Ambient salinity and osmoregulation, energy metabolism and growth in juvenile yellowtail kingfish (Seriola lalandiValenciennes 1833) in a recirculating aquaculture system

Abstract

The effects of salinity on plasma osmolality, branchial chloride cell density, feed consumption and conversion and growth performance of yellowtail kingfish (Seriola lalandi) were evaluated. Fish (11.6 ± 0.6 g) were kept for 29 days at 14, 18, 22, 26 (experimental) and 30 g L−1 (control) salinity in independent, pilot-scale recirculation aquaculture systems. No differences in plasma osmolality or chloride cell numbers in gills were observed, pointing to a strong osmoregulatory capacity in the juveniles. Fish at 14, 18 and 22 g L−1 (7.61 ± 0.19, 7.61 ± 0.01 and 7.61 ± 0.13% day−1, respectively) had higher growth rates than fish at 26 and 30 g L−1 (7.10 ± 0.05 and 6.97 ± 0.06% day−1 respectively). The higher growth rate at lower salinity resulted from increased feed intake; feed conversion was not different. An evaluation of the impact of salinity on growth rate of on-growing stages (till market size) seems warranted to assess whether the profitable effects of low salinity persist in later stages of this important aquaculture species.