The fishery resources living in rivers form a valuable source of food, recreation and aesthetic satisfaction throughout the world. However, the aquatic system which supports such resources is under constant pressure by a number of other users to provide a range of other benefits to the human community. These pressures often conflict with the interests of fisheries by inducing changes in the aquatic environment so that it is no longer able to support fish communities in their previous quantity, quality and diversity. The development and management of fisheries under such conditions becomes not only a problem of direct manipulation of the fish stock and the fishery to ensure optimum yields, but also of minimizing changes in the environment which are detrimental to the fishery. All this requires a level of information which is sadly lacking throughout most of the world. To compensate for this there has to be a high level of extrapolation from systems whose ecology has been more thoroughly studied and understood. At various times the international bodies of FAO dealing with inland fisheries have called attention to the problems of river fisheries development and management and have defined certain areas in particular in which interchange of information and training is required by their various member countries. This Technical Paper has been prepared in response to these requests.
It is intended mainly as a background document for use in training courses on various aspects of river fisheries. For that reason, it is laid out as a series of four independent chapters, each of which could provide the basis for a lecture or series of lectures. The first chapter deals with such general considerations as the form of river systems, the ecology of the fish and the functioning of the fishery as are needed to understand the principles of assessment, impact of other uses and management; as are laid out in the other chapters. The second chapter presents certain of the methods which have been used to successfully assess river fish stocks and the fisheries which depend on them. The third chapter examines other uses of river basins and their effects on the fishery. The final chapter considers various means for management of the fishery including such extensive and intensive aquaculture techniques as are directly related to river fisheries.
Although the prime intention of this Technical Paper is that it be used in conjunction with lectures. It can also be used as an independent work and contains enough information to serve as a primer on the above aspects of fisheries in rivers. As such it is complementary to FAO Fisheries Technical Paper 194 (Welcomme, 1979).