THE USE OF IRRIGATION SYSTEMS FOR SUSTAINABLE FISH PRODUCTION IN PAKISTAN

by
Nasim Akhtar
Aquaculture and Fisheries Research Institute, Pakistan Agricultural Research Council Islamabad, Pakistan

Abstract

The irrigation system of Pakistan is one of the largest integrated irrigation networks in the world, serving 14.4 million hectares of contiguous cultivated land. The waters of the Indus River and its tributaries feed the system. The salient features of the system are three major storage reservoirs, namely, Tarbela and Chashma on the River Indus and Mangla on the River Jhelum; 19 barrages; 12 inter-river link canals and 43 independent irrigation canal commands. The total length of the main canals is 58 500 km, with the field ditches running another 1.6 million km. Pakistan agriculture is predominantly irrigated. Hence the development of rivers for diverting water into canals is basically meant for irrigation supply. However, other uses such as effluent and waste disposal, watering livestock, fishing, recreation, transportation and washing and bathing are also on the increase. Crop production accounts for almost 70 percent of the agricultural gross domestic product (GDP). The major crops are wheat, rice, cotton, sugar cane and maize. Wheat is the leading food grain in Pakistan, and about 79 percent of the total wheat crop comes from irrigated fields.

Fish production in Pakistan during 2000 was 654 500 tonnes, of which 474 400 tonnes (about 72 percent) was caught from the sea whereas 180 000 tonnes was obtained from inland waters, 80 percent of which was captured from a network of rivers, irrigation canals and lakes. Only 20 percent of the inland fish production is contributed by aquaculture. The overall per capita fish consumption is low, about 2 kg/year. Fisheries are secondary users of reservoirs in multipurpose dams. Fisheries management in such reservoirs is still not very advanced. There is no effective data collection system which would assist with determining factors contributing to sustainable use of these reservoirs for fisheries. But it is realized that repeated releases of fish seed produced from hatcheries is an important measure for enhancing reservoir fish stocks. Canal systems have been given low attention in terms of realizing their potential for fish production. Active canals are rarely managed for capture fisheries and there is no cage or pen culture. However, abandoned irrigation canals are to some degree utilized for fish production. Flood control compartments are often stocked naturally with wild juvenile fish, including major carps and other food fish, during floods. Large areas of wetlands resulting from irrigation practices have considerable potential for fisheries development. To further improve the fisheries in waterbodies of irrigation systems will require better planning, improved data collection and evaluation, improvements in infrastructure, better coordination among fisheries organizations, and enforcement of fisheries regulations.

1. Introduction

The fish production propensity of a river system along with its allied structures such as reservoirs and irrigation canals is governed by a set of environmental parameters, especially the water and soil quality which in turn are the function of the geoclimatic conditions under which it exists. The following section provides information for a better understanding of the situation in Pakistan.

1.1 The geoclimatic features

Pakistan is a country of 135 million people. Situated in southwestern Asia it lies between latitudes 24º-37ºN and longitudes 61º-76ºE. The tropic of Cancer passes immediately south of the country. It covers an area of 796 000 km², bordering with Iran in the west, Afghanistan in the northwest, China in the north, and India in the east. Land and water features of Pakistan are given in Annex 1. The landscape includes high mountain ranges of the Himalayas, Karakoram and Hindu Kush with interspersed valleys, high snow-covered mountain peaks like K-2 (8 611 m) and Nanga Parbat (8 126 m), and seven large glaciers. There are vast irrigated plains in the Indus basin, stark deserts and rugged rocky plateaus.

Pakistan consists of two distinct physiographic provinces: the Western Highlands, and the Indus Plain resulting from the deposition of sediments by the Indus River and its tributaries. The Western Highlands extend from the Makran coast in the south to the Pamir Plateau in the north covering most of Balochistan, Northwest Frontier Province (NWFP), the Northern Areas and part of the Punjab Province.

The Indus Plain begins at the southern end of the Himalayas and the Salt Range and stretches to the Arabian Sea. The Indus Plain is the most important physiographic region since it comprises the main agricultural areas of the country. It covers an area of nearly 21 million hectares (mha). The aquifer underlying the Punjab delivers large quantities of water. The flat plain is largely made of alluvium, over 300 m deep, deposited by the Indus River and its tributaries, which flow through the provinces of Punjab and Sindh to the Arabian Sea near Karachi.

The Indus delta and its mangroves are the most significant features of the coastal area. The mangroves area is estimated to be the fifth largest in the world and serves as a nursery for a large variety of fish, shrimps and other marine life.

Pakistan has a large variety of climatic types ranging from temperate climate in the north to hot arid tropical in the south. The northeastern mountainous and submountainous areas receive more than 1 700 mm annual rainfall with the major share (1 000 mm) coming from summer monsoon. On the other hand, the extremely arid plains of southwestern Balochistan receive only 30 mm on the average during the whole year. Thermal regimes exhibit extreme diurnal, seasonal and annual variations. Temperatures fall as low as -26 °C over the northern mountains and reach up to +52 °C over the central arid plains. In the plains, temperatures of 42 °C are recorded at various stations in May-June. The climate of Pakistan is predominantly arid to semi-arid, with a small sub-humid to humid area in the north.

2. Rivers, river systems and agriculture considerations

The Indus river system is the prime source of water in Pakistan and hence called the lifeline of Pakistan. The water resources of the Kharan desert (western Balochistan) and the arid Makran coast (southern Balochistan) are limited and the desert areas in the south (Thar and Cholistan) have no water resources.

