Targeting river operations to the critical thermal window of fish incubation: Model and case study on Sacramento River winter‐run Chinook salmon

Allocating reservoir flows to meet societal and ecosystem needs under increasing water demands climatic variability presents challenges resource managers. Often, rivers have been regulated flow temperature compliance points or mimic historical patterns. Because it is difficult assess if this approach efficient, process-based models are being used design river operations. This paper describes a model for fish incubation survival based on the premise that mortality from thermal stress occurs over critical window (CW) of embryo development. A CW metabolic studies development combined with density-dependent background mortalities describe salmonid egg fertilization fry detection downstream. The calibrated two-decade dataset Sacramento River winter-run Chinook salmon egg-to-fry survival. effects exposure range CWs were explored. Based statistical biological support, two alternative identified control: entire period short duration prior hatching. Survival different assumptions control operations simulated an internet-accessible form model. analysis indicated years limited cold-water resources, targeting releases hatching would yield highest