Analysis of the Cambodian bagnet ("dai") fishery data

This report summarises general and detailed features of catches from the bagnet ("dai") fishery in Cambodia between 1995 and 1999, as monitored by the MRC/DoF/DANIDA Management of the Freshwater Capture Fisheries Project (MFCFP) in Phnom Penh.Fishery data, Cambodia,

Zalinge N, Ngor Peng Bun (2001) Floods, floodplains and fish production in the Mekong Basin: present and past trends

Abstract This paper deals with relationships between hydrology, wetlands and fisheries production in the Mekong River Basin. A five-year monitoring of the bag net ("dai") fishery in the Tonle Sap River (Cambodia) showed a strong correlation between catches and water level in the same year. One taxon making up to 37% of total catches explains most of the relationships between catches and water level. The current overall catch in the Tonle Sap system amounts 230,000 tons a year. When compared with historical surveys, this catch is twice as much as the catch 60 years ago. However when population increase is taken into account, the catch per fisherman has drastically declined. This can be considered as a warning signal of high exploitation rate. There is also a positive relationship between historical catches and water level in the Mekong River. Several hydrological, environmental and ecological variables are likely to influence fish catches in the Mekong River floodplain. Hydrological variables are water level, duration, timing and regularity of the flood. Environmental variables are the total area of floodplain, the area of each type of flooded vegetation, and the presence or absence of dry season refuges. Among ecological variables, fish migration is by far the most important. The importance of fish catches in the economy and the food security of the region requires a very careful approach to water management in the Mekong Basin.

Enhanced low voltage nonlinearity in resonant tunneling metal–insulator–insulator–metal nanostructures

The electrical properties of bi-layer Ta2O5/Al2O3 and Nb2O5/Al2O3 metal–insulator–insulator–metal nanostructures as rectifiers have been investigated. The ultra-thin (1–6 nm) insulator layers were deposited by atomic-layer deposition or rf magnetron sputtering with Al as metal contacts. Variable angle spectroscopic ellipsometry was performed to extract the optical properties and band gap of narrow band gap insulator layers while the surface roughness of the metal contacts was measured by atomic force microscopy. Superior low voltage large signal and small signal nonlinearities such as asymmetry of 18 at 0.35 V, rate of change of non-linearity of 7.5 V�1, and responsivity of 9 A/W at 0.2 V were observed from the current–voltage characteristics. A sharp increase in current at �2 V on Ta2O5/Al2O3 device can be ascribed to resonant tunneling

Subspecies in the Sarus Crane Antigone antigone revisited; with particular reference to the Australian population.

Subspecies are often less well-defined than species but have become one of the basic units for legal protection. Evidence for the erection or synonymy of subspecies therefore needs to be founded on the best science available. Here we show that there is clear genetic disjunction in the Sarus Crane Antigone antigone, where previously the variation had appeared to be clinal. Based on a total sample of 76 individuals, analysis of 10 microsatellite loci from 67 samples and 49 sequences from the mitochondrial control region, this research establishes that the Australian Sarus Crane A. a. gillae differs significantly from both A. a. antigone (South Asia) and A. a. sharpii (Myanmar and Indochina). A single sample from the extinct Philippine subspecies A. a luzonica clustered with A. a. gillae, hinting at the potential for a more recent separation between them than from A. a. antigone and A. a. sharpii, even though A. a. sharpii is closer geographically. The results demonstrate that failure to detect subspecies through initial genetic profiling does not mean discontinuities are absent and has significance for other cases where subspecies are dismissed based on partial genetic evidence. It could also be potentially important for sourcing birds for reintroduction to the Philippines

Distribution, status and conservation of the Bengal Florican Houbaropsis bengalensis in Cambodia

The Bengal Florican is a 'Critically Endangered' bustard (Otididae) restricted to India, Nepal and southern Indochina. Fewer than 500 birds are estimated to remain in the Indian subcontinent, whilst the Indochinese breeding population is primarily restricted to grasslands surrounding the Tonle Sap lake, Cambodia. We conducted the first comprehensive breeding season survey of Bengal Florican within the Tonle Sap region (19,500 km2). During 2005/06 and 2006/07 we systematically sampled 1-km squares for territorial males. Bengal Florican were detected within 90 1-km squares at a mean density of 0.34 males km-2 which, accounting for unequal survey effort across grassland blocks, provides a mean estimate of 0.2 males km-2. Based on 2005 habitat extent, the estimated Tonle Sap population is 416 adult males (333 - 502 ± 95% CI), more than half of them in Kompong Thom province. Tonle Sap grasslands are rapidly being lost due to intensification of rice cultivation and, based on satellite images, we document declines of 28% grassland cover within 10 grassland blocks between January 2005 and March 2007. Based on mean 2005 population densities the remaining grassland may support as few as 294 adult male florican, a decline of 30% since 2005. In response to these habitat declines almost 350 km2 of grassland have been designated as protected areas, set aside for biodiversity and local livelihoods. Conservation activities in these areas include participatory land-use zoning, patrols reporting new developments to government officials, awareness-raising and incentive-led nest protection schemes