Hatchery actions

This document provides additional information about how hatchery actions are implemented in the fall run model for Reorienting to Recovery (R2R). For more more information about the model itself, including the codebase, please see our documentation.

There are 5 harvest actions that can be implemented in the model. Each has an associated number that is used to build a scenario in the R2Rscenarios package.

18: Baseline hatchery
19: Only terminal hatchery / outplanting
20: Phased hatcheries
21: Release 50% in bay
26: Install weir at hatchery

18: Baseline hatchery

If 18 is selected, baseline hatchery logic is used. This is a year-structured data object that shows hatchery releases by year, and numbers are based on current production targets California Hatchery Scientific Review Group, 2012.

19: Only terminal hatchery / outplanting

If 19 is selected, there are no in-river hatchery releases in the model and instead “terminal” hatcheries are utilized, which release hatchery fish at the entry to the ocean to support commercial harvest. While there are many forms of potential outplanting or terminal hatchery logic, this action assumes that juvenile salmonids are imprinted to either a terminal hatchery or to ocean net pen release sites and that there are low stray rates back into the model. This is different than our current trucking outplanting approach which can have high stray rates.

20: Phased hatchery

If 20 is selected, in-river hatchery releases are scaled up by 500% in the first 5 years, and then scaled down by 60% from years 6:10, and then set to 0 for the last 10 years of the model as terminal hatcheries are utilized instead. This is a year-structured data object that shows hatchery releases by year, and baseline numbers are based on current production numbers California Hatchery Scientific Review Group, 2012 before being scaled up.

21: Release 50% in bay

If 21 is selected, the parameter hatchery_release_proportion_bay is set to 0.5, which tells you which proportion of the releases are in-river vs. released at Chipps.

26: Install weir at hatchery

If 26 is selected, the model will scale down proportion_hatchery for each watershed by 20% to approximate the effect of installing a weir at the hatchery. Installations of weirs have been shown to reduce proportion of hatchery fish on spawning grounds, or pHOS, by anywhere from 1% - 48% on different watersheds Wilson et. al, 2019, but can be as high as 75% Wilson & Buehrens, 2023.