Nutritional composition and energetic values of mesopelagic fish from the Tasman Sea

Mesopelagic fish are key prey for higher-order marine predators and may also be a potential source of protein for humans and in feed applications, however, there is currently limited understanding of their nutritional composition. This study presents a detailed examination of the proximate composition, energy density, and essential fatty acid profiles of 16 abundant mesopelagic fish species from the Tasman Sea, encompassing four families. Across mesopelagic species wide ranges were observed in crude protein content (27.4–46.7 % DW; 5.33–11.9 % WW), lipid content (6.83–29.1 % DW; 1.62–6.47 % WW), ash content (22.0–32.9 % DW; 3.60–12.2 % WW), and energy density (13.1–26.0 KJ/g WW). Compared to globally commercial harvested species, Tasman Sea mesopelagic fish have lower protein, lipid, and caloric content but moderate to high levels of docosahexaenoic acid and saturated fatty acids, reflecting the region’s lower productivity. Factors influencing proximate composition, including feeding habits and environmental conditions highlight the complexities underlying the nutritional composition of mesopelagic fish. • Tasman Sea mesopelagic fish have low to moderate lipid, protein and calories. • Mesopelagic fish are nutritionally valuable based on their DHA content. • Tasman Sea mesopelagic fish are less nutritionally favourable than other regions. • Species-specific variations in key nutritional components were observed.