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  • Print publication year: 2015
  • Online publication date: December 2015

1 - Lost fishes, who is counting? The extent of the threat to freshwater fish biodiversity

Summary

INTRODUCTION

Freshwater rivers, lakes and wetlands are among the most threatened ecosystems on the planet, facing growing pressures from an expanding human population and increased socioeconomic development (Ormerod et al., 2010; Vörösmarty et al., 2010; Carpenter et al., 2011). This pressure on freshwater ecosystems is accompanied by correspondingly high levels of threat to freshwater biodiversity (Dudgeon et al., 2006; WWF, 2010; Thieme et al., 2011; Collen et al., 2014), as is clearly demonstrated by the high species extinction rates and levels of threat recorded on the IUCN Red List of Threatened Species (www.iucnredlist.org), hereafter referred to as the IUCN Red List. North American freshwater bivalves are, for example, notable for having the greatest proportion of extinct species worldwide. In Europe, freshwater species top the IUCN Red List with the highest proportion of threatened species. Remarkable twenty-first-century extinctions such as the baiji (Lipotes vexillifer), the golden toad (Incilius periglenes) and the Alaotra grebe (Tachybaptus rufolavatus), just to name a few, are all freshwater species. However, no-one has yet comprehensively assessed the level of threat and extinction rates for freshwater fishes at the global scale – and it is likely that many fishes are disappearing without record.

The twenty-first century is a critical time for the future of freshwater fishes. Human actions have a serious impact on freshwater ecosystems around the world and the freshwater fish species face ever increasing risks. Unless actions are taken rapidly to reduce the multiple threats facing freshwater fishes, many species will be lost. A sobering example, which serves well to demonstrate the severity of the threat, is the perilous state of the world's sturgeons and paddlefishes (Acipenseriformes). Sturgeon have survived on this Earth for 250 million years, but now face the serious possibility of becoming extinct in this century as a direct result of human activities. Illegal fishing, overfishing, obstructions to migratory routes and pollution has resulted in 23 of the 27 sturgeon species being assessed as threatened on the IUCN Red List. Of these, 17 species are Critically Endangered and four are possibly Extinct, including the Chinese paddlefish (Psephurus gladius), the world's longest freshwater fish for which only two adult specimens (both females) have been recorded since 2002. Human exploitation of freshwater ecosystems and the fishes within them must operate within sustainable limits, and critical sites for freshwater species must be identified and protected before it is too late for many species.

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Abell, R., Thieme, M. L., Revenga, C., et al. (2008). Freshwater ecoregions of the world: a new map of biogeographic units for freshwater biodiversity conservation. Bioscience, 58, 403–414.
Albert, J. S., Petry, P. & Reis, R. E. (2011). Major biogeographic and phylogenetic patterns. In Historical Biogeography of Neotropical Freshwater Fishes. Albert, J. S. & Reis, R. E. (Eds). Berkeley, CA: University of California Press, pp. 21–58.
Allen, D. J., Molur, S. & Daniel, B. A. (compilers) (2010). The Status and Distribution of Freshwater Biodiversity in the Eastern Himalaya. Cambridge, UK and Gland, Switzerland: IUCN, and Coimbatore, India: Zoo Outreach Organisation.
Arthington, A. H. & Pusey, B. J. (2003). Flow restoration and protection in Australian rivers. River Research and Applications 19, 377–395.
Baigún, C. R. M., Colautti, D., López, H. L., Van Damme, P.A. & Reis, R. E. (2012). Application of extinction risk and conservation criteria for assessing fish species in the lower La Plata River basin, South America. Aquatic Conservation: Marine and Freshwater Ecosystems, 22, 181–197.
Bates, B., Bunn, S., Baker, P., et al. (2010). National Climate Change Adaptation Research Plan: Freshwater Biodiversity. NCCARF, Griffith University, Australia.
Beatty, S. J., Morgan, D. L., Rashnavadi, M. & Lymbery, A. J. (2011). Salinity tolerances of endemic freshwater fishes of south-western Australia: implications for conservation in a biodiversity hotspot. Marine and Freshwater Research, 62, 91–100.
Berra, T. M. (2001). Freshwater Fish Distribution. London: Academic Press.
Burkhead, N. M. (2012). Extinction rates in North American freshwater fishes, 1900–2010. BioScience, 62, 798–808.
