MP32 powerramp candidate
Status: advanced candidate in the current jmMSE analysis. MP32 has not been adopted. This page reflects the exact jmMSE version 94d4d325ba46220f56097b3de90824c83b7cf3cd and the 25 July 2026 presentation.
1 Identity
| Component | Current definition |
|---|---|
Name in the jmMSE analysis |
tun32, labelled MP32 |
| Stock/index indicator | cpues.ind |
| Indices | Chile_AcousN, Chile_CPUE, Peru_Artis, Peru_Ind, Offshore_CPUE |
| Reference years | 2019-2023 |
| Recent-data window | 3 years |
| How the indices are combined | Mean (combine = "mean", metric = "mean") |
| Harvest control rule | Power ramp (powerramp.hcr) |
| Output | Catch |
| Catch allocation | Split among fisheries using their average catch proportions over the last five years (split.is) |
2 Harvest control rule parameters
| Parameter | Value |
|---|---|
Minimum catch, min |
270 |
Limit metric, lim |
0.1 |
| Trigger metric | 1.42 |
| Target catch | 1500 |
| Initial catch for constraints | 1385 |
Maximum annual decrease multiplier, dlow |
0.85 |
Maximum annual increase multiplier, dupp |
1.20 |
3 Rule
Let \(I_t\) be the annual mean of the standardized index information and
\[ x_t = \frac{I_t-0.1}{1.42-0.1}. \]
Before applying the annual change limit, the current power-ramp rule calculates the catch recommendation as
\[ C_t^* = \begin{cases} 270, & I_t \le 0.1,\\ 270 + (1500-270)x_t^{2.5}, & 0.1 < I_t < 1.42,\\ 1500(0.2+0.8x_t)^{0.6}, & I_t \ge 1.42. \end{cases} \]
Unlike a capped hockeystick, the upper branch continues to rise above the trigger. The annual change rule then prevents the result from falling below 85% or rising above 120% of the previous recommendation. For the first application year, the reference value is 1385.
4 Evidence status
The July presentation identifies MP32 as the optimal powerramp minimum/limit run. The MP29-MP32 comparison reports broadly similar long-term catch and stock performance, with MP32 showing more year-to-year catch variation (IACC) than MP29. The jmMSE robustness analysis carries both candidates forward.
Primary sources: model_tune.R, model_robustness.R, and the July presentation source.
5 Annual application requirements still to resolve
- authoritative provider and annual cutoff for each index;
- precise index standardization performed by
cpues.indand the software version used; - treatment of missing or revised indices;
- catch units and rounding;
- approved catch-allocation update rule; and
- exceptional-circumstances review and decision process.