The effects of photoperiod manipulation on the reproduction of black sea bass, Centropristis striata

摘要

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 degreesC to correspond to seasonal changes in daylength. Reproductive development was monitored by histological analysis of gonadal biopsies and plasma levels of sex steroids (estradiol-17beta, testosterone and 11-ketotestosterone). Females in both regimens were induced to spawn by implantation of 25 mug luteinizing hormone-releasing hormone analogue (LHRHa) when follicle diameters exceeded 500 mum. 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.