A fish catch and fishing practice monitoring survey were conducted from 2008 to 2014 in villages adjacent to the Nam Theun 2 Reservoir and its upstream tributaries. The reservoir fisheries exhibited – the three expected phases following impoundment (i.e. trophic upsurge, trophic depletion and stabilization, respectively). This study focused on assessing fish catches and fishing practices from communities living next to the reservoir, and those living upstream of the reservoir, over these phases, and to identify factors that could influence total fish catch. The fish catch appeared to be higher among communities located next to the reservoir, compared to communities living in upstream areas. Fish catches in the upstream tributaries remained relatively stable after impoundment, with a slight increase in the average catch. The reservoir exhibited a low fish yield, compared to similar reservoirs, which could be linked to its oligotrophic status. The majority of the total catch biomass of the reservoir was comprised primarily of two species (i.e. Oreochromis niloticus; Hampala macrolepidota) since a stabilization of the catches was observed. Reservoir fisheries appeared to be mainly driven by hydrological factors, specifically the influence of the rainy season peak. The results of this study indicated no over‐exploitation of fisheries occurred overall, although the fishery resource is still fragile. Fishing activities are known to occur in protected zones (productive areas with large inundated habitat areas), with higher annual total catch being observed during periods of poor enforcement of these zones. As fisheries have become an important income source for villagers living along the NT2 Reservoir, regulation and adequate management of the reservoir are recommended to maintain the reservoir fisheries as a sustainable activity.

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-The approach of Fish Catch Monitoring of the Nam Theun 2 hydro power project area is documented and describes the fish catch monitoring methodologies implemented for the period from 2006-2014 with special emphasis on changes in the methods and how data collection has evolved in the Xe Bangfai basin.The collected data aimed at documenting changes in the fisheries (e.g. habitat use, daily household catch, gear use and effort) before and after commencement of electricity generation. The methods used rely on social research methods, i.e. recall surveys and household catch logbooks that are provided and maintained by fishermen. The panel survey has demonstrated is appropriateness to monitor and document changes in the fisheries over time with a high level of confidence at relatively low cost. The households participating in the panel remained relatively stable throughout the survey period. The method tends to overestimate fish catches and under estimate the collection of other aquatic animals. The level of effort (fishing days) is consistent between different surveys. The monitoring results provide a good understanding of trends and changes in the fisheries. Key words -fisheries, monitoring, river, logbook, evaluationRésumé -L'approche du suivi des pêches au sein du projet hydro-électrique Nam Theun 2 (Laos) est documentée et décrit les méthodes de suivi des pêches mises en place pour la période de 2006-2014 en mettant l'accent sur le changement des méthodes et la façon dont la collecte des données a évolué dans le bassin de la Xe Bangfai. Les données récoltées visaient à documenter les changements observés au niveau des pêches (par exemple l'utilisation de l'habitat, prises quotidiennes des foyers, moyens et effort de pêche) avant et après le début de la production d'électricité. Les méthodes utilisées s'appuient sur des méthodes de recherche sociale, à savoir les enquêtes faisant appel à la mémoire et les registres quotidiens des prises des foyers qui sont fournis et entretenus par les pêcheurs. Cette enquête par panel a démontré sa pertinence pour suivre et documenter les changements observés au niveau de pêches au fil du temps, ceci avec un niveau de confiance élevé et à un coût relativement faible. Les foyers participants à ce panel sont restés relativement stables sur la

The focus is on the fishery as a whole, i.e. the combination of fish, environment, fishers, and economic and policy context [11,12]. The need to integrate customer demand and marketing to sustainable fisheries management is highlighted in several studies, in particular in the Mekong basin [13]. Thus, we consider here fish supply, fish demand/marketing and the environment policy as the three main pillars of a sustainable fishery, knowing that several other factors such as biological productivity, algae blooms, limnological aspects, landuses in the catchment areas, fishing gears are also important [14]. Our study focuses only on a reservoir fishery, it does not include upstream or downstream fisheries. We set the stage by identifying the various components of a generic tropical reservoir fishery, and then document how much is known and has been done about each component in the case of Nam Theun 2. This highlights strengths and weaknesses in the knowledge base needed for the management of the system. Ultimately, the various degrees of control of managers over the fishery system and its components are identified. Components of a Fishery: the Conceptual PerspectiveThis case study review is based on the analysis of Nam Theun 2 environment, fish resource, fishing, fishers, fish trade, and policies

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