This technical paper presents three case studies of inland fisheries in the context of a multiple-use of land and water resources in the humid tropics of Asia. Two of the three river basins are situated on islands, i.e. the Agno in the Philippines and the Mahaweli in Sri Lanka; one is on mainland Asia, i.e. the Nam Pong Basin in Thailand. Although the river basins have a number of features in common, such as, for example, their size, forest cover and population density, they differ in a number of other environmental aspects and changes induced by the development taking place in their basins. Inland fisheries in all three catchments is represented both by capture and culture components with reservoir fisheries gaining in importance. The studies have shown that while the major constraint to the riverine fisheries has been identified as being the high level of transported sediments originating from eroding lands and mine waste discharge (the Agno Basin), in the reservoirs of Nam Pong and Mahaweli basins it has been the high fishing pressure, in one case non-regulated (Nam Pong), which has caused deterioration of fish stocks. Another constraint in force until recently was of a social (religious) character (Mahaweli Basin). The three studies have shown that in most situations inland fisheries can successfully develop under conditions of the multiple use of the resource.

Among the fishes. a remarkably wide range ofbiological adaptations to diverse habitats has evolved. As weIl as living in the conventional habitats of lakes. ponds. rivers. rock pools and the open sea. fish have solved the problems of life in deserts. in the deep sea. in the cold Antarctic. and in warm waters of high alkalinity or of low oxygen. Along with these adaptations. we find the most impressive specializations of morphology. physiology and behaviour. For example we can marvel at the high-speed swimming of the marlins. sailfish and warm-blooded tunas. air breathing in catfish and lungfish. parental care in the mouth-brooding cichlids and viviparity in many sharks and toothcarps. Moreover. fish are of considerable importance of the survival of the human species in the form ofnutritious and delicious food ofnumerous kinds. Rational exploitation and management of our global stocks of fishes must rely upon a detailed and precise insight of their biology. The Chapman and Hall Fish and Fisheries Series aims to present timely volumes reviewing important aspects of fish biology. Most volumes will be of interest to research workers in biology. zoology. ecology and physiology. but an additional aim is for the books to be accessible to a wide spectrum of non specialist readers ranging from undergraduates and postgraduates to those with an interest in industrial and commercial aspects of fish and fisheries.