The Indus River originates in southwestern Tibet from Lake Nagangla Ringco (31º40’N, 83ºE) and makes a 3 280 km trip to the Arabian Sea, of which 2 480 km is in Pakistan. All the Pakistan major rivers, namely Kabul, Jhelum, Chenab, Ravi and Sutlej, flow into it. The system is like a funnel with a number of water sources at the top converging into a single stream, which flows first northeast, then turns southwest to finally drain into the Arabian Sea. The total length of the Indus River and its tributaries is estimated to be 63 000 km. Aided by a number of smaller tributary rivers and streams, these rivers supply water to the entire Indus Basin Irrigation System. The rivers have their origin at higher altitudes and derive their water mainly from snowmelt and monsoon rains. The catchment area of the Indus covers one million km² and contains several of the world’s highest mountains.

2.1 Irrigation systems

The irrigation system of Pakistan started developing 150 years ago and since the Indus Water Treaty between India and Pakistan (1960) it is the largest integrated irrigation network in the world, serving 13.8 mha of contiguous cultivated land. The waters of the Indus River and its tributaries feed the system. The salient features of the system are three major storage reservoirs, namely, Tarbela and Chashma on the Indus, and Mangla on the Jhelum; 19 barrages; 12 inter-river link canals and 43 independent irrigation canal commands. The total length of main canals is 58 500 km with the field ditches running another 1.6 million km.

Diversion of river waters into canals is made through barrages, which are gated diversion weirs. The main canals in turn deliver water to branch canals, distributaries and minors. The water courses get their share of water through outlets in the irrigation channels. Distribution of water from a water course is effected through a time-schedule or "warabandi" under which each farm gets water for a specified period once a week. The time-share or "wari" is proportional to the farm area owned by a farmer under the command of the water course.

The system draws an average of 127.2 billion m³ of surface water each year for irrigation. Supplemented by an annual groundwater pumpage of some 51.6 billion m³, the average volume of water available at the farmgate is 3 685 m³ per ha. Approximately 3 million individual farms with an average size of about 5 ha benefit from this system.

2.1.1 Barrages

Five barrages (Chashma, Rasul, Qadirabad, Marala and Sidhnai) and a siphon were constructed. The siphon was constructed at Mailsi. There was also improvement and utilization of the existing barrages, Trimmu and Taunsa, and of Balloki Head Works.

2.1.2 Canals

The area served by each branch canal is called canal command and in the Punjab there are 24 canal commands, 5 in NWFP and 15 in Sindh and Balochistan. The total length of canals, their capacity, gross command area and the number of outlets in each province is given in Table 1.

Table 1
Irrigation canal system in Pakistan

The rate of growth in the farmgate water supply has declined in the past years. This will have serious implications for the country’s future food security and while Pakistan possesses an intricate system of irrigation, its productivity and efficiency per unit water availability is perhaps the lowest in the world. This is due to reduced growth and water availability, as there has been no significant water storage development since the completion of Tarbela dam in the 1970s. The water losses are immense as 25 percent is lost from the canal head to the outlet and another 15 percent from the outlet to the farmgate due to poorly linked canals and water courses and inadequate operation and maintenance expenditure in the canal system; a rigid warabandi system and unplanned development of private tube wells is resulting in undermining of the groundwater resources.

The following link canals existed in the Punjab before the water treaty with India: Tripple canals, Upper Jhelum, Upper Chenab and Lower Bari Doab; Haveli canal taken out at Trimmu; Montgomery (Sahiwal) Pakpattan Link Canal; Balloki Sulemanki Link; Marala Ravi Link (MR); Bambanwala-Ravi-Bedian-Diplpur Link (BRBD); a sub-link connecting MR and BRBD.

Eight link canals were completed after the Water Treaty with India, including the Indus Basin Works under Rasul Qadirabad Link, Qadirabad Balloki Link, Balloki-Sulemanki Link No. 2, Taunsa-Panjnad Link and Chashma-Jhelum Link.

A description of link canals and their construction in chronological order are given in Annex 2.

2.1.3 Dams for power generation and water storage

The salient features of large and medium reservoirs of Pakistan are given below. (See also Table 2).

Warsak Dam
In 1960 a dam at Warsak on the Kabul River was constructed for power generation.

Mangla Dam
Under the Indus Basin Treaty, an earthen dam at Mangla on the Jhelum River, 100 m high at an elevation of 1 234 m and having length of crest equal to 3 352 m was constructed to store 6.6 billion m³ of gross storage with a live storage of 5.7 billion m³. The dam has five diversion tunnels 610 m long and 9.1 m in diameter to produce power. Its storage has submerged 27 125 ha. The main storage is in Khad and Poonch rivers and extends to Kanshi.

Tarbela Dam
An earth and rockfill dam, 147.8 m high with crest elevation at 1 565 m and length of 2 953 m was completed in 1975. Its gross storage is 13.2 billion m³ and live storage equals 11.1 billion m³. It has four tunnels each 14.8 m in diameter and 787 m long. A fifth outlet for irrigation has also been constructed. The main storage extends along the old river channel and a portion of the reservoir extends to Siran and to its tributary. It is estimated that the useful life of the storage is 50 years by which time 1.2 billion cubic meter storage will persist for ever.

Table 2
The salient features of large and medium reservoirs of Pakistan

(note: Hydel = hydroelectric)

2.1.4 Medium and small dams

Warsak, Tarbela, Khanpur, Baran and Tando dams are located in the NWFP. A large reservoir was created above Chashma Barrage. Mangla, Rawal, Simly and Namel reservoirs and 13 small dam reservoirs lie in Punjab. Several smaller reservoirs including Hub, Wali Tangi, Nari Bolan, Khushdil Khan and Spin Karez, are located in Balochistan. Gomel Zam and Kalabagh dams are still in the planning stage.

The Water and Power Development Authority (WAPDA), which is in charge of all larger dams in Pakistan, has identified fifteen more dam sites at Sehwan, Mancher Lake, in Chottari Depressions and Hamel Lakes. A few off-storage dams have been proposed, including Gariala, Dhok Pattan and Thal. (For the WAPDA fisheries activities in reservoirs see George, 1992, 1995).

