Migração e movimentos do grumatã (Prochilodus lineatus, Valenciennes, 1836) (Characiformes, Prochilodontidae) no Rio dos Sinos, RS, Brasil, determinados por radiotelemetria

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Life strategy, population structure and behavior are fundamental elements for the comprehension of fish biology and essential for conservation. The grumatã, (Prochilodus lineatus; Prochilodontidae) is a reophilic migratory species of economical importance for local fisheries. It is widely distributed in Brazil. During the last decades grumatã populations seem to have declined due to river damming by power plant constructions, pollution, habitat degradation and heavy fishing pressure. The present study investigated circadian and seasonal activity patterns, spawning migration and habitat use. Between August 2002 and March 2003 nineteen Grumatã were tagged internally with digitally coded radio transmitters (149 MHz). Mobile tracking was carried out weekly by boat or aircraft. Additionally six data loggers recorded movements of tagged fish. Results showed that the mean distance covered per fish and day was positively related with fish weight (r2 =0.3102; p=0.013). Grumatã showed a preference for river reaches surrounded by wetlands (X2= 177.82; p<0.0001; n=362). Their diel activity patterns display one peak in the morning at 07.00, and a second in the afternoon at 15.00. During the night activity is significantly reduced (X2= 6.55; p=0.0105). The seasonal activity pattern shows peaks in October and February, which probably are related to spawning activities. Activity tended to be higher at high water levels and temperatures, although the linear correlation was not significant for either variable (water level r =-0.0914; p=0.7015; r2 = 0.0084; temperature r =0.2120; p =0.3696; r2 = 0.0449). Uncommon weather conditions may have influenced spawning migration behavior and the triggering factors during the study. Heavy rainfalls with constantly high water levels, induced by the El Niño system, characterized the first reproduction period. During the second occurred drought causing low water levels. The study confirms the importance of wetlands in the Sinos watershed for future conservation efforts.

ASSUNTO(S)

migração reprodutiva daily and seasonal activity spawning migration prochilodus lineatus atividade diária e sazonal telemetry biologia geral rádio-telemetria

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