tbuehrens
commented
1 year ago This is super helpful, Kale. Thank you. FWIW Eli Holmes just told Jan today they are moving away from such long term projection time frames…but I don’t have specifics beyond that.
To respond to @ebuhle question in Issue #18...
...I spent some time skimming through various reports, including:
In doing so, I realized that I need to spend more time reading through these existing documents as it relates to monitoring metrics & targets for future iterations of our simulations and synthesizing the results.
Below I've pasted some screen snippets on a variety of topics that would be worth reviewing and circling back on:
Categorical designation of Extinction Risk:
From pg. 20-21 of NMFS (2022)
“There are various ways to refer to extinction risk: viability, persistence probability, extinction risk, or—at the population level—population status. The 2013 recovery plan frequently uses the terms “persistence probability” and “population status.” Only populations with a persistence probability of 95 percent or higher over a 100-year time frame are considered viable. These populations have a population status of high or very high (NMFS 2013a).”
From pg. E7 of Appendix E: LCRFB (2010)
Extinction Thresholds
From pg. 17 and 21 of WLCTRT & ODFW (2006)
QET = "Because of concern about depensatory processes and uncertainty about how both the populations and the models perform at very low population size, we typically model populations to a “quasi-extinction threshold” (QET). Ecological and demographic risk processes not captured in the simple recruitment function model are likely to come into play at abundances below the QET"
RFT = "In developing the viability curve, we have modeled depensation in terms of a simple reproductive failure threshold (RFT). If the population of spawners in any particular year drops below the RFT, the number of recruits from those spawners is set at zero. If the number of spawners in a year is below the RFT, the population is not necessarily extinct because it could be rescued by fish that are still in the ocean that will return in the next few years".
From pg. E7 of Appendix E LCFRB (2010):
CRT = "analysis also considers risks of falling below a conservation risk threshold (CRT) that is greater than the assumed quasi-extinction level. The CRT level might be considered analogous to a point where a population is threatened with falling to lower levels where the risk of extinction becomes significant. For the purposes of this analysis, CRT is defined as a level where diversity is eroded and population resilience may be lost. CRT may be considered to be the risk of being threatened with becoming endangered with quasi-extinction."
Recovery Thresholds/Targets
For context, we've estimated that the Grays Basin (MS, WF, CJ combined) has ~16-17 km of spawning habitat which corresponds to a "small" watershed and thus an abundance target of >1,400 for Persistence Category 4 (Very low risk of extinction). Not certain but guessing this is where the 1,600 in the LCFRB (2010) came from (somehow adding in 200 for the Chinook basin sub-component??)
From pg. 57-58 of WLCTRT & ODFW (2006)
From Ch 6.3 of LCFRB (2010)
Simulation Time Frame
From pg. 3 of McElheny (2020):