Wildlife rangers in Cambodia have sighted 3 new Mekong River dolphin calves born during the spring breeding season this year.
Conservation group WWF, which funds research and protection of the rare dolphin in Cambodia, says the 3 new dolphin babies are a very healthy increase for the total population of just 80 Mekong dolphins.
And the WWF wildlife rangers also reported no signs of adult dolphin deaths during their spring survey of the remote pools in the Mekong where the dolphins live during the low-river season, which is often a perilous time.
The Mekong dolphins are a unique population of Irrawaddy dolphin, named for a river in Myanmar where the species is also threatened. Most Irrawaddy dolphins live near river estuaries and the sea. But the Mekong dolphins are far from the sea and most live their whole lives in the river. In Cambodia only 80 dolphins remain in a stretch of the Mekong River between Kratie province and the Laos border to the north. Another group of about 5 dolphins live in the Mekong below the Khone Falls in Laos.
WWF funds scientific research and protection programs for the Mekong dolphins from a base in Kratie. Protection efforts include encouraging local fishermen to reduce the use of set gill-nets, which can entangle dolphins attracted to the netted fish.
Fossil bones found by farmers digging a new pond in north-east Thailand have been identified as a new species of dinosaur – the ninth dinosaur species found in this part of Thailand and the sixth found nowhere else.
New-to-science Sirindhorna khoratensis was a plant-eating iguanodontid, about 6 metres long, which lived around 120 million years ago.
The new dinosaur takes it genus name from the daughter of Thailand’s King Bhumibol, Princess Sirindhorn, an enthusiastic patron of dinosaur research. Its species name comes from Khorat, the informal name for the city of Nakhon Ratchasima about 400 kilometres north-east of Bangkok.
The fossils were uncovered in 2005 on the outskirts of the city by farmers digging a small reservoir to water their crops of corn and tapioca.
They reported the find to scientists at Nakhon Ratchasima Rajabhat University (NRRU), but the location meant that the dig teams could only collect the fossils when there were no crops in the ground, for a few months each year between 2006 and 2012.
Although the fossils are fragmented, most of the skull and jawbone are complete and Sirindhorna is now one of the best-known iguanodon species in Asia, say the researchers from Japan’s Fukui Prefectural University and NRRU.
Iguanodon-like dinosaurs lived in the early Cretaceous Period between 145 million and 100 million years ago, when most of Southeast Asia was covered by jungles, swamps and shallow seas. They may have traveled in herds for protection against predators, like wild elephants today.
Masateru Shibata, a paleontologist at Fukui Prefectural University and the lead author of the research, told Kyodo News that iguanodons are thought to have colonised Asia from North America and Europe and the new find helped establish their range. Iguanodons from the early Cretaceous Period had also been found in Japan and the latest find from Thailand was “valuable as it shows iguanodons lived in a wide area of Asia,” he said.
Sirindhorna is the ninth new species of dinosaur identified from fossils found in Thailand, all in the north-east Isan region of farmland, mountains and forests that extends from Khorat to Thailand’s Mekong River border with Laos and Cambodia.
It is the second Thai dinosaur named after Princess Sirindhorn — Phuwiangosaurus sirindhornae, a 20-metre long suaropod, was named in her honour in 1994.
North-east Thailand has emerged as a rich source of dinosaur fossils and other archaeological discoveries since the 1970s, when the first fossilized bones were found by prospectors looking for uranium in the broken scarps of Phu Wiang district, 85 kilometres west of the city of Khon Kaen and now a national park.
In 1994, the lucky find of a dinosaur bone by a monk in Kalasin province led to the discovery of a “dinosaur’s graveyard” and five new species. The discovery site has been developed into a renowned dinosaur museum and paleontology institute. Footprints from tyrannosaurs and other species have been found at several sites.
Archaeologists have also discovered important remains of the human occupation of the Middle Mekong Basin, including elaborate pottery and metalwork from grave sites at Ban Chiang and Ban Non Wat in north-east Thailand — relics of Bronze-Age peoples who lived in the region between 3000 and 4000 years ago.
But they have warned that the region’s archaeological heritage is threatened by land development and looting that takes place before scientists can learn what’s there.
Dr Joyce White, an American archaeologist who worked on the Ban Chiang discoveries, said at a public lecture in Bangkok last year that the destruction of archaeological sites across the region would have a lasting impact on future prospects for tourism, education and the rural societies involved.
Dr White was an expert witness for the US Justice Department in a successful prosecution of a US museum that had purchased smuggled artifacts from Ban Chiang and other Thai archaeological sites. The artifacts were returned to Thailand in 2014.
Meanwhile, Sisaket residents are still coping with the drought crisis as the amount of water in the Rasi Salai Dam is at a critical level. Only one of the sluice gates is opened to release water into the streams, in order to conserve the remaining water.
