Population Structure and Growth Patterns of Anchovy and Sardine in the Safi Fishing Area on the Moroccan Atlantic Coast

Abstract

This study explored the growth dynamics of anchovies (Engraulis encrasicolus) and sardines (Sardina pilchardus) in the Safi fishing zone, a biologically productive area along the Moroccan Atlantic coast influenced by persistent upwelling. Over a two-year period (2018–2019), biological data on size, age, and growth patterns were collected and analyzed using the von Bertalanffy growth model. The results indicated that sardines exhibit stable growth patterns, with asymptotic lengths (L∞) ranging from 22.58 to 23.20cm and growth coefficients (K) between 0.36 and 0.40. In contrast, anchovies displayed greater variability in size-at-age, with an average L∞ of 17.33cm and a wide range of K values (0.250–0.818), reflecting their adaptability to fluctuating environmental conditions. The growth-performance index (ϕ) for anchovies (1.88–2.40) was notably higher than values reported in other regions, suggesting enhanced growth efficiency in the nutrient-rich Safi upwelling zone. Length-weight relationships further revealed species-specific strategies: sardines exhibited a shift toward isometric growth (b = 3.007–3.190), while anchovies maintained positive allometric growth (b = 3.134–3.261), indicating faster weight gain relative to length. These findings underscore the distinct metabolic rates and ecological adaptations of the two species, providing valuable insights for refining stock assessment models and supporting sustainable fisheries management in the region.