Effects of phase-shifted
photoperiod regimes on oocyte growth and hormonal profiles in female striped
bass Morone saxatilis
V. Vuthiphandchai, J. Stubblefield, Y. Zohar-2002
Journal of the World Aquaculture Society, 33(3):
358-368 (from Current Contents)
Abstract :
The use of 12-mo long, but phase-shifted advanced and
delayed photoperiod cycles in the regulation of the reproductive cycle was
investigated in captive-reared female striped bass Morone saxatilis during
the 3-yr study in an attempt to control the timing of sexual maturation
under simulated photoperiod conditions. Phase-shifted photoperiod cycles did
not induce a full shift in oogenesis during the first year cycles. but did
in the following years. Spawning time. indicated by maximum oocyte
diameters, was advanced up to 4 mo in females maintained under the
phase-shifted advanced photoperiod. and delayed up to 4 mo when they exposed
to the phase-shifted delayed photoperiod. compared to the natural spawning
time in Spring (March-May). Phase-shifted photoperiod regimes shifted the
profiles of plasma testosterone (T) and estradiol (E-2), corresponding to
the shift of oogenesis in the respective groups, Significant increases in T
and E-2 levels occurred during the vitellogenic phase. and these levels
peaked before the occurrence of maximum oocyte diameters. The studies
demonstrate that phase-shifted photoperiod regimes can be used to control
oogenesis. and have implications for ensuring the year-round supply of
mature female striped bass. particularly in domesticated striped bass.
(Burapha Univ; Fac Sci; Chonburi 20131; Thailand)