โ Scribed by J. J. S. Gurgel; C. H. Fernando
No coin nor oath required. For personal study only.
The reservoir fisheries in the semi-arid Northeast Brazil have been studied 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 characteristics are provided together with total areas of the reservoirs. Unfortunately very little basic limnological data are available.
In all 42 species of fish and crustaceans were introduced into these reservoirs of which only fourteen fish species and one shrimp were successful in establishing self-propagating populations, others being stocked on a regular basis. The recent stocking of Colossoma macropomum and Cyprinus carpio are however unsuccessful in reservoirs.
The fish yield of DNOCS controlled reservoirs for 1950-1990 was 112 kg.ha-I (DAVIES, 1972; GURCEL and OLIVEIRA, 1987). It amounts now to about 20,000 tons annually taking into account incomplete and scaled down reporting of catches. 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 niloricus are given together with a discussion of the fisheries and recommendations for management. The total CPUE varied from 18-1,100 kg.ha-'. However, most fishermen are only part-timers.
It appears likely that very substantial yields of fish are being harvested in Northeast Brazil but are under-reported. Management strategies now in operation in reservoir fisheries are still very pragmatic. With the accumulation of data and generalizations, more viable strategies could be devised.
๐ SIMILAR VOLUMES
The Oulujoki, Iijoki and Kemijoki Rivers in northern Finland, all of them previously important rivers for the fishing of migratory salmonids, were dammed for hydropower production in the 1940s-1960s. Some 20 years after the construction of the last power plant, the fish communities, fishing and the