Implications for Future Survival of Delta Smelt from Four Climate Change Scenarios for the Sacramento–San Joaquin Delta, California

Abstract

Changes in the position of the low salinity zone, a habitat suitability index, turbidity, and water temperature modeled from four 100-year scenarios of climate change were evaluatedfor possibleeffectsondeltasmeltHypomesustrans- pacificus, which is endemic to the Sacramento-San Joaquin Delta. The persistence of delta smelt in much of its current habitat into the next century appears uncertain. By mid- century, the position of the low salinity zone in the fall and the habitat suitability index converged on values only ob- served during the worst droughts of the baseline period (1969-2000). Projected higher water temperatures would ren- der waters historically inhabited by delta smelt near the con- fluence of the Sacramento and San Joaquin rivers largely uninhabitable. However, the scenarios of climate change are based on assumptions that require caution in the interpretation of the results. Projections like these provide managers with a useful tool for anticipating long-term challenges to managing fish populations and possibly adapting water management to ameliorate those challenges.