To prepare a detailed work plan for periods up to June 1987, of rigorous trials and farm management practices for the production of Penaeus indicus, in order to identify ways of maximizing production rates and economic returns.
The basis for any improvement of the shrimp production in Ngomeni aquafarm is to complete the engineering and to reorganize the management from a personnel, administrative and technical point of view.
Engineering: The existing ponds are perfectly adapted to the future research and development programme, as well as to a training or a commercial programme. However, some improvements should be made in order to facilitate the work.
Gate design: The main work during the filling up of the ponds consists in preventing drift wood to break the gate mesh, and in regularizing the pressure of the inflowing water that may split it. The solutions to this problem are simple; first it presupposes the building of advance protection in the main canal to retain the floating wood, and then it requires to redesign the gate to limit the pressure of the water on the mesh. At the same baited crab traps should be placed in the canal to limit the penetration of crabs into the ponds.
Simple suggestions are given in Annex 2 on how to improve the situation. They are based on the basic physical principle of increasing the surface of filtration of the mesh to reduce the flow pressure.
Central ridge design: As it appears that the central ridge does not have any significant role in the production it is recommended to level completely the pond no. 4 and to test it.
Housing facilities and equipment: It is recommended to finish the installation of the facilities in Ngomeni as this is where all the staff should be working. Malindi should be only a liaison office (telephone, post office, etc.). The whole laboratory equipment should rapidly be transferred to Ngomeni, a new field balance will be necessary as the one in Malindi is electric but on the whole the equipment is sufficient and brand new.
Juridical aspect: the Accountancy Mission raised a lot of questions about juridical and legal aspects of the project activities. In fact, when an investor wants to start a business in any country the first person to hire is a lawyer in order to make sure that everything is done according to the law. It is clear that the present project is a parastatal activity and that the Project Manager needs the advice of a competent lawyer from the Fisheries Department. Such questions as the hiring of temporary workers or the retailing of shrimps directly to hotels may not have been done in strict accordance to the law. It is understandable that the staff in charge, being mainly biologists, were not competent in that field but it is also the duty of a Project Leader to ensure himself that work is done in strict accordance with the national laws.
Work and personnel organization: taking into account the specificity of the work in an aquaculture farm - 7 days a week and overtime every now and then - the teamwork must be organized around three basic principles: a clear definition of each job, a real delegation of authority, and a true circulation of information. It is clear that, from this point of view, much remained to be done in the project. Discussions have started about the job definitions and the elaboration of memo-organization but it is clear that it is a long term work that requires the full collaboration of the Project Manager and counterpart who were on leave. Accepting that the biggest pond of the construction work is completed, such organizational work could be the task of an extensionist/fish farm manager.
A team of 24 persons should be more than enough to run 20 ha of ponds.
The most important criticism to bring to the present Ngomeni technology is that it is an incomplete Asian lablab technology. One of the most important steps, the preparation of the lablab, that is the preparation of the food for the shrimps, is poorly conducted. Dr. Padlan, in an early visit to the project, had given a detailed step-by-step procedure to prepare the pond and grow the lablab (Annex 2). However, this procedure has never been completely put into practice. The preparation of the lablab should last from 6 to 10 weeks in comparison to the present 15 to 25 days period.
In order to get even results from one pond to another it is necessary to modify the pond bottoms, especially in areas reclaimed on mangrove. As the first ponds were built on a dry area, the Project Manager probably did not want to destroy that “good soil” and did not apply the recommendations. But when it came to pond P1 and P6, the results were not good; pond P6 was known to be acidic from the start and should have been immediately treated with lime; as it is also high in organics, the bottom required a true transformation to gelatinous mud in order to be used in aquaculture. The difference of quality of soil from one pond to another and its capacity to fix and grow lablab explains most of the good and bad results observed. No true scientific improvements of the procedures can be expected until this step is solved. Anyway, since the next ponds will be built in mangrove areas for the project itself and for external investors, it is strongly recommended to apply the procedures described by Dr. Padlan and to train the staff and the workers in that technology. (Annex 2).
Up to now, the team project has had to collect the fry. As many villagers have been trained, it should be possible to let them collect the fry and to buy it from them. The difficulty in collecting the fry may be due to the fact that collectors are paid on a daily basis and so they have no incentive to collect rapidly when they can keep working for 3 or 4 days, thus ensuring a better revenue. The actual cost of the fry to the project has been estimated to K.Sh. 15 to 20 per 1 000 juveniles, not taking into account the depreciation of the equipment. This corresponds to the price of U.S.$ 1.0 to 1.3 which can be considered as a realistic price for this species. It is thus recommended to develop the buying from private collectors at a price of K.Sh. 10 to 15 per 1 000, depending on the season. This supposes some additional training for local people and a correct methodology to count the fry. This approach had already been tested some time ago but was unsuccessful due to the low price offered (K.Sh. 3 to 4 per 1 000). This method would also permit to have an idea of the real amount of fry available in the wild throughout the year.