Burr, B. M. & Mayden, R. L. (1992). Phylogenetics and North American freshwater fishes. In Systematics, Historical Ecology, and North American Freshwater Fishes. Mayden, R. L. (Ed.). Stanford, CA: Stanford University Press, pp. 18–75.
Campbell, I. C., Poole, C., Giesen, W. & Valbo-Jorgensen, J. (2006). Species diversity and ecology of Tonle Sap Great Lake, Cambodia. Aquatic Sciences, 68, 355–373.
Canonico, G. C., Arthington, A., McCrary, J. K. & Thieme, M. L. (2005). The effect of introduced tilapias on native biodiversity. Aquatic Conservation: Marine and Freshwater Ecosystems, 15, 463–483.
Cappato, J. & Yanosky, A. (2009): Uso Sostenible de Peces en la Cuenca del Plata. Argentina, Brazil & Paraguy: UICN-Guyra-Proteger.
Carpenter, S. R., Stanley, E. H. & Vander Zanden, M. J. (2011). State of the world's freshwater ecosystems: physical, chemical, and biological changes. Annual Review of Environment and Resources, 36, 75–99.
CESCC. (2006). Wild species 2005: the general status of species in Canada [online]. Government of Canada. www.wildspecies.ca/wildspecies2005/index.cfm?lang=e&sec=49&view=10 (accessed 7 August 2013).
Chenoweth, J., Hadjinicolaou, P., Bruggeman, A., et al. (2011). Impact of climate change on the water resources of the eastern Mediterranean and Middle East region: modeled 21st century changes and implications. Water Resources Research, 47, W06506.
Cohen, A., Kaufman, L. S. & Ogutu-Ohwayo, R. (1996). Anthropogenic threats, impacts, and conservation strategies in the African Great Lakes: A review. In: The Limnology, Climatology, and Paleoclimatology of the East African Lakes. Johnson, T. C. & Odada, E. O. (Eds). Amsterdam: Gordon and Breech Publishers, pp. 575–624.
Collen, B., Whitton, F., Dyer, E. E., et al. (2014). Global patterns of freshwater species diversity, threat and endemism. Global Ecology and Biogeography, 23, 40–51.
Contreras-MacBeath, T., Rodrigues, M. B., Sorani, V., Goldspink, C. & McGregor Reid, G. (2014). Richness and endemism of the freshwater fishes of Mexico. Journal of Threatened Taxa, 6, 5421–5433.
Corfield, J., Diggles, B., Jubb, C., et al. (2008). Review of the Impacts of introduced Ornamental Fish Species that have Established Wild Populations in Australia. Canberra:Australian Government, Department of the Environment, Water, Heritage and the Arts.
COSEWIC. (2012). Canadian Wildlife Species at Risk. Committee on the Status of Endangered Wildlife in Canada. www.cosewic.gc.ca/eng/sct0/rpt/rpt_csar_e.cfm (accessed 15 October 2012).
Côté, I. M. & Reynolds, J. D. (1998). Tropical fish: explosions and extinctions. Trends in Ecology and Evolution, 13, 475–476.
Dahanukar, N., Raut, R. & Bhat, A. (2004). Distribution, endemism and threat status of freshwater fishes in the Western Ghats of India. Journal of Biogeography, 31, 123–136.
Darwall, W.R.T., Smith, K.G., Allen, D.J., et al. (Eds). (2011) The Diversity of Life in African Freshwaters: Under Water, Under Threat. An Analysis of the Status and Distribution of Freshwater Species Throughout Mainland Africa. Gland, Switzerland and Cambridge, UK:IUCN,.
Dextrase, A. J. & Mandrak, N. E. (2006). Impacts of alien invasive species on freshwater fauna at risk in Canada. Biological Invasions, 8, 13–24.
Dudgeon, D. (2000). The ecology of tropical Asian rivers and streams in relation to biodiversity conservation. Annual Reviews of Ecology and Systematics, 31, 239–263.
Dudgeon, D. (2005). River rehabilitation for conservation of freshwater biodiversity in monsoonal Asia. Ecology and Society, 10, 15. www.ecologyandsociety.org/vol10/iss2/art15/.
