Fishes of the Sudan

Freshwater Fisheries of the Sudan

EL-Thair Hassan Mohamed Salih

Department of Fisheries ,College of Natural Resources & Environmental Studies, Juba University

 Fisheries resources of the Nile are concentrated, within Sudan, in the five reservoirs that were constructed across the Nile at different dates. The potential holding capacity of these resources is  around 100.000 tons of fresh annually.  These are  summarized in table 1.

 Table 1: Fisheries Resources of the Reservoirs of the Sudan

 Fisheries of the White Nile

 The White Nile is one of the two major tributaries of the Nile. It originates in the Lake Victoria 400 km south of the equator. From Uganda the Bahar el Jebel, the southernmost tributary of the White Nile enters the Sudanese territory at Nimule. The river shows a comparatively slighter variation of flow than the Blue Nile and the Attbarah. Most of its water is lost to evaporation and transpiration in the swampy regions of the Sudd between Bor and Malakal towns in southern Sudan. This is a floodplain area, which is locally known as Toich. Its area ranges between 10000 to 92000 km² at low water and peak flood levels respectively. At Malakal town in the Upper Nile State, the Sobat River flows irregularly from the Ethiopian plateau causing a variation in the flow of the White Nile. The White Nile then flows northwards along the comparatively flat plains of the Central Sudan until it joins the Blue Nile at Khartoum.

 At Jebel Aulia town 80 km South of Khartoum a barrage was constructed in 1937 to regulate the Nile flow for the Egyptian Agricultural calendar. The reservoir is a thin lake that stretches 629 km to the town of Renk.  The reservoir is only second to the Sudd swamps in its fisheries resources, which carries an estimated potential of 15000 tons per annum. The relative high production of the lake is due to the characteristics of the White Nile. The dam causes the current to slow down considerably allowing the water to deposit its particulate matter thus creating a deeper photic zone, rich in primary producers, than that of the turbid Bule Nile. The swampy upstream reaches of the reservoir are excellent breeding grounds that enhance favorable conditions for   fish production. Furthermore the macrophytes that infest the river such as Vosia cuspidata, Echinochloa sp., Cyperus paperus and Eichornia crasspes offer well protected breeding and nursery grounds for the fish. It is thought that the fish stocks in the reservoir are overexploited particularly in places closer to the major consumption areas.

Most of the fishermen in Jebel Aulia reservoir use wooden blank canoes known locally as sharoga. Some fishermen use larger boats made of Acacia blanks. A variety of gears are used. The commonest types of gears are gillnets which are used in a variety of ways. Their mesh sizes range from 2 cm to more than 15 cm. Formerly natural fibre twines were used but now twines are monofilament nylons. In open waters pelagic gill nets are used. In the more vegetated shallow areas bottom sets are preferred. Sometimes nomadic fishermen use drift gill nets as they sail northwards with the currents. The catches in these nets are mostly pelagic species that belong to such genera as Hydocynus, Alestes, Orechromis , Tilapia and medium to small sized Lates and Bagrus.  Long lines are mostly used to capture large bottom-dwellers and their catch is usually composed of catfishes of the genera Bagrus, Clarias, Heterobranchus, Auchenoglanis and Malaptererus. Peach seining is also common and it sweeps considerable areas in a single haul. With a bridle line of not less than 150 m the swept area may get close to 2-5 hectares/haul. Such an exacting gear is used where big Bagrids and Nile Perch are common. Two other varieties of beach seines are used namely: the local bibi and the alfa, the later is claimed to be very nonselective size-wise but no experimental evidence is available. A variety of traps are also found. In 1992 the number of fishermen in the White Nile was estimated at 1775 using about 1200 canoes The major fishing areas are around Renk, El Jeblain, Kosti, Ed Dueim and Jebel Aulia. The expected potential of fish in 1992 was 15000 and the actual production was 10000 tons.

Khashm el Girba Reservoir 

The Khashm el Girba Reservoir was constructed across the river Atbara, a tributary to the Nile, in 1964 to provide irrigation water and hydroelectric power to the then Khashm el Girba Agricultural Scheme. The Atbara has shows the strongest seasonality and extreme flow regime among the five sub-basins of the Nile in Sudan. The Atbara receives its water from the Gangue and the Setit-Takazze. From the Eritrean highlands the river flows in a northwesterly direction to cross the Sudanese borders some 100-km upstream of the Khashm el Girba Dam. It joins the Nile at Atbara town in the Nile State, 320 km north of the confluence of the Blue and White Nile. The overall percentage contribution of the Atbara to the Nile water was estimated at 13% but it ranges from 22% during the flood season to nil. Both before and after the construction of the dam, a great length of the river downstream dries out, except for some intermittent pools, for several months normally from December to may.