The actual counting methodology consists in a personal estimation of one or two observers. This can be useful for only a limited number of “gifted people” known to give a correct estimation. As it is very difficult to assert scientifically the value of such estimation, this methodology cannot be recommended in a training procedure. So two procedures should be used to estimate the number of fry at stocking and it is recommended to compare them for training purpose (Annex 2).
The present stocking rate 20 000 to 40 000 juveniles per ha is a correct density to work with. It is recommended to stick to those numbers for the next year in order to have a stable comparison point; the planned density of 30 000 per ha can be retained. In order to avoid the penetration of post larvae during the operation the mosquito mesh should be maintained for a longer period; some experiments can even maintain it throughout the whole operation. Anyway, by measuring the salinity everyday during a water exchange time it will be possible to measure the exact impact of the small size-mesh on the renewal of water.
During the grow-out period different types of organic and mineral fertilizers should be tested and their direct effects on the growth curve will be measured through weekly sampling of the population. A detailed sampling methodology is given in Annex 2. The samples will be taken every Thursday morning, for example, and immediately processed; the results will be typed, distributed to the staff and discussed during the next day staff meeting in order to prepare the work plan of the following week. The decision to harvest or to use more fertilizer will be taken in accordance with the results. The grow-out period will be increased to 105 or even 110 days.
The first work to be done during the time the ponds are left for gelatinous mud transformation, should be an inquiry about the organic fertilizers available in the area and the costs. The main fertilizers available are chicken manure, cotton seed cake and other cotton seed residue, molasses from the sugar cane industry. However, competition may exist from other agricultural activities and costs of transportation may be too high for some residues from other industrial crops cultivated in the inner areas. In the area of Ngomeni cow dung has to be collected and so the amount available will probably be limited and expensive. So a detailed programme for the use of organic fertilizers cannot be proposed immediately. The project will probably have to develop an original fertilizing schedule; this could mean either to use mineral fertilizers, that are expensive and imported, or to develop its own programme of pits that will favour the organic decomposition of agricultural residues available in the area.
The technique of transferring the shrimp after 4 to 6 weeks of growth in a “nursery” is common in shrimp farming for two reasons. The first one is to be able to count the shrimps and know the exact population after the weakest postlarvae have been eliminated. The second one is to optimize the acrage of ponds available by using the biggest ponds more often. In the case of Ngomeni, a nursery pond can be used to stock juveniles. However, the use of pregrown juveniles will probably create a new situation as this technique develops the feed and the shrimp at the same time. So by introducing bigger juveniles there is a risk to provoke an “overgrazing” during the first weeks that will result in a limited development of lablab and then a limited growth of the shrimps. Consequently the practice of transferring the juveniles should be used with care.
The harvesting organization needs to be improved in order to let the local staff take the whole responsibility of the operation. The participation of everyone to the harvest is a way to consolidate a team spirit.
It has been decided that the project should stop doing the commercialization as it takes too much time, and rather to sell the frozen shrimps in bulk to wholesalers. However, the aquaculture team will cooperate on the installation of the plate freezer in the Ngomeni Fisheries building.
The main parameters to measure are the temperature, the salinity, the dissolved oxygen and the secchi disk reading. A form for collecting the data is presented in Annex 2. It will be also interesting to follow the pH of the soil every now and then.
The measurement of the salinity is presently a rather complicated procedure. A sample of water is taken every 2 weeks before the spring tide and the opening of the gate. The bottle is sent to the office in Malindi where the salinity is measured by the Project Manager using a salinometer based on an electrical method. The results were collected every now and then and eventually reported on the daily record form one or two months after the sampling.
To measure the salinity, two refractometers are available, one brand new as a pH, a D.O. meter and other equipment they have never been used for unknown reasons. One of them is now in the aquafarm where the staff has immediately made use of it. The previous procedure is abandoned and the staff should enter the salinity directly on the data form without sending anymore water samples to Malindi.
In order to secure the supply of juveniles all year round for a starting industry, the creation of a small hatchery will soon be necessary.
The Ngomeni aquafarm is a correct tool but it still has to be improved to permit easier management. Then the farming procedures will have to be corrected in order to give reliable repetitive experiments. The project had already received all the necessary recommendations but they still have to be implemented.
The results proved that P. indicus can be cultured in Kenya without sophisticated technology, but in order to play its role of research, development and demonstration, the farm management has to be seriously modernized. This is a necessary step to improve shrimp aquaculture; the economic aspects of which will be examined in chapter 4.
