Limited inland (freshwater) aquaculture has been attempted in Libya at several sites over the past two decades or so, including stockings of a reservoir in Wadi Kaam and another in Wadi Mjinine (UNIMAC 1975; IAC 1981). Some minor cage culture as well as free stocking has also been undertaken at the spring-fed lake in Abou Dzira, close to Benghazi, and at Ain Kaam, on the coast near Khums. A project at Brak El-Shati, lying in the desert some 600 km from the coast, involved fish culture in ponds filled with used irrigation water (Al Nasih 1990; Al Nasih and Pekli 1993). Stockings have been made with common carp, silver carp, tilapia, catfish, mullet, and eel, and some success has been achieved in the sense of demonstrating that fish culture is possible from a biological point of view. Freshwater fish can be kept alive and even thrive under proper conditions (Abou Dzira, Ain Kaam), or so long as drought does not lower reservoir levels too far (Wadi Kaam, Wadi Mjinine), or so long as project operations continue to receive full cooperation from local community residents (Brak El-Shati). From a planning and development point of view, however, all the freshwater operations seem to be weak on questions of real production costs and potential market demand for the species intended for culture.
In any case, potential wider development of freshwater fish production either on a commercial or subsistence scale is obviously extremely limited due to prevailing geo-climatic conditions. Any realistic consideration of aquaculture in the Libyan context must thus be oriented primarily towards marine operations (mariculture) based along the country's almost 2000 km stretch of Mediterranean shoreline (Map 1, Annex 1), in or around lagoon sites, or at appropriate nearshore or offshore points.5
The broad types of aquaculture operations that are theoretically possible offer different advantages in terms of production performance, and of course entail their distinctive disadvantages and risks as well (cf. Barg 1992). What might work well in one setting could be totally unsuitable in another. Site selection criteria will therefore be heavily conditioned by the type of operation being contemplated (e.g. shore-based ponds vs. raceways; shore-based systems generally vs. lagoon-based cage culture; etc.).
The availability of markets was noted above as a critical basic consideration to bear in mind whatever the type of operation in question. Similarly, issues of water quality and other environmental parameters are of fundamental importance.
Water is the living medium through which oxygen and food reaches farmed aquatic animals. Water also provides the medium through which wastes (ammonia, excess feed, faeces) are eliminated. It is essential therefore that water quality corresponds to the needs of the species selected for culture.
The severity of pollution and other hazards posed by the different and often competing resource use interests that may be associated with particular coastal zones likewise must be assessed. Many such hazards exist, and they have varying effects on aquatic life, as well as the larger marine and coastal environments and the human communities that rely upon them (cf. FAO/UNEP 1987; Clark 1992, MBRC 1992; Rosenthal 1994). Known actual or potential pollution/environmental hazard sites along Libya's coastal zone are indicated on Maps 1 through 4 in Annex 1. Table 1 in Annex 2 provides a general breakdown of coastal resource use or activity types and the environmental changes and negative impacts that may be directly or indirectly linked with them.
3.1.1 Mineral pollution
Industrial effluents and run-off from agricultural lands bearing pesticide and fertilizer residues contribute to mineral pollution. Some chemicals and heavy metals in high concentration (oil, cyanide, Pb, Cu, and Cr, for example) have immediate toxicity. Others (pesticides, detergents, and heavy metals in low concentrations) have deferred effects.
3.1.2 Organic pollution
Large outflows of urban sewage or liquid wastes from agro-industries (slaughterhouses, canneries, dairies, etc.) in nearshore waters generally results in an increase of water turbidity. This can have very deleterious consequences for marine organisms, which generally require at least moderately clear and clean conditions in order to carry out essential photosynthetic and breathing processes. Excessive organic wastes also result in drastic reductions of dissolved oxygen. This puts aquatic animals directly at risk and also increases the chances for outbreaks of disease.
3.1.3 Solid wastes and particulates
Solid wastes and participates pose various risks. Suspended mud or silt resulting from erosion, landfills, or quarrying activity may provoke gill diseases. Plastic bags dumped into the sea can block pumping systems or restrict water circulation inside cages.
3.1.4 Thermal pollution
Thermal pollution may occur when warm water effluents such as from power stations are not properly controlled, thus adding to or compounding the risks linked to other types of pollution.
Salinity levels should be compatible with the requirements of the selected species. For example, requirements for sea bass and sea bream, two popular species for fishfarming in the Mediterranean basin, are between 30 and 38 g/1. Shallow lagoons tend to have highly saline waters due to evaporation and thus are generally not suitable for aquaculture.
The optimum temperature for fish culture activities in the southern Mediterranean area is in the range of 18–22°C.
The lowest temperature reached in Libyan lagoons is about 11°C. This is not lethal for local species, but any temperatures lower than the above range tend to restrict fish growth. Higher temperatures, on the other hand, bring hazards of low oxygen content, proliferation of micro-organisms, and reduced resistance of fishes/shrimps to microbial infections. They should be avoided in aquaculture operations. In shallow Libyan waters maximum temperatures of around 30°C can be reached.
3.2.3 pH levels
Ideally, the pH level for fish farming installations should be between 7 and 8. Sea water pH is within these limits but, inside ponds, it may change because of acidic soil.
5 For an earlier review of inland/on-shore aquaculture installation possibilities in Libya, refer to LIBFISH TBN No. 18 (Vallet 1994b).