Comments:

Quite uncertain assessment
Diagnostics pass;, but quite sensitive to a few settings
Good practices say to use stdevfacI, but it puts less weight on recent observations and not using it reduces assessment uncertainty
High process uncertainty: sdb is estimated to be quite large (0.32) - using a prior to force it down, decreases stock status and increases uncertainty - is the high sdb okay? What is the sdb for the other NEP FUs?
Sensitive to spinup: Removing spinup reduces stock status but increases uncertainty of MSY and Bmsy - longer spinup increases retrospective patterns
Sensitive to input data: Tweedie index model leads to lower uncertainty, but some ini issues and uncertainty of delta-lognormal index model might be more realistic
Sensitive to n: Fox model not useful
Use model without stdevfacI as baseline (less uncertain, slightly lower TAC, really best to down-weight more recent years with fewer positive and more zero hauls?)

Baseline

The current baseline model includes:

relative abundance index from the delta-lognormal index model
relative uncertainty scaling estimated by the index model
spinup period of 10 years (160 time steps)
n fixed to 2 (Schaefer model)
prior for log(r)~N(log(0.38), 0.2) (+bias correction) which corresponds to the same prior used for NEP FU28/29

## Convergence: 0  MSG: relative convergence (4)
## Objective function at optimum: 74.3865016
## Euler time step (years):  1/16 or 0.0625
## Nobs C: 41,  Nobs I1: 40
## 
## Residual diagnostics (p-values)
##     shapiro   bias    acf   LBox shapiro bias acf LBox  
##  C   0.5926 0.8762 0.1186 0.4013       -    -   -    -  
##  I1  0.3956 0.7100 0.5529 0.7868       -    -   -    -  
##  F   0.2744 0.6313 0.1415 0.2986       -    -   -    -  
##  B   0.5949 0.5698 0.0221 0.0915       -    -   *    .  
## 
## Priors
##  logr  ~  dnorm[log(0.372), 0.2^2]
## 
## Fixed parameters
##    fixed.value  
##  n           2  
## 
## Model parameter estimates w 95% CI 
##            estimate       cilow        ciupp    log.est  
##  alpha    1.6828629   0.8781343    3.2250506  0.5204964  
##  beta     0.3374398   0.0712982    1.5970342 -1.0863682  
##  r        0.3299176   0.2318275    0.4695112 -1.1089124  
##  rc       0.3299176   0.2318275    0.4695112 -1.1089124  
##  rold     0.3299176   0.2318275    0.4695112 -1.1089124  
##  m       69.9501728  20.7587412  235.7092192  4.2477832  
##  K      848.0926786 243.1099640 2958.5837603  6.7429899  
##  q        0.0007020   0.0002391    0.0020614 -7.2615535  
##  sdb      0.3260811   0.1866085    0.5697965 -1.1206092  
##  sdf      0.2993334   0.1805663    0.4962190 -1.2061974  
##  sdi      0.5487498   0.4069882    0.7398895 -0.6001128  
##  sdc      0.1010070   0.0285869    0.3568912 -2.2925656  
##  
## Deterministic reference points (Drp)
##           estimate       cilow        ciupp   log.est  
##  Bmsyd 424.0463393 121.5549820 1479.2918801  6.049843  
##  Fmsyd   0.1649588   0.1159138    0.2347556 -1.802060  
##  MSYd   69.9501728  20.7587412  235.7092192  4.247783  
## Stochastic reference points (Srp)
##           estimate     cilow        ciupp   log.est rel.diff.Drp  
##  Bmsys 342.8759917 85.085362 1381.7176493  5.837369   -0.2367338  
##  Fmsys   0.1385914  0.091838    0.2091462 -1.976225   -0.1902527  
##  MSYs   45.3794066  9.275442  222.0153594  3.815058   -0.5414519  
## 
## States w 95% CI (inp$msytype: s)
##                    estimate      cilow       ciupp    log.est  
##  B_2024.94      215.5431783 60.2175720 771.5166887  5.3731613  
##  F_2024.94        0.0701162  0.0194328   0.2529889 -2.6576012  
##  B_2024.94/Bmsy   0.6286330  0.0813120   4.8600364 -0.4642076  
##  F_2024.94/Fmsy   0.5059204  0.1528800   1.6742251 -0.6813759  
## 
## Predictions w 95% CI (inp$msytype: s)
##                  prediction      cilow        ciupp    log.est  
##  B_2027.00      271.7008567 65.4824242 1127.3460990  5.6047017  
##  F_2027.00        0.0701166  0.0151058    0.3254594 -2.6575963  
##  B_2027.00/Bmsy   0.7924173  0.1114072    5.6363048 -0.2326672  
##  F_2027.00/Fmsy   0.5059229  0.1170747    2.1862787 -0.6813710  
##  Catch_2026.00   18.0261036  6.1165067   53.1251620  2.8918209  
##  E(B_inf)       308.2247929         NA           NA  5.7308294

