Sex ratio and size structure of Micropogonias furnieri (Desmarest, 1823) (Perciformes, Sciaenidae) in Sepetiba Bay, Rio de Janeiro, Brazil

Abstract

Sex ratio and size structure constitute basic information in assessing reproductive potential and estimating stock size in fish populations. One hundred fifty-one individuals of Micropogonias furnieri caught by experimental otter trawls, in three zones (inner, central, and outer) of Sepetiba Bay between October 1998 and September 1999 were examined. Males outnumbered females (1.3:1.0) in all zones but no significant differences were detected. Only in the outer zone (5.0:1.0) were male/female rates significantly different according to the chi-square test. No temporal differences were observed in sex ratio. Fish size ranged from 81 to 244 mm total length (TL) with significant differences in 155 to 185 mm TL size classes, where males predominated, and a slightly higher number of females were observed for the smaller size class (TL = 95-150 mm). Size distribution varied according to the zone, with juveniles predominating in the inner and adults in the outer zone. Spatial difference in size structure observed in this study indicates that the inner bay is a rearing ground during the first life-cycle period, and movement toward the sea occurs as fish increase in size.

Length-weight relation, condition factor and gonadosomatic index of the whitemouth croaker, Micropogonias furnieri (Desmarest, 1823) (Actinopterygii: Sciaenidae), caught in Lençóis Bay, state of Maranhão, eastern Amazon, Brazil

“…In studies conducted in Santos Bay (southeastern Brazil), GIANNINI and PAIVA FILHO (1990) caught larger M. furnieri individuals during the summer, which is the rainy season in the northern region of Brazil. VICENTINI and ARAÚJO (2003) found no indication of seasonality by size group in Sepetiba Bay, State of Rio de Janeiro. In this study, the sex ratio of M. furineri off Maranhão was 1.3:1, which differs from that described by VICENTINI and ARAÚJO (2003), who found a ratio of 1:1 for the same species in Sepetiba Bay (state of Rio de Janeiro, southeastern Brazil).…”

“…VICENTINI and ARAÚJO (2003) found no indication of seasonality by size group in Sepetiba Bay, State of Rio de Janeiro. In this study, the sex ratio of M. furineri off Maranhão was 1.3:1, which differs from that described by VICENTINI and ARAÚJO (2003), who found a ratio of 1:1 for the same species in Sepetiba Bay (state of Rio de Janeiro, southeastern Brazil). SANTOS et al (2015) also recorded a majority proportion of males (1.56M:1F).…”

Reproductive Biology of Hilsa Shad Tenualosa ilisha (Teleostei: Clupeidae) During Spawning Migration in the Shatt Al Arab River and Southern Al Hammar Marsh, Basra, Iraq

“…Contradictory views have been expressed by previous investigations in Shatt al Arab (Hussain et al, 1994;Al-Noor, 1998;Mutlak, 2012). Several other reasons suggested for the unequal sex ratios in other studies, including differences in mortality, growth and longevity (Vicentini and Araujo, 2003;Zhang et al, 2009). Sex ratio varies temporally and spatially (Arocha and Barrios, 2009).…”

“…Along the study period, males were slightly smaller than females except in June. Vicentini and Araujo (2003) stated that one highly likely factor to be investigated and that can cause differentiation between sexes is fish growth. It was found that males were predominant in the smaller lengths and females in the larger lengths.…”

Biologia populacional de Pachyurus bonariensis Steindachner, 1879 (Perciformes, Sciaenidae), uma espécie alóctone no sistema hidrográfico da laguna dos patos, Brasil

“…A proporção sexual e a estrutura de tamanho são informações básicas para o potencial reprodutivo e para a estimativa do tamanho do estoque das populações de peixes. Apesar de registrada ocasionalmente em algumas populações de peixes, uma proporção sexual de 1:1 é raramente esperada (Vicentini & Araújo 2003) e esse desvio pode ser atribuído a diversas causas, tais como influência da temperatura na determinação do sexo (Conover & Kynard 1981), mortalidade seletiva por sexo como predação diferencial, comportamento sexual diferenciado, taxa de crescimento ou expectativa de vida.…”