Persian pounds near Little Aden were formerly used as fish and shrimp preserves. Considering the lack of data on management methods at that time, it cannot be advanced that aquaculture took place there except as a very extensive activity. The People's Democratic Republic of Yemen Government, taking an interest in fisheries and mariculture, in 1977 requested the Japanese company Nichiro Gyogyo Ltd. to investigate the feasibility of shrimp culture in the country. Obviously, the objective was to provide a minimum research basis and, in case of success, foreign exchange by marketing the products to Japan or other countries.
Following this request, Japanese trawlers undertook a shrimp survey along the coast of People's Democratic Republic of Yemen in late August 1977, with the following purposes: (i) to determine whether or not the schools of shrimp fry coming to the coastal waters of the country in summer are fit for cultivation and available; (ii) to collect basic information necessary to know if there are any coastal waters fit for shrimp cultivation (Nichiro Gyogyo, 1977).
In accordance with the conclusions of Nichiro Gyogyo, a small shrimp experimental station was constructed on Labor Island, Aden, by the beginning of 1978, based on a joint venture system between the Ministry of Fish Wealth and Nichiro Gyogyo Ltd. Experiments started in April 1978 and are still going on, mainly on cultivation of Penaeus semisulcatus. In May 1979, Nichiro Gyogyo submitted a progress report on experimental cultivation of shrimp in People's Democratic Republic of Yemen (Nichiro Gyogyo, 1979). Following this report (Appendix 2), experimental work went on and a new field research station was designed. Its construction may occur by the end of 1980. According to the results of cultivation in this new facility, in one or two years, the agreement between Nichiro Gyogyo and the People's Democratic Republic or Yemen Government will be reconsidered.
In addition to this main experiment in mariculture, several missions have come to People's Democratic Republic of Yemen to study the biology of marine turtles. The idea of turtle farming had been suggested (FAO, 1973), but nothing has been done up to now despite the high economic interest of these species and their relative capacities to be bred.
The Ministry of Fish Wealth will probably soon be reorganized and the future importance given to aquaculture is still unknown. The staff of the Ministry of Fish Wealth involved in aquaculture experiments includes:
It must be noted that in the near future PDRY could benefit from an extensive training program for fisheries personnel, mainly conducted in the USSR.
Aquaculture facilities consist only of a small shrimp experimental station located at Labour Island (Appendix 2). The location in Aden harbour makes it difficult to get good water quality (oil pollution from ships) and consequently, a new station will be established in Little Aden. As pointed out by a previous expert (Mohamed, 1979), summarized in Appendix 3, the equipment is very poor and research equipment is almost nonexistant This will have to be considerably improved in the future.
The People's Democratic Republic of Yemen lies along the Southwest of the Arabian Peninsula and has a total area of 287 000 km , divided into six governorates. The first governorate consists of Aden and its outskirts, to which have been added numerous islands and especially Socotra (not included in this preliminary investigation). The following governorates lie from west (2nd) to east (6th). Total population has reached 1.7 million, 250 000 of them living in Aden.
The country is mountainous, providing few littoral plains. The mountains decrease gradually in the northeast of the country to end in the desert of Rub al Khali. Only a mere 3 percent of the total area could be used for agriculture, if all other necessary resources for its development were provided. Mountains, semidesert and desert sands constitue the major part of the country.
The PDRY has no available oil deposits up to now and almost no mineral resources. To add to this scarcity of natural resources is lack of fresh water: rainfall is almost nonexistant under a 500 m level on the coastline and of course in Hadramaut and Rub al Khali. In Aden and vicinity, water comes from the Second and Third Governorates and is distributed by pipes in the whole littoral plain. Recently foreign companies have been surveying the underground water resources of PDRY in order to extend agricultural activities.
The climate, especially under 500 m along the coastline, is very harsh, hot and dry from October to April and torrid and humid from May to September. Due to the very difficult conditions, activities must be reduced from June to August when the temperature/humidity levels are too high.
Economical background has been improving in recent years during the First Five Year Plan. Although the country still relies on external assistance for part of its development, it has been exporting fishery products, cotton, salt, tobacco and small industry products. Imports consist of food, machines, cars and trucks and oil products.
An extensive educational programme has been launched to reach higher educational standards.
3.3.2.1 Fresh Water
Traditionally, large cities in PDRY have depended on surface water stored in large cisterns. while small villages and nomad people had to use springs and wells.
Research has been continuing on how to increase water resources, mainly by surveying aquifers. Data are still unpublished. Obviously, freshwater use for aquaculture is out of the question, except on a very limited scale in hatcheries operation,
3.3.2.2 Seawater Quality, Temperature and Salinity
Pollution problems concern only the innermost parts of Aden Bay, due to oil effluents from ships and the sewer system from the city. In any case, this area used for the harbour cannot be reclaimed for aquaculture purposes.
Water temperatures in the coastal areas range throughout the year from 25 to 36° C (Table 3). Very little data are available along the coastline and no recording has been done in the most promising zone for aquaculture. This will have to be corrected as soon as possible by surveying the key points (See Section 4.1.2). What might be advanced is that in shallow sea lagoons like Little Aden, the water salinity is subject to variation to a relatively great extent due to evaporation.
