Review on sex determination process, all-female production and growth performances in Eurasian perch, Perch fluviatiles

Introduction
The sex determination process in Eurasian perch (Perca fluviatilis), that display a sexual growth dimorphism towards females, is mainly under the control of genetic factors, govern by the sex chromosomes system XX/XY, with a probable autosomal influence as proven by sex reversal experiment, gynogenesis and hybridization. Beside this chromosomal control, sex steroids, mainly E2/11KT ratio, are strongly involved in the control of the development of the phenotypic sex, as important sex steroids levels are measured during all the embryonic period, from fertilization (maternal transmission) until the onset of histological differentiation of the gonad. Although the lability of sexual development was clearly established, no effect of temperature on sex differentiation process was described up to now for this species. This lability of the sexual development could be used to control the sex ratio and produce all-female population, that allow the improvement of the productivity under controlled conditions. This paper will review the bases of the sex determination process in E. perch, as well as the different methods of sex control, from hormonally sex reversal treatment to chromosomes set manipulation (triploïdisation and gynogenesis).

Sex determination process
Sex determination process in E. Perch is mainly under the control of sex chromosomes, with female XX and male XY chromosomic system with a probable implication of autosomes. The 11KT to E2 ratio plays a major role in the sex differentiation process in E. perch. No effect of temperature was reported under experimental conditions (Rougeot, 2019).

Sex control and all-female production
In E.perch, hormonal sex control and all-female production could be achieved within 2 generations by naturally or artificially crossing hormonally sex-reversed XX males breeders with normal XX females. The optimal treatment to obtain functional XX male is 5 to 10 mg MT per kg of food applied at 70 mg mean body weight during 30 days. The production of all-female population will allow to improve the productivity about 30% (fig.1).