Growth, recruitment, and mortality parameters for Astyanax altiparanae Garutti and Britski, 2000 and A. schubarti,, Britski, 1964 (Pisces, Characidae) in the Upper Paraná River floodplain, Brazil

Abstract

Data for the characid Astyanax altiparanae and A. schubarti, collected from March 1993 to February 1994, were used for studies of growth, recruitment, and mortality. The results for the A. altiparanae indicated asymptotic growth (L∞) of 18.0cm (standard length) and growth rate (k) of 0.26; the total mortality (Z) estimated from the different methods was 2.23 and two recruitment periods were observed during the year, one in March and the other in November, coinciding with the reproductive season of the species. For A. schubarti a k value of 0.25 and an asymptotic length value of 12.0cm were obtained; the natural mortality rate was 0.84; for this species two recruitment periods were also observed, the first coinciding with the highest spawning level, and the second soon afterwards.