Reproductive biology of the common torpedo, Torpedo torpedo (Linnaeus, 1758) (Pisces, Torpedinidae) from the coast of Senegal (Eastern Tropical Atlantic)

Abstract

Among the five species of genus Torpedo recorded from the coast of Senegal, the common torpedo, Torpedo torpedo is that most cornrnonly caught in the area. Adult males and fernales studied were over 300 mm and 310 mm total length (TL), respectively, with the largest male and the largest female recorded being 445 mm and 550 mm TL respectively. Size at birth was between 102 and 125 mm TL (mean 112.12 mm; s.e.m. 5.58). Weight of eggs ranged frorn 6.2 to 8.0 g (rnean: 7.07; s.e.m. 0.5). Gestation lasts longer, from 6 to 8 rnonths, than in the Mediterranean specimens. A calculated chernical balance of development based on rnean dry weights of the fully developed fetuses and ripe oocytes was 1.58 for T. torpedo. This value shows that this torpedinid is not a pure lecithotrophic species, and the role of the rnother during gestation is not negligible. The fecundity (s.1.) of T. torpedo ranges from 5 to 28 in Senegalese specimens as cornpared to 1 to 9 in Mediterranean specirnens. Male ernbryos and fully developed fetuses are more nurnerous than fernales. Among the free-living specimens, nurnber of males and fernales is practically the same. The cornrnon torpedos from the coast of Senegal are larger and the eggs are heavier than Mediterranean specirnens. Key words: Pisces, Torpedinidae, Torpedo torpedo, Reproductive biology, Senegal, Eastern Tropical Atlantic.Among the five species of genus Torpedo recorded from the coast of Senegal, the common torpedo, Torpedo torpedo is that most cornrnonly caught in the area. Adult males and fernales studied were over 300 mm and 310 mm total length (TL), respectively, with the largest male and the largest female recorded being 445 mm and 550 mm TL respectively. Size at birth was between 102 and 125 mm TL (mean 112.12 mm; s.e.m. 5.58). Weight of eggs ranged frorn 6.2 to 8.0 g (rnean: 7.07; s.e.m. 0.5). Gestation lasts longer, from 6 to 8 rnonths, than in the Mediterranean specimens. A calculated chernical balance of development based on rnean dry weights of the fully developed fetuses and ripe oocytes was 1.58 for T. torpedo. This value shows that this torpedinid is not a pure lecithotrophic species, and the role of the rnother during gestation is not negligible. The fecundity (s.1.) of T. torpedo ranges from 5 to 28 in Senegalese specimens as cornpared to 1 to 9 in Mediterranean specirnens. Male ernbryos and fully developed fetuses are more nurnerous than fernales. Among the free-living specimens, nurnber of males and fernales is practically the same. The cornrnon torpedos from the coast of Senegal are larger and the eggs are heavier than Mediterranean specirnens. Key words: Pisces, Torpedinidae, Torpedo torpedo, Reproductive biology, Senegal, Eastern Tropical Atlantic.Among the five species of genus Torpedo recorded from the coast of Senegal, the common torpedo, Torpedo torpedo is that most cornrnonly caught in the area. Adult males and fernales studied were over 300 mm and 310 mm total length (TL), respectively, with the largest male and the largest female recorded being 445 mm and 550 mm TL respectively. Size at birth was between 102 and 125 mm TL (mean 112.12 mm; s.e.m. 5.58). Weight of eggs ranged frorn 6.2 to 8.0 g (rnean: 7.07; s.e.m. 0.5). Gestation lasts longer, from 6 to 8 rnonths, than in the Mediterranean specimens. A calculated chernical balance of development based on rnean dry weights of the fully developed fetuses and ripe oocytes was 1.58 for T. torpedo. This value shows that this torpedinid is not a pure lecithotrophic species, and the role of the rnother during gestation is not negligible. The fecundity (s.1.) of T. torpedo ranges from 5 to 28 in Senegalese specimens as cornpared to 1 to 9 in Mediterranean specirnens. Male ernbryos and fully developed fetuses are more nurnerous than fernales. Among the free-living specimens, nurnber of males and fernales is practically the same. The cornrnon torpedos from the coast of Senegal are larger and the eggs are heavier than Mediterranean specirnens. Key words: Pisces, Torpedinidae, Torpedo torpedo, Reproductive biology, Senegal, Eastern Tropical Atlantic