"Sacramento River fall Chinook (SRFC) salmon contribute heavily to California and Oregon ocean salmon fisheries and support a Sacramento basin recreational river fishery. An overhaul of the SRFC stock assessment methods commenced in 2008, including development of a new ocean abundance index (the Sacramento Index: SI) and harvest model (the Sacramento Harvest Model: SHM), both of which are currently used for assessment and fishery planning within the annual Pacific Fishery Management Council (PFMC) salmon management process. The SHM is an aggregate-age harvest model that, when combined with the forecast SI , predicts the SRFC spawner escapement and overall exploitation rate given proposed ocean and river fishery management measures. This memorandum provides comprehensive documentation of the SHM, beginning with a description of the basic model structure. Detailed descriptions of the SHM ocean and river submodels, and the methods used to estimate their parameters follow. The SHM has been a central part of PFMC salmon fishery planning since its initial development and will likely remain an important part of that process until improved coded-wire tag and escapement data sets for this stock mature, potentially enabling an age-structured assessment."

National Marine Fisheries Service (NMFS)