Estimation Biomass of Commercial Fish Species in White Nile River, Sudan

International Journal of Marine, Atmospheric & Earth Sciences, 2013, 1(1): 17-26 International Journal of Marine, Atmospheric & Earth Sciences ISSN: 2327-3356 Journal homepage: www.ModernScientificPress.com/Journals/IJMaes.aspx Florida, USA Article Estimation Biomass of Commercial Fish Species in White Nile River, Sudan

Mamoun Makawi Obeida 1,*, Mohammed El Tahir Ali 2, Fathi Mirghani Yousif 3

1Administration of General Fisheries and Aquatic Resources, El Jeblein Fisheries Station, White Nile State, Sudan 2Ministry of Science and Technology, Animal Co-operation, Fisheries Research Center, P.O. Box. 1489, Khartoum, Sudan 3Ministry of Animal Resources and Fisheries, Administration of General Fisheries and Aquatic resources, Natural Fisheries Department, Khartoum, Sudan

* Author to whom corresponding should be addressed: Email: [email protected]

Article history: Received 20 December 2012, Received in revised form 28 January 2013, Accepted 29 January 2013, Published 31 January 2013.

Abstract: Biomass of Commercial Fish Species in Jebel Aulia Dam Reservoir (White Nile) area was analyzed. The average biomass in Kg/ha in the study area under investigation: Oreochromis niloticus 132.07 Kg/ha, Lates niloticus 84.01 Kg/ha, Labeo niloticus 75.53 Kg/ha, Tetraodon lineatus 56.4 Kg/ha and Clarias gariepinus 26.06 Kg/ha. The overall fish biomass was found to be 148.8 Kg/ha.

Keywords: Estimation, Fish Biomass, Fish Species.

1. Introduction

Jebel Aulia Dam was constructed in 1937 across White Nile River, situated 45 km South of Khartoum State. The dam is situated between Longitude 032º29΄ E and Latitude 15º14΄ N, and altitude 377.4 m above sea level and surface area of the dam reservoir extending over 1246 Km2, mean depth range between 2.3-6 m and maximum depth 12 m and design capacity is 3.5 mm3 (Belleman and Khalid, 1998). Reliable statistics do not exist for the Jebel Aulia Reservoir; however, various estimates were made of the yearly production. Henderson (1975) produced a range from 7000 to 8100 ton for 1975 with a potential yield of 15000 t (corresponding to 100 kg/ha/yr). A more precise value of 8216 ton

Int. J. Mar. Atmos. & Earth Sci. 2013, 1(1): 17-26 18 was presented by FAO (1982) with a potential yield of 4500 ton or 30 kg/ha/yr. Asma (1985) calculated the maximum sustainable yield to be 7 363.860 t/yr. Kapetsky (1986) calculated an annual yield of 55 kg/ha for 1981–1982, based on the method of Henderson and Welcomme (1974). Ahmed (1985) recorded that, the total fish biomass of the Jebel Aulia reservoir was about 114.kg/ha. Belleman and Khalid (1998) stated the annual production to be about 4900 ton/year in Jebel Aulia dam reservoir. Hamza (1980) mentioned that, scientific investigations on the White Nile indicate that one hectare of water yield 30 Kg of fish annually. Soviet Research Expedition to the Sudan (1964) reported that, the part of Jebel Aulia reservoir extending from the dam up to Kosti was most suitable for commercial fishing operations. Abdel Rahman (2003) estimated the total annual yield in Jebel Aulia dam to be 115.732 Kg and the maximum sustainable yield 90.706 Kg. Bashir (2007) calculated the fish biomass from Gulee to Jabalein was found to be 119.09kg/ha. Some species of highly economic importance in the area under investigation, Lates niloticus, Oreochromis niloticus, Labeo species, Synodontis species and Schilbe species, were found to contribute in the whole biomass with an average biomass of 37.46 kg/ha , 35.70 kg/ha 30.83 kg/ha, 27.97 kg/ha and 13.07 kg/ha respectively Bashir (2007). Bashir (2007) estimated the stock of the fish in Jebel Aulia reservoir at about 14400 ton/year. The aim of this study was to determine the approximate fish biomass that the Jebel Aulia Dam Reservoir can support in the three sectors from El nuzul to El hashaba.

