Channels for Change in the Mekong: Integrating Multiple Disciplines for New Frontiers in Managing the Mekong River Basin (hosted by AFS)

ROOM: Atlantis, Grand Ballroom 3
Considered one of 35 locations as a hotspot for global biodiversity, the Mekong River supports 1,200 species of fishes with the Lower Mekong Basin yielding an annual wild fish catch of 767,000 tons. The strong connections between the river, its flood plains, the adjoining Tonle Sap Lake, and humans has occurred for over a millennium, as documented by the ancient Angkor civilization. Today, more than 60 million people utilize fishes from the river for food and as a major economic contributor to household incomes. All six countries within the basin have considered or developed dams to support the high demands of energy in the region. Dams, climate change, land use change, and substantial increases in legal and illegal fishing pressures are thought to significantly influence fish biodiversity, productivity, and socioeconomic systems, although the degree and interactions of these environmental stressors are not understood. Previous AFS sessions on the Mekong have provided significant insight to the fisheries and ecological research in this area. In this symposium, we want to encourage interdisciplinary and interactive discussions that present opportunities to overcome challenges and highlight new frontiers for managing the Mekong River Basin. A peer-reviewed special issue publication may be considered from this session.

8:40AM Continuing the Conversation on Mekong River Management at the Annual AFS Conference
  Shaara Ainsley, Stephen J. Walsh, Lee Baumgartner
The Mekong River Basin is experiencing serious challenges from balancing the benefits of hydropower development with the expected fisheries impacts. This symposium builds on two previous meetings that focused on overcoming these challenges. A 2015 AFS symposium brought together international researchers to address fisheries issues of the Mekong Basin. The session described the importance of wild capture fisheries to the economics and human health in the lower basin, as well as the numerous challenges facing inland fisheries in the region. Habitat connectivity and fish passage were highlighted as emerging issues, and researchers discussed innovative technologies that had recently been used to investigate passage in the Mekong Region, as well as presentations on lessons learned from other large river ecosystems including the Amazon and Columbia rivers. A subsequent 2017 AFS symposium brought together researchers working in tropical river systems, including the Mekong, to share lessons about fish ecology, fish migration and passage, dam construction, deforestation, new research tools, and similarities among regions. This presentation will summarize highlights from these two sessions to lay a foundation for this year’s session, which will continue the conversation about the Mekong River Basin and move beyond fisheries towards a more interdisciplinary dialogue.
9:00AM Combing Research, Training, and Outreach to Highlight the Value of a Healthy, Connected Mekong River
  Zeb Hogan, Sudeep Chandra, Chheng Phen, Samadee Saray, Peng Bun Ngor, Teresa Campbell, Sarah E. , Peter Weisberg, Tom Dilts, Sapana Lohani, Chheana Chhut, Erin Loury, Shaara Ainsley, Dee Thao, Flavia Tromboni, Liana Prudencio
A biodiversity hotspot, the Mekong is one of the most productive rivers on Earth, supporting over 70 million people. From the tributary headwaters to the fertile delta and “rice bowl” of Vietnam, the Mekong supports almost 1000 species of freshwater fish, including many rare and endangered species, flood plains and flooded forests that sustain wildlife and local people. The Wonders of the Mekong Project conducts applied research, build capacity, and develop outreach and communications products to highlight the values of biodiversity and ecosystem services associated with the Lower Mekong River. Applied, interdisciplinary research improves understanding, management capacity, and appreciation of a functional and healthy Mekong River for fish, wildlife, and people. Training, capacity building, and workshops share knowledge and perspectives on sustainably managing the Mekong system, particularly in the context of unprecedented environmental change. Communications and media products increase the public’s and government’s valuation and conservation of the Mekong River’s ecosystem services, habitats, cultural heritage, and biodiversity. The outputs and resulting products, developed as an integrated package, will lead to better protection of a vibrant and healthy Lower Mekong system.
