As already stressed above, aquaculture development in the country must be done cautiously. The lack of data in all fields, of trained personnel and of previous experience led to the proposal of a two-step plan for feasibility of mariculture establishment in the country. This will require external technical assistance. This plan has to be carried out in accordance to the General Five Year Plan (1981–85) of PDRY.
The first step should start as soon as possible with, as a main objective, to provide detailed scientific and technical data and to test cultural systems on an experimental basis, while simultaneously ascertaining the local availability of the necessary inputs and how to utilize them for efficient fish/shrimp production.
The second step would consist of a feasibility study and requires pilot scale facilities and gives the possibility of full-scale fish farming within the five years of the Second National Plan.
Simultaneously, a general assessment of a valliculture type of production should be conducted in Little Aden Bay and, provided the results are positive, adequate facilities for this should be constructed.
Starting with the Second General Five Year Plan, this programme has been discussed with Mr A.W. Sharaf, Deputy Minister of Fish Wealth; Mr A. Ghaddaf, Director of Research; Mr A. Al Hamady, Deputy Director, MFW, and Mr P.K. Eapen, Principal Technical Adviser (Fisheries), FAO.
Information should be gathered immediately on:
the availability of juveniles and parent stocks of potential culture species;
a few basic physical parameters, such as tides, water salinities and temperatures near the proposed sites;
the availability of mariculture sites in PDRY by conducting a national site survey;
environmental characteristics of selected sites through detailed investigations, including productivity estimations;
similar experiences in foreign countries, in order to provide general information background to national personnel.
During the proposed studies, it will be necessary to carefully record all related data organized at regular intervals into progress reports. This immediate work programme will last one year,
(a) Objectives. To provide data on seasonal availability, quantities, preferred habitat, capture and transport methodology for the juveniles and parent stocks of potential culture species. Priorities will be given - in decreasing order - to (i) mullets, shrimps, (ii) milkfish, (iii) seabream and Carangidae.
(b) Justification. Data collection is essential prior to any trial of mullet culture. Information on quantities of fry available in the natural environment could help in programming the mariculture production. For shrimp (Penaeus semisulcatus), any large-scale production either in hatchery or relying on catches of adults is very dependent on the availability of “seeds” in the natural environment, at least to bring out the first generation in ponds.
(c) Manpower/equipment (Table 5). One FAO consultant during one month to initiate juvenile surveys. One senior, one junior staff, and one fishermen who can properly use a castnet and one driver (as an embryo of a coastal population dynamics team) for three days per week for mullets and other coastal fishes during four six-week periods per year. Road and water transportation facilities; scuba diving equipment (2); fishing equipment (castnets, small seines); isotherm and aerated container.
For shrimps, agreement with Nichiro Gyogyo Ltd. for research planning (2 or 3 weeks) with PDRY's research vessel to include a shrimp survey along the coast of the 5th and 6th Governorates.
(d) Implementation. At first, data should be collected from local fishermen engaged in this type of Fishery , for several years concerning: (i) the fishing grounds and their annual variations according to external factors such as tides, lunar rhythms, climate, monsoon, etc.); (ii) the efficiency of fishing and (ill) the number of fishermen who fish the related species.
Habitat study: detailed field surveys of inshore areas will provide the necessary information for mapping the preferred habitat of selected fish species. This will require diving to various habitats at different times of the year, depending on breeding season, tides, etc. This study should contribute to the understanding of migrations and facilitate the completion of the following point.
Capture methods. Methods should be developed for efficient capture of large quantities of juveniles of selected species. Small seines (4–5 m long and 1 m deep) made from fine soft mesh should be tried. The catch rates (fish/man/hour) should be recorded, as well as environmental factors.
Biological investigations. These should be made on the available specimen from local markets, local fishermen landings and from the catch of the research team. Whenever it is possible gonads from fresh fish will be sampled once a week in order to estimate the gonadal index. Some tagging experiments should take place in Little Aden Bay on a sample large enough to assess the growth rates in the natural environment.
Transportation system. In order to reduce mortalities to a minimum during the capture and seeding process, appropriate transport devices should be provided. Consequently, an isotherm container, including aeration, will be necessary. This equipment will allow good training of technical personnel in the field so that transportation methods will not be a problem in the future.
