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Baumgartner L.J.,Narrandera Fisheries Center | Daniel Deng Z.,Pacific Northwest National Laboratory | Thorncraft G.,National University of Laos | Boys C.A.,Port Stephens Fisheries Institute | And 3 more authors.
Journal of Renewable and Sustainable Energy | Year: 2014

Tropical rivers have high annual discharges optimal for hydropower and irrigation development. The Mekong River is one of the largest tropical river systems, supporting a unique mega-diverse fish community. Fish are an important commodity in the Mekong, contributing a large proportion of calcium, protein, and essential nutrients to the diet of the local people and providing a critical source of income for rural households. Many of these fish migrate not only upstream and downstream within main-channel habitats but also laterally into highly productive floodplain habitat to both feed and spawn. Most work to date has focused on providing for upstream fish passage, but downstream movement is an equally important process to protect. Expansion of hydropower and irrigation weirs can disrupt downstream migrations and it is important to ensure that passage through regulators or mini hydro systems is not harmful or fatal. Many new infrastructure projects (<6 m head) are proposed for the thousands of tributary streams throughout the Lower Mekong Basin and it is important that designs incorporate the best available science to protect downstream migrants. Recent advances in technology have provided new techniques which could be applied to Mekong fish species to obtain design criteria that can facilitate safe downstream passage. Obtaining and applying this knowledge to new infrastructure projects is essential in order to produce outcomes that are more favorable to local ecosystems and fisheries. © 2014 AIP Publishing LLC. Source

Baumgartner L.J.,Australian Department of Primary Industries and Fisheries | Marsden T.,Australian Department of Primary Industries and Fisheries | Singhanouvong D.,Living Aquatic Resources Research Center | Phonekhampheng O.,National University of Laos | And 2 more authors.
River Research and Applications | Year: 2012

Fish passage through an experimental vertical-slot fishway was assessed at a floodplain regulator on the Mekong River in Central Laos between April and July 2009. Experiments were conducted to investigate the influence of fishway floor slope (1v:15h or 1v:7.5h) on fish passage success with a view to developing a series of optimal design criteria for the construction of vertical-slot fishways at other barriers to fish passage in the Lower Mekong Basin. A total of 14661 fish from 73 species were captured during the experiments. Catches were dominated by riverine (white) (n=51; 69% of total) and floodplain (black) species (n=15; 20%) which represented 19 families in total. The work demonstrated that fish were actively attempting upstream passage from the Mekong River to an adjacent floodplain and displayed strong migratory behaviour during river level rises. Migratory activity was greatest during sharp rises in water level but reduced substantially when river level fell. Fish community composition varied greatly among the two fishway floor slopes and the control group. More fish species were collected from control samples, but the most fish and species were collected when the fishway was configured on a moderate hydraulic slope (1v:15h). A range of size classes were also collected from control and moderate-slope groups, but steeper-gradient catches were dominated by larger fish. This study demonstrated that vertical-slot fishways could provide passage for a biodiverse fish community where fish move laterally onto floodplains. The construction of fishways which consider the local fish ecology and hydrology may therefore represent a valuable management tool to help restore important movement pathways for tropical freshwater fish. © 2011 John Wiley & Sons, Ltd. Source

Bezuijen M.R.,Wildlife Conservation Society | Cox Jr. J.H.,Wildlife Conservation Society | Thorbjarnarson J.B.,Wildlife Conservation Society | Phothitay C.,Living Aquatic Resources Research Center | And 2 more authors.
Journal of Herpetology | Year: 2013

The Siamese Crocodile (Crocodylus siamensis) is critically endangered and, until a decade ago, few remaining wild populations were known to exist. Described here are the first in-depth surveys for C. siamensis in Laos with new field data on ecology and conservation. Small breeding populations of C. siamensis are confirmed to persist in Laos. During surveys between 2003 and 2008, C. siamensis was recorded in 13 sites of six river systems, where at least 36 individuals (1-11 per site) were documented. In all sites, crocodile densities and recruitment rates were extremely low. Eight nests were recorded- -among the first wild nests of C. siamensis to be reported. Perennial, thickly vegetated floodplain lakes are critical dry-season refugia and breeding habitats for C. siamensis in Laos. Opportunistic collection of crocodiles by local communities was observed, and at all sites there is increasing degradation of floodplain lakes for agriculture or economic development. National crocodile records were compiled and indicate that, historically, C. siamensis was widespread in lowland riverine and palustrine habitats of Laos, with most records from Central and South Laos in the Mekong Plain. These records also suggest that a severe range decline has occurred over the past century, although most wetlands remain unsurveyed for crocodiles. Crocodylus siamensis is probably now extirpated from the Lao Mekong and many other wetlands. Remnant C. siamensis populations in Laos are of global importance. All documented breeding sites, and most confirmed national records, are in rural lands outside the national protected area system, and conservation efforts will require community-based approaches. Copyright 2013 Society for the Study of Amphibians and Reptiles. Source

Koizumi N.,Japan National Agriculture and Food Research Organization | Morioka S.,Japan International Research Center for Agricultural science | Quinn T.W.,University of Denver | Mori A.,Japan National Agriculture and Food Research Organization | And 4 more authors.
Conservation Genetics Resources | Year: 2012

Twenty-nine microsatellite loci were isolated and characterized from the genome of Esomus metallicus. Flanking polymerase chain reaction primers were designed and used to amplify these loci in 32 individuals. All loci were polymorphic; with allele numbers ranged from 2 to 27, observed heterozygosity from 0. 031 to 0. 969 and expected heterozygosity from 0. 031 to 0. 957. All conformed to Hardy-Weinberg equilibrium and no evidence of null alleles was observed. Pairwise comparisons between alleles did not detect any cases of linkage disequilibrium. The high level of polymorphisms observed in these microsatellite loci should enhance future investigation of the genetic differentiation and structure of populations of E. metallicus. © 2012 Springer Science+Business Media B.V. Source

Koizumi N.,Japan National Agriculture and Food Research Organization | Morioka S.,Japan International Research Center for Agricultural science | Quinn T.W.,University of Denver | Mori A.,Japan National Agriculture and Food Research Organization | And 4 more authors.
Conservation Genetics Resources | Year: 2012

We isolated and characterized a total of 40 polymorphic microsatellite loci from the genome of Parambassis siamensis. Flanking Polymerase Chain Reaction primers were developed and used to show that all loci were polymorphic with the number of observed alleles per locus in 32 individuals ranging from 2 to 29. The observed heterozygosity ranged from 0. 063 to 0. 969, while the expected heterozygosity varied from 0. 062 to 0. 960. All loci conformed to Hardy-Weinberg equilibrium, none of the loci combinations showed significant linkage disequilibrium, and no loci showed evidence of null alleles. These 40 microsatellite loci should be useful for conducting future investigations into the genetic differentiation and structure of populations of P. siamensis. © 2012 Springer Science+Business Media B.V. Source

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