Effective
hormonal treatments for induction of ovarian maturation and ovulation in the
common Japanese conger Conger myriaster
N.
Horie, Y. Yamada, A. Okamura, S. Tanaka, T. Utoh, N. Mikawa, A. Akazawa,
H.P. Oka-2003
Nippon Suisan Gakkaishi, 69(3): 337-346
(from ISI Current Contents)
Abstract:
We sought effective hormonal treatments to induce ovarian maturation and
ovulation in the common Japanese conger Conger myriaster by using females
cultured for 1.5 years from elver. Effective treatments were human chorionic
gonadotropin (HCG; 100 IU kg(-1) body weight every 2 weeks) in combination
with one of three maturation-inducing steroids* (2 mg kg(-1) body weight).
Of these treatments, the combination of HCG and 20,6-S seemed to be the most
effective. In all fish treated with this combination that survived the
experiment, the oocytes developed to the migratory nucleus stage. The
survival rate of the HCG-treated females was 79%, and buoyant eggs were
obtained from 42% of the females injected with 20beta-S. The fertilization
rate (no. eggs fertilized/total no. eggs ovulated) was 61%+/-30%.
Furthermore, handling stress seemed to affect the egg quality of C.
myriaster, because fertilized eggs were not obtained from females that had
been handled more than 12 times.
(Irago Inst., 377 Ehima Shinden, Atsumi Aichi
4413605, Japan, e-mail: horie@irago.co.jp)