Parental selection for growth and early-life low stocking density increase the female-to-male ratio in European sea bass

Type Article
Date 2021-06
Language English
Author(s) Geffroy Benjamin1, Gesto Manuel2, Clota Frederic3, 5, Aerts Johan4, Darias Maria J.6, Blanc Marie-Odile1, Ruelle Francois1, Allal Francois1, Vandeputte Marc3, 5
Affiliation(s) 1 : MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Palavas-Les-Flots, France
2 : Techn Section for Aquaculture, DTU Aqua, Technical University of Denmark, Willemoesvej 2, 9850, Hirtshals, Denmark
3 : Université Paris-Saclay, INRAE, AgroParisTech, GABI, 78350, Jouy-en-Josas, France
4 : Stress Physiology Research Group, Faculty of Sciences, Ghent University, Ostend, Belgium
5 : MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Palavas-Les-Flots, France
6 : MARBEC, Univ Montpellier, CNRS, Ifremer, IRD, Palavas-Les-Flots, France
Source Scientific Reports (2045-2322) (Springer Science and Business Media LLC), 2021-06 , Vol. 11 , N. 1 , P. 13620 (14p.)
DOI 10.1038/s41598-021-93116-9
Abstract

In European sea bass (Dicentrarchus labrax), as in many other fish species, temperature is known to influence the sex of individuals, with more males produced at relatively high temperatures. It is however unclear to what extent growth or stress are involved in such a process, since temperature is known to influence both growth rate and cortisol production. Here, we designed an experiment aiming at reducing stress and affecting early growth rate. We exposed larvae and juveniles originating from both captive and wild parents to three different treatments: low stocking density, food supplemented with tryptophan and a control. Low stocking density and tryptophan treatment respectively increased and decreased early growth rate. Each treatment influenced the stress response depending on the developmental stage, although no clear pattern regarding the whole-body cortisol concentration was found. During sex differentiation, fish in the low-density treatment exhibited lower expression of gr1, gr2, mr, and crf in the hypothalamus when compared to the control group. Fish fed tryptophan displayed lower crf in the hypothalamus and higher level of serotonin in the telencephalon compared to controls. Overall, fish kept at low density produced significantly more females than both control and fish fed tryptophan. Parents that have been selected for growth for three generations also produced significantly more females than parents of wild origin. Our findings did not allow to detect a clear effect of stress at the group level and rather point out a key role of early sexually dimorphic growth rate in sex determination.

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Geffroy Benjamin, Gesto Manuel, Clota Frederic, Aerts Johan, Darias Maria J., Blanc Marie-Odile, Ruelle Francois, Allal Francois, Vandeputte Marc (2021). Parental selection for growth and early-life low stocking density increase the female-to-male ratio in European sea bass. Scientific Reports, 11(1), 13620 (14p.). Publisher's official version : https://doi.org/10.1038/s41598-021-93116-9 , Open Access version : https://archimer.ifremer.fr/doc/00705/81662/