Akademik Veri Yönetim Sistemi
REGIONAL STUDIES IN MARINE SCIENCE, sa.105011, ss.1-10, 2026 (SCI-Expanded, Scopus)
Recent morphometric analyses challenge the prevailing single-assessment-unit management of Atlantic bonito (Sarda sarda) in the southern Black Sea, identifying phenotype-based population structuring. This study integrated dietary composition, somatic condition, and growth allometry from a synchronised assessment of overwintering ecology across the southern Black Sea (Western: Istanbul; Middle: Sinop; Eastern: Rize) to elucidate the ecological basis of this functional population structuring. The results revealed distinct functional divergence between the Western and Eastern–Middle population units. Atlantic bonito from the Western Black Sea exhibited a generalist “portfolio” strategy, maintaining a high trophic position through opportunistic predation on biomass-rich sardines and cephalopods despite the numerical dominance of zooplankton. This heterogeneous diet coincided with a lower somatic condition but pronounced positive allometric growth. In contrast, the Eastern and Middle regions formed a cohesive functional unit characterised by anchovy dietary specialisation, high somatic condition and isometric growth. A size-corrected general linear model supported functional equivalence in trophic position across all regions, indicating that despite divergent prey pathways, Atlantic bonito occupy comparable ecological roles. These findings indicate functional population structuring, challenging the assumption of ecological panmixia by distinguishing opportunistic, compensatory fish in the West from specialist, storage-oriented counterparts in the Eastern–Middle. Consequently, this structuring provides preliminary grounds for a re-evaluation of basin-wide management in favour of spatially explicit monitoring and assessment frameworks within the GFCM context.