Life-history traits and population structure of Stellifer stellifer (Actinopterygii: Sciaenidae) in a subtropical estuary in southern Brazil

ABSTRACT This study aimed to characterize the population structure and critical life history parameters of Stellifer stellifer (Bloch, 1790) in a Brazilian subtropical estuary. Environmental variables such as pH, salinity, and dissolved oxygen were the most strongly correlated, revealing a spatial gradient in the west-east direction. A total of 1,363 individuals were captured, with the innermost sampling point yielding the highest capture rate (76.8%). Total length ranged from 8.2 to 22.3 cm in females and from 8.5 to 21.1 cm in males, considering both juvenile and adult specimens, and histological analysis revealed five stages of ovarian and testicular development. The reproductive period occurred in spring and summer, characterized by fractional (batch) spawning. Environmental variables, particularly temperature, significantly influenced the monthly distribution of gonadal maturation stages. Natural mortality rates were 1.12 and 1.01 year-1 for females and males, respectively. The age of the population ranged from eight months to six years, with juveniles accounting for 3.3% of the total catch. Females predominated in the smallest and largest length classes, while males were more prevalent in intermediate-length classes. Our results suggest that the abundance and distribution of S. stellifer play a crucial role in maintaining the balance of estuarine ecosystems. Despite being exploited as bycatch in shrimp fishing, the species exhibits a well-defined reproductive process influenced by seasonality and demonstrates rapid growth.