Dudgeon, D. (2011). Asian river fishes in the Anthropocene: threats and conservation challenges in an era of rapid environmental change. Journal of Fish Biology, 79, 1487–1524.
Dudgeon, D., Arthington, A. H., Gessner, M. O., et al. (2006). Freshwater biodiversity: importance, threats, status and conservation challenges. Biological Reviews, 81, 163–182.
Dulvy, N. K., Fowler, S. L., Musick, J. A., et al. (2014). Extinction risk and conservation of the world's sharks and rays. eLife, 3, e00590.
Edds, D. R., Gillette, D. P., Maskey, T. M. & Mahato, M. (2002). Hot-soda process paper mill effluent effects on fishes and macroinvertebrates in the Narayani River, Nepal. Journal of Freshwater Ecology, 17, 543–554.
Eschmeyer, W. N. & Fong, J. D. (2013). Species by family/subfamily. http://research.calacademy.org/research/ichthyology/catalog/SpeciesByFamily.asp (accessed 29 July 2013).
FAO. (2010). The State of World Fisheries and Aquaculture. Rome:Food and Agriculture Organisation of the United Nations.
Finer, M. & Jenkins, C. N. (2012). Proliferation of hydroelectric dams in the Andean Amazon and implications for Andes–Amazon connectivity. PLoS ONE, 7, e35126.
Freyhof, J. & Brooks, E. (2011). European Red List of Freshwater Fishes. Luxembourg: Publications Office of the European Union.
Freyhof, J. & Kottelat, M. (2008). Stenodus leucichthys. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. www.iucnredlist.org (downloaded 31 July 2013).
Froese, R. & Pauly, D. (Eds). (2014). FishBase. www.fishbase.org, version 06/2014.
Fryer, G. & Iles, T. D. (1972). The Cichlid Fishes of the Great Lakes of Africa. London:Oliver and Boyd.
Geiger, M. F., Herder, F., Monaghan, M. T., et al. (2014). Spatial heterogeneity in the Mediterranean Biodiversity Hotspot affects barcoding accuracy of its freshwater fishes. Molecular Ecology Resources, 14, 1210–1221.
Gopal, K. & Agarwal, A. (2003). River Pollution in India and Its Management. New Delhi:APH Publishing.
Groombridge, B. & Jenkins, M. (1998). Freshwater Biodiversity: A Preliminary Global Assessment. Cambridge:World Conservation Monitoring Centre.
Hammer, M., Wedderburn, S. & van Weenen, J. (2009). Action Plan for South Australian Freshwater Fishes. Adelaide:Native Fish Australia (SA) Inc.
Harrison, I. J. & Stiassny, M. L. J. (1999). The quiet crisis: a preliminary listing of the freshwater fishes of the world that are extinct or ‘missing in action’.InExtinctions in Near Time. MacPhee, R. D. E. (Ed.). New York: Kluwer Academic/Plenum, pp. 271–331.
Hosoya, K. (2008). Circumstance of protection for threatened freshwater fishes in Japan. Korean Journal of Ichthyology, 20, 133–138.
IUCN. (2004). Red List Assessment of Madagascar's Freshwater Fishes. http://intranet.iucn.org/webfiles/doc/SpeciesProg/FBU/IUCN_Madagascar_freshwater_fish_2004.pdf
IUCN. (2013). IUCN Red List of Threatened Species. Version 2013.1. www.iucnredlist.org (downloaded 23 July 2013).
Jelks, H. L., Walsh, S. J., Burkhead, N. M., et al. (2008). Conservation status of imperiled North American freshwater and diadromous fishes. Fisheries, 33, 372–407.
Kang, B., Deng, J., Wu, Y., et al. (2013). Mapping China's freshwater fishes: diversity and biogeography. Fish and Fisheries, 15, 209–230.
Kingsford, R. T. (2000). Ecological impact of dams, water diversions and river management on floodplain wetlands in Australia. Austral Ecology, 25, 109–127.
Kottelat, M. & Freyhoff, J. (2007). Handbook of European Freshwater Fishes. Kottelat, Cornol, Switzerland and Freyhoff, Berlin, Germany.
Kottelat, M. & Whitten, T. (1996). Freshwater biodiversity in Asia with special reference to fish. World Bank Technical Paper 343.