[Mr Thanar said] the other project would divert water from the Mekong River to the Chi and Mun rivers in the Northeastern region. The project starts from Chiang Khan district in Loei where water from the Mekong River would be diverted into a new, 100-km canal which will be dug under the project.
The canal will be the water course sending the water into the two rivers in the Northeastern region. The project could feed more water into Ubolratana dam in Khon Kaen and nearby reservoirs. Upper Northeastern provinces will also reap benefits from the project such as Nong Bua Lam Phu and Loei.
The projects, under the department’s 10-year plan, will be forwarded for approval to the National Water Resources Committee, chaired by Prime Minister Prayut Chan-o-cha, in its first meeting next Wednesday. The committee was set up last Wednesday, said Mr Thanar.
Of the vast multitude of fish species in the Mekong River, two closely-related species, Henicorhynchus siamensis and H. lobatus, are of special concern given the rapid rate of hydropower development. Inhabiting the Mekong and Chao Phraya basins (H. siamensis) and the Mekong basin (H. lobatus), these two small-sized cyprinids, collectively referred to as Siamese mud carp, are the most abundant and most economically important fish in the middle and lower Mekong basin. They are harvested in huge numbers, especially in and around Tonle Sap Lake in Cambodia and the Khone Falls area in southern Laos. These species account for 43% and over 50% of the total catch in these areas, respectively, with an overall basin-wide catch being >12% for the two species combined.
The Siamese mud carp populations in the Mekong, or at least some of them, are known to perform long-distance migrations. However, what is known about their migrations is severely limited. In Thailand and Laos, the species undertake upstream migration in the early rainy season above the Khone Falls, whereas in Cambodia, this species migrate upstream at the onset of the dry season below the waterfalls. The latter migrants possibly originate from the Tonle Sap Lake, first descending the Tonle Sap River and then ascending the Mekong mainstream toward and even past the Khone Falls . Spawning takes place in tributaries or floodplains during the wet season, with a peak in May-June. Eggs and larvae are carried to nursery habitats on the floodplain by the water current. At the beginning of the dry season, juveniles move out of the floodplains with the receding water and seek dry season refuge habitats such as deep pools in the Mekong mainstream.
A molecular approach was employed to investigate stock structure in Siamese mud carp Henicorhynchus siamensis populations collected from 14 sites across mainland south-east Asia, with the major focus being the lower Mekong River basin. Spatial analysis of a mitochondrial DNA fragment (ATPase 6 and 8) identified four stocks in the Mekong River basin that were all significantly differentiated from a population in the nearby Khlong River, Thailand. In the Mekong River basin, populations in northern Lao People’s Democratic Republic and northern Thailand represent two independent stocks, and samples from Thai tributaries group with those from adjacent Mekong sites above the Khone Falls to form a third stock. All sites below the Khone Falls constituted a single vast stock that includes Cambodia and the Mekong Delta in Vietnam. While H. siamensis is considered currently to undertake extensive annual migrations across the Mekong River basin, the data presented here suggest that natural gene flow may occur over much more restricted geographical scales within the basin, and hence populations may need to be managed at finer spatial scales than at the whole-of-drainage-basin level.
Below the Khone Falls, H. siamensis migrates upstream from November to February, whereas above the Khone Falls, it migrates upstream from March to September. It migrates in response to changing water levels. As floodwaters recede H. siamensis migrates from the flooded areas back to main river channels, e.g. the Mekong mainstream. Several fishers below the Khone Falls reported that the peak period of upstream migration for H. siamensis occurs one week before the full moon. Above the Khone Falls, migrations appear to be less influenced by the lunar phase. Some fishers along the stretch from Kratie to the Khone Falls in Cambodia were able to determine the speed of migration based on the time it takes for the fish to move between two villages along the river. They estimated the speed at 16 km per day… Below the Khone Falls, H. siamensis migrates downstream from May to September when the water levels start to rise. This corresponds with the peak time for observations of eggs in the fish, i.e. the peak spawning period is believed to occur between May to June.
Migration is usually linked to changes in the water levels. When water levels start to rise during the flooding season, fish migrate from the Mekong mainstream to canals and flooded areas. Near the end of flooding season fish migrate back to the larger rivers. In the Mekong mainstream upstream migrations occur from November to February and downstream migrations from May to September (below Khone falls). The patterns of migration described below the Khone Falls differ from observations made in northern Lao and Thailand, where migrations take place from November to February. This could indicate that a different sub-population is involved in that section of the river. It should be noted that fishers catch this species all year round.
