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.