Tuesday October 17, 2023


In 1981, scientists discovered that female fish exposed to high temperatures developed testes instead of ovaries. Since then, over 1,100 studies on different animal species, including 400 on freshwater fish, have found similar results.

This raises several questions.

Why does this happen? How can this be explained, and does it harm long-term fish populations? Our research has shown that a key factor in explaining this is the over-production of stress hormones as a result of higher temperatures.

No time to adapt

Fish reproductive organs are highly adaptable to environmental changes as, unlike mammals, they have simple structures. Remarkably, even slight changes in water conditions can directly and significantly impact fish metabolism and physiology.

Fish use this to their advantage by using environmental cues to align their reproductive success with seasonal conditions. For example, several fish species, like the yellow sturgeon, breed in the springtime cued by the warmer water temperatures.

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