Growth, food conversion, maintenance and long‐term survival of gilthead sea bream,Sparus auratusL., juveniles after abrupt transfer to low salinity

摘要

AbstractJuveniles of gilthead sea bream,Sparus auratusL., with individual weight 1.92 g, were reared under salinities of 8, 18, 28 and 38o. The transfer to lower salinities (8‐28o) was abrupt. The results showed that better daily growth rates and food conversion efficiencies (FCE) when growing at 28o gave the best performance. Statistically, salinity values above 28o do not significantly affect daily growth rates and daily voluntary food intake. Maintenance requirement decreases linearly with increasing salinity. In particular, a lo decrease of salinity is associated with a 0.014 ( body weight day‐1) increase of daily maintenance requirement. Mortality rates are high at salinities of 8 and 38o (65 and 20 respectively) and minimal (1‐3) for fish reared under intermediate salinities (18‐28o). Finally, scope for growth, expressed as the minimum difference between food amount eaten and food attributed to growth, is better when the fish are kept at a salinity of 28o. This means that most of the food amount eaten is attributed to growth and food wastage is minimal. These results confirm that gilthead sea bream fry show best performance when reared at a salinity