Kottelat, M., Baird, I. G., Kullander, S. O., et al. (2012). The status and distribution of freshwater fishes of Indo-Burma. In The Status and Distribution of Freshwater Biodiversity in Indo-Burma. Allen, D. J., Smith, K. G. & Darwall, W. R. T. (Compilers). Cambridge, UK and Gland, Switzerland: IUCN.
Krishnakumar, K., Raghavan, R., Prasad, G., et al. (2009). When pets become pests: exotic aquarium fishes and biological invasions in Kerala, India. Current Science, 97, 474–476.
Lévêque, C., Oberdorff, T., Paugy, D., Stiassny, M. L. J. & Tedesco, P. A. (2008). Global diversity of fish (Pisces) in freshwater. Hydrobiologia, 595, 545–567.
Lintermans, M. (2004). Conservation status of Australian fishes (2004). Australian Society for Fish Biology Newsletter, 34, 59–64.
Lintermans, M. (2011). Conservation status of Australian Fishes (2011). Australian Society for Fish Biology Newsletter, 41, 94–97.
Lintermans, M. (2013), Conservation and management. In The Ecology of Australian Freshwater Fish. Humphries, P. & Walker, K. (Eds). Collingwood:CSIRO Publishing, pp. 283–316.
Lowe, S., Browne, M., Boudjelas, S. & de Poorter, M. (2000). 100 of the World's worst invasive alien species. A selection from the global invasive species database. Published by the ISSG as a special lift out in Aliens, 12 December 2000, 12 pp.
Lundberg, J. G., Kottelat, M., Smith, G. R., Stiassny, M. L. J. & Gill, A. C. (2000). So many fishes, so little time: an overview of recent ichthyological discovery in continental waters. Annals of the Missouri Botanical Garden, 87, 26–62.
Mace, G. M. & Lande, R. (1991). Assessing extinction threats: towards a re-evaluation of IUCN threatened species categories. Conservation Biology, 5, 148–157.
McAllister, D. E., Hamilton, A. L. & Harvey, B. H. (1997). Global freshwater biodiversity: striving for the integrity of freshwater ecosystems. Sea Wind, 11 .
McDowall, R. M. (1990) New Zealand Freshwater Fishes: A Natural History and Guide. Auckland:Heinemann Reed.
McDowall, R. M. (2006). Crying wolf, crying foul, or crying shame: alien salmonids and a biodiversity crisis in the southern cool-temperate galaxioid fishes?Reviews in Fish Biology and Fisheries, 16, 233–422.
McLeod, R. (2004). Counting the Cost: Impact of Invasive Animals in Australia. Canberra:Cooperative Research Centre for Pest Animal Control.
Minckley, W. L. & Douglas, M. E. (1991). Discovery and extinction of western fishes: a blink of eye in geologic time. In Battle Against Extinction: Native Fish Management in the American West. Minckley, W. L. & Deacon, J. E. (Eds). Tucson, AZ:University of Arizona Press.
Ministry of Environment, Government of Japan. (2007). Red List of freshwater and brackish water fish. www.env.go.jp/press/file_view.php?serial=9944&hou_id=8648
Ministry of Environment, Government of Japan. (2010). Report of Comprehensive Assessment of Biodiversity in Japan (Japan Biodiversity Outlook). Nature Conservation Bureau, Ministry of the Environment, Japan.
Mittermeier, R. A., Myers, N., Mittermeier, C. G. & Robles-Gil, P. (1999). Hotspots: Earth's Biologically Richest and Most Endangered Terrestrial Ecoregions. Mexico: CEMEX, SA and Agrupación Sierra Madre, SC.
Molur, S., Smith, K. G., Daniel, B. A. & Darwall, W. R. T. (Compilers). (2011). The Status and Distribution of Freshwater Biodiversity in the Western Ghats, India. Cambridge, UK and Gland, Switzerland: IUCN, and Coimbatore, India: Zoo Outreach Organisation.
Myers, N. (1988). Threatened biotas: “hot spots” in tropical forests. The Environmentalist, 8, 187–208.
Ng, P. K. L., Tay, J. B. & Lim, K. K. P. (1994). Diversity and conservation of blackwater fishes in Peninsular Malaysia, particularly in the north Selangor peat swamp forest. Hydrobiologia, 285, 203–218.
