Freshwater fisheries conservation can increase biodiversity

Heterogeneity of treatment effects Finally, in Fig 3 we present the results of the heterogeneity analysis, using the approach out- lined in [30], with the ATT being re-estimated locally in the neighborhood of each observation (characterized by their propensity score), allowing for an analysis of the relation (trend) between these local estimates and the propensity score. The program is less effective in driving increases in biodiversity in those villages that were least likely to be included in the program (a decision that, recall, mostly reflects the local importance of fishing activities), with large impacts on biodiversity observed in the (few) villages with relatively higher probability of par- ticipating in ComFishIII. Conclusions and discussion Understanding whether conservation efforts work, in the sense of what they deliver on their direct environmental objectives, requires a larger effort to incorporate impact evaluation into the design of environmental policies and programs. This article presents evidence that, at least in a context such as the Mekong in Lao PDR, it is possible for freshwater conservation initia- tives to achieve improvements in biodiversity. Our analysis quantifies the causal impact of a fisheries management program, centered on the definition of no-take areas (Fish Conservation Zones) on the number of species caught in the previous 12 months. The effects are large (approximately 29 species), and these estimates are robust to the potential importance of unmeasured confounders, an important concern

when using observational data. Our analysis also shows that average impacts are heteroge- neous and that initial conditions (as summarized in the probability of participating in the Fig 3. Heterogeneity of impact of the Community Fisheries program (ComFishIII) on biodiversity. Positive values of Average Treatment on the Treated (ATT) indicate an increase in biodiversity. https://doi.org/10.1371/journal.pone.0233775.g003 PLOS ONE FCZ and biodiversity PLOS ONE | https://doi.org/10.1371/journal.pone.0233775 May 27, 2020 10 / 14