The effects of photoperiod
manipulation on the reproduction of black sea bass, Centropristis striata
R.A. Howell, D.L. Berlinsky, T.M. Bradley-2003
Aquaculture, 218(1-4): 651-669
Abstract:
The black sea bass, Centropristis striata, is
a potential candidate for commercial aquaculture in the United States. One
of the most significant constraints limiting commercial production of black
sea bass is the lack of a reliable supply of eggs and larvae. A narrow
window of annual spawning prevents year-round availability of juveniles for
grow out. The present study reports on the use of photoperiod manipulation
to alter the timing of spawning in C. striata and increase
availability of larvae. Adult black sea bass were maintained under a
simulated natural (SNP) or an accelerated long day (ALD) photoperiod
regimen. Water temperature was adjusted from 14 to 20 °C to correspond to
seasonal changes in daylength. Reproductive development was monitored by
histological analysis of gonadal biopsies and plasma levels of sex steroids
(estradiol-17b,
testosterone and 11-ketotestosterone). Females in both regimens were induced
to spawn by implantation of 25 µg luteinizing hormone-releasing hormone
analogue (LHRHa) when follicle diameters exceeded 500 µm. Acceleration of
the photoperiod advanced the annual cycle of circulating gonadal steroids in
both sexes without altering the profile. The onset of spermiation in males
was unaffected by photoperiod manipulation, but follicle growth and spawning
in females were advanced approximately 2 months by exposure to the ALD
regimen. Of interest, the ALD photoperiod regimen accelerated the time frame
of sexual succession from female to male without reducing the mean volume of
eggs produced per female. These findings suggest that photoperiod
manipulation can be used to alter the timing of reproduction in black sea
bass and increase the supply of eggs for commercial aquaculture.
(Department
of Fisheries, Animal and Veterinary Science, University of Rhode Island,
East Farm, Building #14, Kingston, RI 02881, USA, e-mail of T.M.
Bradley: tbradley@uri.edu)