| 12. CONSERVATION AND MANAGEMENT CONSIDERATIONS OF TINAU RIVER The Tinau river supports 35 fish species of biologically diverse ichthyofauna with predominance of family Cyprinidae. There are serious problems in Tinau River regarding fish conservation and management. 12.1 MANAGEMENT PROBLEMS IN THE TINAU RIVER There are no management activities under way in the riverine fishery in Tinau River. Some of the important management problems associated with the Tinau river are as follows: 12.1.1 Destruction of Natural Habitat by Land Slides Improper land use system and heavy deforestation in the Hilly area cause land slides which destroy the natural fish habitat in the Tinau river (Gross soil loss 286956 ton/yr and soil loss rate 59.18 ton/ha/yr, DSCWM and DSCWMO, 1992). 12.1.2 Destruction of Natural Habitat by Dam Construction Construction of dam without fish ladder for generating electricity in Tinau river has consequently checked the upstream and downstream migration of fishes for their breeding and feeding purposes, e.g., Tor tor. Such a dam may eventually reduce the production which also creates circumstances of extermination of local fish species (Shrestha, 1991). 12.1.3 Use of Destructive Fishing Methods In the Tinau river fishes are being killed by destructive methods like poisoning and dynamiting in the diverted river channel and pool regions respectively. Such fishing methods not only kill the fries, fingerlings and brood fishes but also destroy the breeding habitats of the fish themselves. 12.1.4 Lack of Awareness Lack of awareness about the importance of riverine fishery in the local inhabitants is the major problem for the destruction of riverine fishes. Uneducated local fishermen do not understand the destructive nature of the use of poison, dynamite and the importance of natural habitat of fish. 12.2 RECOMMENDATIONS Although a work on soil conservation and watershed management has been continuing in Palpa district by a project of HMG in combination with Germany and Switzerland, no work has been done for the conservation strategy of fish fauna in the Tinau river by any sector so far. Due to the absence of due priority on the conservation and management of riverine fisheries in Tinau river in the past, there is a degradation of riverine fishes. Therefore, for successful conservation and management of indigenous fish species in the Tinau river, following recommendation can be made. 12.2.1 Ban of Harmful Fishing Implements The fine meshed net like Cast net, Bhureli jal, and mosquito nets which catch fish juveniles must be banned because they reduce the survival rate of fish species. Fish poisons are widely used in diverted river channel, most of which are derived from plant parts such as Khirro (Sapium sps), bark of Kafal (Myrica esculanta), stem of Siudi (Cactus sps) etc. Sometimes very dangerous chemical pesticides like malathion and Metacid are also used which wipe out all the biomass of aquatic life. Hence, public should be made acquainted with the importance of fish conservation and the destructive effects of the poisons. Dynamiting has been reported from the large pool regions of the Tinau river which is a destructive method killing all the types as well as age groups of fishes. Hence, it must be checked and totally banned. Sometimes fishes are being hunted by rock striking method. Although it is less destructive than poisoning and dynamiting, but fish of all the stages is destructed by rock striking, therefore, this should also be banned. Hence, all of these harmful means and methods of fishing must be checked and totally banned for the proper conservation and management of fish biodiversity. 12.2.2 Closed Fishing Seasons Different kinds of fishes breed in different seasons; spawning run of Asala (Schizothorax sps) and Sahar (Tor sps) begin during September and October while many small hill stream fishes spawn in March. Usually, female fishes with thousands of eggs in their ovary are caught in high number during breeding seasons due to which a large quantity of egg resources is being perished by the killing of brood fishes. Thus, fishing activities should be stopped during these months. Setting up of close season increases spawning opportunity and will enhance increase in fish population. 12.2.3 Provision of Fish Way through Dam The hydroelectric dam in Tinau River at Dovan has created a great problem for migratory fishes which has practically obstructed the upward movement of fishes such as Sahar (Tor sps), Gounch (Bagarius bagarius) and Thedi (Labeo angra) etc. The dam should be provided with fish lifts, fish ladder and other by pass facilities to enhance upstream migration of fishes. At the same time, there should be provision for monitoring of the physico-chemical properties, fish fauna and other aquatic life of natural water bodies before and after the construction of hydropower or irrigation dams to enhance the fish production and protection of indigenous species as well as to study the effect of dam on aquatic life and fish fauna. 12.2.4 Fish Sanctuary Closed seasons or prohibited areas are also common devices for protection of rare fish stock as well as common fish stock. The basic aim of such areas is to allow the fish freedom to complete their spawning cycle and early life cycle without being hindered. The area inhabited by rare species of fishes should be protected as fish sanctuary to protect them. Similarly, some of the areas of Tinau River are densely populated with fish fauna (e.g., Dovan locality), which should be protected as fish sanctuary to provide constant and quantitative, increase of fish population throughout the river. 12.2.5 Habitat Improvement For maximum yield, rivers should be maintained in good hydro biological condition. The fluvial processes such as water level, discharge and siltation should be controlled by check dams and further winter desiccation should be avoided by the management of suitable pools by constructing natural rocks or boulder dams across the river during dry spell of summer and winter. Such a practice will improve the fish habitat quality. Deforestation, soil erosion and silting of riverbed have greatly changed the natural environment of the Tinau River. Therefore, management practices must be done to restore the ecological balance for natural fish habitat. 12.2.6 Need for Pollution Control Pollution caused by the disposal of unwanted domestic materials and toxic substances carries adverse effects on biotic communities by impeding reproduction at various levels of food chain which ultimately lead to low fish yield. Therefore, there is an urgent need to check these substances before discharging into the river. 12.2.7 Stocking Fish Population Population of economically important fishes is going down owing to high fishing pressure such as Mahaseer (Tor sps), Snow trout (Schizothorax sps) and many others. Hence, the fishing water of Tinau river may be enriched with fish by releasing hatchery-reared larvae of such important fishes. 12.2.8 Protection of Feeder Stream Most of the fishes spawn in the feeder streams of Tinau River like Dovan Khola, Jhumsa Khola, Sisne Khola, and Dumre Khola etc. Hence, these feeder streams should be declared as fish sanctuary so that it will help to protect migratory spawners. |
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