Shrimp programme. Due to the lack of brackish waters along the coast of PDRY and almost no data on shrimp populations, it is necessary to resume research on natural populations. Surveys should be conducted at least twice a year during one week near Aden and along the coast of the 5th and 6th Governorates in order to provide information on: (i) abundance of P. semisulcatus and the biological cycle in the natural environment; (ii) distribution of other shrimp species.
(a) Objectives. To provide minimum information on tidal fluctuations, water temperature and salinity variations near the selected sites.
(b) Justification. To date, almost no data exist on the above mentioned parameters near the proposed sites and, consequently, it is impossible to promote mariculture activities based only on the available information. Data should be recorded over a period of time as long as possible to provide a sound basis for future developments.
(c) Manpower/equipment required (Table 5). Initially, one senior officer three days a week during two months and one junior staff for training; afterwards, one senior officer for part of a day once a week and one junior staff one day per week. Road and water transport; permanent reference staff for tide reading (fishermen) (See Appendix 5); thermometers, thermographs, refractometer.
(d) Implementation (Section 4.1.4)
(a) Objectives. Previous and present aquaculture missions to PDRY were definitely too short to allow a complete survey of the coastline. Moreover, no scientific equipment was available to gather at least minimum information on the different sites. The national site survey will be planned to give an extensive knowledge of the PDRY coastline in the fields of topography, water quality, fish and shellfish species, social background and communication transportation.
(b) Justification. Preliminary missions have shown that interesting sites for mariculture development exist near Aden (Table 4). In order to promote a well balanced development of the country, it seems necessary to find out, if possible, potential sites for development in all governorates.
(c) Manpower/equipment. One senior officer (possibly from FAO) for two months; one senior national officer for two weeks and one fisherman who knows the proper use of castnets, plus one driver. Road and water transportation. Topographical study equipment; basic physico-chemical analysis apparatus; small fishing and basic biological equipment (binocular microscope, sampling material, etc.) (Table 5).
(d) Implementation. If an FAO consultant has to carry out this work it is recommended to plan the mission between January and April 1981 but to avoid, if possible, summertime which is extremely hot. However, in order to record maximum temperatures and salinities, it would be interesting if a complementary survey could be conducted by the senior Yemen officer trained previously by the FAO consultant.
Since the Persian ponds have already been selected for the shrimp hatchery, Little Aden Bay, including the Persian and the salt ponds should be studied in detail. Near Mukalla, The Urn Bikha lagoon is the most promising site for limited aquaculture development and experiment and it should be carefully surveyed,
(a) Objectives. Gather as much data as possible and train personnel in order to provide a strong scientific and technical background for the next step: feasibility project and pilot scale operations.
(b) Manpower/equipment. One senior officer, one junior staff, one fisherman and one driver two days a week during one year. In the Aden area, these staff should be based at the new laboratory in Little Aden (shrimp station). Equipment should be provided for (i) physico-chemical analysis (D.O. meter, pH meter, salinometer, spectrophotometer, precision balances, drying stove, refrigerator, automatic sampling device, demineralization water unit, chemical products, etc.); (ii) biological research (systematics: conservation media, sampling apparatus, microscopes, etc.); (iii) fish population dynamics (nets and seines); (iv) plankton study set.
(c) Implementation. Physico-chemical analysis should start as soon as possible in the Little Aden area. The research team working presently on the shrimp programme (Labour Island) should perform these analyses.
Information and specialized literature in the mariculture field are dramatically insufficient in PDRY. It seems necessary to build a documentation centre on mariculture, located either at the Ministry of Fish Wealth or at the new shrimp station.
One junior staff would be needed for documentation.
In order to test mariculture technologies adapted to the national context, it seems necessary to establish first a small-scale feasibility project. Because the Persian ponds are available to test extensive fish culture without high investment, the feasibility project in this particular field will almost consist of a pilot-scale project.
to continue the local surveys of mullets (fry and adult), shrimp juvenile and parent stocks and other fishes of particular interest to mariculture;
to develop simple and efficient methods for their capture and live transport;
to assist in the construction of test ponds at Little Aden and to develop the optimal techniques to reuse the Little Aden salt pans as mariculture ponds;
to conduct feasibility studies on the pond cultivation of shrimps and mullets (or other fishes) on a semi-intensive basis;
to assess the potential use of one Persian pond on a semi-extensive basis;
to assist in the formulation and production of better shrimp and fish feed;
to train national personnel in mariculture techniques.
