Abstract
This study aimed to estimate age and growth of the peacock bass Cichla temensis from the rio Negro (Brazilian Amazonia) by analyzing scale annuli. Specimens were captured between October 2011 and September 2012 in the main channel of the river and in adjacent lakes in the municipality of Barcelos, AM, Brazil. Six growth checks were identified on the scales of specimens. The annual variation in body condition observed suggests that fat is accumulated during the dry season. Results for the GSI (gonadosomatic index) showed that peak reproduction occurred in the receding-water period, indicating that the fish had energy deficiencies as a result of reproductive activity. RMI (relative marginal increment) analysis revealed that an annulus is formed once a year during the receding-water period. The population parameters estimated were L50 (length at sexual maturity) = 31.11 cm, L∞ (asymptotic length) = 68.05 cm, k (growth coefficient) = 0.20.year-1 and A0.95 (longevity) = 14 years. Our results corroborate the validity of using growth rings in scales as indicators to estimate the age and growth rate of Cichla temensis in the middle rio Negro.
Highlights
Growth studies of a given fish stock require determining the correct age of the individuals (Weatherley & Gill, 1987), which is essential to estimate the size of the stock, mortality rate and recruitment, among other parameters
Up to six growth annuli were identified on the scales, only the second annulus onwards could be verified as true growth rings
Estimates of age and growth rate in tropical fish using growth rings registered on otoliths and scales have been increasing steadily in recent years (Fabré & Saint-Paul, 1998; Jepsen et al, 1999; Pérez & Fabré, 2003; Cutrim & Batista, 2005; Holley et al, 2008)
Summary
Growth studies of a given fish stock require determining the correct age of the individuals (Weatherley & Gill, 1987), which is essential to estimate the size of the stock, mortality rate and recruitment, among other parameters. In temperate regions the temperature decreases drastically during the winter, causing a reduction in growth and the consequent formation of these marks (Fonteles Filho, 2011). As the annual temperature variation in tropical regions is small, it was believed that it would not be possible to identify growth marks in calcified structures (Fonteles Filho, 2011) and, that this method could not be used to determine age in tropical fish species. For this reason, until recently, growth parameters in these
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