Abstract
This study aimed to estimate the gonadosomatic index, hepatosomatic index, condition factor, and sex ratio of the round sardinella (Sardinella aurita) to determine its spawning season along the Libyan coastal waters. A total of 394 specimens were collected from the Bab Al-Bahr fish market in Tripoli over a full annual cycle from May 2025 to April 2026. Total lengths ranged from 12.08 to 26.3 cm, and body weights ranged from 14.28 to 155.2 g. The results revealed a predominance of females over males, with an overall sex ratio of 1.7 females per male, accounting for 63.47% and 36.53% of the sample, respectively. The condition factor (K) reached its highest value in summer (1.95), followed by autumn (1.82) and winter (1.81), with the lowest value recorded in spring (1.62). The gonadosomatic index (GSI) peaked in winter (3.41), followed by spring (2.49) and summer (2.47), and hit its lowest value in autumn (0.35). The hepatosomatic index (HSI) demonstrated a clear concordance with the gonadosomatic index, peaking in winter (1.18), followed by spring (1.06), and recording minimum values in summer and autumn (0.88). These findings indicate that the round sardinella exhibits high reproductive activity concentrated primarily during the winter and spring seasons, thereby supporting the implementation of fisheries management measures and biological closed seasons to protect the sustainable stock.