Growth study of Sarpa salpa in the Aegean Sea using three growth models

Abstract

In the Mediterranean, Salema Sarpa salpa is among the most economically important coastal fishes. Yet a major gap in its region-specific, and sex-disaggregated data on biology and growth constraining both precise stock assessments and long ecosystem-based fisheries management strategies in the eastern Mediterranean. To address this data deficiency, this study presents an integrative analysis of the species' biological traits, growth parameters, and population structure in İzmir Bay (eastern Aegean Sea, western Türkiye), using a full annual sampling of 319 individuals. Caught individuals comprised 105 males, 82 females, and 132 hermaphrodites. Total length ranged from 16.7 to 38.0 cm, with the most frequent class lengths being 24.1–27.0 cm (29 %) and 27.1–30.0 cm (25 %). The species exhibited isometric growth (b ≈ 3), indicating that weight increases proportionally with length, while gonadosomatic index trends revealed that spawning occurs mainly in autumn. Among the three tested growth models (von Bertalanffy, Gompertz, Logistic), the von Bertalanffy model provided the best fit for the overall population (L∞ ≈ 46.6 cm, K ≈ 0.08), the Gompertz model for males (L∞ ≈ 35.9 cm, K ≈ 0.20), and the von Bertalanffy again for females and hermaphrodites (L∞ ≈ 38–43 cm). These findings indicate proportional length–weight growth and an autumn spawning period. Analysis of otoliths indicated that age-length relationships followed smooth growth patterns, with female size exceeding males in later age classes. Collected data on Sarpa salpa in İzmir Bay provides valuable baseline data for this species’ regional biology; knowledge crucial to fishery management, stock assessment, and ecological monitoring that may serve as a foundation for sustainable conservation of the Aegean Sea.