Diagnostics

Jitter

##          Distance     m      K q  sdb sdf  sdi sdc
## Basevec      0.00 69.95 848.09 0 0.33 0.3 0.55 0.1
## Trial 1      0.05 69.95 848.04 0 0.33 0.3 0.55 0.1
## Trial 2      0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 3      0.03 69.95 848.07 0 0.33 0.3 0.55 0.1
## Trial 4      0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 5      0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 6      0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 7      0.01 69.95 848.09 0 0.33 0.3 0.55 0.1
## Trial 8      0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 9      0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 10     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 11     0.02 69.95 848.07 0 0.33 0.3 0.55 0.1
## Trial 12     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 13     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 14     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 15     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 16     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 17     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 18     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 19     0.02 69.95 848.07 0 0.33 0.3 0.55 0.1
## Trial 20     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 21     0.02 69.95 848.07 0 0.33 0.3 0.55 0.1
## Trial 22     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 23     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 24     0.02 69.95 848.07 0 0.33 0.3 0.55 0.1
## Trial 25     0.01 69.95 848.10 0 0.33 0.3 0.55 0.1
## Trial 26     0.01 69.95 848.09 0 0.33 0.3 0.55 0.1
## Trial 27     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 28     0.02 69.95 848.11 0 0.33 0.3 0.55 0.1
## Trial 29     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 30     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 31     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 32     0.03 69.95 848.07 0 0.33 0.3 0.55 0.1
## Trial 33     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 34     0.01 69.95 848.09 0 0.33 0.3 0.55 0.1
## Trial 35     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 36     0.03 69.95 848.06 0 0.33 0.3 0.55 0.1
## Trial 37     0.04 69.95 848.05 0 0.33 0.3 0.55 0.1
## Trial 38     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 39     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 40     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 41     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 42     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 43     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 44     0.02 69.95 848.07 0 0.33 0.3 0.55 0.1
## Trial 45     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 46     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 47     0.01 69.95 848.08 0 0.33 0.3 0.55 0.1
## Trial 48     0.02 69.95 848.07 0 0.33 0.3 0.55 0.1
## Trial 49     0.04 69.95 848.05 0 0.33 0.3 0.55 0.1
## Trial 50     0.02 69.95 848.08 0 0.33 0.3 0.55 0.1

Prior-posterior

Obs. residuals

Proc. residuals

Retro

##      FFmsy      BBmsy 
## -0.1279614  0.1758665

MASE

Management advice

## SPiCT timeline:
##                                                                           
##       Observations             Intermediate             Management        
##     1983.00 - 2025.00        2025.00 - 2026.00       2026.00 - 2027.00    
##  |-----------------------| ----------------------| ----------------------|
## 
## Management evaluation: 2027.00
## 
## Predicted catch for management period and states at management evaluation time:
## 
##              C B/Bmsy F/Fmsy
## 1. ices35 28.0   0.76   0.80
## 2. ices15 19.7   0.79   0.55

SPiCT assessment report for Nephrops FU31

09/02/2026

Baseline

Diagnostics

Jitter

Prior-posterior

Obs. residuals

Proc. residuals

Retro

MASE

Management advice

Sensitivity scenarios

Scenario groups

Uncertainty scaling

Comparison plots

With uncertainty

Without uncertainty

Spinup

Comparison plots

With uncertainty