BIOGEOCHEMICAL CHANGES IN WHITE SEABREAM (DIPLODUS SARGUS) EARTH PONDS DURING A PRODUCTION CYCLE

摘要

In Portugal and all around southern Europe, marine fish farming is traditionally semi-intensive being carried out in earth ponds. However, during the last years, this activity has been facing difficulties since the production costs are often too highto maintain a sustainable economic activity due to the low productivity of these systems, which rely largely on traditional practices and are often managed on an intuitive basis (Giovannini and Piedrahita, 1994). Thus, a better understanding of the earthpond environment is necessary to develop management practices that optimise the use of resources (Piedrahita, 1988, Culberson and Piedrahita, 1996). The main purpose of the present work, developed in the IPIMAR Aquaculture Research Station located in Ria Formosa (South of Portugal), was to evaluate the environmental changes in semi-intensive earth ponds of white seabream Diplodus sargus L. during a production cycle, and relate it to farming conditions (fish biomass and feeding rate).