Aspects of the biology of Mugil curema (Osteichthyes, Mugilidae) in the Amazon coast, Brazil.

Abstract

Mugil curema is an estuarine and coastal fish species widely distributed in tropical and subtropical regions. It is an important resource for fisheries in Maranhão, among the most exploited and commercialized species. Given its relevance, studies on its reproductive dynamics are essential for effective stock management. This study aimed to analyze the reproductive aspects of M. curema in an estuarine area of the Northeast region of Brazil. Specimens were collected monthly from January to December 2021 in the estuary of the Paciência River, Maranhão, and morphometric data were analyzed to determine maturation stages, reproductive indices, and the size at first maturation. A total of 942 samples of M. curema were analyzed (827 female and 115 male). Females were more abundant (7.19F:1M), with a significantly larger mean size (t-test, p<0.05). The mean total length and mean total weight were 20.44 (± 3.38 cm) and 82.29 g (± 32.20 g), respectively. The weight-length relationship revealed distinct growth patterns: females exhibited positive allometry, whereas males exhibited negative allometry. A higher proportion of juveniles was recorded, indicating that the area functions as a nursery ground. Based on the gonadosomatic index (GSI), peak reproductive activity occurred in May and July; however, females with hydrated oocytes were also observed in other months. A correlation was observed between precipitation and reproductive rates. Histological analysis indicated total spawning, with synchronous development of two oocyte groups. The estimated length at first sexual maturity for both sexes was 19.04 cm. The reproductive aspects of M. curema appear closely linked to environmental conditions and seasonal cycles, highlighting the need for targeted management strategies to ensure the sustainability and conservation of this key fishery resource.