Future Natural Mortality investigations

[aaronmberger-nwfsc]

Rick mentioned:

[The survey selectivity has always looked strange to me with low selectivity for ages that should be fully surveyable by the acoustic survey.

So I forced selectivity to be 1.0 for ages 2+
Then set up M to have 8 breakpoints
8 #_N_breakpoints
2 3 4 5 6 7 8 15 # age(real) at M breakpoints
and estimate M-at-age to be:
Natural_Mortality_endyr
Bio_Pattern Sex Settlement Seas 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1 1 1 1 0.191462 0.191462 0.191462 0.184808 0.185188 0.185876 0.185378 0.185069 0.202992 0.225381 0.24777 0.270159 0.292548 0.314937 0.337326 0.359715 0.359715 0.359715 0.359715 0.359715 0.359715

with logL only 3 pts worse than current base model.]

Runs like this could be revisited with additional planned M runs as well as broader evaluations of t.v. parameter variances in stock assessment (e.g., selectivity, recruitment, potentially age-1 index catchability, etc.)

In addition, we could look more deeply into Rick's thoughts on fully selective age 2+ acoustic biomass index separate from (different 'fleet') the acoustic trawl age composition data. The planned U.S. West Coast Survey Re-Envisioning workshop might bring about related information/ideas.

[aaronmberger-nwfsc]

This is tied to planned work for 2024 (or beyond) so adding 2025 milestone.

[kellijohnson-NOAA]

Rick also mentioned the other day in a presentation that he is giving at ICES that we could add a predator index to the model that informs predation mortality, where the abundance of California sea lions is estimated to have reached its carrying capacity in 2014.

But, the most recent assessment is from 2018 and it only hind casts to 2014. So, I am not sure what we would do for the index since 2014?