Reproductive and growth parameters of Chelon auratus (Actinopterygii, Mugiliformes, Mugilidae) in Bizerte Lagoon, Tunisia

Abstract

Effective management of the golden grey mullet, Chelon auratus (Risso, 1810), in Mediterranean coastal ecosystems, including the Bizerte Lagoon, requires a comprehensive understanding of its biological and growth characteristics. This study aimed to assess the biological and growth parameters of Chelon auratus in the Bizerte Lagoon. Sampling was conducted from January to December 2022. A total of 576 specimens, ranging from 15 to 38 cm in length (TL), were caught. Our results indicated that the size at first maturity was 23.46 ± 0.2 cm TL for females and 22.5 ± 0.18 cm TL for males, corresponding to an age of two years. The gonadosomatic index indicated that the spawning season of C. auratus extends from October to December. The mean fecundity of C. auratus was 1233 oocytes per gram of body weight. The total length–weight ( W ) relationship was estimated at W = 0.0235 × TL 2.6875 . The monthly percentage of specimens exhibiting a terminal translucent zone indicated that growth rings, or circuli, formed once a year during the cold season in January. The back-calculation method confirmed the effectiveness of using scales to estimate age and growth. Based on the analysis of scales from 576 specimens, the parameters of the von Bertalanffy growth model were estimated as follows: L ∞ = 44.25 cm, K = 0.179 a –1 , t 0 = –1.8. A total of six age groups were identified. This study presents the first comprehensive assessment of the reproductive biology, age, and growth of C. auratus in the Bizerte Lagoon, based on year-round sampling. The findings offer valuable insights into the development and reproductive patterns of C. auratus , which will inform the sustainable management of this species in the Bizerte Lagoon.