Estudo da distribuição e abundância de algumas espécies juvenis de camarão no Saco da Inhaca

Abstract

The main objective of the study is to evaluate the influence of environmental factors on the spatial and temporal distribution and the abundance of juvenile shrimp of the Penaeidea family in Saco da Inhaca. The sampling frequency was weekly, for two months, in the period between February and May 1998. The harvests were carried out in the different habitats of Saco da Inhaca, during the day, at the peaks of the high tide of dead and spring tides. A total of 84 trawls were carried out, of which 48 for spring tide and 36 for low tide, using a 2m x 0.5m beam beam and 2mm mesh demersal trawl net to collect the samples. The total capture of recorded species was 2491, corresponding to 2 genera and 6 species, the most abundant being Penaeus japonicus (34.92%) and Metapenaeus stebbingi (34.12%). Muddy and sandy habitats were the ones that, in general, presented the highest numbers of individuals and density. The maximum biomass was observed in the channel-grass. In relation to abundance, there were significant differences between the average length of the species' shells in relation to the type of habitat and in relation to the type of tide. Penaeus semisufcatus did not show significant differences between the average carapace length in relation to the type of tide. The parameters analyzed in each sampling habitat were temperature, salinity, water transparency, depth and organic matter. The highest levels of organic matter and temperature occurred in the muddy and sandy habitat, the greatest variation in salinity was verified in the pneumatophore habitat, and the greatest transparency occurred in the grass channel. In different types of habitats, temperature was shown to positively influence the abundance of Metapenaeus stebbingi and Penaeus semisulcatus while salinity had no influence on the abundance of Penaeus japonicus, Metapenaeus stebbingi and Metapenaeus monoceros. There were differences in species density between day and night.