Seasonal Biochemical Regulation of Lipid Metabolism in Mediterranean Mullet Species

Fish nutritional value is a complex trait, highly influenced by fatty acid composition, which is correspondingly affected by a variety of factors, such as seasonality, abiotic conditions, and genetic background. Herein, the seasonal variations in lipid metabolism and the composition of fatty acids in three economically important mullet species (Chelon auratus, Chelon ramada, and Mugil cephalus) in an appropriate fisheries model marine area, Klisova Lagoon, Greece, were investigated. From seasonal sampling across one year, data regarding the sea temperature, fatty acid profiles in fish fillet, lipid-related gene expression (acc, hoad, and atgl), and key enzymatic activities (citrate synthase, HOAD, and lipase) in liver and muscle were obtained. Biochemical, molecular, and enzymatic analyses revealed pronounced interspecific and seasonal differences in lipid metabolism and the composition of fatty acids among Chelon auratus, Chelon ramada, and Mugil cephalus. M. cephalus exhibited strong metabolic plasticity, with enhanced lipid oxidation during colder periods and increased lipid synthesis and mobilization during warmer months. In contrast, C. ramada and C. auratus generally showed higher PUFA and ω-3 contents, although nutritional quality across all species was largely season-dependent, with colder periods favoring unsaturated fatty acid accumulation. Coordinated seasonal shifts in gene expression and enzyme activities reflected these temperature-driven metabolic regulation and distinct thermal-adaptation strategies. These metabolic traits support the ecological success of mullets in Mediterranean environments and highlight underutilized C. ramada and C. auratus mullet species as nutritionally valuable, sustainable alternatives for regional fisheries and aquaculture, supporting both sustainable fisheries and consumer awareness within the EU seafood market.