The reservoir supports a seasonal fishery from October to July for a group of fishermen who combine fishing with other economic activities; mainly rain-fed agriculture. The average monthly number of fishermen was around 39 in 1993. The fishing gears used are gillnets for pelagic species and long lines for bottom-dwellers. Beach seining is used in shallow waters to catch cichlids and characids. At the onset of the flood season; normally in July, when driftwood and debris washed into the lake tend to damage the gillnets, meshed wire traps baited with crushed sorghum grains mixed with clay are set in shallow waters to catch cichlids.  

Wooden canoes are the major type of fishing crafts in the reservoir. Most of the fishermen camp along the western side of the lake. In camps far from Khashm el Girba town the catch is bought directly from the fishers by wholesale traders who sell the fish in Gedarif, New Halfa and Kassala towns. This trade constitutes some 90% of the catches; the remaining 10% being sold locally at Khashm el Girba. The total annual landings of Khashm el Girba reservoir are in the order of 400 tons but detailed catch statistics are scarce.  

The Blue Nile Fisheries 

The Blue Nile originates in the Lake Tana in the Ethiopian plateau. From an altitude of more than 1000 meters it flows torrentially towards its confluence with the White Nile at Khartoum covering a distance of 1600 km. The Blue Nile basin area is 325000 km³. At low water level the minimum mean discharge of the river is 138 m³ s^-1 which increases to a mean maximum discharge of 5950 m³ s^-1 during the flood season.  

Dams in Roseiris and Sennar towns twice intercept the natural flow of the river. The Roseiris dam was completed in 1966. The reservoir is 80 km long covering an area of 280 km³. The fish produced amount to about 1000 tons year^-1 that is close to the assumed potential. Most of the yield is transported in both fresh and preserved form. Fresh fish is sent to towns mainly in Medani and Khartoum whereas preserved fish is sold locally and transported to the rain-fed agricultural scheme.  

The Sennar dam, erected in 1925, supplies the Gezira irrigation scheme with water. The total area of the impoundment is 160 km³ and the mean depth is 6.5 m. the potential sustainable yield of Sennar reservoir is estimated at about 1100 tons year^-1.  

All along the Blue Nile, fishermen mostly use wooden blank canoes for sailing. A small number of fishermen own mechanized steel and fiberglass boats. The commonest types of fishing gears are floating gillnets; sunken gillnets; beach seines; cast nets and different forms of hook and lines. 

Fisheries of the Lake Nubia 

Lake Nubia is the Sudanese territorial water of the impoundment behind the Aswan High Dam constructed across the Nile in 1964. The lake extends for 140 km in the Sudanese territory when the water level is 180 m above sea level. Following dam closure and the inundation of the rich palm forest and former settlement areas the fish production showed a rise up to a certain tonnage and later stabilized. The current output of 2000 tons is less than the expected yield of 5000 tons year^-1. Since the original inhabitants of the locality were resettled in Eastern Sudan, some time elapsed before the small remaining population shifted to fishing having lost their fertile strips of silty flood plains. It is thought that the distance between major consumption areas and the lake might have contributed to the present low production level, however there is a growing interest among investors to take an active part in the fishery. The fishing gears are similar to those used elsewhere 

Table 2: Some important families of Nile fishes

 Biblography 

Abu Gideiri, Y. B. 1984. Fishes of the Sudan. Khartoum University Press, Khartoum. 164 pp.

Ahmed, A. A. 1985, Final report of the assessment of Jebel Aulia reservoir fisheries. Fisheries research centre, Agricultural research corporation, Khartoum. 54 pp.

Ali, M. T. 1984, Fishes and fisheries of Lake Nubia, Sudan. Hydrobiologia, 110: 305-314.

Ali, M. T. and Abu Gideiri, Y. B. 1984 . Fishes and fisheries of Lake Nubia , Sudan . Hydrobiologia , 110 : 305-314 .

Amirthalingam, C. and Khalifa, M. E. 1956. A guide to the common commercial freshwater fishes in the Sudan. Khartoum Game and Fisheries Department. 197 pp. 

Bailey, R. G. 1993. Guide to the fishes of the River Nile in the Republic of Sudan. Divi-Lip, SCI, Kin. College. London. UK.

El Moghraby , A. 1. 1973. Fishes of the White Nile . pp 16-17. In : Nineteeth annual report 1972-1973, Hydrobiological research unit , University of Khartoum , Khartoum University Press . 31 pp.

Khalid, A. M., Salih, E. H. M. and Haggar, E. A. (2002). A preliminary survey of the  Dinder National Park fish fauna, diversirty and tentative ichthyomass. A report compiled within the auspices of GEF project in Dinder national park.

Mahmoud , Z. M. 1984. Ichthyofauna of the Dinder National Park, Sudan. Afr. J. Ecol., 14:27-29 .

Mishrigi, S. Y. 1970. Fishes of lake Roseires on the Blue Nile. Rev. Zool. Bot Afr., LXXXII: 139-199.

Obeid, M. and Abu Gideiri, Y. B. 1967. Water characteristics, phytoplankton and fish population of the Blue Nile between Khartoum and Sennar, pp 27-33. In: Fourteenth annual report 1966-1967, Hydrobiological research unit, University of Khartoum, KUP. 34 pp.