Seasonality of the feeding behavior and condition factor of Anchovia surinamensis in the floodplains of the Madeira River (Rondônia, Brazil)

Abstract

The Anchovia surinamensis (Clupeiformes: Engraulidae) is known in Brazil as "sardinha-do-gato†and exists in the floodplains throughout Latin-America. It is highly appreciated by the Amazonian riverine communities as a source of animal protein. In this study, we analyzed the dietary preferences and abiotic parameters that influence the condition factor of A. surinamensis that inhabit Cujubim Lake during periods of drought and flood. A total of 105 specimens were captured using three batteries of monofilament nylon nets (measuring 20 m long, 2.5 m high, 40, 60, 80 and 100 mm mesh, measured between opposite knots). The nets were arranged in pre-established positions within the lake and inspected at the times of 18:00, 00:00, 06:00 and 12:00 h. This methodology was utilized to obtain the largest range of fish sizes and to avoid the influence of the nictimeral factor. The results of the analysis of the stomach contents of the individuals confirmed that the species is planktivorous and consumes mainly cladocera and bivalves in the Cujubim Lake, which indicates that there is good food availability in the lake. Our results also demonstrate that, among the physicochemical parameters of the water in Cujubim Lake, pH was the one that most affected the condition factor of A. surinamensis.