Gonadal maturation and histological observations of the grey triggerfish Balistes capriscus Gmelin, 1789 (Teleostei: Balistidae) in the Gulf of Gabès, Tunisia

Objective: To determine the spawning activity using gonadosomatic index (GSI) and gonad histology the Balistes capriscus (Teleostei: Balistidae) of the Gulf of Gabès (Southern Tunisia, Central Mediterranean Sea). Methods: The reproductive biology of the species, based on 756 (480 females and 276 males), collected from commercial catches at several fishing ports including Chebba, Kerkennah and Zarzis at respective GPS coordinates (34°14' N, 11°06' E), (34°45' N, 11°17' E), (33°41' N, 11°48' E) was studied over 28 months (January 2008-April 2010) using GSI and gonad histology. Sizes used in this study ranged from 11.30 to 45.60 cm in fork length. Results: Both GSI and gonad histology suggest that spawning activity occurred mainly between July and mid-September with a peak in July, coinciding with summer time. The first maturation occurred at 20.26 cm fork length for females and 21.30 cm fork length for males. The monthly values of hepatosomatic index and condition factor (K) indicated that the liver is the main organ responsible for the mobilization process of the energizing reserves during the sexual cycle. Conclusions: It is the first inventory of gonadal maturation and histological observations of the grey triggerfish Balistes capriscus Gmelin, 1789 (Teleostei: Balistidae) in the Gulf of Gabès, (Southern Tunisia, Central Mediterranean Sea)