2.1.5 Mini-dams

On the Potowar Plateau damming of watercourses to harness rainwater has created 500 impoundments. These perennial waterbodies are called mini-dams. Besides their irrigation use these multipurpose reservoirs are suitable for fish farming. Their size is generally less than 10 ha, hence they are easily manageable. Some of them already have aquaculture.

2.2 Purpose of the irrigation system

Pakistan’s agriculture is largely based on irrigation. While the development of rivers for diverting water into canals is basically meant for irrigation supply, other uses such as effluent and waste disposal, livestock watering, fishing, recreation, transportation, washing and bathing are common.

2.2.1 The crop sector

Farm production is dominated by crop production, which accounts for almost 70 percent of agricultural GDP. The major crops are wheat, rice, cotton, sugar cane, and maize. Wheat is the leading food grain in Pakistan, and about 79 percent of the total wheat crop comes from irrigated fields. Rice is the second most important crop, and the two major rice-growing provinces are Punjab and Sind, which account for 54 and 36 percent of the area planted. Basmati rice, a high-value export crop and a foreign exchange earner, is grown chiefly in Punjab. Cotton, the most important non-food crop and largest export earner, occupies the second largest area of all crops grown. Besides production of lint, cotton seed accounts for 80 percent of the national oil seed production. Seventy percent of cotton is grown in Punjab. Sugar cane, yet another important cash crop, is grown over 70 000 ha. Maize is grown in both irrigated and rain fed areas and NWFP leads in maize production. The oil seed production has remained nearly stagnant for many years, despite the fact that the demand for vegetable oil has tremendously increased in recent years. The relative importance of coarse grains in the Pakistani diet has declined over time, as tastes have changed and per capita incomes have increased. However, grains such as sorghum, millet and barley constitute a major source of feed and fodder and their importance will increase further if the poultry sector continues to expand at its present rate. Gram accounts for about two thirds of the total acreage under pulses. Fruits and vegetables represent a dynamic segment of Pakistan’s agriculture.

2.2.2 Seepages

The losses from water courses are between 10 to 20 percent with a maximum of 40 percent, half of which is due to evaporation losses while the rest seeps downward. The seepage water recharges the groundwater of the Indus plains. The seepage water has created problems such as waterlogging. To cope with this problem open surface drains and pumping of groundwater has been carried out on a massive scale.

2.2.3 Flow rates and seasonality of the use of irrigation and drainage canals

The base period of irrigation which represents the number of days for a crop season is 183 days for Rabi (winter crop season) and 182 days for Kharif (summer crop season). The total availability of water for irrigation is given in Annex 1.

2.2.4 Pumping system and fish-protection devices

Only two barrages have been provided with fish passes, however, they do not function properly. Tenualosa ilisha, a very popular anadromous species which migrates about 200 km from the coast upstream the Indus River for breeding, is blocked in its spawning migration by an ineffective ladder in the GM barrage. This has resulted in a drastic decrease in its stocks. The Chashma barrage fishway is also not efficient for most of the Indus River fish species. Mangla dam, which has no fish pass, blocks the Tor putitora upstream migration. Subsequently, this popular game fish is becoming rare.

No fish protection devices or refugia for fish are present in canals. Most pumping stations have no fish barriers at the intakes, and where they do exist, they do not work properly.

2.2.5 Water quality in the Indus, Jhelum and Chenab

The concentrations of total dissolved solids in these three major rivers of Pakistan are fairly low, averaging between 120 and 200 mg/litre. The concentration is lowest during the monsoon and increasing slightly during winter months. The chemical composition for the three rivers is given in Annex 3.

The Ravi and Chenab rivers’ water vary in their dissolved salt concentrations, sediment load, as well as in concentrations of Cu, Fe, Mn, Zn, available phosphorus and organic matter content in the sediments. The water quality with respect to salinity is within the safest limits for irrigation. Ca⁺⁺ and HCO₃^- are the dominant ions. The sediment load is, however, rising which indicates increasing erosion in catchments.

2.2.6 Use of agrochemicals/integrated pest management

Plant protection measures in Pakistan are largely limited to the use of pesticides. Undoubtedly, plant protection is an expensive input, but returns are also high. The use of integrated pest management is being slowly adopted.

3. Fish and fisheries considerations

3.1 Fisheries profile

3.1.1 Significance of the fisheries sector and its economic role

Pakistan is a predominantly agricultural country where about two thirds of its 135 million population is dependent, either directly or indirectly, on agriculture. Fisheries, a sub-sector of agriculture, plays a significant role in Pakistan’s national economy and contributes towards the food security of the country. Contributing about 1.0 percent to the total GDP, which is equivalent to about 4.0 percent of the GDP of the agriculture sector, it absorbs 1.0 percent of the country’s labor force. There are about 400 000 fishers, mainly fishing the sea. With their families they depend on fishing for their livelihood. The export of fish and fishery products during 1999-2000 reached 92 000 tonnes, this corresponding to a value of $US 139 million.

Recorded fish production in Pakistan during 2000 was 654 500 tonnes, of which 474 400 tonnes (about 72 percent) were from marine waters and 180 000 tonnes were from inland waters. Eighty percent of the freshwater catch came from wild resources of rivers, irrigation canals and natural lakes. Twenty percent of the inland fish production is contributed by aquaculture. Aquaculture in Pakistan benefits from irrigation, as about 75 percent of the fish ponds in the country are supplied with water by irrigation canals.

Collecting fishery freshwater statistics is highly inefficient so that official statistics fail to include a substantial amount of catches landed at a large number of unknown sites, including subsistence level catches by artisanal fishers and fish captured illegally. If all were to be included, the total catch would be much higher, perhaps twice as high as reported.

