By james art The “Ghost of the Mekong” has reappeared. After nearly two decades without a trace, the elusive giant salmon carp (Aaptosyax grypus) has been spotted again in Cambodian waters, rekindling hope for the species’ survival and prompting calls for urgent conservation efforts in Southeast Asia’s Mekong River. The unusual fish, a hook-jawed carp with a salmon-shaped body, has not been documented since 2005.
An international team of scientists funded by the US Agency for International Development and working with the Cambodian Fisheries Administration has confirmed the existence of the giant salmon carp. Three fish were caught between 2020 and 2023, a significant discovery for a species previously thought to be extinct. The research, published in the journal Biological Conservation, highlights the need for innovative conservation strategies to protect not only salmon carp but also the wider Mekong ecosystem, which has been dubbed the ‘fish superhighway’ and is home to some of the most the largest freshwater fish on Earth.
“The rediscovery of the giant salmon carp is cause for hope not only for this species but for the entire Mekong ecosystem,” said Buniet Chan, lead researcher at Svay Rieng University in Cambodia. “The Mekong ecosystem is the most productive river on Earth, producing over two million tons of fish annually, valued at over $10 billion.”
Measuring up to 1.3 meters (4 feet) and weighing 30 kilograms (66 pounds), this critically endangered species is part of the “megafish” family of freshwater fish that exceed 30 kilograms. The fish is native to the Mekong and remains shrouded in mystery, with fewer than 30 individuals recorded since its official identification in 1991.
“Species like giant salmon carp are irreplaceable and without concerted action they could disappear forever.”
Like many of the Mekong‘As aquatic giants, carp face multiple threats. The discovery of these three individuals suggests that the species still has a foothold in the Mekong‘leads, but its future remains uncertain.
“Aaptosiax the numbers are very low and we don’t‘I don’t know how many populations remain or whether they are connected,” said Zeb Hogan, co-author of the study and director of the USAID-funded Wonders of the Mekong Program at the University of Nevada, Reno. “The rediscovery means that with coordinated international action it may still be possible to save the species from oblivion.”
Surprisingly, the three recent captures were made outside the species’ main range, in Cambodia‘s Sesan and Mekong Rivers‘Stung Treng Province. This unexpected finding suggests that the carp‘Its geographic range may be more extensive than previously thought, giving new hope for its survival.
To better understand the species’ range and behavior, researchers are advocating the use of non-invasive techniques, including environmental DNA analysis. This method allows scientists to detect the presence of the species through genetic material in water samples, offering a less destructive way to track the fish‘s distribution.
The scientists also call for continued community-engaged research. The USAID-funded Wonders of the Mekong program has successfully involved local fishermen in conservation efforts since the program began in 2017. By partnering with people who live along the Mekong and its tributaries, researchers hope to continue collecting important information on carp habitat and behavior.
“Local fishermen have invaluable ecological knowledge and could be instrumental in identifying key habitats and establishing conservation areas,” said Sébastien Brosse of the Université Paul Sabatier in France, one of the study’s‘s co-authors.
The wider Mekong River ecosystem is home to several other threatened species, such as the giant Mekong catfish and the giant freshwater stingray, which rely on the same fragile environment.
The catch of giant salmon carp is a powerful reminder of the rich biodiversity still present in the Mekong River. However, this biodiversity is under threat. Habitat degradation, overfishing and damming have caused widespread damage to the river and its species. Climate change is a new and growing threat as the region faces longer droughts and more severe flooding. To address these issues, scientists are calling for a comprehensive, multifaceted conservation strategy.
“Protecting its habitat would not only secure the future of this rare megafish, but could also support other threatened species in the region, contributing to the overall health of the Mekong‘freshwater biodiversity,” said co-author Michael Grant of the Australian Center for Sustainable Tropical Fisheries and Aquaculture.
Scientists emphasize the importance of conserving species such as the salmon carp, which is only found in the Mekong River.
“The Mekong’s biodiversity is truly unique, and we need to step up our efforts to study and protect it,” said Heng Kong, co-author of the study and director of the Cambodia Inland Fisheries Research Institute. “Species like giant salmon carp are irreplaceable and without concerted action they could disappear forever.”
Of the more than 1,100 species of fish in the Mekong, about 25 percent are found nowhere else on Earth. The Mekong River supports the largest inland fisheries in the world, supporting at least 40 million people.
As a result of the rediscovery, the Cambodian Fisheries Administration added the giant salmon carp to its list of protected species. Ultimately, the survival of the giant salmon carp — and the Mekong’s biodiversity — depends on coordinated efforts across borders, Hogan said.
“This discovery is a call to action to protect the Mekong River and its incredible fisheries and biodiversity,” Hogan said. “The survival of the giant salmon carp depends on the ability of governments, scientists and communities in the Mekong region to increase conservation efforts and work together.”