BIOLOGIA (PAKISTAN) 2012, 58 (1&2), PK ISSN Current status of fisheries in the Mangla Reservoir, Pakistan ABSTRACT

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1 BIOLOGIA (PAKISTAN) 2012, 58 (1&2), PK ISSN Current status of fisheries in the Mangla Reservoir, Pakistan *ZAHID SHARIF MIRZA 1, MUHAMMAD SAJID NADEEM 2, MIRZA AZHAR BEG 3, ABDUL QAYYUM KHAN SULEHRIA 4, SYED ISRAR SHAH 5 1 Fisheries Research & Training Institute, P.O. Batapur, Lahore, Pakistan. 2,3,5 Department of Zoology, PMAS Arid Agriculture University, Rawalpindi, Pakistan 4 Department of Zoology, GC University, Lahore, Pakistan ABSTRACT The present study was conducted to assess the current status of fisheries in the Mangla Reservoir based on the seasonal variation in species composition and annual catches. Data on commercial catch was obtained by stratified random sampling at two landing sites in the reservoir from Jan 2009 to Dec Catch rate and effort estimates from the landing sites were used to estimate the total catch. The data obtained was tabulated and summarized in different groups based on the percentage of each species in the landing. The results showed that the total commercial fish production from the reservoir during the two years varied widely with average total catch of mt. The catches for the year 2010 were 130 mt higher as compared with the catches during the previous year. The four commercial fishes (Cyprinus carpio, Gibelion catla, Sperata sarwari and Wallago attu) contributed 83.4 per cent (52.0 percent by Cyprinids percent by Silurids) of the average catch for the two years. Amongst catch of four commercial fishes, the two Cyprinids contributed 62 percent and the rest was added by two Silurids. On the whole the contribution of the exotic fishes in total catches was mt (5.46 per cent). The results further show that during the months when the water level is near the dead supply level, there is a trend of increasing by catch and tilapia. During January 2009, highest quantities of tilapia (2.79 mt) were recorded from the catches. Keywords: Commercial fishes, Mangla Dam, Cyprinids, Silurids INTRODUCTION Anicuts across the major rivers have existed in Indian subcontinent for several centuries (Panikkar, 1955). These human engineered aquatic habitats were traditionally utilized for water conservation to use for domestic consumption, irrigation and fish culture (Petrere Jr, 1996). In the recent era, a large number of manmade reservoirs have been created by damming the major rivers. These impoundments are complex ecosystems having the characteristics of riverine as well as lacustrine environments (Margalef, 1975; Tundisi, 1996). The important features of a reservoir are watershed pattern, morphometry, and hydrological cycle which determine the productivity levels of these water bodies (Burford et al., 2007). An important feature of large reservoirs is formation of longitudinal gradient of different zones characterized by their physico-chemical as well other limnological characterstics (Serafim et al., 2006; Sthapit et al., 2008; Tundisi & Straskraba, 1999) harboring their own distinct biota (Friedl & Wüest, 2002). Recently manmade reservoirs have been subjected to overfishing due to unchecked commercial exploitations (Allan et al., 2005).To rehabilitate these *Corresponding author: zahids2k@hotmail.com

2 32 Z. S. MIRZA ET AL BIOLOGIA (PAKISTAN) water bodies, various management practices have been suggested including the stock enhancement, introduction of fast growing non-native fishes and reduction of by catch (De Silva, 2000; De Silva & Funge-Smith, 2005). These interventions can only be sucessful if one has accurate information about the current status of stocks in the waterbody. This highligts the need for a thorough investigation of fish population profile before devising any rational management plan for these water bodies. Mangla Reservoir is a large manmade impoundment (surface area 265 Km 2 ) which is being exploited for commercial fishery. The public authorities have been augmenting the fishing stocks reservoir by stocking of hatchery reared seed of different species. There is no accurate information about the current status of commerical catch composition and total fish production from the reservoir. The current study was, therefore, undertaken to assess the current status of fisheries in the Mangla Reservoir based on seasonal variations in species composition and annual catches. This information will form a baseline for future fisheries management plans and help to assess the needs for implementation of conservation measures. MATERIALS AND METHODS Mangla dam is an earth-filled structure constructed on River Jhelum (33 o N, 73 o E) thirty kilometer upstream of Jhelum City (115 km southeast of capital Islamabad). It is a multipurpose reservoir primarily constructed for storage of irrigation water, hydroelectric power generation and flood control. Fisheries and recreation has developed as a byproduct. The reservoir is situated at the junction of two perennial rivers (Jhelum and Poonch) and two non-perennial rivers (Kanshi and Khad) (Sheikh, 2007) and has a square shape with its narrow flanks extending into the river valleys. The reservoir has five basins commonly referred as pockets of the reservoir namely Mangla, Jhelum, Poonch, Khad and Jari (also as Jari Dam).The main physical features of the reservoir are given in Table 1. Table 1:Physical characteristics of Mangla Reservoir Physical Characteristics Value Normal max conservation level (SPD) (m) Min operational level (SPD) (m) Original gross storage (MCM) Original live storage (MCM) 6,586.8 Existing gross storage (MCM) (as per 2005) 5,921 Existing Live storage (MCM) 8,185 Surface area (Km 2 ) Maximum depth (m) 90 Mean depth (m) 22.5 Depth ratio 0.25 Data regarding daily water levels in the reservoir was obtained from Mangla Dam Organization. Species composition and commercial catch data was obtained by stratified random sampling (Anderson & Neumann, 1996) at two

