There are fundamentally two types of marine aquaculture which can be envisaged for Eritrea:
an extensive type where large areas are used and where the feeding of the fish is ensured by the natural productivity of water, which may be enhanced by fertilization, and which could be suitable for species such as mullet, milkfish or shrimp;
a semi-intensive type where part of the food is provided in an artificial form (pellets), which could be suitable for shrimp.
Given the natural presence of mullet, milkfish, and shrimp, along the Eritrean coast, it could be supposed that the environment is suitable for their development as cultured species. Yet it is universally recognised that aquaculture, basically, is economically efficient only when the capture fishery cannot fulfil a solvable demand, inducing an increase of the prices. Thus the utmost caution is necessary when contemplating the development of marine aquaculture for these species. The wild stocks of the Eritrean Red Sea are notably underutilised, and aquaculture cannot compete in any way with a well-exploited capture fishery.
A project just getting underway aims at large-scale mullet and milkfish aquaculture. Stated target production levels are 225,000 tons of fish on 6400 ha of fertilized tidal ponds, at the yield of 35 t fish/ha/yr. There are some very worrisome technical aspects, however.
except in intensive raceway fish culture under highly controlled conditions and with full artificial feeding, no yield figures even approaching those cited have ever been achieved in any aquaculture research center or production site, with any fish species.
the Egyptians, who are experts in mullet culture in fertilized ponds, achieve an average of 500 kg/ha/yr, and can reach 1–2 t/ha/yr in the best locations;
the tides in the Red Sea are between 0.6 and 0.9 m, and moreover the water level varies much more on the influence of wind than on that of the tide, which could make the management of large areas of tidal ponds very difficult if not impossible; and
the ponds are supposed to be stocked with fingerlings collected from the sea, at the average rate of 75,000/ha. This represents a total of 480,000,000 fingerlings, which, if the average weight is 2 g, represents more or less 1000 tons of fingerlings. It is very unlikely that such a quantity would be available.
Technically, it can be said without any doubt that this project will in no way even begin to approach its objectives. Even at a far smaller scale it is very doubtful that this type of aquaculture could be justified. Based on experience in Africa and over the world, it can be assumed that on extensive production schemes, with planktonovorous fish such as mullet and milkfish (or tilapia), selfsustainable development is impossible if the ex-farm price is below 1 US$/kg, and starts to be realistic between 1.5 and 2 US$/kg. The actual ex-fisher price of mullet in Eritrea is 1.75 EBirr/kg (0.35 US$/kg), which makes mullet aquaculture development a very unlikely proposition in the country. Even for a subsistence activity, it is not justified as it would always be much easier and cheaper for the people living on the seaside to get fish by direct capture. One has to remember also that for the time being, even though they are caught, mullet and milkfish are often discarded, which raises the issue of their acceptability to local populations.
Shrimp culture has been developing worldwide at very high rates during the last ten years, to the point that it now represents 50% of a world market representing more than 1 millions. The main areas of development have been Asia and Latin America. Rapid and uncontrolled growth in this sector has led to the outbreak of diseases which in the last months have almost sterilized thousands of hectares of shrimp ponds. It is thus very likely that the big shrimp investors will try to diversify their implantations.
Eritrea has large areas of virgin flat shorelines, where warm sea water is available, and which could be suitable for this type of aquaculture.3 Some important limitations must be kept in mind, however:
the access to the major part of the shoreline is quite difficult, which could be an important constraint for a basically export-oriented activity; the best areas would thus be in the vicinity of Massawa and/or Assab.
if semi-intensive culture is considered, there is an important need of high quality pellets supply. Pellets for the time being cannot be produced in Eritrea. This forces any project to rely on imports -- an unfavourable circumstance (as has been seen in Madagascar) when there is competition with countries where the feed is locally produced.
the waters of the Red Sea are very salty (38 g/l), which lowers their potential natural productivity and is also a constraint to the use of many shrimp species such as Penaeus monodon, which grow far better in low salinity waters. Moreover, no freshwater sources are available on the seaside, which would allow to control the salinity level.
The mission team visited a site selected for shrimp culture development near Hargigo, 10 km south of Massawa. Its topography seems quite favorable, but the soil is very sandy. A detailed soil study is needed to evaluate the possible water losses by filtration. If the filtration is too high, this means loss of nutrients and a need for higher pumping capacities, which increases the exploitation costs and makes the production less competitive on the international market.
Also, one must be careful on the financing of such an operation. The consultancy companies proposing this type of commercial aquaculture often take only a small part of the capital, which they finance by selling their technological input. Moreover, they most of the time take a commission on every imported material (hatchery, pumps, building materials, etc.) which allows them to earn their money even if the project never produces a single shrimp. This is why avoidance of institutional financing of such projects is to be recommended. The commitment of any foreign partner to any such venture should be backed up by sufficient hard money input to effectively link the partner's financial income with the profitability of the exploitation.
While ensuring that investments be kept on a private basis, some measure of government control in terms of location and design of farms is advisable in order to avoid repeating the mistake of uncontrolled development that has been witnessed in Asia and Latin America. It is especially important to guard against the appearance of shrimp diseases in aquaculture establishments that could also contaminate natural stocks, which represent a potentially significant source of foreign exchange earnings for Eritrea.