3.1.2 Major fish stocks, biodiversity and population decline/extinction

There are approximately 200 species of fish in freshwaters of Pakistan, of which a number are endemic. Substantial quantities of commercially important fish are caught from rivers. The inland commercial fishery encompasses about 30 species of which the significant ones are: Labeo rohita, L. dyocheilus, Catla catla, Cirrhinus mrigala, C. reba, Channa striatus, C. marulius, Aorichthys (Mystus) seenghala, A. (M.) aor, Wallago attu, Rita rita, Bagarius bagarius, Tenualosa ilisha, Notopterus notopterus, Tor putitora, Schizothorax spp., Clupisoma nazirri (in cold water streams only). The exotic species, which have managed to escape into the natural systems and have thrived there, also make a small contribution to the total landings from rivers. These include three species of tilapia, three Chinese carps, common carp and two species of trouts. (For lists of species for northern Pakistan, as well as for literature references, see Petr, 1999).

While none of the species are yet recognized as endangered at the national level, at least two of commercial importance, i.e. T. putitora and T. ilisha, may attain the status of endangered species soon if steps are not taken to conserve them. Tor migrates from floodplains to the Himalayan foothills for breeding and the creation of Mangla and Tarbela dams blocked its migration. T. ilisha needs to migrate upstream from the Arabian Sea to breed but ineffective fish ladders in the Guddu barrage on the Indus River hinder the migration. Many northern cold water hill stream loaches of the genus Nemacheilus and Triplophysa are threatened; at least 10 species of cyprinids are rare and vulnerable; cold water indigenous snow trout has a limited range of distribution and is being outcompeted by the introduced exotic trout and thus is of special concern. A number of studies have been done in Pakistan to identify the fish and their natural distribution, however, a large number of species have not been described in terms of their habitat requirement and population structure. The issue becomes more important when we look into the matter from the perspective of the range of climatic and habitat diversity prevalent in the country. Moreover, human activities in the last five decades, such as logging, agriculture, highway construction, diversion and regulation of rivers through creation of dams, barrages and other waterworks, have greatly decreased the number of suitable habitats. Habitat loss has also resulted from organic and other types of pollution, including discharges of toxic substances. Consequently, those species with limited distribution and critical habitat requirements may disappear from inland waters of Pakistan due to habitat loss or modification. In-depth research is imperative, not only to determine distribution, taxonomic status, population size and habitat requirements of these species but also to devise a rational conservation programme for their protection. The research should culminate in a programme of establishment of sanctuaries, nurseries for salvage of juveniles during floods, and hatchery techniques for artificial breeding of vulnerable species.

3.1.3 Present use of irrigation systems for fish production

The inland fisheries of Pakistan consists of three sub-sectors: traditional capture fisheries in rivers, lakes, reservoirs, barrages and other waterbodies; sport or recreational fisheries, primarily in the NWFP and the Northern Areas; and aquaculture in small and large ponds. The current status of capture fisheries is primarily the result of the prevalent institutional framework for inland fisheries management in the country.

The institutional arrangements for fisheries in Pakistan are quite extensive. Inland fisheries is primarily a provincial responsibility. The provinces have jurisdiction over all the waterbodies within their province with the exception of large reservoirs which are managed by WAPDA. Capture fisheries is subject to the Fisheries Ordinance/Acts of the provincial governments with respect to conservation.

Traditional inland fisheries is managed by an auction system and limited licensing of natural waterbodies, for which purpose the rivers, canals, barrage reservoirs and head works are compartmentalized arbitrarily and the fishing rights for each compartment is annually auctioned publicly by the respective Fisheries Department after wide publicity. Likewise, fishing rights for the large and medium-sized man-made reservoirs on rivers are auctioned by WAPDA. Lakes, abandoned canals and dhans (usually large waterbodies created besides canals due to earth excavation and filled by seepage water from canals) are sold by the custodian Fisheries Department to the private sector after competitive marketing. The limited licensing, however, is subject to various regulatory rules, such as closed seasons, which basically are aimed at sustaining the fish productivity and conservation of the species. Whereas the auction system is quite well developed, the departmental capabilities and infrastructure for implementation of such rules are quite inadequate. The management of the waterbodies under this system is not efficient as the magnitude of the resource is not well known. There is a dearth of information on the maximum sustainable yield (MSY) and on fish production. The indicators, however, suggest that the fishing pressure is reaching the ceiling of the MSY. Management needs to pay more attention in order to insure that the resources are not overexploited. The sport and recreational fisheries are managed by licenses, particularly the coldwater fisheries in the riverine systems of the Northern Areas. Fish stock protection and enforcement are major management problems in this sub-sector.

Another reason for neglect of capture fisheries is that most of the expenditure at state level has shifted towards aquaculture rather than capture fisheries in the last decades. The rationale is that aquaculture provides a way of enhancing natural stock and therefore benefits the capture fisheries. However, the freshwater aquaculture is still relatively small scale, with a total farming area of about 50 000 ha. But as there is an element of ownership involved in aquaculture as compared to no ownership in capture fisheries, there is the likelihood that aquaculture will grow fast. This is much more so because of high profitability in aquaculture, feasible environment, and top government support for its growth.

3.1.3.1 Fisheries in large reservoirs

The salient features of reservoir fisheries in Pakistan are:

• Fisheries are secondary users of reservoirs hence in multipurpose dams fisheries have a lower priority.

• The little research already done on reservoir limnology and fisheries is still not adequate for developing thorough management strategies. WAPDA has improved fisheries management in some of the major reservoirs.

• At the departmental level there is no effective data collection system with respect to factors contributing to sustainable fisheries in reservoirs. Training of manpower in the analysis and management of data is particularly lacking.

• The impact of stocking on yield enhancement is not fully understood. In this regard so far no attempt has been made to develop an optimal stocking model for each reservoir. Predictive models for estimating potential yields need an adequate database, which is lacking.