Oberdorff, T., Tedesco, P. A., Hugueny, B., et al. (2011). Global and regional patterns in riverine fish species richness: a review. International Journal of Ecology. Article ID 967631, 12 pages.
OECD (2012). OECD Environmental Outlook to 2050. The Consequences of Inaction. Paris: OECD.
Olden, J. D., Hogan, Z. S. & Vander Zanden, M. J. (2007). Small fish, big fish, red fish, blue fish: size-biased extinction risk of the world's freshwater and marine fishes. Global Ecology and Biogeography, 16, 694–701.
Ormerod, S. J., Dobson, M., Hildrew, A. G. & Townsend, C. R. (2010). Multiple stressors in freshwater ecosystems. Freshwater Biology, 55 (Suppl. 1), 1–4.
Orr, S., Pittock, J., Chapagain, A. & Dumaresq, D. (2012). Dams on the Mekong River: Lost fish protein and the implications for land and water resources. Global Environmental Change, 22, 925–932.
Pippard, H. (2012). The Current Status and Distribution of Freshwater Fishes, Land Snails and Reptiles in the Pacific Islands of Oceania. IUCN: Gland, Switzerland.
Pittock, J., Meng, J., Geiger, M., & Chapagain, A. K. (2009). Interbasin Water Transfers and Water Scarcity in a Changing World – A Solution or a Pipedream?Berlin: WWF Germany.
Posa, M. C., Wijedasa, L. S. & Corlett, R. T. (2011). Biodiversity and conservation of tropical peat swamp forests. BioScience, 61, 49–57.
Qiu, J. (2012). Trouble on the Yangtze. Science, 336, 288–291.
Raghavan, R. (2010). Ornamental fisheries and trade in Kerala. In Fish Conservation in Kerala. Benziger, A. & Sonnenschein, L. (Eds).St. Louis, USA: World Aquariums and Oceans Federation, pp. 169–197.
Raghavan, R., Prasad, G., Ali, A. & Pereira, B. (2008). Exotic fishes in a global biodiversity hotspot – a case study from River Chalakudy, part of Western Ghats, Kerala, India. Biological Invasions, 10, 37–40.
Raghavan, R., Ali, A., Dahanukar, N. & Rosser, A. (2011). Is the Deccan Mahseer, Tor khudree (Sykes, 1839) fishery in the Western Ghats Hotspot sustainable? A participatory approach to stock assessment. Fisheries Research, 110, 29–38.
Raghavan, R., Dahanukar, N., Tlusty, M. F., et al. (2013). Uncovering an obscure trade: threatened freshwater fishes and the aquarium pet markets. Biological Conservation, 164, 158–169.
Rahman, M. J. (2006). Recent advances in the biology and management of Indian shad (Tenualosa ilisha Ham.). SAARC Journal of Agriculture, 4, 76–98.
Reis, R. E. (2013). Conserving the freshwater fishes of South America. International Zoo Yearbook, 47, 1–6.
Reis, R. E., Kullander, S. O. & FerrarisJr, C. J. (Eds). (2003). Checklist of the Freshwater Fishes of South and Central America. Porto Alegre: Edipucrs.
Revenga, C. & Kura, Y. (2003). Status and Trends of Biodiversity of Inland Water Ecosystems. Montreal, Secretariat of the Convention on Biological Diversity, Technical Series no. 11.
Reynolds, J. D., Webb, T. J. & Hawkins, L. A. (2005). Life history and ecological correlates of extinction risk in European freshwater fishes. Canadian Journal of Fisheries and Aquatic Science, 62, 854–862.
Ribbink, A. J. (1988). Evolution and speciation of African cichlids. In Biology and Ecology of African Freshwater Fishes. Lévêque, C., Bruton, M. N. & Ssentongo, G. W. (Eds). Paris:ORSTOM, pp. 35–51.
Schaefer, S. A. (1998). Conflict and resolution: impact of new taxa on phylogenetic studies of the Neotropical cascudinhos (Siluroidei: Loricariidae). In Phylogeny and Classification of Neotropical Fishes. Malabarba, L. R., Reis, R. E., Vari, R. P., Lucena, Z. M. S. & Lucena, C. A. S. (Eds). Porto Alegre: Edipucrs, pp. 375–400.
