Etude preliminaire de la reproduction de Pagellus erythrinus des eaux tunisiennes

Abstract

Pagellus erythrinus (Linne, 1758), a very common fish in Tunisia, constitutes a good material for reproduction study. The changes, in function of the fish length, of the percentage mature individuals and the gonosomatic index average display that P. erythinus seems to be mature at the sizes between: -11 and 15 cm of standard length (or 14 and 18 cm of the total length) for the female individuals. -11,5 and 15,5 cm of standard length (or 14,5 and 18,5 cm of the total length) for the male individuals. The sex distribution analyse in function of fish length indicates that P. erythinus is an hermaphrodite fish of which the sexual inversion is realized in the direction female-male. The population of this fish is divised in 3 fractions: -29,5% remain always females -21,5% males throughout all their life -49% are first females and later males. The monthly changes of gonosomatic index, hepato-somatic index and the condition factor indicate that P. erythinus spawns along Tunisian coasts in april to july with a possibility of a second spawn period in november; this fish seems take its reserves from the liver and not from the muscles.