Este estudo teve como objetivo estimar a idade e o crescimento do tucunaré Cichla temensis do rio Negro (Amazônia brasileira) por meio de anéis nas escamas. Os espécimes foram capturados entre outubro de 2011 e setembro de 2012, no canal principal e lagos adjacentes, no município de Barcelos, AM, Brasil. Seis anéis de crescimento foram identificados nas escamas de C. temensis. A variação anual observada no fator de condição sugere que o acúmulo de gordura ocorreu durante o período de seca. Os resultados de IGS (índice gonadossomático) indicaram que o pico da reprodução ocorreu no período da vazante e que a espécie teve um déficit de energia em seu organismo, devido à atividade reprodutiva. Análise do IMR (incremento marginal relativo) mostrou que há formação de anel uma vez por ano, no período da vazante. Os parâmetros populacionais estimados para C. temensis foram: L50 (comprimento da maturidade sexual) = 31,11 cm; L∞ (comprimento assintótico) = 68,05 cm; k (coeficiente de crescimento) = 0,20.ano-1 e A0,95 ( longevidade ) = 14 anos. Nossos resultados confirmaram a validade do uso das marcas de crescimento, em escamas, para estudo de crescimento de Cichla temensis, como indicadoras da idade e do ritmo de crescimento dessa espécie na região do médio rio Negro.

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.

We conducted a study to test the hypothesis that interconnectedness among island floodplain lakes and the adjacent Solimões River during the flood stage of the hydrologic cycle is enough to maintain similarity in fish species assemblages. Gill net samples were collected during high and low water periods for three consecutive years (July 2004 to July 2006) in four lakes on Paciência Island. Two lakes, Piranha and Ressaca, are connected to the river all year, and the other two, Preto and Cacau, which are in the center of the island, are isolated during low water periods. The abundance, species richness and evenness of the fish assemblages in these lakes did not differ according to their relative positions or the season of the hydrological cycle, which confirmed our hypothesis. However, fish abundance during the dry season was greater than in the flood season. Apparently, the short period of full connection between the lakes is enough to allow the colonization of all fish species, but not to cause similar abundances. Our study indicates that persistence of the species composition of island floodplain lakes is primarily due to the annual replenishment of fish to the lakes during the flood season.