Shaji, C. P., Easa, P. S. & Gopalakrishnan, A. (2000). Freshwater fish diversity of Western Ghats, In: Endemic Fish Diversity of Western Ghats. Ponniah, A. G. & Gopalakrishnan, A. (Eds).Lucknow: NBFGR-NATP publication, National Bureau of Fish Genetic Resources, pp. 35–35.
Smith, I., Cochrane, P., Stephenson, B., & Gibbs, N. (1997). State of New Zealand's Environment 1997. Wellington, New Zealand: The Ministry for the Environment.
Snoeks, J. (2000). How well known is the ichthyodiversity of the large East African lakes?Advances in Ecological Research, 31, 17–38.
Snoeks, J. (2004). The Cichlid Diversity of Lake Malawi/Nyassa/Niassa: Identification, Distribution and Taxonomy. El Paso, TX: Cichlid Press.
Snoeks, J., Harrison, I. J. & Stiassny, M. L. J. (2011). The status and distribution of freshwater fishes. In The Diversity of Life in African Freshwaters: Under Water, Under Threat. An Analysis of the Status and Distribution of Freshwater Species Throughout Mainland Africa. Darwall, W. R. T., Smith, K. G., Allen, D. J., et al. (eds). Gland, Switzerland and Cambridge, UK:IUCN.
Stiassny, M. L. J. & Sparks, J. S. (2006). Phylogeny and taxonomic revision of the endemic Malagasy genus Ptychochromis (Teleostei: Cichlidae), with the description of five new species and a diagnosis for Katria, new genus. American Museum Novitates, 3535, 1–55.
Stiassny, M. L. J., Brummett, R. E., Harrison, I. J., Monsembula, R. & Mamonekene, R. (2011). Status and distribution of freshwater fishes of Central Africa. In The Status and Distribution of freshwater biodiversity in Central Africa. Brooks, E. G. E., Allen, D. J. and Darwall, W. R. T. (Eds.), Gland, Switzerland and Cambridge, UK: IUCN.
Thieme, M. L., Turak, E., McIntyre, P., et al. (2011). Freshwater ecosystems under threat – the ultimate hotspot. In Fresh Water The Essence of Life. Mittermeier, R. A., Farrell, T., Harrison, I. J., Upgren, A. J. & Brooks, T. (Eds). Boulder, CO: CEMEX and iLCP.
Tockner, K., Bunn, S. E., Gordon, C., et al. (2008). Flood plains: critically threatened ecosystems. In: Aquatic Ecosystems. Polunin, N. (Ed.). Cambridge University Press.
Turner, G. F. (1994). Speciation mechanisms in Lake Malawi cichlids: a critical review. Archiv für Hydrobiologie – Beiheft Ergebnisse der Limnologie, 44, 139–160.
Turner, G. F. (1996). Offshore Cichlids of Lake Malawi. El Paso, TX: Cichlid Press.
UNEP. (2010). Blue Harvest: Inland Fisheries as an Ecosystem Service. Penang, Malaysia:WorldFish Center.
Vonlanthen, P., Bittner, D., Hudson, A. G., et al. (2012). Eutrophication causes speciation reversal in whitefish adaptive radiations. Nature, 482, 357–362.
Vörösmarty, C. J., McIntyre, P. B., Gessner, M. O., et al. (2010). Global threats to human water security and river biodiversity. Nature, 467, 555–561.
Voss, K. A., Famiglietti, J. S., Lo, M., et al. (2013). Groundwater depletion in the Middle East from GRACE with implications for transboundary water management in the Tigris–Euphrates–Western Iran region. Water Resources Research, 49, 904–914.
Wong, C. M., Williams, C. E., Pittock, J., Collier, U. & Schelle, P. (2007). World's Top 10 Rivers at Risk. Gland, Switzerland:WWF International.
WWF. (2010). Living Planet Report 2010: Biodiversity, Biocapacity and Development. London: WWF in Association with Zoological Society of London & Global Footprint Network.
Yuma, M., Hosoya, K. & Nagata, Y. (1998). Distribution of the freshwater fishes of Japan: an historical overview. Environmental Biology of Fishes, 52, 97–124.
Ziv, G., Baran, E., Nam, S., Rodríguez-Iturbe, I. & Levin, S. A. (2012). Trading-off fish biodiversity, food security, and hydropower in the Mekong River Basin. Proceedings of the National Academy of Sciences, 109, 5609–5614.