Dr. Hanping Wang
Aquaculture Program Leader
Aquaculture team members recently published two papers related to production of monosex fish and sex control in aquaculture in prestigious aquatic and biological journals. The first paper is about the effect of density on sex differentiation, sexual dimorphism, stress, and related gene expression in yellow perch. It was published by PLOS ONE, which is a prestigious journal published by the Public Library of Science.
In this paper, researchers state that the stocking density does not have an effect on the sexual determination of yellow perch. However, it was concluded that high density is a chronic stress that has adverse effects on fish wellbeing, sexual size dimorphism, growth, survival, expression of stress-related genes, and mobilization of liver reserve.
A stocking density of 1 fish/L or 1,000 fish/m3 is recommended for indoor aquaculture systems to reduce stress, increase survival, and provide a better state of wellbeing and growth performance for rearing management of juvenile yellow perch and, particularly, create a greater advantage for females. The information is important for aquaculture management and practice.
For more information, please visit: doi.org/10.1371/journal.pone.0267904
The second paper, which explores the effect of methyltestosterone (MT) on sex differentiation and growth in juvenile yellow perch, was published by Fish Physiology and Biochemistry – one of the top-ranked aquaculture/fish journals.
In this study, researchers found that the dosage and time of MT-supplemented feed initiation influence the percentage of sex-reversed males and promote growth. Where using higher dosage MT at 50 mg/kg feed could effectively broaden the efficacy of sex-reversal up to 46 days post-hatching in yellow perch, the higher concentrations of MT have evidenced a negative effect on the gonadal development of fish. Hence, the initiation of low dosage 20 mg/kg feed of MT-supplemented feed at 38 dph for 60 days is suggested to produce all-male fish stocks of yellow perch for sex control purposes, as it had effectively produced 100% sex-reversed males, promoted growth, and reduced the total amount of MT used.
The identification of the labile period of sex determination that is manipulated by MT dosage and age of treatment is a valuable progression toward optimizing commercially viable regimes for producing all-female yellow perch, which grow significantly faster and larger than males.
For more information, please visit: doi.org/10.1007/s10695-021-01038-0