Sex Control in Aquaculture: Concept to Practice

Understanding sex determining (SD) mechanisms and related concepts in a wide range of fish species is critical for sex control and large‐scale monosex production in aquaculture, in which monosex culture is superior to mixed‐sex culture. Establishment of phenotypic sex is triggered by SD factor(s), modulated by complex molecular networks, and influenced by environmental conditions, steroid hormones, and endocrine disrupting chemicals. Temperature‐dependent sex determination (TSD) presents in fish, and the feature has been applied to monosex production in several fish species, since many downstream aspects of TSD are shared with genotypic sex determination (GSD). Although SD genes have been identified in some fish, the complex molecular networks involved in sex differentiation remain unclear. Large‐scale monosex production could be achieved in the third generation with sex‐linked markers (SLMs), and in the fourth generation with no available SLMs in fish with a XY or ZW SD mode. There is a great potential for producing large‐scale breeding systems for females in much less time if gynogenesis and sex reversal of XX‐females are combined. In addition, atypical genotypes (YY and WW) have the potential to serve as a biological tools to control invasive species in natural waters. In this chapter, we briefly review the concepts and practices of sex control in fish and aquaculture, based on the achievements during the past two decades.