Reproductive biology of Pseudoplatystoma corruscans (Spix and Agassiz, 1829) and Pseudoplatystoma reticulatum (Eigenmann and Eigenmann, 1889), two species of fisheries importance in the Cuiaba River Basin, Brazil

The aim of this study was to compare the reproductive processes of two large catfishes, Pseudoplatystoma corruscans and Pseudoplatystomareticulatum, from the Cuiaba River Basin. The reproductive process were assessed to: (i) characterizing the population structure and sex ratio; (ii) determining the reproductive period; (iii) estimating and quantify the nutritional status and energy reserves and their relationships with reproductive stages; and (iv) estimating the body length at first gonad maturation (TL50). Individuals were sampled monthly from July 2006 to February 2008 using gill nets, seine nets, hooks, casting nets and trotlines. In addition, 294 individuals were obtained from the artisanal fishery in the city of Cuiaba, Mato Grosso state, Brazil. Total lengths were greater for females for both species, with no significant difference in the sex ratio; growth was considered isometric, except for P.corruscans males. Peak reproductive activity was in December and January. Differences in the hepatosomatic index (HSI) in P.corruscans depended on the gender. In P.reticulatum the HSI did not differ between sexes or among developmental stages. For P.corruscans, the estimated mean total length at first maturity (TL50) was 62.92cm, and for P.reticulatum 57.84cm. Action to ensure the protection of the fish stocks should consider their reproduction processes, which are important for the equilibrium of these populations in the Cuiaba River, as well as for fisheries management.