• Human impacts in watersheds, such as deforestation and discharge of pollutants into streams are but a few of the hazards which have not so far been properly addressed.

3.1.3.2 Fisheries in canals

Although dams, lakes and rivers as components of irrigation schemes have been a big source of fish, the canal systems have been given less attention in terms of realizing their potential for fish production. The active canals, i.e. those with water, are rarely managed for capture fisheries and there is no cage or pen culture. A number of inherent management problems exist in irrigation systems, which results in underutilization of these resources for fisheries. Saline water associated with an irrigation system, as present in drainage canals, provides a suitable environment for fish like tilapia and some crustaceans but no effort has been made towards making use of this resource. Aquatic weeds in irrigation canals could either be harvested and used as fish food or they could be grazed by grass carp but both approaches are yet to be implemented in Pakistan. No attempt has been made to follow the regime of water flow in irrigation canals, the knowledge of which is essential if the canals are to be considered for aquaculture. Pakistan is, however, doing well in utilization of abandoned irrigation canals for fish production. After slight modification these waterbodies are treated as fish ponds. Most of these impoundments have extensive culture systems in which stocking is rarely followed by other management inputs.

3.1.3.3 Flood control compartments and fisheries

Along the Indus River, for about 150 km between the Guddu and Sukkur Barrages, there are numerous flood control compartments with water control gates. They range in size from 10 to 5 000 ha each. Under normal operating procedures, these compartments are filled during the rainy season and subsequently drained a few months later after the floods have subsided. However, the peak flood period also corresponds with the peak of fish spawning. The flood control compartments are often stocked naturally with wild juvenile fish, including the Indo-Gangetic major carps and other food fish. Unfortunately, at the time the compartments are drained a few months later, the fish are still of a fairly small size. However, if these compartments were to be managed as a fish pond and the fish allowed to grow larger, there would be a good potential for better use of an infrastructure that already exists. There are over fifty of these flood control compartments and if only a fraction of them were managed to produce one to two tonnes of fish each year, the potential for increased fish production would be substantial, especially considering the relatively minor investment required.

3.1.3.4 Mini-dam reservoir fisheries

In barani areas, a large number of mini-dams have been created to harness surface runoff, particularly after rains. These are generally created on non-perennial streams and are used for small irrigation schemes. These are unique new waterbodies with a mix of the characteristics of a pond and a reservoir. Most of these mini-dams are privately owned, constructed with government subsidies, and very few of them are used for fish production mainly due to non availability of appropriate fish production methodology for these mini-dams.

3.1.3.5 On-farm pond aquaculture

In a given agriculture system the main aquaculture setups are in the agriculture farmer’s residual farmland. There is also the tendency to build fish farms on marginally productive agricultural land of the farmer. These farms are supplied with either tubewell water or from the irrigation canal. As the dependence on the canal water in fish farming systems is very high, one can consider these ponds to be an integral part of the irrigation system. The management requirements of these canal water-dependent ponds are different due to the high levels of silt in the water and the presence of undesirable fish species entering the pond with the canal water despite all precautions taken to prevent this.

3.1.3.6 Fisheries in residual water storages

Terminal lakes and residual waterbodies have not yet been surveyed for their fish production potential and no development and management programme has been formulated for their use.

3.1.3.7 Wetlands: fisheries perspective

Pakistan is endowed with immense areas of wetlands representing unique and diverse ecosystems. So far, there is no special management technique or plan for utilizing these bodies as a fisheries resource, although recent surveys have concentrated on assessing their potential. Three wetlands have been declared Ramsar sites for preservation and conservation purposes. A list of the important wetlands of Pakistan is presented as Annex 4. For fisheries purposes some of these wetlands are listed under the synonym of natural lakes.

Natural lakes cover an area of 109 780 ha. Some are high altitude coldwater lakes and are therefore well-suited for trout. Most warmwater lakes are in Sind Province and are a great source of fish. A canal feeds Lake Mancher in Dadu District from Lake Kalri. This lake was considered to be one of the best lakes of Sind, but its productivity has diminished due to overfishing and excessive aquatic weed growth.

Lake Kalri is situated about 100 km from Karachi and has two parts: one known as Lake Sonahri and the other as Lake Kalri itself. It has an excessive growth of weeds. Lake Haleji is situated 88 km north of Karachi and is fed by a canal from Lake Kalri. Fish landings from these lakes have been declining.

Many small lakes exist in Thatta and Sanghar Districts and they support good capture fisheries. Lake fisheries in Sind are regulated by the Department of Fisheries (Sind) and their fisheries management plan is mainly regulatory in nature.

3.1.3.8 Fisheries and aquaculture in waterlogged areas

The extent of waterlogged areas is given in Annex 1. Of the millions of hectares of waterlogged areas created due to massive irrigation systems, practically no attempt has been made to use these waterbodies for fish culture. An interesting phenomenon observed during the current prolonged drought in Pakistan is that the water table in many waterlogged areas has gone way down due to acute shortage of water in the canal systems.

3.1.4 Fish marketing

Both marine and inland fish are marketed in Pakistan. The per capita fish consumption is a low 2 kg/year but there is an increasing trend. The per capita consumption, however, varies from place to place. For instance, in coastal areas it is 12 kg/year. The coastal provinces are supplied mainly by marine fisheries while the inland provinces are mainly supplied by inland fisheries. Marine fishes are distributed by train from Karachi (Sind) to major markets in other cities such as Lahore, Multan, Rawalpindi (all in Punjab) and Peshawar (NWFP). Inland fishery products are marketed in all major markets of the urban centers. The fishers bring their catch by boats to collection points on the shore of the lake/reservoir/barrage or river. There the contractors/collectors collect the fish, place them in woven baskets or burlap bags with crushed ice and then transport these, on a daily basis, by public or private transport to the major markets called "fish arrhat". The fish is auctioned here, based on grading by weight/size, species and quality. The availability of fish in the retail market is not only limited but is characterized by irregular supplies, low number of vending slots and inferior facilities for storage, distribution and marketing.

