Northern Delta Lakes, Egypt: Constraints and Challenges
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Northern Delta Lakes, Egypt: Constraints and Challenges Sahar Fahmy Mehanna National Institute of Oceanography&Fisheries, Egypt [email protected] Results and Discussion Introduction Lake Manzala Lake Manzala, the largest of the Northern Delta lakes with total area of about 90 Egypt drives its fish yield from three chief resources; marine (Red and thousand feddans and the depth rarely exceeds two meters. Lake Manzala is the most Mediterranean seas), inland (lakes and River Nile) and aquaculture (Fig. 1). These productive lake in Egypt where the mean annual fish production from the lake is 60 fisheries are one of our chief sources of wealth. If we give them due care, we can thousand ton. increase our national income and solve many of our problems such as the food Lake Borollus deficiency especially animal protein and unemployment, . Lake Borollus, the second largest Delta lakes, with total area of about 70 thousand The lakes' fisheries play an important role in Egyptian economy, where they provide feddans with an average depth of 1.2 m. The mean annual fish production from the about 39% of harvested fish in Egypt. The Egyptian Mediterranean coast exhibits lake is 48 thousand . six lakes or lagoons which are situated along the Nile delta coast (Northern Delta Lake Edku lakes) and to the east of the Suez Canal (Fig. 2). These lakes are namely, from west Lake Edku is situated approximately 35 km east of Alexandria. It is a shallow to east, Mariut, Edku, Borollus, Manzala, Port-Fouad and Bardawil. All of them, eutrophic lake rarely exceeding 1.5 m in depth, The mean annual fish production with the exception of Lake Mariut, are directly connected to the sea. The following from the lake is 9,000 ton. of catch and effort statistics showed that there is a steady decrease in fish abundance Lake Mariut and annual fish production harvested from the natural resources of Egypt.. Lake Mariut is the smallest of the Delta lakes, occupies about 17000 feddan. It is Lakes Red sea Mediterranean sea Nile Aquaculture actually isolated from the open sea. The depth ranges from 0.6 to 2.7 m and the mean annual production is 5,000 ton Surplus production model The obtained results (Fig. 4) revealed that, the fish stocks under the current fishing effort are overexploited and the estimated precautionary target reference points advised the reduction of fishing effort by about 57%, 43%, 44% and 47% for Manzala, Borollus, Edku and Mariut fisheries, respectively. 20 70000 10 60000 Lake Manzala Lake Borollus 60000 t) 8 t) 16 a a o o 50000 b b g 40000 g ) ) in n n n i 12 6 o sh h 40000 t ( fi (to / fis n / d ld o Fig. (1). Fisheries resources of Egypt n el ie i 30000 (t Y (to 8 Y 4 E E U 20000 P U 20000 C P C 4 2 10000 0 0 0 0 0 2000 4000 6000 8000 0 5000 10000 15000 20000 Effort (fishing boats) Effort (fishing boats) 20 12000 7 6000 Lake Edku Lake Mariut ) t 6 a 5000 10000 t) o 16 b oa g 5 ) g b in 4000 8000 ) n n h i o h is 12 on t s 4 ( /f (t n /fi 3000 d 6000 ld l to e ie ( i ton 3 Y 8 ( Y E 4000 E 2000 U PU 2 P C 4 C 2000 1 1000 0 0 0 0 0 500 1000 1500 2000 2500 3000 0 500 1000 1500 2000 Effort (fishing boats) Fig. (2). Northern Delta Lakes, Egypt Effort (fishing boats) Fig. (4). MSY, f and 2/3 f for the four Northern Delta lakes. Objectives MSY MSY The Northern Delta lakes are the most productive Egyptian lakes (Fig. 3). Also, Constraints they are internationally important sites for wintering water birds, providing valuable habitat for them. The present study was undertaken to: •Degradation, habitat loss, filling up and drought which lead to decreasing the area • Evaluate the current status of the fisheries of Northern Delta lakes of all Delta lakes by more than 70% of their origin areas. • Summarize the main problems facing the development and management of these •Pollution: Delta lakes are the most polluted area in Egypt. They receive great valuable fish resources and how to overcome them. amounts of industrial, municipal and agricultural wastewater without treatment •Spread of aquatic plants which covered large areas from these lakes. Manzala Borollus Edku Mariut Bardawil Port Fouad •Over-fishing, illegal fishing practices and illegal harvesting of fish fry. Timsah&Bitter lakes Qarun Wadi El-Raiyan •The blockage of Boughazes (the connections with open sea) Nasser Toshka •High levels of eutrophication resulting from the increased nutrient influx from agricultural drains carrying large amount of washed and leached fertilizers and pesticides. •The low awareness of fishermen about environmental issues and the importance of fisheries regulation measures. Recommendations •Studying the biology, dynamics and reproductive cycle of the commercial fishes of these lakes as this is an important step in establishing guidelines for fishery- regulation measures and construction a management policy for the rational Fig. (3). Fish production from the Egyptian lakes. exploitation of the lake fish resources. •Controlling and optimizing the water quality of these lakes. Materials and Methods •Regulation of mesh sizes, controlling gear types used and prohibition of the destructive ones and developing suitable fishing gear for shallow lakes. Fishery statistics during the period 1987-2006 were obtained from the fisheries •Continuous clearance of Boughazes. offices of the General Authority for Fish Resources Development. These data were •Revision of fisheries laws and improving the system for collecting and compiling analyzed to estimate catch per unit effort (CPUE). The maximum sustainable yield fisheries statistics. (MSY) and the optimum fishing effort (f ) as biological reference points, for the opt •Examining the water inflow of the agricultural drainage canals and different drains four lakes were estimated using the logistic production model of Schaefer. The regularly to control polluted water inflow into these lakes. 2 equation used is: dBt/dt = rBt – r/K * Bt where Bt is the biomass of the stock at time t, K is the carrying capacity of the habitat where the stock lives and r is the Acknowledgment intrinsic rate of growth of the stock. Schaefer's model has K = - a/b, BMSY (the I would like to express my grateful thanks to my colleague Zaki Sharawy for his equilibrium biomass for MSY)= K/2, MSY = aK/4 and fMSY = a/2. Subsequently, 2/3 f have been calculated as a precautionary reference point. time and appreciated help in presenting this poster. Also , my deep gratitude thanks MSY are due to organizing committee for their help and continuous encouragement..