3 VOL. 58 (1&2) FISHERIES IN MANGLA RESERVOIR 33 landing sites in the reservoir from Jan 2009 to Dec 2010 (making for a complete overlap of 2 hydrological and fishing years). Fishing days were taken as primary sampling units (eight fishing days per month) and two secondary sampling units (landing sites) during each month. Weight and species of fish landed by every fourth boat coming at selected landing site were recorded. The specimens were identified and classified with the help of standard key (Mirza & Sandhu, 2007) using morphometric characters. Catch rate and effort estimates from the landing sites were used to estimate the total catch following the procedure recommended by Sparree & Venema (1998). This was based on the assumptions, that the sample areas were sufficiently representative since they covered all the landing sites on the dam. The data obtained was tabulated and summarized in different groups based on the percentage of each species in the landing. Fish species forming more than 10% of the total catches were treated individually while the rest were grouped into Chinese Carps (Bighead, Silver and Grass carps), Tilapia, and commercially important other native fishes. Catches of commercially undesirable species were grouped together as by-catch. RESULTS AND DISCUSSION The total commercial fish production from the reservoir and its composition during two years period are shown in Table 2. The results show that total catches from the reservoir during the two years varied widely with average total catch of mt. The catches for the year 2010 were almost 130 mt higher as compared with the catches during the previous year. The total catch from the four commercial fishes, Cyprinus carpio, Gibelion catla, Sperata sarwari and Wallago attu, formed per cent of the total average catch for the two years. Amongst these, the two Cyrprinds formed 52 per cent of the total catch and 62 per cent of the catch of total catch of four commercial fishes. Similarly the two Silurids formed 31 per cent of the total catches and 48 per cent of the total catches of four commercial fishes. On the whole the contribution of the exotic fishes remained mt (5.46 per cent) out of total catches. The remaining fish catches came from the other indigenous fishes like Tor macrolepis, Labeo rohita, Labeo calbasu, Cirrhinus mrigala, Channa marulius etc. The results show that during the months when the water level is near the dead supply level, there is a trend of increasing by catch and tilapia. During January 2009, highest quantities of tilapia (2.79 mt) were recorded from the catches. In general the amount of total commercial catches inversely followed the pattern of water fluctuation in the dam. The comparison of total catches with hydrograph of Mangla reservoir from Jan 2009 to Dec 2010 is shown in Fig 1. The hydrograph show that during the year 2010, the average water level in the dam remained m ( ft) which is lower than the average level ( m or ft) of Although the average water level remained low during 2010 but the dam remained at full-supply-level (FSL) for 48 days during 2010 as compared to 29 days during As far as the lowest level of water in the dam is concerned the water level did not fall to its dead storage level during 2009 and the lowest recorded level was m ( ft). On the other

4 34 Z. S. MIRZA ET AL BIOLOGIA (PAKISTAN) hand the dam water remained at dead storage level from 27 th to 28 th February and 8 th March to 21 st March (16 days) in Lower reservoir levels resulted in higher commercial catches during the months of December to April and even reached upto mt during Feb Fig., 1: Relationship of monthly variation in water level (A) and commercial fish catches (B) from the Mangla Reservoir from Jan-2009 to Dec Months Fig., 2: Relative share of different categories of fishes in commercial catches from Mangla reservoir (Jan-2009 to Dec-2010) Note: WA = Wallago attu, SS= Sperata sarwari, GC=Gibelion catla, CC= Cyprinus carpio, EX=Exotic species, and ON = other native species

5 VOL. 58 (1&2) FISHERIES IN MANGLA RESERVOIR 35 Table 2: Estimated catches (mt) of commercial fish from the Mangla dam from Jan-2009 to Dec-2010 Months W. attu S. sarwari G. catla C. carpio Other Native GC/SC/BH Tilapia By-Catch Total Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total Total Average Percent 19% 12% 25% 27% 4% 2% 5% 6% 100%