9:20AM Environmental Effects of Dam Construction in the Se Kong, Se San, and Sre Pok (3S) Rivers of the Lower Mekong Basin: A Literature Review
  Sarah E. , Sapana Lohani, Liana Prudencio
The Mekong River is characterized by large-scale fish migrations, which support approximately 65 million people. Rapid hydropower development is providing energy for developing countries, but is also threatening biodiversity and food security. The Se Kong, Se San, and Sre Pok Rivers (the 3S basin) are shared by Cambodia, Laos, and Vietnam and form a major tributary to the Lower Mekong River. Forty two dams have been built, are under construction, or are planned in the 3S Basin. Over the past decade, the effects of building dams on streamflow, biodiversity, fish production, sediment connectivity, nitrate loads, and more have been modeled and analyzed. This talk summarizes recent literature, focusing on tradeoffs between hydropower development and environmental impacts in the 3S basin, and highlighting data availability and ongoing information gaps.
09:40AM Break
1:10PM The Effect of the Lower Sesan 2 Dam on the Biogeochemistry of the 3S System
  Flavia Tromboni, Sudeep Chandra, Liana Prudencio, Peng Bun Ngor, Samadee Saray, Zeb Hogan
The Mekong River supports the largest freshwater fishery in the world. The integrity of this ecosystem is threatened by many proposed dams and there is little quantitative limnological information available in dammed areas. The Lower Sesan 2 dam (LS2) was recently built in the Sesan/Srepok confluence, two tributaries of the Mekong. We assessed the impact of the LS2 on the biogeochemistry of the system, sampling three sites above the dam (in the Sesan and Srepok), two in the reservoir, and four below (in the Sesan and in the Mekong). We measured nutrient concentrations, sediment particle sizes, metabolism, and carried out interviews with local fishing families to assess changes in fish catches. Preliminary results suggest that reduction in flow velocity above the dam leads to sediment deposition and increased primary production with water clarity. Sites above the dam, in the Sesan, were net autotrophic except in the Srepok. Right below the dam, Sesan River is net heterotrophic but returned to autotrophy in the mainstem of the Mekong. Nutrients (organic carbon and nitrogen) were higher in the Mekong and below the dam than they were above the dam. Fishing families reported higher catches right below the dam, after the dam was constructed.
1:30PM A Vulnerable Moment in the Mekong: Critical Connections of Migratory Fishes to the Hydrologic Rhythms in Space and Time
  Peng Bun Ngor, Zeb Hogan, Samadee Saray, Teresa Campbell, Sudeep Chandra
Mekong River’s hydrology is characterized by its extreme seasonality and predictability, with regular wet and dry seasons. Life cycles of many fishes developed and adapted to such hydrologic rhythms for thousands of years. The basin’s fish assemblages are extremely diverse and represented by long-distance migratory species, seasonally migrating between regions and supporting ecosystem functioning and services to millions of people across space and time. However, during migrations and refuge, fishes are also highly vulnerable to high fishing mortality as fishers grasp the important moments, effectively capturing them for food and economic earnings. The intense and targeted fishing pressure combined with other stressors (e.g. efficient/destructive fishing methods, flow alterations, habitat loss, agricultural intensification/expansion, urbanization, pollution, invasive species and open-access nature of fisheries) increase mortality and decrease recruitment. This raises concerns about fish biodiversity status in supporting long-term food security. This study (i) reviews existing data and knowledge on hydrology, fish migration/distribution patterns and factors driving changes to Lower Mekong Basin’s fish stocks, (ii) identifies critically vulnerable moments of high fishing mortality in connection to hydrologic cycles across space and time, and (iii) suggests effective measures to reduce high fishing mortality moment to guide the region’s fisheries management and conservation efforts.
1:50PM Early Life History of a Shark Catfish Pangasianodon Hypophthalmus in Lower Mekong River, Cambodia
  Samol Chhuoy, Zeb Hogan, Utsugi Kenzo, Peng Bun Ngor
Fish early life history studies are fundamental to understand population dynamics, and reliably estimate age and growth, useful to assess fish birth date, spawning ground and recruitment success. Otoliths are a powerful tool to investigate fishes’ early life stage. This study investigates a shark catfish, Pangasianodon hypophthalmus’s early life history. It is native to the Mekong and used to be abundant in wild catches. It is now listed ‘endangered’. Cambodian Mekong River seems to be one of the world’s last wild habitats for the species. The study uses daily fish larval data collected between June-September 2015 in the Mekong River in Phnom Penh and hatchery-raised larvae, collected daily for 30 days. Sagittal and lapillus otoliths are extracted from 390 wild larvae and 150 hatchery-raised larvae for processing and analysis. The study will (i) investigate relationship between ages and otolith ring increments of hatchery-raised larvae; (ii) predict wild larval ages, based on (i); and (iii) assess spawning grounds based on (ii), time lags in daily flow that carries drifting larvae between hydrological stations along Cambodian Mekong River and distances between the sampling site and hydrological stations. The results will provide a scientific basis to guide the species’ management and conservation measures.