2. Materials and Methods

A routine sampling was under-taken at three sampling stations which represent different ecosystems (lacustrine, semi-lacustrine and riverine), El hashaba (032° 12’E and 14° 18’ N), Kosti (032°40’E and 13°10’N) and El nuzul (032° 47’ E and 12° 37’N). Three samples of commercial beach seine nets were used with mesh sizes 110-60 mm in both sides of seine net and 50 mm in the center of net, depth 224-275cm, length 450-560 meter, warp rope length vary according to operation range from (420 to 450 meter) and 6-12 men usually operate the net. For biomass estimation beach seines were used. Each beach seine encircled an area of 800 m2 approximately. After seining the catch in each haul was sorted to species and specimens of each species were weighed and standard, total and fork length measured as appropriate. For the estimation of biomass, the confidence limit model of the software PASGEAR (Kolding and Skålevik, 2007) was used. For each haul it was assumed that the percentage of fish caught in the effective pass of the gear was hundred per -cent.

3. Results and Discussion

3.1. Results

In El nuzul sector the stock of Lates niloticus, Oreochromis niloticus, Tetraodon lineatus, Distichodus niloticus, Labeo niloticus, Malapetrus electericus and Clarias gariepinus ranges from 45- 148.8 Kg/ha. The stock Tetraodon lineatus, Hydrocynus foraskalii, Alestes beremoze, Bagrus bajad, Brycinus nurse, Synodontis schall and Polypterus senegalus ranges from 5.2 to 15.2 kg/ha show in Table 1 and Fig. 1. The other species in the three sectors ranged from 0.3 – 12.6 kg/ha.

Table 1: Average fish biomass in Kg/ ha in El nuzul sector, White Nile 95% Confidence Species Mean S. D S. E N Lower Upper Lates niloticus 148.8 179.3 54.1 11.0 28.3 269.3 Oreochromis niloticus 126.2 99.9 28.8 12.0 62.8 189.7 Tetraodon lineatus 77.5 126.7 36.6 12.0 0 158.0 Distichodus niloticus 51.2 63.4 21.1 9.0 2.5 100.0 Labeo niloticus 41.7 51.9 15.0 12.0 8.8 74.7 Malapetrus electericus 26.0 28.5 9.0 10.0 5.7 46.4 Clarias gariepinus 25.0 17.6 5.9 9.0 11.4 38.5 Hydrocynus forskalii 15.2 12.3 4.6 7.0 3.8 26.5 Alestes baremoze 13.5 21.1 7.0 9.0 0 29.7 Bagrus bajad 12.5 8.7 3.9 5.0 1.7 23.4 Brycinus nurse 11.7 12.5 6.2 4.0 0 31.4 Others 11.2 22.9 3.5 42.0 4.0 18.3 Synodontis schall 6.4 6.3 2.2 8.0 1.1 11.7 Polypterus senegalus senegalus 5.2 3.8 1.7 5.0 0.4 9.9 S.D = Standard Deviation S.E = Standard Error

Fig. 1: Average fish biomass in Kg/ ha in El nuzul sector, White Nile

In Kostit the stock of Lates niloticus, Oreochromis niloticus, Tetraodon lineatus, Hydrocynus foraskalii, Clarias gariepinus, Labeo niloticus and Alestes baremoze ranges from 10.8-79.8 Kg/ha. The stock of Malapetrurus electericus, Bagrus bajad and Synodontis schall ranged from 9.0-9.3 kg/ha show in Table 2 and Fig. 2.

