Evaluation of a new practical low-cost method for prioritising the remediation of fish passage barriers in resource-deficient settings

Abstract

A key challenge in fishery restoration strategies is prioritising fish passage remediation efforts to achieve optimal ecological and socio-economic outcomes. Various methodologies have been developed for assessing and prioritising the mitigation of fish passage barriers, but they have been designed for developed countries where site data and/or other resources are often readily available. We evaluated a new practical, low-cost basin-scale approach — referred to as the Fish Barrier Prioritisation Support System (FBPSS) — for assessing and prioritising the remediation of fish passage barriers of all types (i.e. large dams, small irrigation structures and road crossings) in resource-deficient settings, like those typical of developing countries. The FBPSS applies a five-stage decision-support framework to prioritise barriers for remediation based on geospatial, biological and socio-economic criteria. The stages involve identifying all potential barriers within the target basin using satellite imagery; conducting GIS analysis to rank the barriers for further investigation; field-validating the highest ranked barriers to ground-truth the GIS analysis results; identifying the highest priority field-validated barriers affecting fisheries productivity; and further refining the list according to socio-economic considerations. We applied the FBPSS to the Bago catchment in Myanmar as a case study, and then validated its effectiveness by comparing the fragmentation impacts (as measured by the Dendritic Connectivity Index) of the FBPSS-prioritised large dams with those of all large dams. The FBPSS successfully identified 876 potential barriers in the Bago catchment, and then systematically assessed these barriers using its filters to produce a prioritised list of 23 barriers for cost-effectively achieving optimal fishery and community benefits. The validation analysis revealed that the high priority FBPSS-combined barriers were responsible for 97–100% of the fragmentation of the combined barriers (with all large dams included). Our findings suggest that the FBPSS could be used as a practical decision support tool, in conjunction with expert knowledge, for prioritising the mitigation of fish passage barriers in resource-deficient settings. Future research could compare the results of the FBPSS with those of an optimisation model to assess how the two approaches perform under different scenarios, and to identify key modelling features that could potentially be integrated into the FBPSS.