• Genetics explain the sex change of bars, according to the results of an Ifremer study published this week in the journal PNAS.

  • Young bass with a weaker female genetic orientation masculinize at high temperatures in the first few months of their existence.

Fish that change sex during their life depending on their environment, the case has been heard for a few years. We know for example the phenomenon in clown fish or sea bream. On the other hand, that genetics come to put its two cents and explain this sexual reversion, here is which is new. This was observed by the experiment carried out on more than 2,000 young bars in the Ifremer laboratory in Palavas-les-Flots (Hérault), the results of which are the subject of a publication this week in the journal. PNAS.

"The fish are distributed linearly at birth," explains Benjamin Geffroy, researcher in fish physiology at Ifremer.

There are those with a major genetic tendency, male or female, and those in the middle, who have a weaker genetic orientation.

And the temperature of the water will play a determining role.

Everything is played out in the first 100 days of their existence.

It is during this period that the young bar will determine its sex.

For the study, they were distributed in two basins, one heated to 16 degrees, the other to 21 degrees.

In the first, males and females are distributed in equal proportions once the sex has been determined.

In the second, males represent 75%.

Results that are also of interest to the fish farming sector

"By studying the distribution of genes, we were able to detect that 25% of young bass had a weaker female genetic orientation," continues the researcher. They are the ones who masculinize at high temperatures in the first months of their existence. ”Precious information for two reasons. First of all for the fish farming sector, which can thus hope to play on the temperature of the water to have the desired sex, that of the females. Indeed, they are the ones who put on weight the best and ensure the best breeding performance: for the same amount of food, their growth rate is 30% higher compared to males.

The other lesson of this research concerns the effects of global warming on wild sea bass.

There is a risk, for the survival of the species in the natural environment, of an impoverishment of female bass in warmer water.

Benjamin Geffroy, however, refuses to give in to alarmism: "Fish do not reproduce at the same time, and for the temperature to act, it must occur at a precise moment of development".

However, he has just arrived in Chile to work on this issue in warmer water, on the salmon population this time.

Planet

Mediterranean: We know why sardines are affected by dwarfism

Planet

Marseille: An unprecedented study reveals that sea water receives less mercury than estimated

  • Languedoc-Roussillon

  • Montpellier

  • Palavas-les-flots

  • Marseilles

  • Ifremer

  • Research

  • Global warming

  • Fish

  • Aquaculture

  • Planet

  • 0 comment

  • 0 share

    • Share on Messenger

    • Share on Facebook

    • Share on twitter

    • Share on Flipboard

    • Share on Pinterest

    • Share on Linkedin

    • Send by Mail

  • To safeguard

  • A fault ?

  • To print