The following is a letter written by Mekong river expert and conservationist Alan Potkin submitted today to the Mekong River Commission’s online stakeholder consultation concerning the Don Sahong dam. The construction of the Don Sahong dam on the Mekong’s Hou Sahong channel in Siphandon, Laos is a project sparking extreme controversy in the Mekong region. Despite Vietnam’s and Cambodia’s condemnation of the dam along with a massively successful petition campaign gaining more than 250,000 signatures and increasing local and international coverage of the controversial project, construction for the dam is likely to begin by the end of the year.
Indeed “now is the time to separate fact from fiction”…
Notwithstanding his Googleable scientific publications being exclusively in quantitative algology, rather than in any aspect of ichthyology (not least fish taxonomy, physiology, and reproductive or migratory behaviors), I had consistently argued that we should accept that Dr Peter Hawkins, Don Sahong’s Environmental Manager, was speaking and acting in good faith until proven otherwise…
Until this latest announcement by him that the altered dry season hydrology above and below Siphandone, following the new release regime
from the Lançang Jiang cascade of hydropower dams in Yunnan PRC, will now make it “easier for fish to migrate” through alternate channels other than Hou Sahong during the dry season.
Well, maybe yes and maybe no.
According to years of fieldwork conducted there by Dr Tyson Roberts and Profs. Ian Baird and Water Rainboth, amongst others,
no less than 150 species of fish transit through, or are resident, in Siphandone. Other than their basic taxonomy, almost nothing is known in
sufficient empirical detail about any ofthem to understand exactly what ecological and behavioral cues initiate bi-directional migration and successful reproduction: Water temperature? Current velocity and/or stream stage? Phases of the moon? Subtle chemical alterations? Angle of the sun in the sky/polarization of insolation?
How much change in elevation per unit of lineal distance could be encompassed within a particular species’ genetically-determined
metabolic parameters and swimming musculature to still be a manageable pathway?
All essentially unknown!
The planet’s best understood migratory fishes are the salmonidae of the northern hemisphere, which in any given inland waterway probably never exceed four or five different species having themselves much in common. Yet even now ichthyologists are far from certain over exactly how salmonids are capable of navigating to, and infallibly identifying, precisely that reach of river/tributary wherein they were originally spawned, perhaps even a decade earlier, with most of those intervening years as adults spent offshore in the oceans.
And if any or all of that that were known in exact and correct detail about one or two or three of the most economically and nutritionally
important Mekong species, there would yet be another 140 species, at least, which might be responding to completely different sets of stimulae and environmental cues.
I would be delighted to have these assertions proven false by aquatic ecologists holding credible expertise far greater than my own.
Once again, I would note that available to whomever might successfully navigate far upstream into several of our interactive eBooks, notably
“Mekong-Orwell” —mostly about the Pak Mun debate Xayaboury and Don Sahong— there are linked online videos showing the
rather underdeveloped state-of-the-art of “fish friendly” turbines, and showing the general impassibility of even a 70cm artificial obstruction erected across the migratory pathways of one of the most robust and powerful N. American fish species, but one which lacks any evolutionary history of jumping.
Thanks as always, for all due consideration.
Access the interactive media links below to learn more about Alan Potkin’s work on Mekong issues.