Fish weighing 2-3 kg fetch prime prices in the market. The price is also dependent on the degree of freshness and the market demand/supply situation. The market itself is seasonal with best prices during the coolest winter months. Other factors which affect fish price include location of the market (city, for instance), species of the fish, closure of canals for removal of sand (for a month during the first calendar year).

It is estimated that post-harvest losses from river capture fisheries are 20 percent. Inferior handling and distribution, inadequate infrastructure and poor marketing practices characterize the marketing system.

3.2 Management measures for increasing fish production in various types of inland waterbodies

Although the capture fisheries management in rivers, reservoirs and canals has been improving, there is still much to be done. There is a great scope for improvement in planning, data collection, infrastructure, and for better coordination among different fisheries organizations involved with the same resource at the macro- as well as micro-level. The large dams are primarily built for hydroelectric power generation and irrigation. To operate these systems specialized departments are involved. However, fisheries are still given very little power to interfere with the water distribution pattern which is dictated by the major uses. In WAPDA, its own Fisheries Department is responsible for fisheries management of the large water storages serving irrigation and hydroelectricity production. For at least 20 years this department has been implementing a programme of fisheries development in these reservoirs. The fisheries beyond these reservoirs, both up and downstream, remain beyond the WAPDA jurisdiction. Rivers are under the provincial fisheries departments, and the barrages and irrigation canals are under the provincial irrigation departments, with fisheries in them being the responsibility of provincial fisheries departments. There is no body at the state level to guide activities of these fisheries organizations to devise a rational fisheries management programme for waterbodies serving irrigation purposes.

Several of the known management inputs are being used in Pakistan with the objective of sustaining the current fish production levels from the river/irrigation systems. Practices such as species introductions, artificial recruitment, introduction of new species and regulatory measures including closed seasons are not properly understood and hence these are applied as and when deemed suitable but without working out their rationality and strategic planning. It can be said that the overall advancement and development towards understanding and follow up action plans for irrigation system fishery-cum-aquaculture is still very much in its infancy, in Pakistan as well as in some other countries in the arid zone of Asia.

3.2.1 Fish introductions and stocking

The previous two decades have seen the introduction of the herbivorous cyprinids silver carp and grass carp, of common carp and very recently of bighead carp and three cichlids, Oreochromis niloticus, O. aureus and O. mossambicus. These species were introduced into Pakistan for pond aquaculture to fill the vacant trophic niches of the major carp-based polyculture system in warm water regions. Insofar as introduction of grass and silver carp is concerned, their stocking in open water has posed not much of a problem as in their environments the species meet with only indifferent breeding success. The interrelationship between indigenous carps and Chinese carps in open waters of Pakistan is not yet fully understood, but it is known that in India silver carp is a severe competitor with catla. Stocking enhancement in open systems needs careful follow-up monitoring and evaluation of the introduced exotic species in terms of both their growth rate and reproduction.

The river system modified for hydroelectric power generation, and its allied canal system, are the dominant areas for further development of inland capture fisheries. Of the total inland fish production in the country about 25 percent comes from six reservoirs.

It is realized that enhancement of fish production through repeated releases of stocking material produced in hatcheries is an important management measure in reservoir fisheries. Such a stock enhancement technique supplements or sustains a population of species that already exists or that was introduced before. Some reservoirs in Pakistan have been stocked for a number of years. These stocking programmes have been implemented without properly understanding the causes behind some declines in fish production, and with only a limited knowledge of the inherent productivity of some reservoirs. This has resulted in failure of some stocking programmes in the past because factors such as overfishing, poor fisheries management and degradation of aquatic environment have not been simultaneously addressed.

3.2.2 Other measures applied to achieve sustainable fish production in a variety of irrigation waterbodies (e.g. fisheries laws and regulations and their enforcement)

Experience has shown that uncontrolled fishing and destructive fish capture methods deplete fishery resources, with logical consequences for those who depend on fishing. To control illegal fishing a number of laws and regulations already exist.

The Indian Fisheries Act, which came into being in 1897, provides a basis for the current Fisheries Act of Pakistan; it has been adopted with some modifications by each of the provinces of Pakistan. Provisions against public nuisance such as pollution exist in the Pakistan Penal Code, Criminal Code and State and Local Acts, by which legal powers are conferred upon the State. Inspectors of Factories control proper treatment of industrial effluents before disposal. Such provisions have not always prevented the pollution.

Restrictions have been imposed on the use of certain nets during specified parts of the year as well as on the mesh size. Closed season, i.e. restriction on fishing during a certain period of the year, mostly covers the period from 15 April to 15 August. In the 1960s, the Government prohibited catching of rohu, mrigala, mahseer and catla smaller than 25.4 cm. Certain areas have been declared as "protected waters" or sanctuaries and closed to fishing. Restrictions on the sale of illegal-size fish and issuing of fishing licenses are other regulatory measures.

While the Fisheries Act and the legislation exist, the machinery for the enforcement of the regulations in most cases is so inadequate that the objectives are hardly fulfilled. Despite legal prohibition, the capture and destruction of brood fish and juveniles in large quantities are commonly practised all over the country and are largely responsible for the impoverishment of fish stocks. Legislation based on empirical knowledge is of doubtful utility. There is thus a need to discard legislation of suspect importance and instead formulate and enforce regulations based on the analytical approach of unit populations of different species of fish in rivers and allied irrigation structures such as reservoirs, barrages, etc.

