Etude de la pêche et de la biologie de la coryphene Coryphaena hippurus en Tunisie: Résultats préliminaires

Abstract

In this study, 1063 Coryphaena hippurus individuals have been sampled between September 1998 and December 1999. The data show that the individuals captured during the fishing season are all juveniles (<6 months old). The first-catch size is 16 cm (F.L.) and correspond to a weight of 50 g. The evolution of the monthly mean size of the captures indicate that the dolphinfish has a fast growth in tunisia coastal waters. These sizes vary from 20 to 50 cm (F.L.) between the begining and the end of fishing season.The Gonadosomatic Index (GSI) of the males vary from 0.180 ( sigma = 0.07 ; n = 25) in August, 0.247 ( sigma = 0.203 ; n = 41) in September, 0.213 ( sigma = 0.19 ; n = 11) in October and 0.375 ( sigma = 0.24 ; n = 4) in November. The females GSI's are always higher than males ones. It's vary from 0.305 (s = 0.15 ; n = 35) in Augustt, to 0.437 ( sigma = 0.148 ; n = 64) in September, 0.134 ( sigma = 0.078 ; n = 38) in October and 0.450 ( sigma = 0.120 ; n = 14) in November. The sex-ratio of the individuals captured during the fishing season, is of 2 females for 1 male. The size-weight relationship gives positive allometric growth and there is no significative difference is observed between sexes for the sampled sizes (18 cm < F.L. < 50 cm): W = 0.0102 L.F super(3.0155) (n = 595 ; r super(2) = 0.98) both sexes.