Protein intake inadequacy has been considered to be one of the major nutritional problems worldwide for many years and it appears that this issue will continue to increase sharply in the coming decades. This deficiency can be partly overcome by the effective use of protein-rich bioresources such as mollusks. In the present study, the oyster Pinctada radiata, collected from the Aegean Sea, is fully nutritionally characterized as a new non-indigenous bioresource concerning mainly its protein, carbohydrate and fat composition during the different seasons of the year. The results showed that the protein content of the pearl oyster is at satisfactory levels, with its maximum value in winter and minimum in summer. On the contrary, its fat and carbohydrates are at low levels, with their maximum values in the summer period. Regarding the profile of fatty acids, polyunsaturated fats are in the highest proportion, which is very encouraging, as a diet rich in this kind of fat is desired. The entire nutritional profile of the studied oyster demonstrates its high nutritional value and supports its possible use as a “new” seafood source for human consumption in the Mediterranean.

The Mugilidae family comprises several euryhaline species of significant ecological and economic value in global fisheries and aquaculture. Despite close taxonomic relationships, Chelon auratus, Chelon ramada and Mugil cephalus differ notably in physiological traits, seasonal energy allocation and tissue composition, influencing both ecological roles and commercial value. This study investigates the effect of seasonality on the fish flesh quality and metabolic gene expression of these three commercially important mullet species, collected from their natural habitat in Klisova Lagoon, Greece, by analyzing proximate composition (moisture, ash, protein, lipid), hepatosomatic index (HSI) and expression of lipid metabolism genes. M. cephalus showed lower protein and lipid content than C. ramada and C. auratus. In this context, expression of key lipid metabolism genes (fabp, pparg, cpt) reflected these differences not only between species but also revealed patterns which differed between examined tissues and seasons. Notably, this study provides the first characterization of these genes in the species examined. HSI data further indicated species-specific and seasonal strategies for energy storage. The results contribute to refining harvest timing strategies, enhancing post-harvest handling practices, in an effort to promote market differentiation and eventually to improve the economic viability of the mullet fishery sector.