Morphometric, Meristic and Growth Patterns of Sphyraena afra from the Escravos Estuary.

Abstract

This study presents a biological assessment of Sphyraena afra from the Escravos Estuary, focusing on morphometric and meristic traits, length, weight relationship, and condition factor. A total of 189 specimens were collected from artisanal landings between May 2023 and April 2024. Sixteen morphometric and five meristic parameters were measured to evaluate body proportions and fin structure. Total length ranged from 12.40 to 42.00 cm, and body weight from 10.00 to 292.00 g. Notable variation was observed in pelvic fin rays (range: 9-15) and pectoral fin rays (range: 5-6), while dorsal spines were consistent across individuals. Principal component analysis revealed that the first two components explained 100% of the total variation. PC1 was dominated by morphometric traits associated with body size, while PC2 was largely influenced by meristic characters. The length-weight relationship followed the equation: 𝑊 = 0.0043𝑇𝐿2.9547 with a high correlation coefficient (R² = 0.986), indicating near-isometric growth. The mean condition factor (K = 0.3740 ± 0.0048) suggests moderate physiological condition and supports evidence of slow but steady growth. Although morphometric traits were size-dependent, the observed meristic variation may reflect environmental or developmental influences. These findings provide a useful baseline for future ecological assessments, monitoring, and stock evaluation of S. afra in Nigerian estuarine waters. Further studies integrating genetics, ecology, and broader spatial data are recommended to support sustainable management of this species.