Restoring Fish Passage to Wetland Habitats of the Lower Mekong Basin: What Goes up, Must Come Down

A large proportion of the Lower Mekong Basin (LMB) fish community benefits from access to off-channel wetlands, which provide productive feeding, breeding and nursery habitats. But the construction of weirs and floodgates to regulate wetland flooding and protect crops, has created barriers to fish passage and isolated productive fish habitats from the Mekong River. While fish ladders can be used to re-establish floodplain access for wetland fish, it is also critical to protect return migrations out of wetlands back to the Mekong. This presentation will outline the ‘state-of-the-art’ in research aimed at understanding the movement of fish out of wetlands in the LMB and the preliminary steps being taken to optimise the design of weirs and floodgates to ensure safe downstream passage. Ultimately the safe downstream passage of fish needs to be promoted without compromising the irrigation needs of communities who rely heavily on floodplain cropping for their livelihood.