REPRODUCTIVE BIOLOGY OF <i>Bagre marinus</i> (MITCHILL, 1815) (SILURIFORMES: ARIIDAE) FROM COASTAL WATERS OF RIO GRANDE DO NORTE, BRAZIL

Fish belonging to the family Ariidae are important fishery resources throughout the Northeast region of Brazil. Despite the socio-economic importance, few studies have been published on the reproductive aspects of sea catfish, Bagre marinus. The present study investigated the reproductive biology of B. marinus from the coastal waters of Rio Grande do Norte, Brasil. A total of 96 specimens of B. marinus were captured, consisting of 53 females and 43 males, with the help of artisanal fleet, at depths ranging from 6 to 22m during the period of March 2013 through May 2014. The results show that the total length of females varied from 22.5cm to 55.9cm (39.5 ± 5.9) and total weight from 53g to 1850g (539.1 ± 319.2), and for males from 29cm to 54.5cm (39.2 ± 4.9) and 45g to 1583g (496.3 ± 262.2). The angular coefficient for grouped sex (b=3.06) indicate that this species show isometric growth. The sex ratio was 1M: 1.2F, but showed no significant difference between the expected proportion (c2= 0.835). Length at first sexual maturation (L50) for grouped sex was 39 cm of total length. Females and males showed four stages of gonad maturation. Values of gonadosomatic index (GSI) and maturation stages of gonads indicate that the reproductive period of B. marinus occurrs between the months of December to April, with peak activity in March and April. Keywords: Bagre marinus; sex ratio; length at first sexual maturation; reproductive period