The European hake Merluccius merluccius (Linnaeus, 1758) is one of the main fishery resources in the Mediterranean Sea and plays a key ecological role as a mid- to high-trophic-level predator linking demersal and mesopelagic food webs. As a species capable of feeding throughout the water column, European hake interacts with multiple trophic compartments, serving as a major predator of commercially and ecologically important fish and crustaceans, while also constituting prey for larger predators.
The present study investigates the dietary preferences of the species and their interannual and spatial variability in the central Mediterranean Sea (Strait of Sicily, GSA 16). Diet composition was assessed through stomach content analysis of specimens collected annually between 2018 and 2024 within the Italian Data Collection Framework (DCF), through scientific trawl surveys (MEDITS) and monitoring of commercial catch (CAMPBIOL). To account for ontogenetic dietary shifts, specimens were grouped into three size classes: young-of-the-year (YOY, ≤15 cm TL), juveniles (15–28 cm TL), and adults (>28 cm TL). Diet composition was analysed using the percentage Prey-Specific Index of Relative Importance (PSIRI; Brown et al., 2012), considering size class, spatial distribution, and year of sampling as explanatory variables.
Results confirmed the known preference of YOY for Mysida and Euphausiacea, with a progressive shift in larger individuals toward a diet dominated by Decapoda and Osteichthyes. Prey composition also varied among years, with Osteichthyes and Decapoda alternating as the dominant prey groups. Spatial analyses revealed greater dietary heterogeneity in the western sector of GSA 16.
These findings provide evidence of trophic plasticity in M. merluccius, suggesting that its feeding strategy responds to spatial and temporal variations in prey availability. Such dietary flexibility highlights the species' adaptive role within marine food webs and should be considered when evaluating the productive potential of fishery resources under an ecosystem-based fisheries management approach.