In April of 2022, Lao and Australian researchers anesthetized more than 230 fish, inserted small glass tubes containing tracking devices into their guts and once revived released them into the Mekong River near Vientiane in Laos.
More than a year later, five of the fish were detected by a sensor at the top of the contentious Xayaburi dam, far upstream from Vientiane, according to a study funded by Australia’s international aid budget published in June.
To get there, they swam about 350 kilometers [217 miles] and once in the vicinity of the enormous dam, found an entrance to its gradually ascending 480 meter-long fish ladder, reached the end of it without being devoured by bigger fish and then waited in a lock until hitching a ride up to the reservoir.
The five fish were all Goldfin tinfoil barbs, a species that is economically important for Mekong livelihoods and which comprised a third of the fish released by the researchers.
The results, the study concluded, showed the importance of including fish passages like that at Xayaburi in new dams built across the Mekong. The river, Southeast Asia’s longest, sustains a rice bowl delta, the world’s largest inland fishery and the livelihoods of tens of millions of people in Laos, Vietnam, Cambodia and Thailand.
At the heart of the research, however, is a fundamental conflict of interest.
The fish detection data was supplied by Thailand’s CK Power, the operator and major shareholder of the Xayaburi dam, which has a vested interest in results or conclusions that support its plans for more hydropower dams on the Mekong.
Two of the top Mekong experts, who were not involved in the study, told RFA that the results support another conclusion: no more dams should be built on the river.
The health of the Mekong’s fisheries is in large degree tied, many researchers say, to the ability of the hundreds of species of fish to migrate and complete their reproductive cycles unhindered. Dams are also problematic because they block the sediment that nourishes and keeps intact the Mekong Delta –a highly productive rice bowl.
A report this month by the International Crisis Group red flagged the possibility of large migrations of people and increased social tensions in parts of Southeast Asia in future decades if fish populations and rice growing are compromised by Mekong dams.
Three further dams have been approved by Laos for the stretch of river traveled by the fish and another north of Xayaburi, the Luang Prabang dam, now under construction by CK Power.
“It is hard to assess the capacity of the Xayaburi dam’s fish pass to allow fish to pass based on this study, and in fact, I don’t think that is the main point of the paper,” said Ian Baird, a Mekong fisheries researcher at the University of Wisconsin.
“The main point is that fish migrate past places where future dams are located, which indicates that the impacts of those dams on fish need to be carefully considered,” he said.
“I would recommend that no more Mekong dams be built, but that is not a point that the authors of the paper make.”
Three executives at CK Power, including its communications and sustainability chief Tuangporn Bunyasaranand, did not respond to questions about the study, including: if and how the researchers were able to independently verify the data provided by CK Power and whether the company will share the results of other Mekong fish tagging carried out under the multi-year research program, which totals about 3,500 fish.
The study says none of its authors have any competing interests. One of the authors is a senior executive at CK Power. His contribution to the research is not defined whereas the roles of the other authors is.
Another author is the owner of an Australian company that supplies fish-tracking technology including the type used in the study, which also recommended the tracking research be carried out for another decade.
Despite the study being publicly funded, the researchers can’t comment on it because of intellectual property agreements, one of the authors told RFA. The data, the person said, is owned by CK Power.
This person provided other information that purported to cast the results in a positive light, but said they could not be quoted because of the intellectual property agreements.
The lead researcher, Lee Baumgartner of Australia’s Charles Sturt University, did not respond to emailed questions or phone calls.
Philip Hirsch, a human geography professor at University of Sydney who has carried out Mekong research since the 1980s, said it was problematic that the study does not question or provide independent verification of the data supplied by the hydropower company.
“This is publicly funded research, published in a peer-reviewed scientific journal, so it is important to ensure that the results and their interpretations are backed up by data that has been acquired with an appropriate degree of transparency,” he said.
It is also contentious that public money is funding research for a profit-driven enterprise, which the researchers told RFA claims the research as its intellectual property, Hirsch added.
However, he said he surmises the fish detection data may well be accurate because in his view it is not very impressive.
Since only 6.5% of the released fish reportedly made it past the Xayaburi dam, any further dams on that route would reduce that small fraction still further.
That would be the case even if something like 50% or 60% of fish could get past a dam, since each successive dam would quickly whittle down the proportion that completes the entire journey to a single-digit percentage.
“For me, this is the major argument against any further blockage of an already seriously – and from an energy demand perspective unnecessarily – damaged river system,” Hirsch said.
There are also other factors that further compound the challenges, he said. For example, fish passages are for upstream migration but fish as well as their larvae also move downstream.
Other research has shown that pressure changes inside the dams cause fish organs to implode as they are sucked along by the velocity of water heading to the turbines. Turbine-blade strike is also a cause of fish deaths.
Australia’s Center for International Agricultural Research, or ACIAR, which administered the A$1.9 million (US$1.3 million) funding for the research from 2019 to mid-2024, has said more than 3,500 fish were tagged.
It could not explain why only results for some 230 fish were available. A spokesman said the agency would ask the researchers but provided no further information after two days.
The research program has been allocated A$5.9 million of new funding to continue until 2029.
Its thrust appears to be enabling further Mekong dams despite also bemoaning their risks.
ACIAR’s description says the research aims to evaluate the effectiveness of fish passages, minimize the potentially harmful impacts of hydropower projects and influence the design of future dams.
That approach is consistent with the priorities of governments in the region, which have given precedence to nationalistic projects and the narrow interests of dam builders at the expense of the broader interests of the lower Mekong basin.
Over the objections of neighbors, Laos pressed ahead with Xayaburi, commissioned in 2019, and the Don Sahong dam. Cambodia, meanwhile, began construction this year of a 180-kilometer (112-mile) canal that will link a tributary of the Mekong to the Gulf of Thailand, raising concerns in Vietnam about reduced water flow into the rice-growing delta.
Research into the effectiveness of the Xayaburi fish passage also has inherent limitations because of the dearth of pre-dam data.
“One species passing the Xayaburi Dam really does not say much about the success or failure of the fish pass,” said Baird, the University of Wisconsin professor.
“There was not sufficient baseline fish data collected before the Xayaburi dam was built to really assess how well the fish pass works.”
Edited by Taejun Kang.