Designing freshwater protected areas (FPAs) for indiscriminate fisheries

Abstract

Freshwater protected areas (FPAs) are increasingly important for biodiversity conservation, given the intensive use of these systems for water, energy and food production. However, the fisheries benefits of FPAs are not well understood, particularly for indiscriminate fisheries typical of tropical systems. Here we report the results of a model that tests the fisheries effects of no-take protected areas in conditions unique to indiscriminate riverine/ floodplain systems. The model has a generalized form applicable to a wide range of systems. We also report the results of the general model, as well as those from a specialized form parameterized for the Tonle Sap lake, Cambodia. Both the general and Tonle Sap versions of the model show that FPAs can pay important fisheries benefits, especially where it is difficult to control fishing mortality through gear restrictions or other means. The harvest and profit benefit response curves have similar shapes, with additional FPAs paying high dividends at less than approximately 50% FPA coverage, and then truncating and declining thereafter. In the specific setting of the Tonle Sap of Cambodia, FPAs would pay a large increase in harvest because current FPA coverage is low. It may be counterintuitive to community fisheries managers in Cambodia that the best way to increase harvest is to restrict fishing, but at very high levels of fishing effort, reducing effort or area fished will improve both harvest and profit. In Cambodia, it may make sense to maximize harvest rather than profit because fishers living in poverty need to maximize protein offtake, but the benefits of FPAs remain. Similar considerations may apply in many freshwater and indiscriminate fisheries.

Fish Diversity, Endemism, Threats, and Conservation in the Jinsha River Basin (Upper Yangtze River), China

“…2012; Hannah et al. 2019). Given that different endemic fish species may be adapted to different habitats, the location and size are important considerations when setting up reserves.…”

Priority knowledge needs for management of migratory fish species in Cambodia

“…technical or policy briefs; Kim et al, 2019). Positive examples in the region include the design and management of fish passage around irrigation infrastructure in Lao PDR (Baumgartner et al, 2019), spatial planning of protected areas in the Tonle Sap Lake (Hannah et al, 2019) and determination of spawning sites in the 3S river system (Elliott & Chheng, 2017). Communities in Cambodia have engaged in research activities and used research results to define management goals, and have also conducted continuous monitoring to determine the impact of their interventions (Freed et al, 2020).…”

Identifying Indicators to Evaluate Community-Managed Freshwater Protected Areas in the Lower Mekong Basin: A Review of Marine and Freshwater Examples

“…Engaging local people to designate and enforce community-managed protected areas has emerged as a conservation strategy in tropical marine ecosystems [29,30] as well as freshwater environments [9,31,32]. Community participation in resource management is prevalent in Southeast Asia, including the Lower Mekong Basin (LMB), often linked to the process of decentralization [28,32,33], and has been applied to the management of coastal areas, mangrove forests, wetlands, and riverine deep pools [33][34][35][36]. Many countries have adopted community based or co-managed FPAs for fishes in river and lake environments, which go by various names, including Community Conserved Zones in the Philippines [32], Fish Conservation Areas in Cambodia [37], Fish Conservation Zones in Lao People's Democratic Republic [31,38], reserves in Thailand [39], and Freshwater Fish Safe Zones in India [40].…”

“…This should inform realistic expectations of what FPAs are designed to accomplish. Those that primarily restrict fishing activity may help alleviate the threat of overharvest on fish populations [28], but might have little impact on other threats, which could influence their effectiveness. In recognition of these important spatial considerations, managers designing evaluations of FPA effectiveness may need to incorporate external threat assessments and comparative monitoring at sites upstream and downstream of FPA boundaries.…”