2:10PM Predicting Fish Migration Triggers in the Lower Mekong Basin with Random Forest Modeling
  Liana Prudencio, Sarah E.
The Mekong Basin is home to more than 800 fish species, with at least 165 migratory species. Increased water development, including hydropower dam construction and concurrent habitat loss, puts migratory fishes at risk. Fish in the Lower Mekong Basin migrate upstream to the Se San, Se Kong, and Sre Pok Rivers (the ‘3S’ system) for spawning, then larvae drift downstream on the Mekong toward the Tonle Sap River. Previous literature suggests discharge, water level variations, changes in water quality, rainfall, and the lunar cycle are possible migration triggers. However, potential drivers of fish migration have largely been identified through local knowledge and systematic analysis of fish migration triggers is needed. We use random forest modeling to correlate streamflow (timing, magnitude, and duration), water level, precipitation, and the lunar cycle with larvae abundance downstream of spawning sites to identify triggers that cue fish migration in the Lower Mekong Basin. Preliminary findings of this research will be presented, alongside interviews with locals who fish in this study region. The random forest model and local fishing perspectives provide a synthesized discussion that highlights the conditions needed by migratory fish species and how water development may change these conditions.
2:30PM Predictive Statistical Modeling for Forest-Cover Change in Lower Mekong Basin
  Sapana Lohani, Peter Weisberg, Thomas Dilts, Sarah E.
The Mekong River is one of the world’s important river systems, known for its unique flood pulse hydrology, productivity, and human dependency in one of the world’s poorest and most underdeveloped regions. Flooded forests provide critical terrestrial nutrient inputs and habitat for a wide range of fishes. However, the Mekong River is under threat from anthropogenic stressors, including loss of forest cover and land-use change. We investigated the spatiotemporal pattern of deforestation in the Cambodian Mekong Basin as the intersection of biophysical processes with human land-use practices. Our study applied a machine learning approach to hindcast tree cover change over a 29-year period (1988-2016) using the Landsat satellite archive. We developed statistical, predictive models of deforestation as influenced by dams and associated infrastructure, hydrology (inundation timing and extent), climate change, fire, socio-economic variables (population density, proximity to roads), proximity to previous deforestation, and previous forest fragmentation. Preliminary results showed that more than 40% of the primary forests were deforested over our 29-year study period, with relatively more deforestation in floodplain areas than upland areas. Future hydroelectric developments and climate change potentially contribute to deforestation in the Lower Mekong Basin, with repercussions on flooded forests, riparian ecosystems, fisheries, and food security.
2:50PM Refreshment Break
3:20PM Communicating the Wonders of the Mekong to Build Support for Conservation
  Erin Loury, Chheana Chhut, Dee Thao, Zeb Hogan
Communication plays an important role in building understanding and support for science and conservation. One of the goals of the Wonders of the Mekong project is to communicate the region’s diverse wonders, including its richness of wildlife and fishes, its unique hydrology, and its deep cultural connection to the people of the region. Through the use of images, video, and original stories, the project has used Facebook and other social media channels to reach an audience of Cambodians and other Southeast Asians. This effort has included the creation of the Mekong Conservation Heroes program, which uses online profiles of stories, photos, and video to shine a spotlight on inspiring individuals working to study, protect, and communicate the Mekong’s many wonders. Through the use of diverse communication approaches, we hope to foster a deep sense of appreciation and value of the Mekong River and the many services it provides, especially among those living in the Mekong Basin.
