Aspects of the reproductive biology of the brown ray Raja miraletus (Chondrichthyes: Rajidae) from the Coast of Senegal (Eastern Tropical Atlantic)

• Published in: Cahiers de biologie marine Vol. 48; no. 2; pp. 169 - 178
• Main Authors: CAPAPE, Christian, DIATTA, Youssouph, AMADOU ABDOULAYE SECK, GUELORGET, Olivier
• Format: Journal Article
• Language: English
• Published: Roscoff Ed. de la station biologique 01-01-2007
• Subjects: Agnatha. Pisces; Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Chondrichthyes; Fundamental and applied biological sciences. Psychology; Marine; Raja miraletus; Rajidae; Sea water ecosystems; Synecology; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Equatorial Atlantic; Senegal; Atlantic Ocean; Africa; AS, Tropical Atlantic; ASE, Senegal, Dakar; ASE, Senegal; Marine environment; Vertebrata; Reproduction; Hydrobiology; Raja miraletus; Senegal; Pisces; Rajidae; Eastem Tropical Atlantic; Biology; Chondrichthyes; Reproductive Biology
• ISSN: 0007-9723; 2262-3094

The brown ray, Raja miraletus is commonly landed at the fishing sites of the Senegalese coast. Adult males and females are mostly captured in spring and summer. The smallest sexually mature male and female were 270 mm and 310mm disc width, respectively. The largest male and the largest female adults were 380 mm and 415 mm disc width, respectively, and weighed 1205 g and 1336 g, respectively. They were the largest R. miraletus reported to date for both males and females. There was no significant relationship total mass versus disc width between males and females. Diameter of the largest yolky oocytes ranged from 18 to 23 mm (mean plus or minus standard deviation: 19.9 mm plus or minus 1.4), and weighed from 1.8 to 2.3g (mean: 2.1 g plus or minus 0.1). Vitellogenic activity practically occurred throughout the year, especially in spring and summer with a peak in April-May. Females carrying egg cases were found from November to June. Egg cases had 88-97 mm in length with horns (mean: 92.1 mm plus or minus 2.9), and 48-52 mm without horns (mean: 50.4 mm plus or minus 1.1), their width were 28-32 mm (mean:30.3 mm plus or minus 1.1) and they weighed 8.7-9.9 g (mean: 9.3 g plus or minus 0.4). An estimation of the fecundity based on the occurrence of egg cases during one year and number of yellow oocytes counted in adult females allows us to consider it from 71 to 178.Original Abstract: La raie miroir Raja miraletus est debarquee en relative abondance sur les sites depeche de la cote du Senegal. Males et femelles adultes sont le plus souvent captures au printemps et en ete. Le plus petitmale et la plus petite femelle matures avaient 270 mm et 310 mm de largeur discale, respectivement. Le plus grand maleet la plus grande femelle adultes avaient 380 mm et de 415 mm de largeur discale et pesaient 1205 g et 1336 g, respectivement. Ce sont les plus grands specimens males et femelles de R. miraletus signales a ce jour. Il n'y a pas de relation significative entre la masse totale et la largeur discale entre males et femelles. Le diametre des plus grands ovocytes riches en vitellus se situait entre 18 et 23 mm (moyenne plus or minus ecart-type: 19,9 mm plus or minus 1,4), et ils pesaient entre 1,8-2,8 g (moyenne:2,1 g plus or minus 0,1). L'activite vitellogenetique avait lieu pratiquement toute l'annee, et plus particulierement au printemps et en ete avec un pic en avril-juin. Les femelles portant des ufs encapsules sont capturees de septembre a juin. Les capsules oviferes avaient une longueur avec cornes entre 88-97 mm (moyenne: 92,1 mm plus or minus 2,9), sans cornes entre 48-52 mm (moyenne: 50,4 mm plus or minus 1,1), leur largeur etait entre 28-32 mm (30.3 mm plus or minus 1,1) et ils pesaient incluant les ovocytes fecondes entre 8,7-9,9 g (moyenne: 9,3 g plus or minus 0,4). Une estimation de la fecondite fondee sur la presence d'ufs encapsules et d'ovocytes jaunes au cours de l'annee chez les femelles adultes, nous amene a la considerer comprise entre 71 et 178.