Ciclo de vida e dinâmica populacional do caparari Pseudoplatystoma tigrinum Valenciennes 1840 (Pisces; Pimelodidae), no rio Apure, bacia do rio Orinoco.

Abstract

The caparari (Pseudoplatystoma tigrinum) is a species with high commercial importance for human food in the Apure basin with wide distribution in the high and low plains The population dynamic of this species was assessed using commercial fishery landing data in the high plains (2002- 2003) and low plains (1996-2003). The identification of the stock was done using geometric morphological analyses. Population structure was also analyzed by length and age. Population parameters were estimated (growth, mortality, recruitment) for fish stock assessment by yield per recruitment. The result of stock identification procedures using morphometric data for the cranium and otoliths, confirme just one population present in the Apure river basin, with some differences noted for catfish from the Caparo River. The population struture is dominated by fish from the annual class of three years. The age structure also showed a truncate distribution from three year class in both the high and low plains. This species mean length at capture has been declining constantly for the last six year, and seasonal variation in size was detected. The sex ratio was dominated by females in both regions. The condition factor did not show seasonal variation. The weight-length relationship showed a reduction of regression coefficient in the low plains and the growth parameters of von Bertalanffy model were Lt=119,9*[1-e (-0,17*(t-1,052)] for females and Lt= 108,6*[1-e(-0,19*(t-1,184)] for males. The natural and total mortality were 0,42 and 1,33 respectively, and longevity was estimated to be 14 years. The population parameters of P. tigrinum showed aspects characteristic of a kstrategist species. The resulted of yield compared with recruitment indicates that there is increasing overfishing. A proposal for fisheries management based on adaptive management discussed.