Rare sighting of a critically endangered fish in the Mekong raises conservation hopes

Photo: Pixabay/Quangpraha 

The Mekong giant salmon carp is a freshwater fish and it may not strike the unitiated as a particularly exotic specimen. Yet scientists in Cambodia were elated at seeing a member of this species (Aaptosyax grypus) in local waters.

The reason for that is that the fish had not been seen for two decades and was believed to have gone extinct locally. “1999 was the last recorded sighting of the giant salmon carp in Cambodia. We did not expect to see their return,” Thach Panara, a prominent local scientist, told a local newspaper.

The 6kg specimen, which died soon after being caught by a fisherman near a hydroelectric dam on the river, belongs to a critically endangered species that has seen its habitat shrink greatly over the past decades in the Mekong.

“We are sorry it’s dead, but it’s still important for us as scientists. This may indicate that they are still present in the freshwaters of Cambodia,” the scientist explained.

Such unexpected finds are encouraging in the Mekong, which is one of the world’s most biodiverse waterways but one increasingly beleaguered by wanton development.

In recent years rampant dam-building projects by China and Laos have caused massive environmental harm to the river, driving numerous aquatic species to the brink of extinction. The number of the Mekong giant salmon carp alone has dropped by some 90% owing to habitat loss and overfishing, scientists say.

“According to the most recent study, conducted in 2017-2018, it was determined that the giant salmon carp was likely extinct in Cambodia and only to be found in the least number in Thailand and Laos,” said Chea Seila, programme manager for the Wonders of the Mekong project.

The carp, which can grow to 130cm in length and weigh as much as 30kg, is a carnivore with a pronounced lower jaw. Its fate is symptomatic of the extensive loss of biodiversity in the Mekong. Earlier this year the death of the last surviving cetacean known as the Mekong River dolphin in a stretch of the river in southern Laos raised alarms among conservationists.

At the same time, however, scientists have recently discovered a total of 224 species new to science in a series of finds in the Mekong in a testament to its great biodiversity. In all, 155 plants, 16 fish, 17 amphibians, 35 reptiles and one mammal were identified in Thailand, Cambodia, Laos, Myanmar and Vietnam by hundreds of scientists from across the globe.

Among the discoveries were a yellowish brown slug snake with unique scale patterns and a special bamboo in Laos (the first known case of succulence in bamboos), whose stem can inflate and deflate based on how much water is available to it.

“The Greater Mekong region is one of planet Earth’s most important biodiversity hotspots, highlighted by the endless number of new species discovered there every year,” the World Wide Fund for Nature says.