Why it matters
Gender bender
9th August 2008
Gender ratios of fish skewed by warmer waters
Fish in warming water - especially shallow lakes and ponds - prone to skewed sex ratios
Climate change is nudging many species, including polar bears, songbirds and trees, toward extinction by, for example, causing their prey to move. And some animals are experiencing another consequence: Climate change may be skewing their gender ratios.
A study published in the journal PLoS Biology shows that the gender of at least 40 fish species are determined by temperature. Warmer water always mean more male fish and even small temperature rises could drive large shifts. A 1.5-degree Celsius rise (considered “very likely” by the Intergovernmental Panel on Climate Change) will shift the fish to 62 per cent males, on average, from 50 per cent. But some species are more sensitive than others. Atlantic silversides, important commercially in South America, see males rise to 73 per cent with a 1.5-degree rise – and up to 98 per cent with an increase of four degrees.
Even in fish with genetically determined gender, warmer water can produce more males by inhibiting the enzymes that produce estrogen.
“Remember that there are 30,000 species of fish in total worldwide and the sex-determination mechanism is only known for a few of them,” says Francesc Piferrer, of the Institute of Marine Sciences in Barcelona, lead author of the study. “This could be bad news.”
Published in The Green Report in The Globe and Mail
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