Observations on the reproductive biology of the blackchin guitarfish, Rhinobatos Cemiculus E. Geoffroy Saint Hilaire, 1817 (Chondrichthyes, Rhinobatidae) from the coast of Senegal (Eastern Tropical Atlantic)

• Autores: Y. Diatta, A. A. Seck, M. Diop, O. Guélorget
• Localización: Scientia gerundensis, ISSN-e 2385-4758, ISSN 0213-5930, Nº. 27, 2004, págs. 19-30
• Idioma: inglés
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• Resumen

  • The blackchin guitarfish, Rhinobatos cemiculus, is commonly caught off the coast of Senegal. Adult males and females studied were over 1550 rnm and 1630 mm total length (TL), respectively, with the largest male and the largest female recorded measuring 2330 mm and 2450 mm and weighing 28.1 kg and 55.0 kg, respectively. Females were significantly heavier than males. The diameter of ripe oocytes ranged from 42 to 46 mm (mean: 43.45 * 1.05). They weighed from 33.0 to 36.1 g (mean: 34.17 * 0.92). The smallest specimens observed were 400 and 420 mm TL and weighed 210 and 145 g, respectively. Egg weight increased with female TL. Gestation lasted from 5 to 8 months. An embryonic diapause was observed when the Senegalese waters were relatively cold, between December and March. A calculated chernical balance of development based on mean dry weights of the fully developed fetuses and the egg weight was 1.85. Ovarian fecundity was not significantly higher than uterine fecundity. The two categories of fecundity ranged from 16 to 24 and there was no relationship between them and female TL.