(a) Location. Administrative support will be provided from the headquarters of the Ministry of Fish Wealth in Aden, while field work will take place in the new mariculture station located in Little Aden.
(b) Phasing. The project will last one year. It will involve several phases and, depending on availability of local personnel, will be devoted to all previously mentioned studies during the immediate work programme (Section 4.1) (except the national site survey), to detailed topographical site survey, soil surveys, test ponds design and construction and laboratory tests on feed. Training of senior personnel in mariculture management techniques and feed technology will be first obtained in a foreign country (Japan, if possible) through one month visits and later at the project itself. Junior staff will be trained at the field station by the senior personnel through a short training course and practical field experience.
(c) Programme elements
(i) Continuance of physico-chemical and biological studies of immediate work programme, plus hydrological studies of Little Aden Bay, soil surveys, design and construction of two fish ponds close to the shrimp station, studies on the Persian ponds and reconstruction of sluice gates of pond number 2 (Fig, 2.1).
(ii) Reinforcement of the shrimp station, which will become a field base adequately equipped: electricity (including electrical generator), water pumps, housing facilities, etc.
(iii) Design, construction and test of two ponds. Since natural productivity is involved in semi-intensive fish production, the two ponds will be different sizes: pond number 1 = 0.1 ha (25 × 40 m); pond number 2 = 1 ha (X × Y × 1.5 m) where X and Y will be based on existing salt pond dikes in order to minimize the costs. In the first pond, productivity and fertilization will play a minor role in fish culture, whereas in pond number 2, natural productivity and fertilization are expected to be much more important. Additional feeding will be kept at a rather low level in pond 2, as opposed to pond number 1, Ponds will be filled initially at high tide. Then, water supply, including water exchange and evaporation will be guaranteed by electric pumps (water acceleration device with a very low head of water) powered if possible by solar cells. Regular observation of the ponds will be done from the water and engineering points of view to better assess construction design.
(iv) The mariculture feasibility study will be conducted both in shrimp farming (Nichiro pond) and in fish farming. Stocking of the test ponds will be with available juveniles of various species, mullets and others; fertilization and feeding. Performance of the fish ponds will be studied: analysis of water quality (pH, temp., salinity, D.O., plankton, turbidity), bottom sediment quality, fish growth related to water exchanges and fertilization. Continuation of shrimp production feasibility study with Nichiro.
(d) Support
PDRY support for the feasibility project (Table 6)
Facilities/buildings: land for marine test ponds, housing (2 labourers, watchmen), laboratory, office, store
Personnel: 3 aquaculturists (12 m/m each)
1 feed technologist (6 m/m)
2 technicians (12 m/m each)
4 labourers/fishermen (12 m/m each)
2 watchmen/drivers (12 m/m each)
Equipment: vehicle (1 pickup truck), fishing equipment (small boat with engine)
Supplies: for operation of offices, laboratories and farm (fertilizers and feed)
Miscellaneous: operating cost for equipment, boats and vehicles
Donor support for the feasibility project (Table 7)
Facilities: two ponds, sluice gates on Persian pond
Personnel: one marine aquaculturist (12 m/m) with good practical experience in wild fry surveys in coastal waters and in management of aquaculture facilities; engineer consultants (hatchery techniques, civil engineering, feed production).
Equipment: pickup truck (1); surveying equipment (1 set); speed boat and engine (1); portable water quality analysis (1 full set: pH meter (1), oxymeter with salinity compensation (1), salinity meter (1), recording oxymeter (1), recording thermographs (2)): meteorological kit (1); fish transport tank with small air compressor (1); water pumps (2); electric generator (1); feed equipment (1 kit: feed mixers (2), feed cutter (1), feed sundryer (1)); biological research equipment (plankton set (2), spectrophotometer (1), microscope (1)).
Training: one senior officer for a four-week study tour to Japan (shrimp culture: hatcheries and pond culture techniques) and to China (semi-intensive fish culture in big ponds); phasing: beginning of the feasibility project.
Follow-up evaluation of a short-term mission (15 days) to evaluate the results of the feasibility study and to prepare the pilot scale project implementation if necessary.
