Compositions of gilthead sea bream (Sparus aurata Linnaeus, 1758) from different culture systems

Abstract

The aim of the present study was to investigate the effects of seasons (summer and winter) on the proximate, amino acid and fatty acid compositions of gilthead sea bream fish fed with commercial diets in sea cages and earthen ponds in the Aegean Sea in Türkiye. In general, the nutrient composition of the diets met the nutritional needs of the fish. Proximate analysis of fish fillets revealed that fish reared in earthen ponds had the lowest moisture and highest lipid content in the winter season (p < 0.05). Although fillet protein contents were comparatively higher in the winter (p < 0.05), there was no significant difference between systems in the same season (p > 0.05). Growing gilthead sea bream in marine cages produced fillets with high contents of the essential fatty acids (EFA) eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). On the other hand, the 18:1n-9 and 18:3n-3 contents of fish reared in earthen ponds increased by 25.64 and 18.80% respectively, compared to those in marine cages. Fillet content of total n-3 fatty acid were comparatively higher (p < 0.05) in gilthead sea bream from marine cages, and this increase was even more evident in the winter months. The n-3/n-6 ratios of fillets were significantly high in gilthead sea bream from marine cages in the summer. The levels of the essential amino acids (EAAs) arginine and leucine were higher in fillets from both systems in the winter. On the other hand, fillet contents of lysine were higher in the summer. In general, the total EAA content of fillets was higher in fish from the sea cages in summer. EAA/NEAA ratios in both systems in summer and winter were found to be at good levels in terms of fish fillet quality. Fillet contents of EFA and EAA from both systems and seasons were found to be good for human consumption and will have positive effects on human nutrition. In conclusion, commercial diets used in feeding gilthead sea bream improved the proximate, fatty acid and amino acid compositions of fillets to a good extent. Different seasons and culture systems may affect the nutritional composition of fish fillets, especially on fillet EFA contents. Results of fillet samples in marine cages and earthen ponds in summer and winter showed that the fish were of good quality for human health. Evaluation of the results in the present study shows that that gilthead sea bream can also be successfully cultured in earthen ponds in areas unsuitable for agriculture.