Rotenone calibration of fish density and biomass in a tropical stream sampled by two removal methods

Abstract

A catch-depletion method was applied using two sampling gears in three sites of a small tributary of the Corumba River (Goias State, Brazil) in two seasons. The gears were: a double stick net (DSN) in one site and electric fishing (EF) in two sites. The calibration of both gears was performed using rotenone. EF was almost sufficient to establish a complete local species list, but DSN was not. Underestimation of calculated density (N) and biomass (B) values for DSN and EF amounted to 62 and 29%, respectively. The results of N and B obtained by EF were too imprecise to calculate secondary fish production to be applied in a field bioenergetics model. We could not conclusively prove that mean body weight of sampled populations was significantly lower for fish caught by EF, although all of these means were higher for fish collected by rotenone, at each site and on two sampling occasions.