Inland fisheries contribute about ten percent to the global fish production and Asia is the leading producer of inland fish, accounting for over 80 percent of the total. Until recently, the inland fisheries sector had taken back stage in fisheries development plans, particularly so given the emphasis being placed on aquaculture development throughout the world, Asia being no exception. Aquaculture development in most Asian countries is beginning to face major problems in respect of primary and secondary resource availability, as well as environmental concerns and related public perception. As a result, inland fishery development is seen as a non-invasive, less resource intensive mode of increasing foodfish supplies, particularly to the rural poor. Consequently, inland fisheries in Asia has begun to reemerge, gaining the attention from governments, development authorities and the general public that they richly deserve.
Inland fisheries in Asia are mostly rural, artisanal activities, catering to rural masses and providing an affordable source of animal protein, employment opportunities and household income. Stock enhancement is an integral component of most inland fisheries. With recent advances in artificial propagation techniques for fast-growing and desirable fish species and the consequent increased availability of seed stock, such activities are beginning to affect inland fishery production in most Asian countries. Indeed, new avenues of production such as culture-based fisheries are being increasingly adopted and are seen as a way forward in most countries. Inland fishery activities also have a distinct advantage, in that their development is less resource intensive than is aquaculture, for example. Furthermore, they are generally more environmentally non-invasive.
Apart from a few possible exceptions, stock enhancement in all inland waters has not been successful, and this is particularly the case for large lacustrine waterbodies and for rivers. The economic viability of stock enhancement of such waterbodies has not been demonstrated in any Asian nation, their fisheries being dependent on naturally recruited stocks, perhaps requiring only occasional replenishment of broodstock. The most successful stock enhancements in Asia are in the floodplain beels and oxbow lakes in Bangladesh, where the use of small waterbodies that are not capable of supporting fisheries has led to culture-based fisheries where stock and recapture rates are very high. Culture-based fisheries development, however, requires major institutional changes. These are now being addressed by the respective governments in the region, and thus culture-based fisheries are generally considered to have the greatest potential for further development. Added advantages of culture-based fisheries are that they are considerably less resource intensive, and by and large, are community-based activities that can generate synergies that are advantageous to the community. The main problem facing their development is the possibility of over production and glutting of the market. This results because harvesting is mostly based on the hydrological regimes of the waterbodies in a given region, occurring when the water levels are receding. This problem, however, is not insurmountable and can be addressed through the introduction of planned, staggered harvesting, intercommunity cooperation and improved marketing channels.
Stock enhancement in inland waters will continue to be influenced by fingerling availability. In general, although the volume of fry production of sought-after fish species is thought to be adequate, there is a bottleneck in fingerling availability. This again is mostly felt in the culture-based fishery programmes in which fingerling availability has to coincide with the filling of small waterbodies, which tend to be, by and large, rain fed. In the case of floodplain enhancement, the problem is less compounded because flooding and the spawning of preferred species often coincide. One of the major concerns of stock enhancement in inland waters is its possible effects on biodiversity. This is for two reasons: firstly, most countries depend wholly or partially on exotic species for stock enhancement, and secondly, freshwater fishes are known to be among the most threatened of vertebrates. Thus, major studies should undertaken to evaluate the current situation, so that remedial steps can be taken, if needed, without causing a major impact upon some of the stock enhancement practices that are gaining momentum.