Freshwater fisheries conservation can increase biodiversity

connected to the implementing agency (either WWF or the local government) and the fact that FCZ had been defined at least three years before the time of this evaluation should con- tribute to minimize any experimenter effects (positive or negative). This approach also has important advantages, chiefly among them its low cost and the reduction of concerns about seasonality. Taken together, these advantages allow for the collec- tion of data on a large number of treated and control villages, hence avoiding the shortcoming of case studies or very small samples. Results Treatment effects As shown in Table 1 we don’t find differences in (pre-program) village characteristics. In addi- tion, the location of the 32 villages studied suggests a relatively random dispersion of the two types of villages across the territory (see Fig 1). We do observe, however, significant differences in (post-program) management rules: ComFishIII villages are much more likely to establish a local no-take area, to define restrictions on catching particular species, to pay people to moni- tor the enforcement of local regulations or to define progressive penalties for continued breaching of local regulations. Accompanying these differences, species richness is clearly much higher in program villages (Fig 2). To rigorously quantify the average impact of the program, treated and control villages are first matched one-to-one on the propensity score using the nearest neighbor algorithm [31]. The results are presented in Table 2: the implementation of ComFishIII leads to a substantial

increase in biodiversity, with the number of species caught in the last 12 months increasing by Fig 2. Number of species caught in treated (ComFishIII) and control villages Box plot with extreme values (minimum and maximum) and the three quartiles of distribution of number of species. https://doi.org/10.1371/journal.pone.0233775.g002 PLOS ONE FCZ and biodiversity PLOS ONE | https://doi.org/10.1371/journal.pone.0233775 May 27, 2020 8 / 14