

(ix) if culture experiments are promising, the development of methods of maturation, spawning and hatchery production of larvae of the species.

7.3 Research approach

Considerable information on the behaviour of P. duorarum, including its moulting frequency, cannibalistic tendencies if any, and its salinity and pH tolerances, can be obtained through laboratory experiments. Well-planned regular sampling with suitable collection gear will be necessary, to determine the distribution and availability of shrimp larvae and juveniles.

Laboratory rearing of larvae and even juveniles may be necessary to work out methods for their rapid identification in the field. Methods used elsewhere for the transport of larvae and juveniles can be tried under local conditions, and modifications found necessary made to improve their efficiency.

Methods to be tried for expediting the improvement of brackishwater pond soils through leaching and liming have already been referred to on page 12. These should be tested in shrimp ponds also and the behaviour of shrimps on improved pond bottoms observed.

The methods to be adopted for preparing feeds using locally-available feed ingredients, have been described earlier and these would apply also for shrimp feeds. Modifications will be necessary in the formulae and processing methods to meet the nutritional needs of the shrimp and its feeding habits. Use of clam meat readily available in brackishwater areas, may substantially improve the quality of feeds for shrimps.

Rearing of shrimp food organisms should be undertaken in laboratory or outdoor tanks. Comparative experiments of feeding larvae with live food and specially prepared artificial feeds should be carried out, to determine their relative merits.

A series of factorially designed production experiments, incorporating the main variables such as Stocking density, feed, feeding method, feeding rate, water quality, nature of pond bottom and growing period, should be carried out with proper monitoring of health and water conditions. Based on the yields obtained and Operating costs, economic viability should be determined.

As mentioned earlier, if the production experiments demonstrate the technical and economic feasibility of shrimp culture, the Centre should, at a later stage, start studies on controlled reproduction and hatchery production of larvae, so as to make farming less dependent on natural seed. For this, methods already developed elsewhere can be used. Modifications found necessary should be incorporated to make the system efficient.


Previous Page Top of Page