FISHERIES IN SEMIARID NORTHEAST BRAZIL WITH SPECIAL REFERENCE TO THE ROLE OF TILAPIAS

The reservoir fisheries in the semi-arid Northeast Brazil have been st udied based on the data collected by the Department of Action Against Droughts and placed against the background of what is known of similar fisheries in the tropics elsewhere. Of about 60,000 reservoirs in the region, DNOCS controls about 100 reservoirs since 1970. Physical char acteristics are provided together with total areas of the reservoirs. Unfortunately very little basic limnological data are available. In al l 42 species of fish and crustaceans were introduced into these reserv oirs of which only fourteen fish species and one shrimp were successfu l in establishing self-propagating populations, others being stocked o n a regular basis. The recent stocking of Colossoma macropomum and Cyp rinus carpio are however unsuccessful in reservoirs. The fish yield of DNOCS controlled reservoirs for 1950-1990 was 112 kg.ha-1 (DAVIES, 19 72; GURGEL and OLIVEIRA, 1987). It amounts now to about 20,000 tons an nually taking into account incomplete and scaled down reporting of cat ches. This indicates a total fish catch from 60,000 reservoirs in the Northeast of Brazil of very substantial size. The CPUE and catches of all species and that of Tilapia rendalli and Oreochromis niloticus are given together with a discussion of the fisheries and recommendations for management. The total CPUE varied from 18-1,100 kg.ha-1. However, most fishermen are only part-timers. It appears likely that very subs tantial yields of fish are being harvested in Northeast Brazil but are under-reported. Management strategies now in operation in reservoir f isheries are still very pragmatic. With the accumulation of data and g eneralizations, more viable strategies could be devised.