Reproductive biology and population parameters of commercially important Characiformes from the Araguari River, state of Amapá, Brazil

Abstract

The present study aimed to estimate the length-weight relationship, relative condition factor (Kn), gonadosomatic index (GSI) and mean length at first maturity (L50) for 11 fish species serving as a subsidy for fisheries management of the Upper and Middle Araguari River. Samplings were conducted in the 2011-2014 period, with experimental fisheries and landing data; fish were measured (cm), sexed, and total weight (g) and gonad weight (g) were recorded. The length-weight relationship for all species had r2 above 0.76, indicating isometric growth for A. inermis, A. falcatus, Charax sp., L. melanosticus, L. maculatus, S. eingemani. On the other hand, H. aimara, B. cuvieri, M. asterias, M. romboidalis and M. ternetzi showed allometric growth, the first two species with positive growth and the rest, negative. The combination of the relative condition factor (Kn) and the gonadosomatic index (GSI) was a good indicator of the reproductive period for A. inermis, A. falcatus, B. cuvieri and M. ternetzi. The estimated L50values presented a minimum value of 12 cm for M. asterias, and a maximum of 28.6 cm for H. aimara. This study is of paramount importance for fisheries management and conservation of the studied area, especially as it is the first study for some species in the region.