The effects of exogenous
androgens on ovarian development and sex change in female orange-spotted
protogynous grouper, Epinephelus coioides
S.-L. Yeh, Ch.-M. Kuo, Y.-Y. Ting, Ch.-F. Chang-2003
Aquaculture, 218(1-4): 729-739
The efficacy of various doses of an androgen mixture,
containing testosterone (T), 17a-methyltestosterone
(MT), and testosterone propionate (TP) in equal ratios, for induction of sex
change in protogynous orange-spotted grouper, Epinephelus coioides,
was examined. The androgen mixture, with doses from 1 to 20,000 µg/kg BW,
was implanted into each fish (body weight 1.7 kg) in July (post-spawning
season), and gonadal stage and plasma T were monitored at various time
intervals for a period of 90 days. Gonadosomatic (GSI) and hepatosomatic
indices (HSI), gonadal histology, sex steroids (T,
11-ketotestosterone=11-KT, and ESTRADIOL=E2) in plasma were determined after
90 days of implantation. The implanted T was released to plasma for 60 days.
All androgen mixtures at doses higher than 1000 µg/kg BW were capable of
inducing a sex transition and completion of spermatogenesis up to the
functional male phase. Low doses of androgens induced ovarian development
and higher GSI and HSI indices than in the control and other groups.
Significantly higher plasma T levels were found in the developing and
spermiating males as compared to the females and intersex-transitional fish.
No significantly difference of plasma levels of E2 and 11-KT was found in
the control and all the androgen-treated groups (during the nonreproductive
season). Therefore, it is concluded that the stimulation of sex change or
ovarian development is dependent on the dose and time course of implanted
androgens. Plasma T levels were correlated with the development of
controlled male phase in protogynous grouper, E. coioides.
of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan, ROC,
e-mail of CH.-F. Chang: