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1
Stone, R. "Dam-building threatens Mekong fisheries." Science 354, no. 6316 (December 1, 2016): 1084–85. http://dx.doi.org/10.1126/science.354.6316.1084.
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Vu, An V., Kent G. Hortle, and Du N. Nguyen. "Factors Driving Long Term Declines in Inland Fishery Yields in the Mekong Delta." Water 13, no. 8 (April 7, 2021): 1005. http://dx.doi.org/10.3390/w13081005.
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The Mekong basin’s fisheries are important sources of food, income, and livelihoods for millions of people in six countries. However, fish yields appear to have declined in recent years according to reports from local fishers throughout the basin. It is important to understand the factors driving the decline in fisheries so that they can be adequately managed. We analysed interview data from 1020 fishers in the Mekong Delta in Vietnam in 2014 to identify trends in catch rates and the possible factors driving the trends. Most of the fishers (68–90%) reported that their catch rates had declined over the previous five years, although some fishers stated that their fish catches had remained stable or even increased. They identified eleven factors that they believed contribute to declines in fish catches, among which the use of illegal gears and overfishing were considered most important, with other factors relatively unimportant. Separately, long-term datasets (1995–2016) showed a general decline in commercial fish catches, which was positively correlated with peak water levels (which indicate flood levels), and negatively correlated with the intensification of rice farming, especially where flooding has been prevented to allow a third annual rice crop. Some data suggests that fishing effort has declined significantly in recent years, so an apparent downward trend in catches is not likely to be a result of overfishing as believed by fishers, which suggests that fishers are not aware of or under-rate the significance of hydrological and land-use/landscape changes. Due to the exceptional importance of the Mekong fishery and the interactions with other more dominant sectors, improved data collection is required to quantify changes in fisheries that result from land use and hydrological changes, and to guide planning which would better resolve competing demands for water and land use.
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Baran, E., and C. Myschowoda. "Dams and fisheries in the Mekong Basin." Aquatic Ecosystem Health & Management 12, no. 3 (September 24, 2009): 227–34. http://dx.doi.org/10.1080/14634980903149902.
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Friend, Richard M., and David J. H. Blake. "Negotiating trade-offs in water resources development in the Mekong Basin: implications for fisheries and fishery-based livelihoods." Water Policy 11, S1 (March 1, 2009): 13–30. http://dx.doi.org/10.2166/wp.2009.001.
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A revitalised hydropower development narrative is emerging in the Mekong in which the concept of ‘trade-offs’ plays a central role. The importance of and risks to capture fisheries in the Mekong is such that any degradation has huge social, economic and environmental implications. While potential impacts of hydropower development on capture fisheries are acknowledged in this emerging narrative, it is argued that these are less than anticipated previously, that impacts can be assessed, mitigation measures introduced and trade-offs negotiated. The concept of trade-offs has an immediate appeal but it is also problematic. It draws attention away from considering development objectives and options towards focusing on impacts, and infers a technical approach as opposed to a political process of decision making. This paper draws on anthropological approaches to development policy to consider the implications of a hydropower narrative based on trade-offs in light of experience in the Mekong Basin, and to consider alternative ways of framing debate on hydropower and capture fisheries.
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Bush, Simon R. "Contextualising fisheries policy in the Lower Mekong Basin." Journal of Southeast Asian Studies 39, no. 3 (September 11, 2008): 329–53. http://dx.doi.org/10.1017/s0022463408000349.
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AbstractDevelopment policies for fishery resources within the Mekong River Basin are increasingly divided between aquaculture and capture fisheries. The modern production orientation of aquaculture has been adopted by government and NGOs and justified by the rhetoric of poverty alleviation and rural development. In contrast, capture fisheries has been subjugated as an activity that reaffirms the dependency of the rural poor on natural resources. This paper critically analyses the division between aquaculture and capture fisheries in Cambodia, Thailand and Lao PDR by tracing the emergence and influence of ‘development narratives’ used to justify contemporary policy and practice.
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SNEDDON, CHRISTOPHER, and COLEEN FOX. "Inland Capture Fisheries and Large River Systems: A Political Economy of Mekong Fisheries." Journal of Agrarian Change 12, no. 2-3 (March 5, 2012): 279–99. http://dx.doi.org/10.1111/j.1471-0366.2011.00350.x.
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Jensen, J. G. "Managing fish, flood plains and food security in the Lower Mekong Basin." Water Science and Technology 43, no. 9 (May 1, 2001): 157–64. http://dx.doi.org/10.2166/wst.2001.0529.
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The “Lower Mekong Basin” in this paper refers to the part of the Mekong River Basin which is shared by Cambodia, Laos, Thailand and Viet Nam, all members of the Mekong River Commission, consisting of approx. 2,400 km of mainstream river, numerous tributaries and huge flood plains. Few river basins produce as much fish as the Mekong River Basin, and the fishery in the Lower Mekong Basin is among the biggest and most productive inland fisheries in the world. The flood plains of the Lower Mekong produce some four times as much fish per square kilometre as the North Sea, which is among the most productive marine areas in the world. It is quite clear that the fisheries in the Mekong Basin are very important for the population in respect to their food security and income. Its importance in nutrition is highest in the rural areas, where there are few other low cost sources of protein, and even in highland areas fish is of crucial importance in the diet. Most fish species in the Mekong Basin are migratory, and the economically most important ones are certainly so. However, with economic development gaining speed, the impact on migratory patterns and the competition for the water resources are becoming stronger. The water resources offer a large number of opportunities, and a lot of economic activities need access to the water resources for their development. However, what is seen in one sector as an opportunity may be considered as a threat in another, and a careful balance is necessary in order not to lose opportunities in important sectors. The fate of a large number of river basins in the world is frightening. Most have been left biologically near dead, with some of the big rivers reduced for a time, or forever, to be used as waste water canals for the new industries, and others almost dried out from excessive water extraction before they reach the sea.
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Yoshida, Yuichiro, Han Soo Lee, Bui Huy Trung, Hoang-Dung Tran, Mahrjan Keshlav Lall, Kifayatullah Kakar, and Tran Dang Xuan. "Impacts of Mainstream Hydropower Dams on Fisheries and Agriculture in Lower Mekong Basin." Sustainability 12, no. 6 (March 19, 2020): 2408. http://dx.doi.org/10.3390/su12062408.
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The riverine ecosystems of the Mekong River Basin possess the world’s most productive inland fishery and provide highly productive food crops for millions of people annually. The development of hydropower potential in the Mekong River has long been of interest to governments in the region. Among the existing 64 dams, 46 dams have been built in the Lower Mekong Basin (LMB) to produce up to 8650 MW of electricity. Additionally, of the 123 proposed built hydropower dams, eleven hydropower plants have been nominated for the river mainstream and are expected to install a total of 13,000 MW in the LMB countries. However, serious concerns have intensified over the potential negative economic consequences, especially on fisheries and agriculture in Cambodia and Vietnam. To date, most of the concerns have concentrated on the impacts on hydrology, environment, livelihood, and diversity in the LMB attributed to hydropower development. This paper, however, discusses the fishery and agricultural sectors of the LMB and focuses on the downstream floodplains of Cambodia and Vietnam. The dam construction has caused greater losses of biodiversity and fisheries than climate change in the LMB. The reduction of 276,847 and 178,169 t of fish, 3.7% and 2.3% of rice, 21.0% and 10.0% of maize will contribute to a decrease of 3.7% and 0.3% of the GDP of Cambodia and Vietnam, respectively. Lao PDR may benefit the most revenue from electricity generation than the other country in the LMB, as most of the proposed dams are projected in the country. Cambodia burdens 3/4 of the reduction of total capture fishery destruction, whilst Lao PDR, Thailand, and Vietnam endure the remaining 1/3 losses. The tradeoff analyses reveal that losses of capture fisheries, sediment or nutrients, and social mitigation costs are greater than the benefits from electricity generation, improved irrigation, and flood control of the LMB region. The socioeconomic and environmental damage caused by hydropower dams in developing countries, including the Mekong, is greater than the early costs in North America and Europe. It is proposed that dam construction for hydropower in the Mekong River, as well as other rivers in developing countries, should be gradually removed and shifted toward solar, wind, and other renewable resources.
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Linh, Vo Le Gia. "Describing Urban Artisanal Fisheries in Vietnam's Lower Mekong River: A Student's Ventures into Fisheries Science." Fisheries 41, no. 9 (August 24, 2016): 519–23. http://dx.doi.org/10.1080/03632415.2016.1210966.
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Schmitt, R. J. P., S. Bizzi, A. Castelletti, J. J. Opperman, and G. M. Kondolf. "Planning dam portfolios for low sediment trapping shows limits for sustainable hydropower in the Mekong." Science Advances 5, no. 10 (October 2019): eaaw2175. http://dx.doi.org/10.1126/sciadv.aaw2175.
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The transboundary Mekong Basin has been dubbed the “Battery of Southeast Asia” for its large hydropower potential. Development of hydropower dams in the six riparian countries proceeds without strategic analyses of dam impacts, e.g., reduced sediment delivery to the lower Mekong. This will impact some of the world’s largest freshwater fisheries and endangers the resilience of the delta, which supports 17 million livelihoods, against rising sea levels. To highlight alternatives, we contribute an optimization-based framework for strategic sequencing of dam development. We quantify lost opportunities from past development and identify remaining opportunities for better tradeoffs between sediment and hydropower. We find that limited opportunities remain for less impactful hydropower in the lower basin, where most development is currently planned, while better trade-offs could be reached with dams in the upper Mekong in China. Our results offer a strategic vision for hydropower in the Mekong, introduce a globally applicable framework to optimize dam sequences in space and time, and highlight the importance of strategic planning on multiple scales to minimize hydropower impacts on rivers.
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Pin, Kakada, Savat Nut, Zeb Hogan, Sudeep Chandra, Samadee Saray, Bunthang Touch, Phen Chheng, and Peng Ngor. "Cambodian Freshwater Fish Assemblage Structure and Distribution Patterns: Using a Large-Scale Monitoring Network to Understand the Dynamics and Management Implications of Species Clusters in a Global Biodiversity Hotspot." Water 12, no. 9 (September 8, 2020): 2506. http://dx.doi.org/10.3390/w12092506.
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Mekong River Basin is one of the world’s fish biodiversity hotspots. Fisheries of the Cambodian Mekong are characterized by high diversity and productivity. However, few studies have focused on broad scale patterns and fish assemblage structure of this important system at a national level. Here, we describe spatial and seasonal variation in fish assemblages by analyzing one year of daily fish catch data sampled at 32 sites covering Cambodia’s main inland water bodies. We recorded 125 fish species. Four clusters were distinguished based on assemblage composition similarity, and 95 indicator species were identified to characterize each of the identified assemblage clusters. High diversity fish assemblages were associated with the upper Mekong system and Mekong/Bassac/Tonle Sap Rivers in Kandal Province and southern Tonle Sap Lake while lower diversity assemblages were observed in the Mekong River in Kratie and the northern area of the Tonle Sap Lake. We find significant variation in the assemblage composition between wet and dry seasons, indicating strong seasonal species turnover within clusters. Length–weight relationship analysis indicated a negative allometric growth among a majority of indicator species, reflecting suboptimal conditions for growth. Our study establishes contemporary structure and diversity patterns in the Lower Mekong River system of Cambodia, which can be used to map fish biodiversity hotspots and assess key indicative fish stocks’ statuses for conservation and management.
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Baumgartner, Lee J., Craig A. Boys, Chris Barlow, and Mike Roy. "Lower Mekong Fish Passage Conference: Applying innovation to secure fisheries productivity." Ecological Management & Restoration 18, no. 3 (September 2017): E8—E12. http://dx.doi.org/10.1111/emr.12272.
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Huynh, Van Da, Awais Piracha, and Hayley Saul. "Impact of Climate Change to Tourism Sector in the Vietnamese Mekong Delta." Review of European Studies 11, no. 4 (November 6, 2019): 44. http://dx.doi.org/10.5539/res.v11n4p44.
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Mekong Delta Region of Vietnam is forecasted to have one of world’s most severe impacts from climate change. There is a big knowledge gap in research on climate change impacts on tourism in this area. While climate change’s impacts on agriculture and fisheries have received much attention from authorities and researchers, impacts on tourism have largely been ignored. This paper presents findings from a field study the authors conducted to fill the research gap on climate change’s impact on tourism in Mekong River Delta. The study based on spatial analysis and questionnaires and interviews of local tourism leaders, tourism businesses and tourists discovered that climate change is a real challenge for region’s tourism businesses. Vulnerable tourism businesses in low and flat delta such as Mekong needs more attention and practical actions from international organizations and local entities in the era of climate change threats.
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Patricio, Harmony C., Stephen A. Zipper, Matthew L. Peterson, Shaara M. Ainsley, Erin K. Loury, Sinsamout Ounboundisane, and Doug B. Demko. "Fish catch and community composition in a data-poor Mekong River subcatchment characterised through participatory surveys of harvest from an artisanal fishery." Marine and Freshwater Research 70, no. 2 (2019): 153. http://dx.doi.org/10.1071/mf17338.
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Many inland artisanal fisheries have not been surveyed by scientists. In this study we used some participatory research methods to characterise a data-poor fishery in a tributary of the Mekong River. Sixteen local villagers from four villages were trained to record harvest data along a 25-km reach of the lower Nam Kading River. Catch records included 65 fish genera representing at least 93 species, with 11 species of concern on the IUCN Red List. During 894 individual fisher landing surveys, a total of 1433.8kg of fish catch was reported. The majority of fishers (87%) used nets, and the catch per unit effort with gill-nets averaged 66g net–1h–1. Analysis revealed differences in catch rates and the genus assemblage among villages. High levels of diversity, and the presence of species assessed as endangered by the IUCN Red List, highlight the need for further studies and conservation interventions in the area. The National Fisheries Law in Lao PDR provides a unique opportunity for co-management, because shared management between civil society and government is written into the law and implemented extensively. Participatory research activities can serve as a bridge for communities to engage with government to inform fisheries management.
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Ringler, Claudia, and Ximing Cai. "Valuing Fisheries and Wetlands Using Integrated Economic-Hydrologic Modeling—Mekong River Basin." Journal of Water Resources Planning and Management 132, no. 6 (November 2006): 480–87. http://dx.doi.org/10.1061/(asce)0733-9496(2006)132:6(480).
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ADAMSON, ELEANOR A. S., RALF BRITZ, and SOPHA LIENG. "Channa auroflammea, a new species of snakehead fish of the Marulius group from the Mekong River in Laos and Cambodia (Teleostei: Channidae)." Zootaxa 4571, no. 3 (March 27, 2019): 398. http://dx.doi.org/10.11646/zootaxa.4571.3.7.
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Channa auroflammea is a new freshwater fish species of the Marulius group from the Mekong River system. Previously reported as C. marulius, C. cf. marulius, or C. aff. marulius, C. auroflammea is readily distinguished from C. marulius and other members of the Marulius group by a different colour pattern, and a DNA barcode sequence at least 6.5% divergent from other members of the group. Comparison of counts of vertebrae, dorsal-fin rays, and lateral-line scales reveals that these counts are lower in the Mekong C. auroflammea than in C. aurolineata from the Salween and Irrawaddy-Chindwin, higher than in the Marulius group species C. pseudomarulius and C. marulioides, but similar to those in C. marulius. Channa auroflammea is known from the Mekong river and tributaries in Laos and Cambodia, where it forms a regular component of the wild fisheries catch from the rivers Tonle San and Tonle Srepok. Literature records of Channa marulius from China appear to be based on confusion originating with Cuvier’s description of Ophiocephalus grandinosus.
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Pokhrel, Yadu, Mateo Burbano, Jacob Roush, Hyunwoo Kang, Venkataramana Sridhar, and David Hyndman. "A Review of the Integrated Effects of Changing Climate, Land Use, and Dams on Mekong River Hydrology." Water 10, no. 3 (March 3, 2018): 266. http://dx.doi.org/10.3390/w10030266.
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The ongoing and proposed construction of large-scale hydropower dams in the Mekong river basin is a subject of intense debate and growing international concern due to the unprecedented and potentially irreversible impacts these dams are likely to have on the hydrological, agricultural, and ecological systems across the basin. Studies have shown that some of the dams built in the tributaries and the main stem of the upper Mekong have already caused basin-wide impacts by altering the magnitude and seasonality of flows, blocking sediment transport, affecting fisheries and livelihoods of downstream inhabitants, and changing the flood pulse to the Tonle Sap Lake. There are hundreds of additional dams planned for the near future that would result in further changes, potentially causing permanent damage to the highly productive agricultural systems and fisheries, as well as the riverine and floodplain ecosystems. Several studies have examined the potential impacts of existing and planned dams but the integrated effects of the dams when combined with the adverse hydrologic consequences of climate change remain largely unknown. Here, we provide a detailed review of the existing literature on the changes in climate, land use, and dam construction and the resulting impacts on hydrological, agricultural, and ecological systems across the Mekong. The review provides a basis to better understand the effects of climate change and accelerating human water management activities on the coupled hydrological-agricultural-ecological systems, and identifies existing challenges to study the region’s Water, Energy, and Food (WEF) nexus with emphasis on the influence of future dams and projected climate change. In the last section, we synthesize the results and highlight the urgent need to develop integrated models to holistically study the coupled natural-human systems across the basin that account for the impacts of climate change and water infrastructure development. This review provides a framework for future research in the Mekong, including studies that integrate hydrological, agricultural, and ecological modeling systems.
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Navy, Hap, and Madhusudan Bhattarai. "Economics and livelihoods of small-scale inland fisheries in the Lower Mekong Basin: a survey of three communities in Cambodia." Water Policy 11, S1 (March 1, 2009): 31–51. http://dx.doi.org/10.2166/wp.2009.002.
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This paper presents economic analysis, viability and trade-off issues for small-scale (family) inland capture fisheries in three fishing communities, each representing a distinct floodplain characteristic in Cambodia. The average net profits of family fishing was US$12 and US$4.6 per trip during the open (October to May) and close (June to September) seasons, respectively; but real profit—deducting the cost for family labour from net profit—was only US$4.5 and US$1.6 during the open and close seasons, respectively. The return from family fishing varied greatly across sites surveyed, depending on the quality of the fishing grounds, hydro-ecology settings, local institutions, and socio-economic factors. The high degree of seasonality, the spatial variation of returns and costs of capture fisheries suggest interdependence of fishing activities with basin-level water allocation policies, and also related trade-off in the fisheries sector with water allocation and water resources management policies. There is also now an urgent need for synergy of the various rural development efforts with that of fisheries policies in the Mekong River Basin.
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Lynch, Abigail J., Lee J. Baumgartner, Craig A. Boys, John Conallin, Ian G. Cowx, C. Max Finlayson, Paul A. Franklin, et al. "Speaking the same language: can the sustainable development goals translate the needs of inland fisheries into irrigation decisions?" Marine and Freshwater Research 70, no. 9 (2019): 1211. http://dx.doi.org/10.1071/mf19176.
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Irrigated agriculture and inland fisheries both make important contributions to food security, nutrition, livelihoods and wellbeing. Typically, in modern irrigation systems, these components operate independently. Some practices, commonly associated with water use and intensification of crop production can be in direct conflict with and have adverse effects on fisheries. Food security objectives may be compromised if fish are not considered in the design phases of irrigation systems. The 2030 Agenda for Sustainable Development provides a framework that can serve as a backdrop to help integrate both sectors in policy discussions and optimise their contributions to achieving the Sustainable Development Goals (SDGs). Inland fisheries systems do play an important role in supporting many SDG objectives, but these contributions can sometimes be at odds with irrigated agriculture. Using case studies of two globally important river catchments, namely the Lower Mekong and Murray–Darling basins, we highlight the conflicts and opportunities for improved outcomes between irrigated agriculture and inland fisheries. We explore SDG 2 (Zero Hunger) as a path to advance our irrigation systems as a means to benefit both agriculture and inland fisheries, preserving biodiversity and enhancing the economic, environmental and social benefits they both provide to people.2
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Kelson, Suzanne J., Zeb Hogan, Christopher L. Jerde, Sudeep Chandra, Peng Bun Ngor, and Aaron Koning. "Fishing Methods Matter: Comparing the Community and Trait Composition of the Dai (Bagnet) and Gillnet Fisheries in the Tonle Sap River in Southeast Asia." Water 13, no. 14 (July 9, 2021): 1904. http://dx.doi.org/10.3390/w13141904.
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The Tonle Sap Lake and River ecosystem in the Lower Mekong Basin of Southeast Asia is one of the most productive inland fisheries globally but is currently threatened by overfishing, dam construction, and climate change. We compare the catch composition and amount from 2007–2013 of two fishery gear types, the bagnets of the largest commercial fishery, the Dai fishery, and gillnets, which are deployed ubiquitously by independent fishers. We found that the two methods captured a similar number of genera (81 and 88 in the Dai and gillnet). Catches of both fisheries were dominated (>75%) by three genera that migrate longitudinally, Henicorhynchus, Labiobarbus, and Paralaubuca. The catch of the Dai fishery followed annual variation in the flood pulse extent, but the gillnet catch did not. We used resource selection ratios to quantify selection pressure by the gillnet fishery, relative to the Dai fishery, on fish from different genera and trait groups. The gillnet selected for fish that migrate laterally from the floodplain to the main river and for higher trophic level fish. Gillnets may target groups of fish that are less impacted by the long-standing Dai fishery. For both fisheries, we note a need for monitoring fish lengths in order to understand the effects of selection on population dynamics and species-specific trait changes.
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Nuon, Vanna, Sovan Lek, Peng Bun Ngor, Nam So, and Gaël Grenouillet. "Fish Community Responses to Human-Induced Stresses in the Lower Mekong Basin." Water 12, no. 12 (December 15, 2020): 3522. http://dx.doi.org/10.3390/w12123522.
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The Mekong River is one of the world’s largest rivers and has an annual captured fish production of about 2.3 million tonnes, equivalent to around 11 billion USD. Although the Mekong provides important ecological and socioeconomic benefits to millions of people, it is facing intensive change due to anthropogenic stressors. Therefore, it is necessary to understand the changes to the spatiotemporal fish communities to inform sustainable fisheries management. Here, we aimed to characterize patterns of the fish communities and identify the ecological status of each fish community using daily catch data from 2007 to 2018 at 25 monitoring sites in the Lower Mekong Basin (LMB). The collected data were classified by a self-organizing map into four main groups. Group 4 represented the lower Vietnam Mekong Delta (VMD), while groups 1, 2, and 3 were subdivided into subgroups 1a (upper LMB), 1b (upper and middle LMB), 2a (Mekong River below the Khone Falls and Sesan River), 2b (Mekong River below the Khone Falls and Sekong, Sesan and Srepok (3S) Rivers), 3a (Floodplain-Tonle Sap and Songkhram) and 3b (upper VMD). Among the 571 species recorded, 119 were identified as indicator species. Based on the abundance and biomass comparison curves, the fish community of 2b was in a healthier condition with a positive W-statistic value while the rest had a negative W-statistic value. The highest species richness and diversity were observed in 3a and 2b, so these subgroups deserve high management and conservation priority. Likewise, 1a should also be considered as a high priority area since it harbors several endangered and long-distant migratory fishes. It was also noticed that the fish communities of groups 3 and 4, located far from the hydropower dams, remained mostly unchanged compared to those of groups 1 and 2, close to the mainstream and tributary dams in the upper LMB and 3S Rivers.
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Arias, M. E., T. Piman, H. Lauri, T. A. Cochrane, and M. Kummu. "Dams on Mekong tributaries as significant contributors of hydrological alterations to the Tonle Sap Floodplain in Cambodia." Hydrology and Earth System Sciences 18, no. 12 (December 18, 2014): 5303–15. http://dx.doi.org/10.5194/hess-18-5303-2014.
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Abstract. River tributaries have a key role in the biophysical functioning of the Mekong Basin. Of particular interest are the Sesan, Srepok, and Sekong (3S) rivers, which contribute nearly a quarter of the total Mekong discharge. Forty two dams are proposed in the 3S, and once completed they will exceed the active storage of China's large dam cascade in the Upper Mekong. Given their proximity to the Lower Mekong floodplains, the 3S dams could alter the flood-pulse hydrology driving the productivity of downstream ecosystems. Therefore, the main objective of this study was to quantify how hydropower development in the 3S, together with definite future (DF) plans for infrastructure development through the basin, would alter the hydrology of the Tonle Sap's Floodplain, the largest wetland in the Mekong and home to one of the most productive inland fisheries in the world. We coupled results from four numerical models representing the basin's surface hydrology, water resources development, and floodplain hydrodynamics. The scale of alterations caused by hydropower in the 3S was compared with the basin's DF scenario driven by the Upper Mekong dam cascade. The DF or the 3S development scenarios could independently increase Tonle Sap's 30-day minimum water levels by 30 ± 5 cm and decrease annual water level fall rates by 0.30 ± 0.05 cm day−1. When analyzed together (DF + 3S), these scenarios are likely to eliminate all baseline conditions (1986–2000) of extreme low water levels, a particularly important component of Tonle Sap's environmental flows. Given the ongoing trends and large economic incentives in the hydropower business in the region, there is a high possibility that most of the 3S hydropower potential will be exploited and that dams will be built even in locations where there is a high risk of ecological disruption. Hence, retrofitting current designs and operations to promote sustainable hydropower practices that optimize multiple river services – rather than just maximize hydropower generation – appear to be the most feasible alternative to mitigate hydropower-related disruptions in the Mekong.
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Arias, M. E., T. Piman, H. Lauri, T. A. Cochrane, and M. Kummu. "Dams on Mekong tributaries as significant contributors of hydrological alterations to the Tonle Sap Floodplain in Cambodia." Hydrology and Earth System Sciences Discussions 11, no. 2 (February 18, 2014): 2177–209. http://dx.doi.org/10.5194/hessd-11-2177-2014.
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Abstract. River tributaries have a key role in the biophysical functioning of the Mekong Basin. Of particular attention are the Sesan, Srepok, and Sekong (3S) rivers, which contribute nearly a quarter of the total Mekong discharge. Forty two dams are proposed in the 3S, and once completed they will exceed the active storage of China's large dam cascade in the upper Mekong. Given their proximity to the lower Mekong floodplains, the 3S dams could alter the flood-pulse hydrology driving the productivity of downstream ecosystems. Therefore, the main objective of this study was to quantify how hydropower development in the 3S would alter the hydrology of the Tonle Sap floodplain, the largest wetland in the Mekong and home to one of the most productive inland fisheries in the world. We coupled results from four numerical models representing the basin's surface hydrology, water resources development, and floodplain hydrodynamics. The scale of alterations caused by hydropower in the 3S was compared with the basin's definite future development scenario (DF) driven by the upper Mekong dam cascade. The DF or the 3S development scenarios could independently increase Tonle Sap's 30 day minimum water levels by 30 ± 5 cm and decrease annual water level fall rates by 0.30 ± 0.05 cm d−1. When analyzed together (DF + 3S), these scenarios are likely to eliminate all baseline conditions (1986–2000) of extreme low water levels, a~particularly important component of Tonle Sap's environmental flows. Given the ongoing trends and large economic incentives in the hydropower business in the region, there is a high possibility that most of the 3S hydropower potential will actually be exploited and that dams would be built even in locations where there is a high risk of ecological disruptions. Hence, retrofitting current designs and operations to promote sustainable hydropower practices that optimize multiple river services – rather than just maximize hydropower generation – appear to be the most feasible alternative to mitigate hydropower-related disruptions in the Mekong.
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Cochrane, T. A., M. E. Arias, and T. Piman. "Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap system." Hydrology and Earth System Sciences 18, no. 11 (November 17, 2014): 4529–41. http://dx.doi.org/10.5194/hess-18-4529-2014.
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Abstract. The rapid rate of water infrastructure development in the Mekong Basin is a cause for concern due to its potential impact on fisheries and downstream natural ecosystems. In this paper, we analyze the historical water levels of the Mekong River and Tonle Sap system by comparing pre- and post-1991 daily observations from six stations along the Mekong mainstream from Chiang Saen (northern Thailand), to Stung Treng (Cambodia), and the Prek Kdam station on the Tonle Sap River. Observed alterations in water level patterns along the Mekong are linked to temporal and spatial trends in water infrastructure development from 1960 to 2010. We argue that variations in historical climatic factors are important, but they are not the main cause of observed changes in key hydrological indicators related to ecosystem productivity. Our analysis shows that the development of mainstream dams in the upper Mekong Basin in the post-1991 period may have resulted in a modest increase of 30-day minimum levels (+17%), but significant increases in fall rates (+42%) and the number of water level fluctuations (+75%) observed in Chiang Saen. This effect diminishes downstream until it becomes negligible at Mukdahan (northeast Thailand), which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse (southern Laos), alterations to the number of fluctuations and rise rate became strongly significant after 1991. The observed alterations slowly decrease downstream, but modified rise rates, fall rates, and dry season water levels were still quantifiable and significant as far as Prek Kdam. This paper provides the first set of evidence of hydrological alterations in the Mekong beyond the Chinese dam cascade in the upper Mekong. Given the evident alterations at Pakse and downstream, post-1991 changes could also be directly attributed to water infrastructure development in the Chi and Mun basins of Thailand. A reduction of 23 and 11% in the water raising and falling rates respectively at Prek Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan, and Sekong sub-basins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.
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Cochrane, T. A., M. E. Arias, and T. Piman. "Historical impact of water infrastructure on water levels of the Mekong River and the Tonle Sap System." Hydrology and Earth System Sciences Discussions 11, no. 4 (April 24, 2014): 4403–31. http://dx.doi.org/10.5194/hessd-11-4403-2014.
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Abstract. The rapid rate of water infrastructure development in the Mekong basin is a cause for concern due to its potential impact on fisheries and downstream natural ecosystems. In this paper we analyse the historical water levels of the Mekong River and Tonle Sap system by comparing pre and post 1991 daily observations from six stations along the Mekong mainstream from Chiang Sean (northern Laos), to Stung Treng (Cambodia), and the Prek Kdam station on the Tonle Sap River. Observed alterations in water level patterns along the Mekong are linked to temporal and spatial trends in water infrastructure development from 1960 to 2010. We argue that variations in historical climatic factors are important, but they are not the main cause of observed changes in key hydrological indicators related to ecosystem productivity. Our analysis shows that the development of mainstream dams in the upper Mekong basin in the post-1991 period have resulted in a significant increase of 7 day minimum (+91.6%), fall rates (+42%), and the number of water level fluctuations (+75) observed in Chiang Sean. This effect diminishes downstream until it becomes negligible at Mukdahan (northeast Thailand), which represents a drainage area of over 50% of the total Mekong Basin. Further downstream at Pakse (southern Laos), alterations to the number of fluctuations and rise rate became strongly significant after 1991. The observed alterations slowly decrease downstream, but modified rise rates, fall rates, and dry season water levels were still quantifiable and significant as far as Prek Kdam. This paper provides the first set of evidence of hydrological alterations in the Mekong beyond the Chinese dam cascade in the upper Mekong. Given the evident alterations with no precedence at Pakse and downstream, post-1991 changes can also be directly attributed to water infrastructure development in the Chi and Mun basins of Thailand. A reduction of 23 and 11% in the water raising and fall rates respectively at Prek Kdam provides evidence of a diminished Tonle Sap flood pulse in the post-1991 period. Given the observed water level alterations from 1991 to 2010 as a result of water infrastructure development, we can extrapolate that future development in the mainstream and the key transboundary Srepok, Sesan and Sekong subbasins will have an even greater effect on the Tonle Sap flood regime, the lower Mekong floodplain, and the delta.
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Lu, You, Fuqiang Tian, Liying Guo, Iolanda Borzì, Rupesh Patil, Jing Wei, Dengfeng Liu, Yongping Wei, David J. Yu, and Murugesu Sivapalan. "Socio-hydrologic modeling of the dynamics of cooperation in the transboundary Lancang–Mekong River." Hydrology and Earth System Sciences 25, no. 4 (April 9, 2021): 1883–903. http://dx.doi.org/10.5194/hess-25-1883-2021.
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Abstract. The transboundary Lancang–Mekong River basin has experienced dynamics of cooperation over the past several decades, which is a common emergent response in transboundary coupled human–water systems. Downstream countries rely on the Mekong River for fisheries, agriculture, navigation and ecological services, while upstream countries have been constructing dams to generate hydropower. The dam construction and operation in upstream countries have changed the seasonality of streamflow in downstream countries, affecting their economic benefits. More recently, cooperation between upstream and downstream countries has been enhanced throughout the river basin. In this study, we introduce a quantitative socio-hydrological model to simulate hydrological processes, reservoir operations, economic benefits, policy feedbacks and therefore dynamics of cooperation within the Lancang–Mekong River basin. The model reproduces the observed dynamics of cooperation in the basin revealed by sentiment analysis of news articles. Hydrological variability such as droughts and human activities associated with reservoir operations affect dynamics of cooperation between the riparian countries, with importance attached to indirect political benefits of upstream playing an important role in the enhancement of cooperation. In this way, our study generated understanding of emergent cooperation dynamics in this transboundary river basin, and the socio-hydrological model used here provides a useful new framework to investigate and improve transboundary water management elsewhere.
