Mortalidade mensal em uma população de Donax hanleyanus Philippi, 1847 (Mollusca, Bivalvia, Donacidae)

Resumo

The rate of instantaneous mortality, monthly mortality, and monthly survival were calculated to a population of Donax hanleyanus on a beach of Rio Grande do Sul, Brazil, by monitoring two age groups during 12 months. Distribution of monthly frequencies for 28 length classes was determined. A graph of the modal values permitted us the identification of two age groups in September, 1998, which were utilized in this study. The rate of instantaneous mortality (Z) was 0.715 (=71.5%); the rate of monthly survival (Sm) 0.489 (=48.9%) and monthly mortality (M) was 0.511 (=51.1%), to the two age groups, during the period between September, 1998 and June, 1999.