3.3 Use of agrochemicals and biodegradability

Organochlorines, organophosphates, carbamates and synthetic pyrethroids are the common agricultural insecticides. All insecticides vary in degree of biodegradability and toxicity to fish. Fenvalerate, one of the pyrethroids effectively used for pest control in cotton and a variety of other crops in Pakistan, is highly toxic to fish. Bioaccumulation of xenobiotics in aquatic species is increasing alarmingly and this is also increasing the potential human health hazard. A variety of fish species show absorbance and accumulation of many contaminants such as pesticides and bactericides, polychlorinated biphenyls and heavy metals. Due to the lipophylic characteristics of many of the insecticides, they (especially pyrethroids) are absorbed by fish, even at low concentrations in the water. The toxicity caused to fish may not be immediately harmful, but most of the insecticides disturb haematological and metabolic processes by inhibition/activation of enzymatic activities and cause tissue damage.

3.4 Other pollutants

Degradation of rivers, reservoirs and canal systems has been on the increase due to the rapid pace of industrialization, poor environment management in the catchments and a variety of other factors. Apart from the direct entry of industrial, municipal and thermal wastes, the pollution load carried by the upstream rivers also accumulates in the reservoirs. The environmental degradation in reservoirs and barrages is caused mainly by the waste discharge from industrial, municipal and agricultural sources. High rate of siltation due to poor catchment management also affects the biological productivity. The need to reduce the amount of pollutants reaching rivers, lakes and reservoirs in order to mitigate their impact on fish and fisheries, is hardly receiving any attention in Pakistan.

4. Intersectoral cooperation to optimize the use of irrigation systems for fish production

Water engineering has played an important role in Pakistan agriculture for over 5 000 years. The agriculture irrigation schemes have impacted the natural river systems by transforming fluvial conditions to a combination of fluvial and lacustrine conditions, with additional unique features of their own in adjoining canals in terms of spatial variations of certain habitat variables. The ecology of reservoirs is radically different from that of the parent rivers. Dams alter river hydrology both up- and downstream. Another unique feature of reservoirs and irrigation canals, which makes them distinctly different from their natural counterparts, is the water renewal pattern marked by swift changes in levels, inflow and outflow. The complexity of managing an altered water regime for sustainable fish production, therefore, is more complicated than managing a natural system. It is no longer a capture fishery alone; to achieve a sustainable and reasonable fish production which can support fisheries requires a mix of capture and culture fisheries. In turn, this requires management inputs which consider a multitude of factors, which can only be discussed with the full participation of all users of the water resources, such as irrigation and hydropower engineers, crop production specialists, and other parties involved in the use of water. Socio-economic aspects must be included in any fishery management considerations pertaining to the full development of fishery potential in waterbodies of irrigation systems.

4.1 Suggestions for improvement

Keeping in mind the complexity of the social, economic and ecological factors involved in the formulation of a sound management policy and in the implementation of a programme of sustainable fish production development from irrigation systems, the following steps need to be considered.

Availability of data

The most important thing is the availability of data on the resource and the rate of fish stock exploitation.

The inadequacy of knowledge about the resource biology, different habitats, stocks, behavior and dynamics of individual fish species, population structure and recruitment pattern in relation to river modifications/development in the country needs to be addressed. A sound data base is essential for comprehensive analysis of biological and environmental factors required for the formulation of an integrated fisheries management plan for various types of waterbodies representing an irrigation system.

All large, medium, small and mini-dam reservoirs need to be classified according to their morphometric, physical and biological parameters on the basis of time-series data. This data should be analysed under a unified theme and a goal to which the data is harnessed under a holistic approach. Countries sharing the resource should join in this process. The process will facilitate rationalizing efforts for sustainable use for fisheries development of reservoirs and other irrigation system waterbodies.

Better use of irrigation and drainage canals for fish production

Since fish production from irrigation systems is generally extractive in nature, selective stocking either for correcting imbalances in species spectrum or to fill vacant ecological niches assists in enhancing fish production. Wherever possible one or more of the following enhancement measures should be applied, together with conventional fisheries management practices. The implementation strategy, however, anticipates a profound knowledge of the system, its dynamics, and follow-up monitoring and evaluation of the stock enhancement programme in the waterbody where applied.

The following are some enhancement strategies:

• Stocking in suitable portions of irrigation systems to improve recruitment, altering fish assemblage structure to favoured species or to maintain such species that would not breed naturally in the system.

• Introduction of new/exotic fish species, in compliance with the Code of Practice, to exploit underutilized habitats

• Engineering the environment through provision of structures such as fish ladders to enable migration to improve levels of reproduction, etc.

• Systematic removal from the system of unwanted fish species which either compete with or predate upon target species.

• System modification for improved and reliable availability of nutrient-rich water from irrigation channels to feed fish ponds.

Cage and pen culture

Introduction of cage culture should be considered for suitable waters of irrigation systems. Pen culture development is encouraged where the morphology of rivers and reservoirs allows such structures to be installed.

Control of water-borne diseases using fish

Many rivers and irrigation systems have transboundary connections which facilitate the dispersion of fish diseases. What is needed is fish disease legislation, and capacity building through training and infrastructure development.

Mitigating effects of pollution

The existing legislation needs to be enforced, the environmental protection agency strengthened, and pollution "hot spots" ameliorated by implementing a rational management plan.

Non-utilized waterbodies

• Establish a scheme to study the different options for fish production in irrigation canals, especially through aquaculture.

• Use grass carp in canals partially choced with weeds for attaining dual benefits of commercial fish production and weed control.

• Large water areas created by waterlogging need to be assessed for their suitability for fish culture.

• Appropriate technologies for fish culture under fluctuating salinities need to be identified.

• Abandoned canals, flood compartments and seepage tanks besides canals are potential habitats that could be harnessed judiciously for aquaculture.

• Mini-dams offer suitable environment for fish production in a multiple-use scenario but this will require intensive experimentation for optimum resource utilization.