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Jerde, Christopher L., Andrew R. Mahon, Teresa Campbell, Mary E. McElroy, Kakada Pin, Jasmine N. Childress, Madeline N. Armstrong, et al. "Are Genetic Reference Libraries Sufficient for Environmental DNA Metabarcoding of Mekong River Basin Fish?" Water 13, no. 13 (June 26, 2021): 1767. http://dx.doi.org/10.3390/w13131767.
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Environmental DNA (eDNA) metabarcoding approaches to surveillance have great potential for advancing biodiversity monitoring and fisheries management. For eDNA metabarcoding, having a genetic reference sequence identified to fish species is vital to reduce detection errors. Detection errors will increase when there is no reference sequence for a species or when the reference sequence is the same between different species at the same sequenced region of DNA. These errors will be acute in high biodiversity systems like the Mekong River Basin, where many fish species have no reference sequences and many congeners have the same or very similar sequences. Recently developed tools allow for inspection of reference database coverage and the sequence similarity between species. These evaluation tools provide a useful pre-deployment approach to evaluate the breadth of fish species richness potentially detectable using eDNA metabarcoding. Here we combined established species lists for the Mekong River Basin, resulting in a list of 1345 fish species, evaluated the genetic library coverage across 23 peer-reviewed primer pairs, and measured the species specificity for one primer pair across four genera to demonstrate that coverage of genetic reference libraries is but one consideration before deploying an eDNA metabarcoding surveillance program. This analysis identifies many of the eDNA metabarcoding knowledge gaps with the aim of improving the reliability of eDNA metabarcoding applications in the Mekong River Basin. Genetic reference libraries perform best for common and commercially valuable Mekong fishes, while sequence coverage does not exist for many regional endemics, IUCN data deficient, and threatened fishes.
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Ou, Chouly, and Kirk O. Winemiller. "Seasonal hydrology shifts production sources supporting fishes in rivers of the Lower Mekong Basin." Canadian Journal of Fisheries and Aquatic Sciences 73, no. 9 (September 2016): 1342–62. http://dx.doi.org/10.1139/cjfas-2015-0214.
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Seasonal hydrology is assumed to be an important reason why the Lower Mekong Basin supports highly productive and biodiverse inland fisheries. We used C and N stable isotope ratios of tissue samples to estimate primary production sources supporting fish biomass in the Mekong and three large tributaries in Cambodia. We used a Bayesian mixing model to estimate relative contributions of four alternative production sources — seston, benthic algae, riparian grasses, and riparian macrophytes. There was little seasonal variation in isotopic signatures of riparian plants, but benthic algae and seston showed large seasonal shifts in carbon ratios. Seston and benthic algae were the most important production sources supporting fish biomass overall during the dry season, and riparian vegetation was the most important source during the wet season. Sources contributed differentially to biomass of trophic and habitat guilds, especially during the dry season. A dam on the upper Sesan River has changed hydrology, channel geomorphology, and other factors and, compared with the other three rivers, its fish biomass appears to derive from algae to a greater extent.
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Sultana, Parvin, and Paul Thompson. "Methods of consensus building for community-based fisheries management in Bangladesh and the Mekong Delta." Agricultural Systems 82, no. 3 (December 2004): 327–53. http://dx.doi.org/10.1016/j.agsy.2004.07.007.
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Lauri, H., H. de Moel, P. J. Ward, T. A. Räsänen, M. Keskinen, and M. Kummu. "Future changes in Mekong River hydrology: impact of climate change and reservoir operation on discharge." Hydrology and Earth System Sciences Discussions 9, no. 5 (May 25, 2012): 6569–614. http://dx.doi.org/10.5194/hessd-9-6569-2012.
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Abstract. The transboundary Mekong River is facing two on-going changes that are estimated to significantly impact its hydrology and the characteristics of its exceptional flood pulse. The rapid economic development of the riparian countries has led to massive plans for hydropower construction, and the projected climate change is expected to alter the monsoon patterns and increase temperature in the basin. The aim of this study is to assess the cumulative impact of these factors on the hydrology of the Mekong within next 20–30 yr. We downscaled output of five General Circulation Models (GCMs) that were found to perform well in the Mekong region. For the simulation of reservoir operation, we used an optimisation approach to estimate the operation of multiple reservoirs, including both existing and planned hydropower reservoirs. For hydrological assessment, we used a distributed hydrological model, VMod, with a grid resolution of 5 km × 5 km. In terms of climate change's impact to hydrology, we found a high variation in the discharge results depending on which of the GCMs is used as input. The simulated change in discharge at Kratie (Cambodia) between the baseline (1982–1992) and projected time period (2032–2042) ranges from −11% to +15% for the wet season and −10% to +13% for the dry season. Our analysis also shows that the changes in discharge due to planned reservoir operations are clearly larger than those simulated due to climate change: 25–160% higher dry season flows and 5–24% lower flood peaks in Kratie. The projected cumulative impacts follow rather closely the reservoir operation impacts, with an envelope around them induced by the different GCMs. Our results thus indicate that within the coming 20–30 yr, the operation of planned hydropower reservoirs is likely to have a larger impact on the Mekong hydrograph than the impacts of climate change, particularly during the dry season. On the other hand, climate change will increase the uncertainty of the estimated hydropower impacts. Consequently, both dam planners and dam operators should pay better attention to the cumulative impacts of climate change and reservoir operation to the aquatic ecosystems, including the multibillion-dollar Mekong fisheries.
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Ackiss, Amanda S., Binh T. Dang, Christopher E. Bird, Ellen E. Biesack, Phen Chheng, Latsamy Phounvisouk, Quyen H. D. Vu, Sophorn Uy, and Kent E. Carpenter. "Cryptic Lineages and a Population Dammed to Incipient Extinction? Insights into the Genetic Structure of a Mekong River Catfish." Journal of Heredity 110, no. 5 (March 19, 2019): 535–47. http://dx.doi.org/10.1093/jhered/esz016.
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Abstract An understanding of the genetic composition of populations across management boundaries is vital to developing successful strategies for sustaining biodiversity and food resources. This is especially important in ecosystems where habitat fragmentation has altered baseline patterns of gene flow, dividing natural populations into smaller subpopulations and increasing potential loss of genetic variation through genetic drift. River systems can be highly fragmented by dams built for flow regulation and hydropower. We used reduced-representation sequencing to examine genomic patterns in an exploited catfish, Hemibagrus spilopterus, in a hotspot of biodiversity and hydropower development—the Mekong River basin. Our results revealed the presence of 2 highly divergent coexisting genetic lineages which may be cryptic species. Within the lineage with the greatest sample sizes, pairwise FST values, principal component analysis, and a STRUCTURE analysis all suggest that long-distance migration is not common across the Lower Mekong Basin, even in areas where flood-pulse hydrology has limited genetic divergence. In tributaries, effective population size estimates were at least an order of magnitude lower than in the Mekong mainstream indicating these populations may be more vulnerable to perturbations such as human-induced fragmentation. Fish isolated upstream of several dams in one tributary exhibited particularly low genetic diversity, high amounts of relatedness, and a level of inbreeding (GIS = 0.51) that has been associated with inbreeding depression in other outcrossing species. Our results highlight the importance of assessing genetic structure and diversity in riverine fisheries populations across proposed dam development sites for the preservation of these critically important resources.
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Nguyen, Cong Trang, Anna Vila-Gispert, Xavier D. Quintana, Au Van Hoa, Thanh Phunong Nguyen, and Ngoc Ut Vu. "Effects of salinity on species composition of zooplankton on Hau River, Mekong Delta, Vietnam." Annales de Limnologie - International Journal of Limnology 56 (2020): 20. http://dx.doi.org/10.1051/limn/2020018.
