Effects of fisheries zoning and environmental characteristics on population parameters of the tambaqui (Colossoma macropomum) in managed floodplain lakes in the Central Amazon

Fisheries zoning and the influence of biotic and abiotic factors in the spatial distribution of Colossoma macropomum (Cuvier) in the Piagacu-Purus Sustainable Development Reserve, Central Amazon, during 2012-2013 were evaluated. The relative abundance and population parameters of the C.macropomum were compared between conservation (no-take zone) and fishing (open to fishing zone) lakes. The fish were collected by experimental fishing in 2012 and 2013. A total of 296 individuals were captured, most of which were from the conservation lakes (62.8%). Higher proportions of larger adults and individuals were found in the conservation lakes, although no significant difference in the average C.macropomum catch-per-unit-effort was found between the lake categories. Abundance was positively influenced by zooplankton density (r(2)=0.53, P<0.03). Therefore, it is hypothesised that conservation lakes may serve as refugia for juveniles due to the high availability of planktonic food available during the dry season. Although there were environmental differences between the two lake types, the relative success of management models that use no-take zones in freshwater habitats was highlighted. Finally, the importance of zooplankton as a factor in the distribution of C.macropomum among floodplain lakes was emphasised.