Interest in mariculture in the PDRY was stimulated by the high prices of shrimps (Penaeus sp.) on the international market as a possible means to help the country in seeking foreign exchange. The fact that Japanese companies were working in PDRY was an even more decisive factor, since it appeared possible to acquire shrimp culture technology from them and Nichiro Gyogyo decided to contribute financially to this experimental approach. The original interest can still be found in the way shrimp culture is developing in the country. However, this “cash culture” must be considered as a high risk activity in the present state of knowledge and technology in PDRY and actual development cannot be expected unless considerable efforts are made in various fields of the culture process (See Section 4).
Beside shrimp culture, turtle culture has been considered in the past. Current international regulations and the poor state of demand on national markets did not allow turtle culture in PDRY. Nevertheless, interest in turtle culture might be resumed considering the availability of juveniles and the favourable grazing grounds of Khor Omera (Section 3.5.2). In addition, despite international regulations, fishermen from the small village of Imran, west of Aden, culture small turtles and are getting a rather good control of the first stages. On the whole, they obtain interesting results (70 percent in survival rates from one day to 6 to 8 months, feeding them on minced fish and keeping the turtles in small tanks 1.5 × 0.8 × 0.3 m), not only in breeding but also in marketing (a 20 cm diameter turtle is sold for between 7 and 15 Dinars).
It appears that fish might be used in pond culture provided the supply of juveniles could be guaranteed. Potential species are: mullets, milkfish, breams and maybe some Carangidae. It has been reported that fry of mullets were very abundant before the big trawlers went into operation. Now schools of mullet fry and other species can be observed from the seashore in many places, but in relatively low quantity. No scientific data exist in the country on the local availability of juveniles of mullets and other fish species which might be of interest for mariculture production. If these stocks are to be exploited for mariculture production, as well as effectively protected against detrimental human actions (large trawlers in the fry grounds) and if a rational balance between fishing of fry for culture and fisheries on natural stocks has to be kept, then it is necessary to collect basic biological data (Section 4.1).
Agriculture has been developing in the past years and, in case of need, it would not be difficult to provide inorganic fertilizers for pond management in extensive mariculture. On the contrary, industrial production of poultry and cattle is still limited and organic manure is not available for mariculture.
Due to the limited time during the assignment and incompatibility in the respective schedules, it has been almost impossible to gather valuable data in this specific field. However, the Public Fish Meal Corporation can supply fish meal in case of need. The poultry industry is now under experiment and development and a small unit for experimental diets is available, even if most of the feed is presently imported. Moreover, the facilities for artificial feed production are located in Little Aden and this would considerably help an aquaculture development programme in the Persian ponds.
In order to determine whether production of artificial diets is economically possible in PDRY, a complete study of feed ingredients and prices is necessary and should be conducted as soon as possible.
This first mission in PDRY lasted effectively 11 days and the whole background of aquaculture had to be considered. The coastline, as already mentioned, has 1 555 km and therefore it has been impossible to make a detailed survey of potential sites for aquaculture. Considering the observations of the Ministry of Fish Wealth staff, only some obviously potential sites for mariculture have been toured. In the future, it would be necessary to carry out a general survey of the coastline (Section 4.1.3) in order to allow a balanced development of mariculture in the country, whenever it is possible.
Experiments in aquaculture will have to be done in environments as suitable as possible. This implies that, for the first trials, all factors which can help to attain promising results very quickly, must exist on the few selected experimental sites: (i) good natural environment; (ii) proximity of a big city; (iii) feed and other like inputs (technical background); (iv) skill. In order to select the most suitable places for this experimental work, all parameters have been entered as inputs in Table 4.
It clearly appears that, depending on the priorities given by the Government, three sites could be selected from the very beginning: (1) Persian ponds and the Little Aden area; (2) Um Bikha in the Mukalla area, and (3) Khor Omera in the Second Governorate. If positive results could be obtained on these sites and if other resources (i.e., sites) have to be mobilized, then, paying great attention to the environment, the Khormaksar ponds in the Aden area (requiring high investment), as well as the Rukub and Buish lagoons in the 5th Governorate might be used.
Before any investment is made, it appears very important to proceed to a detailed investigation of the sites mentioned (Section 4). A general description of the sites visited is given in Appendix 4.
Limitations to mariculture development in PDRY which might reveal themselves in the future should be carefully weighed before going into large scale development. A two-step plan should, therefore, be considered (Section 4) as an attempt to minimize risks.
During the first period, various investigations should clear up the actual doubts concerning mainly the following possible limitations:
numbers of shrimp juveniles/adults and of fish juveniles which might be used for aquaculture;
population dynamics of turtles and international regulations for turtle culture;
the maximum water temperature/salinity in ponds and the possible techniques required to keep these parameters to acceptable values;
soil qualities which have not been studied in the different sites; medium/fine sand is largely predominant and might not hold water at low tides; further soil analyses are necessary to clear up this point (Section 4.2.2);
the growth and survival rates of various fish/shrimp species when cultured in such an extreme environment;
the type of mariculture system to be selected, by a detailed study of tides and pond characteristics. Considering the limited tides (mean range: 1 m), it is very unlikely that an extensive mariculture system, such as tidal pools, will be feasible (except valliculture in Little Aden Bay). Additional equipment (pumps, etc.) might be necessary to keep good control of physicochemical parameters, dissolved oxygen and salinities especially;
the last limitation in PDRY (investment capacity is excluded from this review) concerns the availability of skilled personnel at all levels of responsibility. In the past, there has been very little practical mariculture work. The experience of the existing staff is, therefore, very limited in this field and further training will be required. Additional staff will have to be recruited and trained as well. As far as possible, such training is best performed on site under local conditions; some external training, however, might be necessary for senior personnel to specialize in particular techniques required by selected culture systems.