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The area surrounding the Hau River is one of the most important aquaculture and fisheries areas in the Mekong Delta, Vietnam. Fish, shrimp farms and fishers rely of the natural zooplankton production in the incoming water to sustain production. Zooplankton samples were collected from July 2017 to June 2018 using a zooplankton net with mesh size of 60 μm at 3 sites on Hau river at Tran De (river mouth), Dai Ngai (midpoint) and Cai Con (farthest salt intrusion area on Hau river). Qualitative and quantitative samples of zooplankton together with salinity level were determined monthly at each sites. The salinity was found to fluctuate from 0 to 20‰ in the study area. A total of 137 zooplankton species were recorded including 26 species of Protozoa (19%), 47 species of Rotifera (34%), 12 species of Cladocera (9%), 44 species of Copepoda (32%) and 8 other taxon (6%). Copepod and rotifer prevailed with high densities (19.9 × 103 ind m−3 and 19.7 × 103 ind m−3, respectively), whereas protozoa and cladocera were less abundant with 6.8 × 103 ind m−3 and 4.9 × 103 ind m−3, respectively. When salinity increased to more than 5, protozoa and copepods were more abundant and reached a peak at 20 with 25.0 × 1036 ind m−3 and 53.0 × 103 ind m−3, respectively. Regression analysis indicated that the density of zooplankton was significantly correlated to salinity variation. Protozoa and copepod were positively correlated with salinity, whereas cladocera and rotifer were negatively correlated with salinity. The impacts of climate change could exacerbate the seasonal fluctuations in salinity and zooplankton composition.
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Arthur, R. I., and R. M. Friend. "Inland capture fisheries in the Mekong and their place and potential within food-led regional development." Global Environmental Change 21, no. 1 (February 2011): 219–26. http://dx.doi.org/10.1016/j.gloenvcha.2010.07.014.
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Kang, Bin, Daming He, Lisa Perrett, Hongyuan Wang, Wenxian Hu, Weide Deng, and Yunfei Wu. "Fish and fisheries in the Upper Mekong: current assessment of the fish community, threats and conservation." Reviews in Fish Biology and Fisheries 19, no. 4 (April 3, 2009): 465–80. http://dx.doi.org/10.1007/s11160-009-9114-5.
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Naughton, George P., Zeb S. Hogan, Teresa Campbell, Peter J. Graf, Charles Farwell, and Naruepon Sukumasavin. "Acoustic Telemetry Monitors Movements of Wild Adult Catfishes in the Mekong River, Thailand and Laos." Water 13, no. 5 (February 27, 2021): 641. http://dx.doi.org/10.3390/w13050641.
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Research on fish movement and habitat use in large tropical rivers is urgently needed to protect fisheries that are a primary source of protein for millions of people. In this pilot study, acoustic telemetry was used to monitor movements of wild catfishes in a 94.6 rkm reach of Mekong River, where it functions as the border between Thailand and Lao People’s Democratic Republic (PDR). Twenty fish were tagged and released in May 2006 and monitored through May 2007 with 17 fixed-site acoustic receivers. Ten receivers had detection probabilities ranging from 0.67 to 1.00, and five receivers had detection probabilities of 0.50 or less. Detection probability was not correlated with river width. Eighteen (90%) of the tagged fish were detected by at least one receiver. Monitoring durations of individual fish ranged from 0.1 to 354.4 days. The longest total movement was 88.3 rkm, while the longest upstream movement was 52.1 rkm. Movement rates ranged from 0.1 to 156.7 rkm/d. This work provided preliminary data on movement patterns of wild Mekong catfishes. The methods and lessons learned from this study can be used for future positional telemetry research to address management-relevant uncertainties about migration corridors, habitat use, efficacy of fish reserves, and river development planning.
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Lauri, H., H. de Moel, P. J. Ward, T. A. Räsänen, M. Keskinen, and M. Kummu. "Future changes in Mekong River hydrology: impact of climate change and reservoir operation on discharge." Hydrology and Earth System Sciences 16, no. 12 (December 5, 2012): 4603–19. http://dx.doi.org/10.5194/hess-16-4603-2012.
Full textAbstract:
Abstract. The transboundary Mekong River is facing two ongoing changes that are expected to significantly impact its hydrology and the characteristics of its exceptional flood pulse. The rapid economic development of the riparian countries has led to massive plans for hydropower construction, and projected climate change is expected to alter the monsoon patterns and increase temperature in the basin. The aim of this study is to assess the cumulative impact of these factors on the hydrology of the Mekong within next 20–30 yr. We downscaled the output of five general circulation models (GCMs) that were found to perform well in the Mekong region. For the simulation of reservoir operation, we used an optimisation approach to estimate the operation of multiple reservoirs, including both existing and planned hydropower reservoirs. For the hydrological assessment, we used a distributed hydrological model, VMod, with a grid resolution of 5 km × 5 km. In terms of climate change's impact on hydrology, we found a high variation in the discharge results depending on which of the GCMs is used as input. The simulated change in discharge at Kratie (Cambodia) between the baseline (1982–1992) and projected time period (2032–2042) ranges from −11% to +15% for the wet season and −10% to +13% for the dry season. Our analysis also shows that the changes in discharge due to planned reservoir operations are clearly larger than those simulated due to climate change: 25–160% higher dry season flows and 5–24% lower flood peaks in Kratie. The projected cumulative impacts follow rather closely the reservoir operation impacts, with an envelope around them induced by the different GCMs. Our results thus indicate that within the coming 20–30 yr, the operation of planned hydropower reservoirs is likely to have a larger impact on the Mekong hydrograph than the impacts of climate change, particularly during the dry season. On the other hand, climate change will increase the uncertainty of the estimated reservoir operation impacts: our results indicate that even the direction of the flow-related changes induced by climate change is partly unclear. Consequently, both dam planners and dam operators should pay closer attention to the cumulative impacts of climate change and reservoir operation on aquatic ecosystems, including the multibillion-dollar Mekong fisheries.
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Kingston, D. G., J. R. Thompson, and G. Kite. "Uncertainty in climate change projections of discharge for the Mekong River Basin." Hydrology and Earth System Sciences Discussions 7, no. 4 (August 23, 2010): 5991–6024. http://dx.doi.org/10.5194/hessd-7-5991-2010.
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Abstract. The Mekong River Basin comprises a key regional resource in Southeast Asia for sectors that include agriculture, fisheries and electricity production. Here we explore the potential impacts of climate change on freshwater resources within the river basin. We quantify uncertainty in these projections associated with GCM structure and climate sensitivity, as well as from hydrological model parameter specification. This is achieved by running pattern-scaled GCM output through a semi-distributed hydrological model (SLURP) of the basin. These pattern-scaled GCM outputs allow investigation of specific thresholds of global climate change including the postulated 2 ºC threshold of "dangerous" climate change as simulated using outputs from seven different GCMs. Detailed analysis of results based on HadCM3 climate scenarios reveals a relatively small but non-linear response of annual river discharge to increasing global mean temperature, ranging from a 5.4% decrease to 4.5% increase. Intra-annual (monthly) changes in river discharge are greater (from −16% to +55%, with greatest decreases in July and August, greatest increases in May and June) and result from complex and contrasting intra-basin changes in precipitation, evaporation and snow storage/melt. Whilst overall results are highly GCM dependent (in both direction and magnitude), this uncertainty is primarily driven by differences in GCM projections of future precipitation. In contrast, there is strong consistency between GCMs in terms of both increased potential evapotranspiration and a shift to an earlier and less substantial snowmelt season. Indeed, in the upper Mekong (Lancang sub-basin), the temperature-related signal in discharge is strong enough to overwhelm the precipitation-related uncertainty in the direction of change in discharge, with scenarios from all GCMs leading to increased river flow from April–June, and decreased flow from July–August.
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Ng, Ting Hui, Ekgachai Jeratthitikul, Chirasak Sutcharit, Samol Chhuoy, Kakada Pin, Arthit Pholyotha, Warut Siriwut, Ruttapon Srisonchai, Zeb S. Hogan, and Peng Bun Ngor. "Annotated checklist of freshwater molluscs from the largest freshwater lake in Southeast Asia." ZooKeys 958 (August 11, 2020): 107–41. http://dx.doi.org/10.3897/zookeys.958.53865.
