要旨
Abundance and body size variations of the prawn Macrobrachium amazonicum (HELLER, 1862) have
been studied in a Central Amazonian floodplain lake, on Careiro Island. The highest number of captures
and smallest sizes have been observed beneath floating macrophyte meadows. This suggests that these
meadows serve a nursery habitats. The densities registered in the Amazon river were three times lower
than in the lake. Maximum densities were recorded during low-water periods, while minimum densities
were found during high water periods. These results point to a relationship between current force and
catchability. In the floodplain lake, prawn abundance seems to be related to macrophyte expansion during
the periods of rising water; the lowest captures were registered at high water, which is probably due to the
spatial dispersion as the water volume increases. River prawn populations are characterized by larger sizes
than the ones in the lake. They show a well-marked pattern of seasonal variation in size, with larger sizes
found during periods of rising water and smaller sizes predominating during high-water periods. On the
contrary, lagoonal prawns show maximum sizes during high-water, and smallest sizes during low-water
periods.
Despite its good fishing potential (up to 200 g/trap), the native prawn is not exploited in the Amazonas, but imported from the State of Pará. Artesanal prawn fishing in floodplain lakes, or extensive culture
in ponds for carnivorous fish or human consumption, can be a commercially lucrative activity for sustainable regional economic development.
