LAKE FITRI IN CHAD: SOCIO-ECONOMIC, ENVIRONMENTAL AND TECHNICAL ASPECTS OF FISHING AND DETERMINATION OF SOME PHYSICO-CHEMICAL WATER PARAMETERS

Lake Fitri is the second largest lake ecosystem in terms of area after Lake Chad. The purpose of this study was to assess the socio-economic, technical and environmental aspects of fishing and to determine some physico-chemical characteristics of the waters from Lake Fitri in Chad. Surveys were carried out from March 03 to April 08 and from July 10 to August 06, 2019 among 400 fishermen, processors and merchants from four islands of Lake Fitri where there is a high level of fishing activity. Standard methods were applied for the physico-chemical analysis of the water. The results revealed that fishing was mainly practiced by 74%, 10%, 15% and 1% respectively of Chadians, Nigeriens, Nigerians and Cameroonians. Marketing is carried out by 60% of Chadians, 20% of Nigerians and 20% of Nigerians. The study found a use of a variety of fishing gear and techniques, including 26% of longlines, 16% of standing nets, 25% of nets with polystyrene floats and 39% of nets. Financial contributions show that fishing represents a significant source of currency for this department. The water of the 4 islands of Lake Chad had mean pH, temperature and conductivity values of 8.90 ± 0.66, 25.61 ± 1.75 °C and 363.26 ± 75.41 mS/cm respectively. Water turbidity ranged from 0.33 to 0.90 with a mean of 0.55 ± 0.17 NTU, dissolved oxygen ranged from 13.46 to 19.17 mg/L with a mean of 17.04 ± 1.68 mg/L. There was a significant difference between the values for temperature, turbidity and dissolved oxygen (p<0.0001), but no difference was observed for pH and electrical conductivity. Catches remain below the potential indicated by the FAO for water bodies of this type (between 100 and 750 kg.ha-1.year-1), which shows that there may be room for increasing fish production of this lake. The very lax management and use of fishing gear (traps) observed in these sites could constitute a threat to the maintenance of biodiversity and the productivity of natural ecosystems.