Article

Environmental Biology of Fishes

, Volume 96, Issue 1, pp 57-66

First online:

Population ecology of Red-bellied Piranha Pygocentrus nattereri Kner, 1858 (Characidae: Serrasalminae) in the Negro River, Pantanal, Brazil

  • Wagner VicentinAffiliated withPrograma de Pós-Graduação em Ecologia e Conservação, Universidade Federal de Mato Grosso do Sul - UFMS Email author 
  • , Fábio Edir dos Santos CostaAffiliated withLaboratório de Ictiologia, Centro de Pesquisas em Biodiversidade - CPBio, Universidade Estadual de Mato Grosso do Sul - UEMS
  • , Yzel Rondon SúarezAffiliated withLaboratório de Ecologia, Centro Integrado de Análise e Monitoramento Ambiental – CinAM, Universidade Estadual de Mato Grosso do Sul - UEMS

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Abstract

This study defined some population parameters for growth of the Red-bellied Piranha (Pygocentrus nattereri) in the Pantanal, based on the bimonthly length-frequency distribution of individuals in samples taken from October 2005 through August 2008 in the Negro River. The samples were taken by means of gill nets and cast nets, with meshes of 1.5–8 cm between adjacent knots. The standard length of the fish ranged from 10.2 to 30.2 cm with a mean of 20.51 ± 3.39. The gonadosomatic index (GSI) varied significantly among months (F = 5.45; p < 0.01), it was significantly higher from October to February, and was positively correlated and synchronized with day length (rs = 0.92; p < 0.01) and rainfall (rs = 0.70; p < 0.01). It was desynchronized from and not correlated with river level (rs = 0.12; p = 0.69). The GSI reached the highest values and ripe individuals were more frequent in December, prior to the months of highest river levels from February to April. The estimated growth parameters were L∞ = 31.8; k = 0.45; Rn = 0.204. In the Pantanal, P. nattereri has a life expectancy (6.9 years) compatible with the 7 cohorts indicated by the growth curve. Sexual maturation occurred at around 15.4 cm, after 1.6 years.

Keywords

Length frequency ELEFAN Sexual maturation Gonadosomatic index