Northern African freshwaters give shelter to 128 fish species and subspecies which inhabit permanent rivers, freshwater lakes, and springs of underground waters such as oases. Out of these, some 32 species are unique to the region (endemic). The majority (22 out of 32 assessed) are represented by minnows, barbells and carps (Cyprinidae family) which are at the same time the most common and threatened fish in the northern African basins, with the Barbus (barbells) representing 20% of the total number of regional freshwater fishes and 59% of the total endemics. Among the 35 fish species threatened with extinction, 10 are endemic to the region, meaning that if they go extinct, they will disappear from the planet, adding to the 24 species which are already extinct, 1 of these being endemic (Salmo pallaryi).
North Africa Freshwater Fish
Although poor in water resources, the North Africa region shows a good representation of aquatic and wetlands habitat and monitoring freshwater basins is important to prevent the loss of these ecosystems. Freshwater fish species have been identified as one of the priority taxa indicators for the overall conservation status of wetland ecosystems.
More than a quarter (27.3%) of the total 128 taxa assessed at regional level were found to be threatened with extinction; among these, 20.3% are Vulnerable (VU), 6.3% are Endangered (EN) and one species (0.8%), the Sahara aphanius (Aphanius saourensis), is Critically Endangered (CR). A further 1.6% of the total taxa assessed are Near Threatened, while a fifth (20.3%) is listed as Least Concern. Almost one in three species (32%) are however considered Data Deficient. As regards the uniqueness of the region, 10 of the 32 species endemic to North Africa are categorized as threatened (CR, EN, VU).
All evaluated taxa
The highest degree of species richness in North Africa can be found in the north and west of the region (Morocco, Algeria and Tunisia) and along the Nile River in Egypt. This distribution is related to the limited river systems and wetland areas in these countries; with only a very few species surviving in other habitats such as oases or in more stressful conditions.
The most threatened species is the Sahara aphanius (Aphanius saourensis) (CR), endemic to Algeria, suffering an increasing decline in its population due to the introduction of the invasive North American Mosquitofish (Gambusia holbrooki). Other threatened taxa are mostly found in the Nile, especially in the Lower Nile, due to water pollution and human impacts. Species present in the river systems of Morocco flowing into the Atlantic and the Mediterranean Sea include a relatively high number of threatened fish that are susceptible to extinction due to the decline in the extension and quality of freshwater habitats and the seasonality of the presence of water bodies.
The Mediterranean coastal rivers of Algeria and Tunisia, especially those of Numidia and surroundings, show the highest concentrations of endemic fish. The geographical position, the heterogeneous landscape, as well as the importance of the hydrographic system explain this uniqueness. The central and western parts of Morocco are also of particular importance for the endemic freshwater fish of the region as 19 of the 27 endemic taxa occur in this area.
A significant number (18%) of freshwater fishes has disappeared from the region. The Nile River basin in Egypt seems to have the highest degree of extinction (22 of the 23 Regionally Extinct species inhabited this basin) in North Africa. The only species Extinct at the global scale (since the 1930s) is the endemic salmonid Salmo pallaryi, native to the Atlas Mountains in northern Morocco. The introduction of the common carp, Cyprinus carpio, is thought to be the reason for its disappearance and, even if not yet assessed, its widespread dissemination is expected to be detrimental.
Data deficient taxa
Almost one third (32%) of the assessed freshwater fishes is Data Deficient. Six endemic species have been classified in this category, highlighting the lack of information available to evaluate their status and the evident need for more research in this direction.
Major threats to fishes
The main causes for the decline of freshwater fish in North Africa are habitat loss due to human activities, and natural disasters, such as drought and temperature extremes. These threats affect more than 60% of the total freshwater fish and a 25% of all threatened freshwater fishes of the region. More than 85% of the Endangered and Vulnerable freshwater fishes are also threatened by dam construction and groundwater extraction, in addition to water pollution.
- Habitat loss caused by groundwater extraction from rivers and wetlands, and water pollution related to the intensification of agriculture, result to be the major threats, affecting respectively the 92% and the 62% of the species assessed and listed as threatened. Among natural disasters, drought is becoming also a major problem, transforming permanent streams into seasonal or temporary flows.
- The construction of dams, which modify river quality features, hydrological landscapes, and species migratory routes, have also been identified as a major threat to 26 fish taxa.
- Invasive species and harvesting for food are also affecting freshwater fish in North Africa but to a lesser extent. The introduction of Gambusia, considered as invasive, has been shown to be one of the main threats to the only Critically Endangered species in the region, Aphanius saourensis, an endemic species which has already disappeared from several sites.
Conclusion and conservation recommendations
- Implementation of an Integrated River Basin Management (IRBM) approach, aiming to guarantee a river’s sustainable utilization in short, medium and long-term time scales to stop fish population decline and prevent species extinctions.
- Regulation of the impacts of dam construction on the lifecycle of fish populations by providing a continuous environmental flow and envisaging by-passes for migrant species.
- Reforestation of river margins could help reduce the amount of slime and sediments carried by river flows that can clog the fish gills.
- The reinforcement of sustainable fishing techniques and the protection of habitats and species are additional measures which could prove valuable for freshwater fishes.
- The levels of chemicals in pesticides and fertilizers should be reduced to avoid water pollution
- More sustainable water irrigation techniques for an efficient use of both surface and ground waters should be promoted.