
TY  - JOUR
A1  - Lessa, Rosangela 
A1  - Santana, Francisco 
A1  - Menni, Roberto 
A1  - Almeida, Zafira 
T1  - Population structure and reproductive biology of the smalltail shark (<emph type="2">Carcharhinus porosus</emph>) off Maranh&#227;o (Brazil)
JF  - Marine and Freshwater Research
JO  - Mar. Freshwater Res.
Y1  - 1999
VL  - 50
IS  - 5
SP  - 383
EP  - 388
KW  - 
UR  - https://doi.org/10.1071/MF98127 
N2  - C. porosus is common throughout the year in shallow waters off the Maranh&#227;o coast, northern Brazil, where it is the most abundant elasmobranch species. Of 1128 smalltail sharks collected from June 1984 to November 1987 in gill-nets from coastal waters, ~80% were juveniles. Male and female numbers did not differ from a 1:1 ratio. Modal classes were 50.0&#8211;60.0 cm (TL) for both sexes. A 120.5 cm female was the largest specimen caught and a 29.4 cm male was the smallest. Age distribution for the whole sample ranged from 0 to &#62;12 years. The length&#8211;weight relationship did not differ significantly between the sexes. Diameter of ovarian follicles, presence of eggs/embryos and nidamental gland traits in females point to a major physiological change toward maturity at about 70.0 cm. Vitellogenesis was first observed at 63.0 cm, and the smallest of the six pregnant females was 70.0 cm. There was a significant relationship between the number of embryos and female size. From September to November, ovulation and newborns were observed in catches. Resumo. Carcharhinus porosus &#233; comum ao longo do ano em &aacute;guas rasas do norte do Brasil onde &#233; a esp&#233;cie mais abundante entre os elasmobr&acirc;nquios. De 1128 exemplares coletados em &aacute;guas costeiras de junho 1984 a novembro 1987 em redes de emalhar ~80% eram jovens. O n&uacute;mero de machos e f&ecirc;meas n&#227;o diferiu da raz&#227;o 1:1. A classe modal foi a de 50.0&#8211;60.0 cm para ambos os sexos. Uma f&ecirc;mea de 120.5 e um macho de 29.4 cm corresponderam ao maior e ao menor exemplar capturado, respectivamente. A distribui&ccedil;&#227;o de idades na amostra total variou de 0 a &#62;12 anos. Arela&ccedil;&#227;o peso&#8211;comprimento n&#227;o mostrou diferen&ccedil;as significativas entre os sexos. O di&acirc;metro dos ov&oacute;citos, presen&ccedil;a de embri&otilde;es/ovos e largura da gl&acirc;ndula nidament&aacute;ria nas f&ecirc;meas indica aquisi&ccedil;&#227;o da maturidade em 70.0 cm. Foi estabelecida uma rela&ccedil;&#227;o significativa entre o n&uacute;mero de embri&otilde;es e o tamanho das femeas. Entre setembro e novembro ocorre a ovula&ccedil;&#227;o e rec&#233;m nascidos foram observados nas capturas. 
ER  -