• Natural lakes such as Mancher in Pakistan, which are continuously fed by canal water, are unique systems offering challenges for fisheries through blending fish culture with capture fisheries.

• River floodplains, with their diversity of lakes and other types of backwaters, can be more efficiently used for fish production that they are at present.

Fish production potential

The following activities may be considered as steps to enhance fisheries in waterbodies of irrigation systems:

• Models tested in other parts of the world should be tested through a validation process to assess their suitability for improving fish yields.

• Factors limiting development of well-functioning fisheries cooperatives, including those slowing down the pace of improvement of the social welfare, particularly of small-scale operators, need to be reappraised. Community participation should be a viable option for improving the current fisheries management efforts.

• Constraints to fisheries technology, distribution and financing need in-depth evaluation.

5. Recommendations

Most of the following recommendations for improvement of fisheries in waterbodies serving irrigation focus primarily on the region, especially on the need for regional cooperation. Some recommendations are pertinent to problems in the individual countries.

• A comprehensive national survey for assessment and analysis of fishery resources in irrigation systems including rivers, reservoirs and canals is essential for developing sound management strategies.

• Development of a regional fisheries resource information system for creation of a regional database for waterbodies represented in irrigation systems, is recommended. This to be established in parallel with the strengthening or establishment of a similar information center in each participating country.

• Initiation of a collaborative international fish conservation programme including conservatory aquaculture to safeguard the most vulnerable species.

• Sharing of knowledge and information for increasing fish catches through improved harvesting technology particularly for reservoirs.

• Organization of an international workshop on fish production potential of irrigation and drainage canals.

• A collaborative regional research project for development of saline inland water aquaculture.

• Capacity building at national level for assessment of the impact of global change on inland fisheries and environment.

• Regional programme of research capacity building and linkages with international research organizations.

• A regional scientific study programme to address the problem of pollutants arising from irrigated agriculture, including their speciation, adsorption of pollutants on sediments, and impacts on fish, especially in drainage canals and waterbodies established from residual/drainage waters.

• Governments should seriously consider establishing protected zones in freshwaters for fish species endangered by modifications of natural waterbodies by irrigation structures.

References

George, W. 1992. Review of inland fisheries of Pakistan. FAO Fisheries Report No. 458, Suppl.: 47-81. Rome, FAO.

George, W. 1995. Review of fishery management in Water and Power Development Authority (WAPDA) reservoirs in Pakistan. FAO Fisheries Report. No. 512, Suppl.: 141-153. Rome, FAO.

Petr, T., 1999. Coldwater fish and fisheries in Pakistan. FAO Fisheries Technical Paper. No. 385: 122-137. Rome, FAO.

Annex 1

Pakistan’s resource base (source: WAPDA, Pakistan, and Pakistan Economic Survey)

135 million people (33 percent urban population)

LAND

WATER

WATERLOGGED AREA

Annex 2

Construction of canals (in chronological order)

Earliest canals

Canals constructed between 1900 and 1930

• During this period triple canals such as Upper Jhelum, Upper Chenab and Lower Bari Doab. were constructed in the Punjab.

• The eleven Sutlej Valley canals were taken out of the four barrages constructed on the Sutlej canal system of the Punjab.

• Upper Swat Canal was taken out at Amandara in NWFP.

• In Sindh Sukkur Barrage was completed, including seven canals.

Canals constructed between 1930 and 1960

• Thal canal taken out of Indus at Kalabagh.

• Haveli canal opened in 1939, taken out at the confluence of Jhelum and Chenab.

• Taunsa Barrage in 1959 to provide weir controlled supplies to D.G. Khan and Muzaffargarh canals.

• Bambanwala-Ravi-Bedian-Dipalpur link by widening the existing Raiya Branch and providing a siphon through the Ravi to serve Bedian and Dipalpur.

• Balloki Sulemanki lined link.

• Kotri barrage was constructed to divert 1 171 m³/sec into the four canals, three on the left bank and one on the right.

Canals constructed during 1960 to 1970

• Guddu barrage was completed in 1963 out of which two canals from the right and one from the left were taken out.

• In NWFP high-level canals were taken out of the Kabul River above Warsak dam. The left bank canal and the right bank canal. The right bank canal bifurcates into gravity canal and lift canal.

• On the Kurrum a weir was constructed and a canal was taken out. An earthen dam 38.7 m high, with a storage capacity of 106 800 000 m³, was also constructed.

Link canals existing before the Water Treaty with India

• Triple canals, Upper Jhelum, Upper Chenab and Lower Bari Doab constructed between 1905 to 1915.

• Haveli canal taken out at Trimmu in 1937.

• A link called Montgomery (Sahiwal) Pakpattan to carry 24.7 m³/sec was constructed.

• Balloki Sulemanki Link.

• Marala Ravi Link (MR).

• Bambanwala-Ravi-Bedian-Diplpur Link (BRBD).

• A sub link connecting MR and BRBD.

Indus Basin Works

Link canals

• They included eight links constructed for Indus Basin Works. These were: Rasul- Qadirabad Link, Qadirabad-Balloki Link, Balloki-Sulemanki Link No.2, Taunsa-Panjnad Link and Chashma-Jhelum Link.

Barrages

• Five barrages and a siphon constructed. These included Chashma, Rasul, Qadirabad, Marala and Sidhnai. A siphon was constructed at Mailsi.

• Improvement and utilization of the existing barrages. These included Trimmu and Taunsa Barrages and Balloki Headworks.

Annex 3

Chemical analysis of water of the rivers Indus, Jhelum and Chenab (meq/litre)

Note: CO₃ and boron nil, NO₃ traces.
Source: Pakistan Council for Water Resources Management

Annex 4

Wetlands of Pakistan

Source: WWF, Pakistan

This list, still incomplete, is based on GIS studies currently under way in Pakistan.