Environmental DNA collection could be a “silver bullet” for tracking and protecting critically endangered fish in the Mekong, according to a new report.

The technique – which involves filtering DNA in shed skin from river water – was put to the test at six deep Mekong River sites, including two in Cambodia, in the study Trails of river monsters: Detecting critically endangered Mekong giant catfish, published in this month’s Global and Ecology Conservation journal.

Lead author Eva Bellemain said that the study had detected the Mekong giant catfish in one Thai location; but given the complexity and size of the river and rarity of the species, she said this was a promising find.

“Extracting DNA from the water is relatively new, and it’s non-invasive, so you don’t need to harm the fish,” she said.

She said her team was now refining their research in order to calculate the number of fish in an area, rather than determining their mere presence.

The report said DNA detection could help at-risk fish, as “the status of many iconic threatened species is poorly known” and mostly relies on interviews with fishermen or sampling of fish captured through commercial harvests.

Eric Baran, senior scientist with NGO World Fish, said tracing fish DNA could help conservation efforts.

“Most critically endangered species in the Mekong are giant species . . . because they are naturally rare, easy to catch and usually take many years before reaching their sexual maturity,” he said in an email.

“Knowing better where they migrate or reproduce could help keep their migration routes open and protect their breeding sites.”