PREDICTING AQUACULTURE WASTE FROM GILTHEAD SEABREAM (SPARUS-AURATA) CULTURE USING A NUTRITIONAL APPROACH

A model to estimate the waste production from sea cage culture was est ablished. Using known feed inputs of nitrogen, phosphorus and organic matter, the model quantifies waste discharge from seabream culture. Da ily feed intake and growth in Sparus aurata fed a commercial diet with known composition were measured and found to be dependent on fish wei ght and water temperature. Digestibility of the commercial feed was me asured using chromic oxide as a marker and collection of feces by stri pping. The proximate composition of Sparus aurata at different sizes w as determined and nitrogen and phosphorus content were on average 28.5 and 7.2 g . kg(-1) body mass, respectively. Excretion of ammonia-nitr ogen and inorganic phosphorus after metabolic processes was calculated as the difference. (C) Ifremer/Elsevier, Paris.