Growth, gonadal development, and fish fillet quality in diploid and triploid turbot, Scophthalmus maximus, originated from the Black Sea

This study was carried out to investigate the effect of triplodization on growth, gonadal development, proximate and fatty acid composition of muscle tissue of the Black Sea turbot, Scophthalmus maximus, from 21 to 48 months of age. Diploid and triploid turbot, originated from a single family, were reared under identical culturing conditions. Growth and gonadosomatic index (GSI) were evaluated quarterly, whereas carcass yield, hepatosomatic index, viscerosomatic index, proximate composition, and fatty acid content of muscle tissue were evaluated at 21, 36, and 48 months of age. The weight gain by time and the final length and weight of diploid and triploid fish at the end of the growth experiment were similar. Specific growth rates fluctuated according to the reproductive cycle and showed a decreasing trend with age. A positive correlation between time and GSI was determined in diploid males and females. In terms of carcass yield, there was no significant difference between ploidy groups at the same age. The best carcass yield was recorded at 36 months of age. A significant difference in hepatosomatic and viscerosomatic indexes among the age groups was determined. The moisture, ash, protein, and lipid content of diploid and triploids at the same age were found to be similar except for the protein and moisture content at 48 months of age. A degree of variability in terms of fatty acid composition with age and ploidy status was detected, yet crude lipid content of ploidy groups remained similar at the same age but showed a decreasing trend with increasing age. Triploid turbot contained more PUFA n-3 in all ages, whereas muscle tissue of diploid turbot contains more PUFA n-6. At the end of the experiment, at 48 months of age, MUFA content of diploid turbot was significantly higher than that of triploid turbot, whereas PUFA n-3 content of triploid turbot was significantly higher than that of diploid turbot. SFA and PUFA n-6 contents were comparable among ploidy groups. In conclusion, it could be stated that triploidy induction does not improve growth, carcass yield, and crude lipid content in the Black Sea originated turbot cultured under natural environmental conditions.