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).

Reproductive cycle,sexual maturity and fecundity of Nemipterus furcosus(Valenciennes,1830)

Understanding the reproductive biology particularly sexual maturity,reproductive cycle and fecundity of fish is useful for fisheries management.Unfortunately,there is no information about reproductive biology of Nemipterus furcosus.This study addresses this deficit for N.furcosus.We conducted a 12-month study to understand the reproductive biology particularly the sex ratio,sexual maturity,fecundity and reproductive cycle of N.furcosus at the east coast of peninsular Malaysia.Results indicated that ratios of male and female were statistically similar up to 19.0 cm TL(total length).Male outnumbered female above 19.0 cm TL(P<0.05).The fecundity ranged between 54,970 and 236,938 with a mean fecundity of 102,477±43,580(standard deviation).Male and female fish reached first sexual maturation at almost same size,15.8 and 15.6 cm,respectively.This information is needed to determine the lowest acceptable harvest length of this fish under the management aim to enter all female fish for reproduction minimum one time in their life.We estimated the reproductive period of N.furcosus applying oocytes diameter,histological examination of ovaries and monthly mean GSI.All of these methods gave a consistent result about spawning season,which appeared to be from March to July with peaks in March and June.Based on this result,N.furcosus spawners can be protected during March to July for entering the reproductive stock.Apart from artificial breeding,the results of this study might facilitate future efforts at fine-tuning fishing effort for a proper management of N.furcosus.