Some aspects on the reproductive cycle of European conger eel, Conger conger (Linnaeus, 1758) (Osteichthyes, Anguilliformes, Congridae) captured from Western Algerian coasts: a histological description of spermatogenesis

Abstract

The aim of this work was to study the annual reproductive cycle of European conger eel (Conger conger,Linnaeus, 1758) through analysis and description of spermatogenesis. A sample of 168 males was capturedbetween September 2008 and August 2009 from the Western coast of Algeria, from Béni Saf. Fish length andweight varied between 26.20-112 cm and 0.45-3.44 kg, respectively.Condition factors (K), gonadosomatic index (G.S.I.) and hepatosomatic index (H.S.I.) were calculatedmonthly. Factor K reached the minimum in August/September (0.10%) corresponding to reproductive periodand a maximum in January (0.18%). Although G.S.I. values revealed to be statistically not significant, therewere two peaks for G.S.I., the first in March, denoting the beginning of spermatogenesis, and the second inAugust/September, indicating the reproduction period. H.S.I. reached a peak in December (1.90%), then thevalue decreased to a minimum in April.Histological analysis of testis allowed us to distinguish 5 stages summarized as follows: Stage 1:Spermatogonia A; Stage 2: Spermatogonia B; Stage 3: Spermatocytes and spermatids; Stage 4: Spermatocytes,spermatids and spermatozoa (cytodifferentiation of spermatids into spermatozoa); Stage 5: Spermatozoa(spermiogenesis or cytodifferentiation of spermatids into spermatozoa)