3:40PM Is Co-Management a Better Solution to Fisheries Resources Management: Case of the Tonle Sap River and Lake
  Samadee Saray, Peng Bun Ngor, Zeb Hogan
Cambodia is the first country in Asia that removed private, commercial user rights (fishing lot system) and introduced fisheries co-management involving local resource users in the use and management of fisheries resources. A series of policy reform on fisheries management has been implemented since 2001 and noticeably in 2012, when all the unique, century-old fishing lots have been abolished. Such a policy change has opened larger space for local community participation in managing inland fisheries. As a result, ~516 community fisheries (CFis) have been established countrywide, including 228 CFis in the Tonle Sap Lake to co-manage the fisheries. Better or worse, the policy decision towards co-management has its pros and cons. Its downside is that fishers perceive that catches are gradually declining, comparing to the situation when the fisheries were managed under fishing lot system. This study will be based on fisheries policy reviews, field interviews with key stakeholders namely former fishing lot owners, fisheries officers and CFi members in Tonle Sap River and Lake regarding their perceptions on the two management systems towards effective fish resource management. Drawing on lessons learnt from the two fisheries management systems, we expect to suggest solutions towards better fisheries management in Tonle Sap.
4:00PM Developing a Sustainable Fishery in a Subtropical Dam Reservoir – Case of Nam Theun 2 Dam in Lao PDR
  Eric Baran, Theodorus Visser, Maud Cottet, Anne Tessier, Eric Guerin, Jean Guillard
In the Mekong the Nam Theun 2 hydropower project promoted a reservoir fishery as part of an integrated development approach. The aquatic environment of this fishery has been extensively studied. Fishing effort has been monitored, but its regulation remains weak. Harvest monitoring underlines the rapid evolution of the reservoir towards an oligo-mesotrophic status, with a naturally low fish production. Social studies have focused on socioeconomic aspects, and aspirations or constraints of the fishing community are not documented. Self-consumption has been emphasized, but not detailed. Fish prices and the value of the fish officially traded have been monitored, but a study of non-official trade, of the demand and of the competition remains to be undertaken. On the policy side, facilitation initiatives and access restrictions are well documented but an analysis of the pros and cons of the regulatory measures remains to be done, and the fish trade policy framework is not documented. Last, our analysis identifies the various degrees of control of managers over the fishery system and its components. Overall, this analysis highlights the need to apprehend a controlled reservoir fishery as a combination of aquatic habitat, fish, fishers and their economic and policy environment.
4:20PM Managing Cambodia’s Migratory Fish: A Vision for Success
  Teresa Campbell, Erin Loury, Shaara Ainsley, Sudeep Chandra, Tom Dilts, Vittoria Elliott, Pelle Gatke, Dana Lee, Sapana Lohani, Peng Bun Ngor, Sarah E. , Chheng Phen, Liana Prudencio, Samadee Saray, Flavia Tromboni, Herman Wanningen, Peter Weisberg, D
Migratory fish are vital to Cambodian livelihoods, yet their abundance – especially of large-bodied migratory fish – is decreasing at an alarming rate. A comprehensive management plan is needed to monitor and protect this valuable resource. Here, we present the results of collaborative efforts to define a vision for the successful management of Cambodia’s fish migrations and a practical roadmap for achieving that vision. The vision is built on expert opinion and examples from case studies in other systems. Successful management of Cambodia’s migratory fish was identified as: sustainable migrations that preserve human welfare and livelihoods, maintain ecosystem function, and exist within clean, well-managed, and connected habitats. Management should be carried out by a multi-level infrastructure of partners and stakeholders that is supported by informed resource users and the general public. Although there are challenges to implementing this vision, managers can learn from and apply successful strategies implemented elsewhere. Despite declining population trends and increasing threats to these migrations, several priority migration corridors in Cambodia are still intact and support substantial migrations. A cohesive management plan with coordination between organizational levels and stakeholders can help sustain populations of migratory fish to support food security and maintain ecological integrity.

Organizers: Liana Prudencio, Peng Bun Ngor, Flavia Tromboni, Samadee Saray
Supported by: Wonders of the Mekong Project

Location: Atlantis Hotel Date: October 1, 2019 Time: 8:40 am - 5:00 pm