Sex Determination and Reversal in the Black Sea Bass (Centropristis striata)
|Christopher Benton||UNH - Department of Biological Sciences|
|James DeGraaf||UNH - Department of Biological Sciences|
|Kate Strait||UNH - Department of Biological Sciences|
|Brian Hooper||University of New Hampshire|
|Stephanie Hillsgrove||University of New Hampshire|
|Regan Gibson||University of New Hampshire|
|Adam Argeropoulos||University of New Hampshire|
Continued growth of the U.S. aquaculture industry requires identification of new culture species and expansion of existing markets. One species with enormous potential for culture is the black sea bass (Centropristis striata). Due to high consumer demand and limited seasonal availability, this species consistently commands high prices in the restaurant trade, ethnic markets and seafood stores.
We have been exploring various aspects of black sea bass culture over the past five years. To date, we have developed protocols for spawning induction and larviculture and identified environmental conditions favorable for juvenile survival. In the wild, black sea bass are protogynous hermaphrodites. As such, the majority of individuals develop first as females, remain females for three-five years, and then undergo sexual succession to become functional males. This process is exacerbated in culture and often entire cohorts of female broodstock undergo sex inversion after one spawning season in captivity. Additionally, culture conditions promote male sexual differentiation and precocious puberty, which limits somatic growth.
The proposed studies are designed to address these problems by examining the time course and environmental factors that influence sex differentiation and reversal. Specifically, we will investigate whether black sea bass, like many other teleosts, exhibit temperature-dependent sex determination, if photoperiod initiates precocious puberty, and if population density and sex ratio impact the rate of sex inversion.
1) Determine the developmental stage at which sex differentiation occurs
2) Examine the effects of rearing temperature and population density on sex differentiation
3) Determine the effect of photoperiod on rate of sexual development
4) Characterize the relative growth rates of male and female black sea bass reared in captivity
5) Determine if social structure or density influences initiation of sex reversal
Juvenile black sea bass will be reared at different temperatures and densities, serially sampled and examined histologically for gonadal development. Juveniles will be raised under different photoperiod regimes for 10-month periods to determine the rate of sexual maturation and relative growth rates of males and females. Adult black sea bass will be cultured at different sex ratios and densities to determine the social effects on sex inversion.
Due to high consumer value and limited seasonal availability, the black sea bass has enormous potential as an aquaculture candidate and we have been examining favorable culture conditions for the past five years. Two remaining problems must be addressed before profitable commercialization of this species can be realized:
1) Controlling precocious puberty in males
2) Preventing sex reversal of female broodstock.
Completion of the proposed studies will increase profitability of black sea bass culture by improving somatic growth of juveniles and diminishing the need to replenish wild, female broodstock.
The major impact of the project was that we provided information that prevents, or at least delays, the process of sex change in black sea bass. Therefore, growers can maintain their (female) broodstock for longer periods of time without the necessity of replenishing them from the wild.
Available from the National Sea Grant Library (use NHU number to search) or NH Sea Grant
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