Conservation of White Sturgeon in the Lower Columbia River: 250 Million Years and Counting

White sturgeon Acipenser transmontanus are uniquely adapted to the large river systems they inhabit, and the Columbia River downstream of Bonneville dam supports the most productive white sturgeon population in the world.  Conserving the species and its ecological niche into the foreseeable future will maintain important social, cultural and economic benefits currently provided by this population segment.  Though white sturgeon in this river reach are not at risk of extinction, proactive preservation and management measures are essential.  Accordingly, we have prepared a conservation plan, identifying benchmarks by which progress toward the desired population status may be measured, that will ensure a healthy, viable, genetically diverse and productive white sturgeon population in the lower Columbia River.  We use an age structured population simulation model to determine desired and conservation status thresholds in terms of life stage specific abundance, natural population productivity and overall probability of persistence.  Furthermore, we developed objectives and adopted metrics for geographic distribution, genetic diversity, available spawning and rearing habitat, individual growth and condition, and life stage specific survival.  The conservation plan also describes biotic and abiotic limiting factors, threats, and critical constraints, such as pinniped predation (biotic) and flow variation (abiotic), that collectively impede the population’s ability to progress towards the desired status.  Additionally, the plan identifies critical uncertainties and data gaps, such as the impacts of global climate change, which could potentially affect the viability of the lower Columbia River white sturgeon population segment.  Exploring these uncertainties and data gaps is an essential step in addressing them, and subsequently moving forward with adaptive conservation efforts.  We compiled a suite of recommended management actions as well as research, monitoring and evaluation activities to enable and monitor progress towards the desired population status and the amelioration of existing limiting factors and data gaps.  Finally, this plan will follow the tenets of adaptive management.  We base the assessments of critical constraints and limiting factors, and the management actions and measures intended to address them, on the best science currently available.  However, the white sturgeon life cycle is extremely long and complex, and uncertainty remains regarding action effectiveness and the outcome of recommended research, monitoring, and evaluation measures.  As part of the adaptive management process the plan describes periodic review and check points to facilitate the modification of conservation strategies as necessary to achieve the desired population attributes.