Table 2: Average fish biomass in Kg/ ha in Kosti sector, White Nile 95% confidence Species Mean S.D S.E N Lower Upper Lates niloticus 79.8 129.2 40.8 10.0 0 172.1 Oreochromis niloticus 73.4 43.5 13.1 11.0 44.1 102.6 Tetraodon lineatus 39.3 25.4 10.4 6.0 12.6 65.9 Hydrocynus forskalii 26.1 20.7 6.6 10.0 11.3 40.9 Clarias gariepinus 20.9 21.2 5.3 16.0 9.6 32.2 Labeo niloticus 16.9 15.6 5.2 9.0 4.9 28.9 Alestes baremoze 10.8 5.6 2.0 8.0 6.1 15.5 Malapetrurus electericus 9.3 5.7 2.0 8.0 4.5 14.1 Bagrus bajad 8.9 5.8 2.4 6.0 2.8 14.9 Synodontis schall 9.0 9.5 4.7 4.0 0 24.1 Others 12.6 21.7 4.9 20.0 2.5 22.8

Fig. 2: Average fish biomass in Kg/ ha in Kosti sector, White Nile

The fish stock in El hashaba composed of many species. The species Labeo horie is the largest stock (357.8 kg/ha) and only found in this sector in comparison to the other two sectors Table 3 and Fig. 3.

Table 3: Average fish biomass in Kg/ ha in El hashaba sector, White Nile 95%confidence Species Mean S.D S.E N Lower Upper Labeo horie 357.8 678.3 339.2 4.0 0 1436.3 Oreochromis niloticus 197.2 542.0 163.4 11.0 0 561.6 Labeo niloticus 168.9 479.5 151.6 10.0 0 511.5 Clarias gariepinus 41.4 43.9 17.9 6.0 0 87.4 Bagrus bajad 35.7 58.7 19.6 9.0 0 80.9 Tetraodon lineatus 31.3 58.5 23.9 6.0 0 92.6

Fig. 3: Average fish biomass in Kg/ ha in El hashaba sector, White Nile

The stock of Oreochromis niloticus, Labeo niloticus, Clarias gariepinus and Bagrus bajad ranges from 35.3-197.2 Kg/ha. The stock of Tetraodon lineatus, Hydrocynus foraskalii, Lates niloticus, Synodontis schall, Alestes beremoze, Malapetrurus electericus, Polypterus senegalus and Brycinus nurse ranged from 2.7 to 31.3 kg/ha. In the three sectors without including Labeo horie the stock of Oreochromis niloticus is 132.07 Kg/ha represented 27.5%, Lates niloticus is 84.01 Kg/ha (17.5%), Labeo niloticus is 75.53 Kg/ha (15.7%), Tetraodon lineatus is 56.4 Kg/ha (11.7%), Clarias gariepinus is 26.06 Kg/ha (5.4%), Hydrocynus foraskalii is 22.46 Kg/ha (4.7%), Bagrus bajad is 21.85 Kg/ha (4.5%), Malapetrus electericus is 16.36 Kg/ha (3.2%), Alestes baremoze is 11.77 Kg/ha (2.4%), Synodontis schall is 8.89 Kg/ha (1.8%) and others 25.26 Kg/ha (5.3%) shown in Table 4 and Fig. 4.

Table 4: Average combined fish biomass in Kg/ ha in the three sampled sectors, White Nile 95% Confidence Species Mean S.D S.E N Lower Upper Oreochromis niloticus 132.07 309.03 53 34 23.96 240.19 Lates niloticus 84.01 137.14 24.63 31 33.27 134.75 Labeo niloticus 75.53 272.78 48.99 31 0 176.45 Tetraodon lineatus 56.4 95.03 19.4 24 15.85 96.94 Clarias gariepinus 26.06 26.28 4.72 31 16.33 35.78 Others 25.26 134.58 13.01 107 0 50.76 Hydrocynus foraskalii 22.46 22.55 4.51 25 13.03 31.88 Bagrus bajad 21.85 40.52 9.06 20 2.92 40.79 Malapetrus electericus 16.36 21.08 4.49 22 6.96 25.75 Alestes baremoze 11.77 14.7 3.29 20 4.9 18.64 Synodontis schall 8.89 7.98 1.94 17 4.78 12.99

Fig. 4: Average combined fish biomass in Kg/ ha in the three sampled sectors, White Nile

