Estudo da variação espaço-temporal da estrutura da população e aspectos reprodutivos de Sillago sihama (pescadinha comum) no estuário dos Bons Sinais, província da Zambézia

Abstract

This study examined the spatiotemporal variation in the population structure and reproductive characteristics of Sillago sihama (common whiting) within the Bons Sinais estuary, located in Zambézia Province, Mozambique. Samples were collected during both the dry and rainy seasons using two main fishing gears—chicocota and beach seine—across three estuarine zones: Hilalane (upper estuary), Chuabo Dembe (middle estuary), and Marrubune (lower estuary). Concurrently, environmental parameters such as salinity, temperature, and water transparency were recorded. In the laboratory, the specimens were subjected to biometric analysis, which involved measuring total length, weighing the individuals, and evaluating gonadal maturation stages. The results showed that the S. sihama population predominantly comprises juveniles, with only a small proportion reaching the size at first maturity (L50). Regarding spatial variation, larger fish were predominantly found in the lower estuary, while seasonally, the greatest lengths were observed during the rainy season. The analysis of gonadal maturation indicated a predominance of immature individuals, suggesting that the estuary serves a vital role as a nursery ground for the species. The overall sex ratio was found to be 1.1 males for each female, which did not significantly deviate from the expected 1:1 ratio. However, seasonal variations were observed, with a balanced sex distribution during the rainy season and a greater predominance of males in the dry season. These findings underline the importance of the estuary as a critical habitat for the growth of S. sihama, highlighting the need for management measures to ensure the sustainability of both the species and local fishing activities.