Effects of High Levels of Total Dissolved Solids in Walker Lake, Nevada, on Survival and Growth of Lahontan Cutthroat Trout

Walker Lake, Nevada, is an endorheic terminal lake experiencing significant increases in total dissolved solids (TDS) because of culturally derived reductions in inflow and continued evaporative water losses. Maintenance of the Walker Lake fishery for native Lahontan cutthroat trout Oncorhynchus clarki henshawi requires artificial propagation because fish no longer have access to suitable spawning sites upstream in the Walker River. In recent years, survival of the stocked fish has been very low. We examined survival and growth of Lahontan cutthroat trout in response to present and anticipated total dissolved solids (TDS) concentrations in Walker Lake. Laboratory experiments indicated that current TDS levels in Walker Lake adversely affected both survival and growth of Lahontan cutthroat trout, and any increase in TDS is likely to further decrease survival. Larger fish are more tolerant of high concentrations of TDS. Acclimation to diluted Walker Lake water improves subsequent survival when fish are exposed to undiluted Walker Lake water. Acclimation for 3 d to TDS levels between 3,669 and 10,300 mg/L should improve stocking success in Walker Lake and may provide a means of increasing the fishery in the short term; however, long-term prospects for trout survival in Walker Lake are poor unless sufficient good-quality water reaches the lake to offset the continued increase in total dissolved solids concentration as a result of evaporation.