Maturation of native oyster Crassostrea gasar at different diets in the laboratory

Abstract

This study evaluated the influence of different microalgae diets on gonadal tissue maturation of the native oyster Crassostrea gasar in the laboratory, between March and May 2010, totalizing 60 days. Ninety-six oysters, collected from an experimental farm located on Florianópolis/SC, were transferred to the laboratory and maintained in three different diet treatments: Isochrysis galbana, Chaetoceros müelleri and a mix diet of both species in a 1:1 ratio. The oysters were conditioned in 3 L experimental units at a water flow rate of 300 mL min^-1 and constant aeration. Food was provided in a continuous flow system, at a density of 16 x 10⁴ cells mL^-1. The mean water temperature and salinity during the experimental period were 24.36 ± 1.23°C and 29.4 ± 3.08 respectively. Fortnightly, six oysters randomly sampled from each treatment were examined for histological analysis. The condition index was analyzed at the beginning and the end of the experiment. The initial mean height and weight of the oysters were 68.25 ± 6.73 mm and 60.89 ± 14.19 g respectively, and the final mean height and weight were 69.20 ± 5.97 mm and 70.04 ± 17.42 g respectively. The sex ratio for the treatments was 1.2 male for each female and 19.5% of the oysters were considered indeterminate. The condition index was not affected by treatments and there was no improvement on the gonadal tissue maturation of the native oyster C. gasar subjected to different microalgae diets during the conditioning period.