Sex Reversal and Masculinization according to Growth in Longtooth Grouper Epinephelus bruneus

Abstract

To understand the sex reversal characteristics in the longtooth grouper (Epinephelus bruneus), this study examined the sex reversal and artificial masculinization of wild caught E. bruneus reared in indoor rearing tank after a 17α-methyltestosterone injection. To domesticate a broodstock, 64 wild caught E. bruneus, between 47.0 to 110.0 cm in total length and from 1.5 to 21.4 kg in body weight, were reared in indoor rearing tank (4.0 to 5.0 m wide, and 2.5 to 3.0 m depth) for four years. Seven specimens showed sex reversal from female to male during indoor rearing condition, whose total length and body weights were from 63.0 to 99.0 cm and from 4.4 to 13.2 kg, respectively. After inducing artificial masculinization in 14 female E. bruneus with a 17α-methyltestosterone (2.0 mg/kg BW) implants for 3 years, spermiation occurred in 9 specimens (total length: 54.0 to 68.0 cm, body weight: 2.3 to 4.3 kg). Among the female to male sex reversals, two specimens returned back to being female, whose body weights were 2.8 kg (initially 2.6 kg) and 2.7 kg (initially 2.3 kg). Therefore, this study suggested that E. bruneus (> 3.0 kg) was more effective in masculinizing by 17α-methyltestosterone implants.

Induction of Primary Male in Juvenile Red Spotted Grouper Epinephelus akaara by Immersion of 17α-Methyltestosterone

“…Androgen administration including 11-ketotestosterone (11-KT) and the synthetic 17α-methyl-testosterone (MT) widely used for sex reversal induction in grouper, but various dose concentrations and methods of hormone administration ( Chao & Lim, 1991 ; Tsuchihashi et al, 2003 ; Lee et al, 2010 ). However, these methods of hormone administration have problem such as incomplete sex inversion and reverted back to being females during the next reproductive period ( Marino et al, 2000 ; Sarter et al, 2006 ; Oh et al, 2013 ). Therefore, the most effective treatment time for artificial sex change induction by steroid hormone is during gonadal sex differentiation.…”

Beta-Hydroxysteroid Dehydrogenase Genes in Orange-Spotted Grouper (Epinephelus coioides): Genome-Wide Identification and Expression Analysis During Sex Reversal

“…Low serum E2 levels and increased 11-KT levels are probably the events mediating protogynous sex change in grouper (Bhandari et al, 2003). In addition, exogenous androgens could artificially induce the sex reversal of groupers from female to male (Chen et al, 2011;Oh et al, 2013;Murata et al, 2014). However, little is known about the expression profiles of sex steroid synthesis and metabolism genes in the natural sex reversal process.…”

Epigenetics in aquaculture – the last frontier

“…Depending on the produced species, and considering its reproductive biology and culture system, there are several benefits in sex control, including the decrease in the impact of phenotypic sex on product quality, prevention of precocious maturation, production of monosex populations due to differences in growth rate and economic value between sexes, and increase in mating systems stability, among others (Piferrer et al 2012;Ventura et al 2012;Oh et al 2013;Budd et al 2015). The mating system stability, in particular, refers to the structure of a group in relation to sexual behaviour, including species-specific pattern of male-female associations, how the mates are acquired, patterns of parental care by each sex, among others (Rios-Cardenas & Morris 2009).…”