3.2. Disscusion

Four commercial fish species Lates niloticus, Oreochromis niloticus, Labeo niloticus and Clarias gariepinus were selected for calculation of the average fish biomass in the study area. Contribution of Lates niloticus with an average biomass in the three sectors (El nuzul, Kosti and El hashaba) were 148.8, 79.8 and 17.0 Kgs/ha. These results indicate that the value in El hashaba was low compared to other sectors; in spite of the same method of capture used. Number of fish which were analyzed in the three sectors close in number and these may reflect what is called ‘depletion or intensive capture’ of these species due to increased use of seine nets in the northern part of Jebel Aulia Reservoir. Oreochromis niloticus in the three sectors was 126.2, 73.4 and 197.2 Kgs/ha (Tables 1, 2 and 3). These calculations reflected the low value of the catch, the low values due to increased number of fishermen, different types of fishing methods and boats were used, highly consumption in Kosti and Rabak Towns (preferable species for consumer). Labeo niloticus was high in El hashaba reaching 168.9 Kg/ha compared to El nuzul 41.7 Kg/ha and Kosti 16.9 Kgs/ha. It reflects that the genus Labeo of mud- feeding fishes with suctorial mouth which adapted to live in lacustrine environment and migratory fish. In the three sectors Clarias gariepinus was 25.0, 20.9 and 41.4 Kgs/ha, in El hashaba (the value high in El hashaba compared to the other two sectors). Kapetsky (1986) calculated an annual yield of 55 Kg/ha for 1981-1982, FAO (1982) with a potential yield of 4500 tons or 30 Kg/ha/yr. (quoted by Knaap, 1994). Bashir (2007) calculated the fish biomass of Lates niloticus, Oreochromis niloticus, Labeo sp, Synodontis sp and Schilbe sp in Jebel Aulia Reservoir. He found that the contribution of these species in the whole biomass with an average biomass of 37.46 kg/ha, 35.70 kg/ha 30.83 kg/ha, 27.97 kg/ha and 13.07 kg/ha respectively. However, this study concentrated also on four species (Lates niloticus, Oreochromis niloticus, Labeo niloticus and Clarias gariepinus) in the three sectors representing various environments, average combined fish biomass in Kg/ ha in the three sampled sectors, White Nile: were Lates niloticus 84.01, Oreochromis niloticus 132.07, Labeo niloticus 75.53, Clarias gariepinus 26.06, Tetraodon lineatus 56.4, Hydrocynus forskalii 22.46, Bagrus bajad 21.85, Malapterurus electericus 16.36, Alestes baremoze 11.77, Synodontis schall 8.89 and others 25.26 Kgs/ha. These values are greater than the values calculated by Bashir (2007) in spite of the same statistical program PASGEAR, A database package for experimental and artisanal fishery data (Kolding, J and Skålevik, A. 2006). The variation may be due to the use of various types of fishing methods (gill nets with different mesh sizes and beach seine net); he covered an area extending from Gulee to El Hedaib, and while in present study three areas were covered representing different habitats.

Henderson (1975) produced a range from 7000 to 8100 ton for 1975 with a potential yield of 15000 tons. Amore precise potential value of 8216 tons/year was presented by FAO (1982) with a potential yield of 4500 ton or 30 Kg/ha/yr. Asma (1985) calculated the maximum sustainable yield to be 7363 to 8600 ton/year (quoted by Knaap, 1994). When compare the above values and present result, overall fish biomass in Kg/ha in the White Nile from El hashaba to El nuzul was 148.8 Kg/ha, although, all these studies were done in Jebel Aulia Reservoir.

4. Conclusions

From this study, the average biomass in Kg/ha in the study area is Oreochromis niloticus 132.07 Kg/ha, Lates niloticus 84.01 Kg/ha, Labeo niloticus 75.53 Kg/ha, Tetraodon lineatus 56.4 Kg/ha and Clarias gariepinus 26.06 Kg/ha. The overall fish biomass was found to be 148.8 Kg/ha. It is strongly recommended that long term program of inland fisheries stock assessment should be designed and study conducted to supply real statistical data which can be used for proper management and sustainable utilization of the resource

References

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