6 36 Z. S. MIRZA ET AL BIOLOGIA (PAKISTAN) Relative share of different categories of fishes in the monthly catches is also shown in Fig., 2. The results show that the contribution of two Silurids in total catches was higher from February to May which then decreased. During these months, water level in the dam is at or near its dead storage levels. On the other hand the contribution of two Cyprinids was higher from September to December when the dam was at its full supply level (FSL). The decrease in catches of the Cyprinids was accompanied by the corresponding increase in the Silurids. Similarly, the contribution of exotic fishes increased during the months of January to May. The proportion of by catch increased during the months in which the dam was near its dead storage level. Mirza et al. (1989) published a checklist of 52 species recorded from the Mangla reservoir out of which at least 12 (Shah, 1996) are used as food fish. The ichthyofauna of the reservoir is similar to that of River Jhelum downstream (Mirza & Ahmad, 1987; Mirza, 2006).The current study showed that the main catches from the reservoir consisted of four species (two Cyprinids and two Silurids). Additionally the proportion of exotic Chinese carps has also increased significantly. On the other hand the catches of traditionally important commercial fishes like Labeo rohita, Labeo calbasu, Tor macrolepis, Channa orientalis etc. have decreased and total catches from these fishes hardly reached 8 mt. Traditionally Mahseer (Tor macrolepis) and Soul (Channa orientalis) have been the popular game fish in the reservoir. Discussions with fishermen revealed that the population of these game fishes have drastically declined during the last decade or so. When the total fish catches from the dam were converted to catches per hectare per year, the results showed that the figures varied widely between the two years. The average fish catches from the dam remained kg ha -1 yr -1 with a value of kg ha -1 yr -1 during 2009 and kg ha -1 yr -1 during Historically fish production from Mangla reservoir has been fairly low with average being kg/ha/year during past decade (MFD, 2002). On the other hand the potential yield estimates of productive Asian reservoirs have been estimated from 34 to 84 kg ha -1 (Sukumaran & Das, 2005). This shows that the commercial fish production from Mangla reservoir is far below those of similar reservoirs in the region. The percentage of different groups in the composition of fish fauna of a reservoir varies according to the evolutionary history which is closely related to the geological history of the river basin and niche availability (Petrere Jr, 1996). The ecology of Mangla dam has undergone changes especially resulting from high sedimentation rates (Butt et al., 2010; Izhar-ul-Haq & Abbas, 2007) and changes in precipitation pattern in catchment basin (Archer, 2003; Archer & Fowler, 2004). Seasonally the flows are the lowest during winter (October to January) and touch the highest level usually from the May to June. Rainfall plays a significant role in Mangla catchment. The hydrological cycles of the lake starts in August with a rise in the water level and a filling that takes place quickly, the maximum level being reached by November. Then the level begins to fall slowly in December and faster from April to June, when the electricity demand is at its peak along with the discharges for the summer crops. Additionally a number of other factors also played their role in the alteration of ecological conditions of the dam during the last two decades. These include the increased sewerage/ pollution, sedimentation, overfishing and introduction of exotic species in the

7 VOL. 58 (1&2) FISHERIES IN MANGLA RESERVOIR 37 dam. Apparently, these factors individually or in composite manner may have caused the changes in ecology of the dam resulting in the changes in fish fauna and resulting commercial catches. The fishery development and management of the dam is under the control of the Directorate of Wildlife and Fisheries, under the Department of Forestry, Government of the Azad Jammu and Kashmir (AJK). Legislative guidance for the state of AJK is provided by the West Pakistan Fisheries Ordinance of The document includes the specifics on the leasing of water bodies, restriction on destructive fishing practice, licensing, gear restrictions, and on fishing close seasons. In addition to the fisheries ordinance, more specific regulations are provided in the West Pakistan Fisheries Rules of 1965.Currently, the fishing rights of the dam are leased out by the AJK government for a period of three year through open bid system during the month of August. The fishing contractor is solely responsible for the exploitation of the fisheries resources of the water body for the period leased out. It was observed that in order to maximize his profits, the fishing contractor tries to scoop maximum quantities of fish during the last year of his lease period which also increases the by catch. On paper the fisheries department overview the whole process of exploitation. On ground with the shortage of manpower and limited resources of the department, it is very difficult to control the indiscriminate and unjustified fishing practices taking place in the vast stretches of the reservoir. Current management activities are limited to periodic stocking of the Mangla dam, primarily the Major or Chinese carps, and the periodic lease of fishing rights of the water body. Both Major carps and Chinese carp species are stocked at the fry or fingerling stage with stocking size less than 5 cm. Increasing human population and urbanization processes along with industrialization are continuously imposing threats to the already fragile fisheries resources. These threats include overfishing, electro fishing, poisoning, use of explosives, degradation of spawning grounds, and water pollution. The present study also concluded that the commercial catch composition has changed over the last two decades. It is recommended that studies should be carried out to model the potential fish production from the reservoir. REFERENCES Allan, J., Abell, R., Hogan, Z., Revenga, C., Taylor, B., Welcomme, R., & Winemiller, K., Overfishing of inland waters. Bioscience, 55(12): Anderson, R. O., & Neumann, R. M., Length, weight, and associated structural indices. Fisheries techniques, 2nd edition. American Fisheries Society, Bethesda, Maryland, 5: Archer, D., Contrasting hydrological regimes in the upper Indus Basin. Journal of Hydrology, 274(1-4): Archer, D. R., & Fowler, H. J., Spatial and temporal variations in precipitation in the Upper Indus Basin, global teleconnections and hydrological implications. Hydrology and Earth System Sciences, 8(1):

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