Fish of the genus Henicorhynchus are small migratory cyprinids and one of the most important groups in the Lower Mekong Basin and Chaophraya River basin ﬁsheries, especially the Siamese mud carp Henicorhynchus siamensis (Sauvage, 1881). This ﬁsh is a common catch whereby in thebasin area four sub-populations were recently identiﬁed (Adamson et al., 2009). H. siamensis is also the main ﬁsh catch produced by the commercial bag-net ﬁsheries in Tonle Sap, Cambodia, where it constitutes more than 60% of the catch and accounts for almost 10% of the total value generated (Deap et al., 1998). Moreover, H. siamensis is ranked as the top species commonly consumed by Cambodians. These advantages play a crucial role as the most important animal food for the poor (Kent, 1997) and also fulﬁll a role as a dietary source of vitamins and minerals (Rooset al., 2007). The importance of this ﬁsh is also acknowledged in the Cambodian currency, the ÔrielÕ, which is named after the Cambodian common name for H. siamensis of “trey riel” (Volbo-Jørgensen and Poulsen, 2000).
H. siamensis is also well known for its migratory habit oflateral migration into the ﬂoodplains during the ﬂood season and then returning to the rivers when the ﬂood waters begin torecede (Rainboth, 1996). But it is also known not to prosper inimpoundments (Lamberts, 2001; Chheng et al., 2004), as itslife cycle depends on the river ⁄ ﬂood regime. However, H. siamensis can successfully inhabit man-made lakes in Thailand as well as in the Lao PDR, and is among the candidates for a ﬁsh stock enhancement program to increase ﬁsh production in inland water bodies in the region (Jutagate 2009). Knowledge of the life cycles of many important SoutheastAsia freshwater ﬁsh species is still very fragmentary, especially when they inhabit an uncommon environment (Volbo-Jørgen-sen and Poulsen, 2000). Given the importance of H. siamensis to ﬁsheries in many parts of major Southeast Asian rivers, this study aimed to investigate the key facets of the H. siamensis life history (Froese et al., 2000), i.e. reproduction, feeding and growth. A goal was to see whether this small cyprinid could ﬂourish and support a small-scale artisanal ﬁshery in a reservoir and to evaluate its potential as a source of protein and micronutrients as well as income for the local people in the vicinity of the reservoir.
Most fish species living in the Mun River are unable to climb or are for other reasons not using the ladder installed on Pak Mun Dam. This is especially true for large species most important in wild-capture fisheries. The ladder is unsuccessful in maintaining fish spawning migrations because few or no gravid females of any species climb it. Various proponents of Pak Mun Dam claim that its main impact on fish is that they cannot swim upstream and downstream past the dam. This is far from the only impact. The real problem is not with the ladder. Rather Pak Mun Dam itself is ecologically unfriendly to fishes.
A reservoir outflow is not a normal river. The abnormal flow regime and other artificial features in the outflow of Pak Mun Dam have severe impacts on fishes for 4.5 km until it joins the Mekong mainstream which dissipates (but is also effected by) its negative impacts. Pak Mun Reservoir is also very unfriendly to fish. This apparently is due mainly to having its bottom smothered by silt and its open water with an exceptionally heavy silt load at all times because of the highly abnormal “run of the river” flow conditions.
When the water level in Pak Moo Reservoir is at 108 m. “peak electricity generation” causes daily fluctuations in water flow downstream from Pak Mun Dam and daily draw-downs in the reservoir that disturb fish habitats and disrupt fish migration. If reservoir water levels are too low, the amount of water released from the sluice gates may be less than the lowest flow that normally occurs for only a few days or weeks of particularly dry years (if the reservoir level falls below 94 m the outflow will stop altogether). During minimum outflow the water quality also can be much poorer than that of normal dry-season low water without the dam. The other extreme occurs when water has to be released to prevent the reservoir itself from over-flowing. Opening the sluice gates on the spillways when the reservoir level is high can create a destructive torrent far stronger than any that occurred during the worst floods in the Moo River before Pak Moo Dam. Maximum as well as minimum outflows from Pak Moo Reservoir are lethal to fish.
The problem of Pak Mun Dam and fisheries may be summarized as follows: an artificial and hostile downstream environment (reservoir outflow) and an artificial and hostile upstream environment (reservoir) are connected by artificial and hostile corridors (fish ladder and dam spill-ways). The resulting impact accumulation has devastating over-all effects on fish habitats and fish species. Pak Mun Dam together with its 35-km long reservoir and 4.5 km reservoir outflow is a major geographic barrier to all kinds of fish movements between the Mekong and the Mun.
BAN PHUM SAROL school in eastern Thailand has an unusual display of pieces of broken metal in the foyer. At first glance they look a bit like machine parts and water pipes. But a closer look reveals what they are: melted and twisted fragments of shrapnel, the fins from mortar bombs, and the casings of rockets fired from Katyusha launchers.
In 2011, this primary school a few kilometers north of the disputed Preah Vihear temple was on the front line of an escalating border conflict between Thai and Cambodian troops that claimed dozens of lives.
The first warning came when a mortar round struck the playground in the late afternoon. Fortunately the children had already gone home, although some teachers were still at work. Over the next few hours, the school, nearby homes, and streets of the village came under heavier fire from Cambodian artillery.