Tag Archives: fish ladders

Letter to the Mekong River Commission on the Don Sahong Dam

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.
http://www.sethathirath.com/mekong_actual_outcomes1.final_cfp.pdf
http://www.sethathirath.com/nam_phit/digital_mekong_planning.pdf
http://www.sethathirath.com/mekong_orwell_eBook/pak_mun_homepages.pdf
http://www.sethathirath.com/mekong_fish_atlas_4.1/welcome.pdf
http://sethathirath.com/EFDNW_UNESCO_1.4.1/nongchanh%20interactive/EFDNW_poster/nongchanh_poster_homepage.pdf
http://vimeo.com/86935784

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Filed under Cambodia, Current Events, Laos, Malaysia, Mekong River, SLIDER, Sustainability and Resource Management, Vietnam, water

Biodiversity in China’s Rivers Under Extreme Threat

As a result of decades of unchecked development and poor decision making, China’s inland rivers are suffering a crisis and are in the midst of severe losses of biodiversity.  Currently there is a serious lack of conservation measures and a shortage of funding to protect endangered aquatic species.

According to an expert from Changjiang Fishery Resources Managing Committee, there used to be more than 1,100 species in the Yangtze River, including more than 370 fish species, over 220 zoobenthos (organisms which live on the riverbed), and hundreds of aquatic plants. The rapid development of economic zones in the Yangtze River basin has caused a rapid decline in aquatic biological resources. Now many species like the Chinese river dolphin and the Chinese paddlefish face extinction.  The famous Reeves’ Shad, once important to local fisheries, has not been seen for many years. “Living fossils” such as the Chinese sturgeon have also rapidly decreased in numbers and at an even faster pace.

It is baffling to me that when we were initially constructing the Three Gorges Dam, we didn’t learn from the experiences of developed countries that built fish ladders for migratory fish. Even Vietnam and Laos, our neighbors to the south are installing fish ladders in their new hydropower projects.  Since the formation of the Three Gorges Reservoir, the dam has blocked the migratory routes that the fish need in order to reproduce.  The “transform rivers into lakes” strategy seeks to inundate rapids and exposed shoals in the river to promote for the safe passage of ships, but many fish that are used to living in the rapids are gradually migrating upstream resulting in a reshuffling of river basin ecosystems.  The dam has also had a major impact on yearly fish catches. During this year’s rare summer droughts, thousands of fishermen along the water basin were left with empty nets. Continue reading

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Filed under China, Energy, Environment and sustainability, Governance, water