Rice field fisheries: Wild aquatic species diversity, food provision services and contribution to inland fisheries

The need to produce sufficient food for people whilst also maintaining biodiversity and ecosystem integrity is one of the most pressing challenges in the 21st century. This challenge is exemplified in wetlands and deltas of Southeast Asia that have been transformed to intensify rice production and have subsequently lost the naturally present wild aquatic species that previously bolstered local food and nutrition security. In contrast, rice producing areas where natural hydrologic flows and ecosystem processes are retained can sustain aquatic biodiversity and fisheries. These rice field ecosystems are present in many Asian countries, but are sparsely documented, underappreciated, and currently face development pressure including farming intensification and habitat fragmentation from infrastructure development. To understand the fisheries and food security contributions of wild aquatic species in contemporary rice field ecosystems, we examine the Tonle Sap region of Cambodia. We used household surveys and experimental fishing to measure wild aquatic species richness present in rice field ecosystems and in local catch. We also used household surveys to estimate rice field fishery productivity (as annual catch weight per hectare) and to examine variation in fishing effort and total catch weight across seasons and habitats. Finally, we investigated catch use and the contribution of fish catch to household consumption. We identified a total of 158 wild aquatic species, which included around twice the number of finfish species (n = 135) identified by previous studies (n=35-70). Overall, 92% of fish catch (by weight) was from five habitat types within rice field ecosystems. Fishing effort and catch weights were relatively evenly spread across habitats during the dry season and were primarily from rice fields during the flood season. In both flood and dry seasons, rice field fishery catch provided around 60% of the fish and aquatic animals consumed in surveyed households. Our findings illustrate the substantial contributions rice field fisheries make to household food security and to national fisheries production. Drawing on lessons from rice farming intensification across the region, we discuss the implications of our findings for rice field ecosystems, food security, and rice intensification policy futures in Cambodia and other rice-producing nations.