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The Tonle Sap Lake in Cambodia is a crucial freshwater biodiversity hotspot and supports one of the world’s largest inland fisheries. Within the Tonle Sap basin, freshwater molluscs provide vital ecosystem services and are among the fauna targetted for commercial harvesting. Despite their importance, freshwater molluscs of the Tonle Sap basin remain poorly studied. The historical literature was reviewed and at least 153 species of freshwater molluscs have been previously recorded from throughout Cambodia, including 33 from the Tonle Sap basin. Surveys of the Tonle Sap Lake and surrounding watershed were also conducted and found 31 species, 15 bivalves (five families) and 16 gastropods (eight families), in the Tonle Sap basin, including three new records for Cambodia (Scaphula minuta, Novaculina siamensis, Wattebledia siamensis), the presence of globally invasive Pomacea maculata and potential pest species like Limnoperna fortunei. This study represents the most comprehensive documentation of freshwater molluscs of the Tonle Sap basin, and voucher specimens deposited at the Inland Fisheries Research and Development Institute, Cambodia, represent the first known reference collection of freshwater molluscs in the country. In order to combat the combined anthropogenic pressures, including invasive species, climate change and dams along the Mekong River, a multi-pronged approach is urgently required to study the biodiversity, ecology, ecosystem functioning of freshwater molluscs and other aquatic fauna in the Tonle Sap basin.
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Fox, Coleen, and Christopher Sneddon. "Political Borders, Epistemological Boundaries, and Contested Knowledges: Constructing Dams and Narratives in the Mekong River Basin." Water 11, no. 3 (February 26, 2019): 413. http://dx.doi.org/10.3390/w11030413.
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The Mekong River Basin of mainland Southeast Asia is confronting a series of intertwined social, political, and biophysical crises. The ongoing construction of major hydroelectric dams on the river’s main channel and tributary systems—particularly in the basin’s lower and more populated reaches—is leading to significant socioecological changes. Multiple scientific studies have suggested that proceeding with the planned dam construction will disrupt the region’s incredibly productive fisheries and threaten the livelihoods of millions of basin residents. These effects will almost certainly be exacerbated by global and regional climate change. Yet increased understanding of the adverse consequences of dams for the Mekong’s hydrological and ecological processes is having minimal impact on decision-making around hydropower development. While local communities, non-governmental organizations (NGOs), and certain scientists draw on this knowledge to oppose or question accelerated dam building, state officials and hydropower developers have turned to the expertise of engineering and technological assessments in order to justify dam construction. Drawing on work in political geography, political ecology, and science and technology studies (STS), we ask two primary questions. First, why does engineering/technological knowledge retain so much legitimacy and authority in the face of mounting scientific knowledge about ecological change? Secondly, how are narratives of progress deployed and co-produced in the contested epistemologies of large dams as development? We conclude with some examples of how contestations over dams seem to be shifting epistemological boundaries in meaningful ways, creating new spaces for knowledge production and transfer. To answer these questions, we focus on three contested dams that are at various stages of construction in the basin: the nearly complete Xayaburi Dam, the under-construction Don Sahong Dam, and the planned Pak Beng Dam. The research advances understandings of the politics of contested knowledges as they become manifest in the conceptualization and governance of large dams in transboundary basins.
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Grundy‐Warr, Carl, and Shaun Lin. "The unseen transboundary commons that matter for Cambodia's inland fisheries: Changing sediment flows in the Mekong hydrological flood pulse." Asia Pacific Viewpoint 61, no. 2 (February 17, 2020): 249–65. http://dx.doi.org/10.1111/apv.12266.
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Kingston, D. G., J. R. Thompson, and G. Kite. "Uncertainty in climate change projections of discharge for the Mekong River Basin." Hydrology and Earth System Sciences 15, no. 5 (May 13, 2011): 1459–71. http://dx.doi.org/10.5194/hess-15-1459-2011.
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Abstract. The Mekong River Basin is a key regional resource in Southeast Asia for sectors that include agriculture, fisheries and electricity production. Here we explore the potential impacts of climate change on freshwater resources within the river basin. We quantify uncertainty in these projections associated with GCM structure and climate sensitivity, as well as from hydrological model parameter specification. This is achieved by running pattern-scaled GCM scenarios through a semi-distributed hydrological model (SLURP) of the basin. Pattern-scaling allows investigation of specific thresholds of global climate change including the postulated 2 °C threshold of "dangerous" climate change. Impacts of a 2 °C rise in global mean temperature are investigated using seven different GCMs, providing an implicit analysis of uncertainty associated with GCM structure. Analysis of progressive changes in global mean temperature from 0.5 to 6 °C above the 1961–1990 baseline (using the HadCM3 GCM) reveals a relatively small but non-linear response of annual river discharge to increasing global mean temperature, ranging from a 5.4 % decrease to 4.5 % increase. Changes in mean monthly river discharge are greater (from −16 % to +55 %, with greatest decreases in July and August, greatest increases in May and June) and result from complex and contrasting intra-basin changes in precipitation, evaporation and snow storage/melt. Whilst overall results are highly GCM dependent (in both direction and magnitude), this uncertainty is primarily driven by differences in GCM projections of future precipitation. In contrast, there is strong consistency between GCMs in terms of both increased potential evapotranspiration and a shift to an earlier and less substantial snowmelt season. Indeed, in the upper Mekong (Lancang sub-basin), the temperature-related signal in discharge is strong enough to overwhelm the precipitation-related uncertainty in the direction of change in discharge, with scenarios from all GCMs leading to increased river flow from April–June and decreased flow from July–August.
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Duong, Thuy-Yen, Sophorn Uy, Phen Chheng, Nam So, Thanh-Hien Thi Tran, Ngoc-Tran Thi Nguyen, Robert Pomeroy, and Hillary Egna. "Genetic diversity and structure of striped snakehead (Channa striata) in the Lower Mekong Basin: Implications for aquaculture and fisheries management." Fisheries Research 218 (October 2019): 166–73. http://dx.doi.org/10.1016/j.fishres.2019.05.014.
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Leong, Ching, and Farhad Mukhtarov. "Global IWRM Ideas and Local Context: Studying Narratives in Rural Cambodia." Water 10, no. 11 (November 13, 2018): 1643. http://dx.doi.org/10.3390/w10111643.
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This article investigates how the “constructivist turn” in public policy and international political economy informs the interaction of global ideas and local practice in water governance. We use the implementation of ideas associated with Integrated Water Resources Management (IWRM) in the Lower Mekong river basin. This article provides some explanation of the attitudes in the villages in Cambodia due to the Sesan 2 Dam, which would see the relocation of thousands of people, damage fisheries, and inflict high coping costs on villagers. Based on 24 in-depth interviews with villagers, commune heads and local community leaders, we find diverse narratives which transcend the “pro or anti” dam narrative. We find four narrative types—myths, stories, noise and informed opinion, which relate to each other in degrees of social meaning and ideational force. Of these, the first two are more likely to be useful in terms of mobilization and policy-making. This typology provides a framework for analysis of social change in the studied villages and other contexts of policy translation. We should state that these four types are not separate from each other but are linked along two axis which together conscribe the four types of narratives outlined.
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Nguyen, Thanh Huu, Tho Phu Nguyen, and Hang Thi Thuy Nguyen. "SURVEYING THE CURRENT SITUATION OF USING PROBIOTICS, CONTROLLING DISEASES AT SHRIMP FARMINGS IN THE CA MAU PENINSULA OF VIET NAM." Scientific Journal of Tra Vinh University 1, no. 40 (December 30, 2020): 180–88. http://dx.doi.org/10.35382/18594816.1.40.2020.630.
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In order to provide the basis for the application of scientific and technological advances, reorganizing shrimpfarming in sustainable and bringing high economic value to the Mekong Delta. The study surveyed the current situation of breeds, farming methods, environmental monitoring control, Vibrio sp. and the use of probiotics of shrimp farmers in the Ca Mau peninsula by interviewing 200 shrimp farmers and 20 specialized fisheries officers in Ca Mau, Soc Trang, Bac Lieu and Kien Giang provinces. The results showed that the shrimp breeds selected for farming originated from the Central and Southwest provinces. There are four popular farming methods: intensive, semi-intensive, improved extensive, and rice-shrimp. The intensive farming had the highest rates of the initial quarantine of shrimp postlarvae (74%) and Vibrio test (57%). All shrimp farmers workingon the intensive and semi-intensive farmings used probiotics. The rates of probiotic use in the improved extensive and riceshrimp farmings were lower, only 60% and 40% respectively. The results suggested that shrimp farmers working on the semi-intensive and intensive farmings paid more attention to the use of probiotics as well as the test to prevent the disease in shrimp.
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Loury, Erin K., and Shaara M. Ainsley. "Identifying Indicators to Evaluate Community-Managed Freshwater Protected Areas in the Lower Mekong Basin: A Review of Marine and Freshwater Examples." Water 12, no. 12 (December 16, 2020): 3530. http://dx.doi.org/10.3390/w12123530.
