Abstract
Results concerning the biology of the ichthyofauna of the hydroelectric reservoir of Curuá-Una during the months of August and November 1982 and February 1983 are presented.
Collections were made in 24 h runs using gill-nets of varying mesh size at five stations (four above and one below the dam).
The 2,282 fish caught represented 13 families and 50 species. The greatest number of species (36) accured at station I, furthest from the dam (796 specimens from 12 families) while station IV, closest to the dam had only 8 species (from 5 families).
In terms of numbers of specimens, three species account for more than 75 % of the captures, i.e.:
Hemiodopsis sp., Serrasalmus rhombeus, and Auchenipterus nuchalis.
Using MARGALEF'S Diversity Coefficent values for stations decreased from stations I to IV,
while station V, below the dam had a higher value.
Comparing these data with those of a previous study (1977 - 1978) we confirmed a long term
trend in the species abundance and composition in the reservoir as the lake matures.
