Assessing the euryhaline characteristics and metabolic responses of meagre (Argyrosomus regius) when reared under different salinities: Opportunities for aquaculture refinement

Abstract

The aquaculture of meagre (Argyrosomus regius), a commercially important fish species, is still under development towards its full potential and optimized production. While its key strengths in fish farming, including high growth rate, efficient feed conversion ratio, superior flesh quality, nutritional value, size, and established husbandry techniques, are well-known, further scientific research can unlock additional rearing opportunities for this species. As migratory fish, meagre spends its early life stages in estuaries before moving to coastal and offshore areas, experiencing diverse environmental conditions that significantly influence its feeding behavior, growth, and reproduction. Despite its adaptability, meagre production has been limited to sea cages and land-based salt ponds. Considering its high tolerance to a wide range of factors, particularly salinity, the present study aimed to evaluate the stress and biochemical costs associated with rearing meagre fingerlings under hypo-osmotic environments. The objective was to enhance aquaculture practices and explore the possibility of cultivating this species in more diverse locations without compromising productivity. Meagre fingerlings were reared under different salinities for 28 days, namely at 5, 10, 20, and 30 PSU. Growth rate was calculated, and biochemical responses associated with oxidative stress and energy metabolism were measured in muscle, liver, and heart tissues. Meagre fingerlings displayed remarkable euryhaline characteristics at the biochemical level, as evidenced by their limited response to the varying salinity conditions. An increase in oxidative stress responses and energetic demand was found, together with higher growths, at higher concentrations (20 and 30 PSU), farther from the meagre isoosmotic concentration (∼10 PSU). Understanding these biochemical responses enhances our knowledge of aquaculture techniques and paves the way for adapting and expanding operations to diverse environmental conditions and practices. By leveraging the euryhaline potential of meagre, this research contributes to the sustainable growth of the aquaculture industry while offering new perspectives to produce this valuable fish species.