Fishing for DNA / A new method to help track the Mekong’s rare wildlife

Southeast Asia Globe –

Scientists are rapidly developing new DNA-methods to identify what kind of life is present in rivers, lakes and the ocean. Advocates of the method claim that it has the potential to revolutionise the way environmental monitoring is done.

It began two decades ago with a spoonful of frozen soil. DNA fragments extracted from the depths of the Siberian earth allowed scientists to reconstruct an entire ice age ecosystem, painting a vivid picture of the mammoths, bison and other long-dead creatures that roamed the frozen steppes thousands of years ago. The literally ground-breaking study revealed that DNA is all around us, released as faeces, urine or skin tissue. This method of gathering traces of animals’ genetic code from the wider world, known as environmental DNA – or eDNA for short – is a rapidly expanding field of molecular biology that may hold the key to monitoring Southeast Asia’s fast-changing ecosystems.

Enter the Mekong giant catfish. When scientists and conservationists in Southeast Asia wanted to test the eDNA method to target a threatened species in tropical waters, this enormous animal – the largest freshwater fish in the world – was an obvious choice. Despite many local people viewing the catfish as a sacred animal, the species has been decimated in recent years, likely due to overfishing and habitat degradation, with conservation organisations now categorising the once-thriving fish as ‘critically endangered’.

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