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Protected areas are frequently established as a management tool to conserve terrestrial and aquatic habitats and species. Monitoring and evaluation are a necessary part of adaptive management to determine whether such protected areas are effectively meeting their objectives. While numerous initiatives have developed methods to evaluate terrestrial and marine protected areas (MPAs), similar efforts and resources are lacking for freshwater protected areas (FPAs), which have become widespread as a community-based fisheries management approach in the Lower Mekong Basin (LMB). This review summarizes published literature on the evaluation of marine and freshwater protected areas to provide guidance on the evaluation of community-managed FPAs in the LMB. Specifically, the review examines several indicators related to common objectives of aquatic protected areas and provides considerations for measuring these indicators in the context of community-managed freshwater protected areas in the LMB. Key conclusions include that first, FPAs should be established with clearly defined objectives, and these objectives should inform the selection of indicators for evaluation. Second, indicators identified for MPAs are highly relevant to FPAs, although methods may require adaptation to a freshwater environment. Finally, socioeconomic and governance indicators are overlooked in both MPA and FPA evaluations compared to biophysical indicators, and interdisciplinary assessment teams could ensure these indicators receive adequate consideration.
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Baumgartner, Lee J., Craig Boys, Tim Marsden, Jarrod McPherson, Nathan Ning, Oudom Phonekhampheng, Wayne Robinson, Douangkham Singhanouvong, Ivor G. Stuart, and Garry Thorncraft. "A Cone Fishway Facilitates Lateral Migrations of Tropical River-Floodplain Fish Communities." Water 12, no. 2 (February 13, 2020): 513. http://dx.doi.org/10.3390/w12020513.
Full textAbstract:
Fisheries in many tropical river-floodplain systems are under threat from physical obstructions caused by ongoing river infrastructure development. There is a growing need for innovative, cost-effective technologies to mitigate the impacts of these obstructions. This study examined the effectiveness of a new cone fishway for facilitating lateral migrations of river-floodplain fish communities in the Lower Mekong Basin in Lao PDR. We assessed the species richness, size range, abundance and biomass of fish able to pass through a cone fishway, using paired entrance and exit sampling during both dawn/day and dusk/night. Overall, a diverse range of taxa (76 species) and size classes (25–370 mm) ascended the cone fishway. The total size range of fishes observed at the fishway entrance was similar to that at the exit, although the fish at the entrance were significantly smaller (in length) than those at the exit, during both diel periods. Additionally, there were significantly higher abundances of fish at the entrance than at the exit, but there was no difference in total biomass, again for both periods. These results suggest that, with further development, the cone fishway design has considerable potential for facilitating the lateral migrations of diverse tropical river-floodplain fish communities at low/medium head infrastructure.
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Campbell, Teresa, Kakada Pin, Peng Ngor, and Zeb Hogan. "Conserving Mekong Megafishes: Current Status and Critical Threats in Cambodia." Water 12, no. 6 (June 25, 2020): 1820. http://dx.doi.org/10.3390/w12061820.
Full textAbstract:
Megafishes are important to people and ecosystems worldwide. These fishes attain a maximum body weight of ≥30 kg. Global population declines highlight the need for more information about megafishes’ conservation status to inform management and conservation. The northern Cambodian Mekong River and its major tributaries are considered one of the last refugia for Mekong megafishes. We collected data on population abundance and body size trends for eight megafishes in this region to better understand their conservation statuses. Data were collected in June 2018 using a local ecological knowledge survey of 96 fishers in 12 villages. Fishers reported that, over 20 years, most megafishes changed from common to uncommon, rare, or locally extirpated. The most common and rarest species had mean last capture dates of 4.5 and 95 months before the survey, respectively. All species had declined greatly in body size. Maximum body weights reported by fishers ranged from 11–88% of their recorded maxima. Fishers identified 10 threats to megafishes, seven of which were types of illegal fishing. Electrofishing was the most prevalent. Results confirm that Mekong megafishes are severely endangered. Species Conservation Strategies should be developed and must address pervasive illegal fishing activities, alongside habitat degradation and blocked migrations, to recover declining populations.
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Le, Xuan Thinh, Xuan Hien Dang, and Ngoc Trinh Truong. "Effect of phytase on the water quality of Vietnamese pangasius ponds." Journal of Vietnamese Environment 10, no. 1 (August 10, 2018): 16–21. http://dx.doi.org/10.13141/jve.vol10.no1.pp16-21.
Full textAbstract:
Striped catfish (Pangasianodon hypophthalmus) is freshwater fish that is raising mainly in the Mekong Delta. The research was implemented at the Model Farm (College of Aquaculture and Fisheries), Can Tho University during 6 months from May to November of 2016 and aimed to evaluate the water quality between two treatments of feed in the pangasius production for proposing a better environmental management method. The treatment 1 (control treatment, CT) has two ponds used feed without adding phytase and treatment 2 (experiment treatment, ET) includes two ponds used feed with adding phytase. The results showed that the temperature, pH, DO, TSS, COD, BOD, N-NO2-, N-NO3-, TKN, TAN were not significantly different (p>0.05) between the CT and ET ponds. At the experiment pond (EP), the factors (TP: 2.28 mg/L; P-PO43-: 1.24 mg/L) which has P release to the environment are less than control pond (CP) (TP: 2.62 mg/L; P-PO43-: 2.13 mg/L). These results suggested that the addition of phytase in feed could contribute to reducing the nutrient to the water body of pangasius pond.
Cá tra (Pangasianodon hypophthalmus) là loài thủy sản nước ngọt được nuôi chủ yếu ở các tỉnh Đồng bằng sông Cửu Long. Nghiên cứu được thực hiện trong 6 tháng từ tháng 05 – 11/2016 tại Trang trại mẫu đặt tại Khoa Thủy sản, Trường Đại học Cần Thơ nhằm đánh giá chất lượng nước giữa 2 nghiệm thức thức ăn trong giai đoạn nuôi cá thịt để đề xuất biện pháp quản lý chất lượng nước ao nuôi tốt hơn. Nghiệm thức 1 (nghiệm thức đối chứng, CT) gồm 2 ao nuôi sử dụng thức ăn không bổ sung enzyme phytase, nghiệm thức 2 (nghiệm thức thí nghiệm, ET) gồm 2 ao nuôi sử dụng thức ăn có bổ sung enzyme phytase. Kết quả thí nghiệm cho thấy giá trị nhiệt độ, pH, DO, TSS, COD, BOD, H2S, N-NO2-, N-NO3-, TKN, TAN ở mức phù hợp cho ao đối chứng (CT). Tại ao thí nghiệm (ET) (TP:2,28 mg/L; P-PO43-: 1,24 mg/L) lượng P thải ra ít hơn so với ao CT (TP: 2,62 mg/L; P-PO43-: 2,13 mg/L) chứng tỏ việc bổ sung enzyme phytase trong thức ăn đã góp phần làm giảm lượng lân thải ra môi trường nước trong nuôi cá tra.
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Morton, Lois Wright, and Kenneth R. Olson. "The Pulses of the Mekong River Basin: Rivers and the Livelihoods of Farmers and Fishers." Journal of Environmental Protection 09, no. 04 (2018): 431–59. http://dx.doi.org/10.4236/jep.2018.94027.
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Hoanh, C. T., T. P. Tuong, K. M. Gallop, J. W. Gowing, S. P. Kam, N. T. Khiem, and N. D. Phong. "Livelihood impacts of water policy changes: evidence from a coastal area of the Mekong river delta." Water Policy 5, no. 5-6 (October 1, 2003): 475–88. http://dx.doi.org/10.2166/wp.2003.0030.
Full textAbstract:
The coastal zone of the Mekong river delta has experienced rapid economic and environmental changes during the last decade. Given the nature of the environment and the level of dependence on the natural resources base, policies for land and water were very influential in this process. The emphasis on rice created an imperative to control saline intrusion, which was realized through the construction of major engineering works over an extended period (1994-2000). The inertia built up by this process led to a divergence between policy and practice, and adversely affected the livelihoods of fishers and of those farmers who live on aquaculture. This prompted the government to rethink the rice-focus policy, in favor of a land and water policy for balanced rice and aquaculture production. This paper describes an analytical process, which was adopted to explore the feasibility of adopting the new policy for the balanced development of both rice and shrimp production and discusses the impact of the new policy on farmers’ livelihoods.