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Induction and potential use of monosex populations of pikeperch (Sander lucioperca) in intensive farming
ŠVEJDA, Pavel
The aim of this study was to induce monosex populations of pikeperch using the method of direct masculinization and direct feminization in order to change sex and evaluate the production parameters and body indices of the treated groups of pikeperch. For direct masculinization, 17 -methyltestosterone was used at a dose of 30 or 50 mg.kg-1 for 30 or 60 days. For direct feminization, 17 -estradiol was used at a dose of 30 mg.kg-1 feed for 30 days. Individuals of pikeperch with TL = 51.52 +- 4.19 mm and W = 1.23 +- 0.26 g, FC = 0.9 +- 0.3 were used for the experiment. In the experiment, direct feminization achieved a sex ratio 98.3 % of females and 1.7 % of males. This is the first record of an almost all-female population induced with 17 -estradiol. The highest level of masculinization of the tested individuals was achieved in the group exposed to 17 -methyltestosterone at a dose of 30 mg.kg-1 feed for 60 days. In this population, 75 % of individuals with male genital tissue were found, of which 21.7 % were individuals whose testicular sperm could be used to produce an all-female population. In groups treated with 17 -methyltestosterone for 60 days, the presence of "neomales" and intersex (hermaphrodite) individuals was observed. The experiment revealed that the use of the hormones 17 -methyltestosterone and 17 -estradiol can temporarily cause growth suppression, particularly during and shortly after exposure of individuals to these hormones. However, it does not have a lethal effect on individuals in the doses we applied. The higher growth rate of pikeperch females was not confirmed in the test. Females treated with 17 -estradiol did not show higher weight gains compared to the control group. A significant difference in the achieved final weight was not observed between both sexes in the control group at the end of the experiment.
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