SBR- Content.pmd - INBO

State of the Basin Report - 2003Flood plain river systems are highly vulnerable for a number of reasons: they often face conflictingdemands from different sectors (fisheries, forestry, water abstractions, hydropower, water drainage,industry, navigation, etc.); and impacts from upstream such as damming, pollution, and deforestation.These all have negative impacts on flora, fauna and the livelihoods of people downstream. Inlandwaters of the Asian region provide more than half the world’s inland capture fisheries yield, andyet, despite their high values, flood plain river habitats are now amongst the fastest disappearing ofall ecological habitats. 7As this chapter indicates, the Mekong Basin’s aquatic ecosystem is still in good condition, but thereare a number of threats to the fishery which must be understood and addressed, or the fishery couldbe decimated in as little as a generation. In the chapter that follows, research findings are presentedon capture fisheries, aquaculture and other aquatic products such as food, medicines and buildingmaterials which are harvested from wetlands. The topics covered in the chapter include: biodiversity;the numbers of people involved in the fishery; consumption, yield and economic value; threats tofisheries; and the extent of, potential for, and threats to aquaculture.1. The importance of varied habitat and migrationsThe habitat mixture in the Mekong River Basin is extremely diverse and while this resourcecomplexity is maintained by appropriate management measures, the fishery resource will remainrich in both biodiversity and productivity. Habitat diversity is greatest in the floodplain areas offlooded grasslands, flooded forests, as well as small and large river channels and permanent andtemporary lakes and pools. Each type of habitat is used by different fish species for different activitiessuch as spawning, nursing, shelter and feeding. Key habitats must be kept accessible through thefloodplain channels.Figure 1. Generalised life cycle of migratory Mekong fishes, in relation to seasonal conditions.Source: Adapted from Hoggarth et al. 1999The main river channels are comparatively unproductive because stronger currents and shiftingsubstrates result in lower primary production. 8 The quantity and quality of water in rivers is vitalfor maintaining system productivity.102