Freshwater fisheries conservation can increase biodiversity

finally, [10, 11] for Lao People’s Democratic Republic (hereafter, Lao PDR), perhaps the oldest documented example, and also the one where our analysis is based. Although these examples suggest that the difficulties in implementing freshwater conserva- tion are not universal or unsurmountable, they tell us little about whether they “work” in the sense that they contribute to avoid reductions in biodiversity. This is a shortcoming that is shared with earlier conservation work: in the mid-2000s, [12] asked whether biodiversity con- servation investments were “money for nothing?”, and [13] suggested we were “shooting in the dark”. Almost 10 years later, similar questions are still being asked: [14] asks why is the evi- dence on win-win interventions so poor while [15] decry the lack of evidence on the impacts of biodiversity conservation on poverty (and vice-versa) as the missing Randomized Control Trials. The solution advocated by these authors is to mainstream impact evaluation into the design and implementation of conservation programs [16, 17], with the objective of addressing the identified knowledge gaps in terms both of conservation effectiveness. The work presented in this article contributes to that growing literature. Our data comes from Lao PDR, a landlocked country where the Mekong, one of the richest and most threat- ened river basins in terms of freshwater biodiversity [1, 18], seems to never be far away. Build- ing on indigenous knowledge, that guided their initial definition and enforcement, fish

conservation zones or FCZs (as these no-take areas are locally known) have been incorporated in the practice of multiple programs, even while their impacts remained largely unknown. Here, we present estimates of the causal impact of the establishment of FCZs on biodiversity, by evaluating the impact of a fisheries management program that is centered on their definition. Methods Freshwater fisheries conservation in Lao PDR: ComFishIII There is a long history of local knowledge about the definition of no-take areas as a mechanism to manage local fisheries in Lao PDR [11]. Those areas rely on the exclusion of fishing in deep pools—parts of the stream where water level is high enough during the dry season so as to pro- vide a suitable habitat year round, and where the slower flow creates a suitable place for spawn- ing [19–21]. This knowledge has been incorporated in different fisheries conservation programs in Lao PDR, including the third phase of the Community Fisheries program (ComFishIII), imple- mented by WWF Laos, during the period 2012-2015, in collaboration with the Ministry of Agriculture and Forestry (MAF) and with local participation of village authorities. Its guide- lines [22] reflected both the recognition of the importance of local knowledge regarding fisher- ies conservation [11] and a legal framework that emphasizes the co-management of local fisheries [23]. Its implementation involved a series of decisions by WWF and MAF that, typically, started with the preparation of a list of potentially eligible villages, presented to WWF by the District

representatives of MAF. This list reflects perceptions of the importance of fishing (number of households who fish, existence and importance of alternative livelihoods) and implicitly assumes that these criteria reflect a healthy ecosystem, as no baseline data on biodiversity is ever collected. This initial submission is then followed by a series of steps that end with the development of local regulations to manage fisheries (see Fig A in S1 Appendix). The first of these steps, consensus building, is the one that matters most to understand pro- gram placement. It includes an analysis of the potential importance of fishing to local liveli- hoods, the social context of local fisheries (including analysis of conflicts around local fisheries and of social cohesion, proxied by village history, including recent episodes of resettlement, PLOS ONE FCZ and biodiversity PLOS ONE | https://doi.org/10.1371/journal.pone.0233775 May 27, 2020 2 / 14