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UncertaintyHow do hydrosystem operations affect fish survival (including salmonids, eulachon, sturgeon, lamprey, and other focal species)?
ThemeHydrosystem flow and passage operations
SubthemeHydrosystem effects on survival
Criticality Level Priority
Rationale Information is needed to assess project compliance with mandated targets, understand impacts of management actions on fish, and understand where and when the largest sources of mortality are occurring so that corrective actions can be taken. For example, the Federal Columbia River Power System Juvenile Dam Passage Performance Standards and Metrics (NOAA Fisheries, FCRPS Supplemental Biological Opinion, section requires an “average across Snake River and Lower Columbia River dams of 96% average dam passage survival for spring Chinook and steelhead and 93% average across all dams for Snake River subyearling Chinook.” This is currently being monitored by PIT-tagging (and JSATs tagging in the US Army Corps of Engineers-funded projects) juvenile salmon. Some tagged fish are detected during their downstream migration and then as returning adults, and statistical methods are used to estimate survival probabilities, straying rates, etc. The Comparative Survival Study reports (CSS 2015) examine how juvenile survival and smolt-to-adult returns (SARs) change in response to changes in flow and spill. A life cycle model is being constructed by the CSS that models survival from eggs to spawners so that impacts on changes in survival due to management actions such as changing spill can be predicted. Without such knowledge, the consequences of management actions will be unknown and potentially ruinous for stocks.

last updated: Jan 27, 2016