Illustrative 2027 TAC calculation

How the Candidate Procedures Would Produce 2027 Advice

This is a calculation plan, not a 2027 TAC recommendation. None of the candidate management procedures (CMPs) has been adopted. A numerical recommendation cannot be produced until the complete annual index data, the previous catch-advice value, and the rules for data timing, missing values, rounding, and allocation have been confirmed.

This page shows how the data available for the 2027 decision would be passed through each CMP. It also identifies where the approximately 630 kt estimate from the 2026 northern Chile acoustic survey could, and could not, be used.

1 First settle which data year applies

The current MSE runs use a one-year data delay and a one-year management delay. Under that tested timing:

the CMP calculation made in 2026 produces catch advice for 2027;
the most recent observations used are from 2025;
the three-year CMPs use 2023–2025 data; and
MP23 uses 2021–2025 data because its current comparison run has a five-year averaging window.

The 2026 northern Chile acoustic estimate therefore does not enter the 2027 calculation as it was tested in the MSE. It would first enter the following annual calculation, for 2028 advice.

Using observations from 2026 for the 2027 TAC would require a same-year data rule. That would change the timing assumed in the tested CMP and should be specified, coded, and checked before it is used. Under such a revised rule, the three-year window would be 2024–2026 and the MP23 window would be 2022–2026.

2 Data required

Eight CMPs use all five indices. Two use the four CPUE and fishery indices and exclude the acoustic survey.

CMPs	Annual series required	Is the northern Chile acoustic survey used?
MP18, MP23, MP24, MP29, MP31, MP32, MP43, MP44	Northern Chile acoustic survey (`Chile_AcousN`), Chile CPUE, Peru artisanal index, Peru industrial index, and offshore CPUE	Yes, when its data year falls within the approved window
MP35, MP36	Chile CPUE, Peru artisanal index, Peru industrial index, and offshore CPUE	No

For every series, retain the value, unit, survey or fleet coverage, source, revision status, and date received. Values must be comparable with those used in the 2019–2023 reference period.

3 Turn the observations into the CMP indicator

The raw indices are on different scales, so they cannot be averaged directly. The current procedure performs the following calculation.

3.1 Express each series relative to its reference-period average

For index $j$ in year $y$,

\[ R_{j,y} = \frac{\text{index }j\text{ in year }y} {\text{mean of index }j\text{ over 2019--2023}}. \]

A value of 1 means that the observation equals its own 2019–2023 average. A value of 1.25 means it is 25% above that average.

The reported acoustic estimate of about 630 kt cannot be entered directly into the harvest rule. If its year is eligible, it must first be checked against the same northern Chile acoustic series and converted to

\[ R_{\text{acoustic},2026} = \frac{630\text{ kt}} {\text{mean northern Chile acoustic biomass over 2019--2023}}. \]

The reference-period mean is not recorded on this site, so this contribution cannot yet be calculated here.

3.2 Combine the available series within each year

For each year, average the relative values for the indices required by the CMP. This gives one combined annual index $A_y$.

The analysis code averages the non-missing series. Before an operational calculation, the Scientific Committee should decide whether a missing required series may be omitted or whether it stops the calculation. A missing value should never be omitted without being reported.

3.3 Average across the recent years

The indicator supplied to the harvest rule is:

\[ I = \text{mean of the combined annual indices over the approved recent years}. \]

For the tested 2027 timing, use 2023–2025 for all CMPs except MP23, which uses 2021–2025. Calculate two versions of $I$: an all-index value for MP18, MP23, MP24, MP29, MP31, MP32, MP43, and MP44, and a CPUE/fishery-index value for MP35 and MP36.

4 Apply each harvest rule

The table gives the current settings. Catch quantities use the units of the jmMSE analysis; those units and the final rounding convention must be confirmed before providing formal advice.

CMP	Information	Rule	Minimum	Limit	Trigger	Target or slope
MP18	All five indices, 3 years	Hockeystick	0	0	5.796875	Target 5000
MP23	All five indices, 5 years	Straight slope	0	0	—	Slope 821.875
MP24	All five indices, 3 years	Hockeystick	0	0	1.5125	Target 1750
MP29	All five indices, 3 years	Hockeystick	270	0.1	2.125	Target 2000
MP43	All five indices, 3 years	Hockeystick	270	0.1	3.0625	Target 2000
MP31	All five indices, 3 years	Hockeystick	270	0.3	1.984375	Target 2000
MP32	All five indices, 3 years	Power ramp	270	0.1	1.421875	Target 1500
MP44	All five indices, 3 years	Power ramp	270	0.1	1.9140625	Target 1500
MP35	Four CPUE/fishery indices, 3 years	Power ramp	270	0.1	1.4921875	Target 1500
MP36	Four CPUE/fishery indices, 3 years	Hockeystick	270	0.1	2.21875	Target 2000

For a hockeystick CMP, the preliminary catch advice is the minimum at or below the limit, rises in a straight line between the limit and trigger, and equals the target at or above the trigger.

For MP23, the preliminary advice is $821.875 \times I$ when $I$ is above zero.

For MP32, MP35, and MP44, let

\[ x = \frac{I-\text{limit}}{\text{trigger}-\text{limit}}. \]

The preliminary advice is the minimum when $I$ is at or below the limit. It is

\[ \text{minimum} + (\text{target}-\text{minimum})x^{2.5} \]

between the limit and trigger, and

\[ \text{target}(0.2+0.8x)^{0.6} \]

at or above the trigger. Unlike the hockeystick, the power-ramp advice can continue to rise above its stated target.

5 Apply the annual change limit

MP18, MP23, MP24, MP29, MP31, MP32, MP35, and MP36 limit the change from the previous year’s catch advice to a 15% decrease or a 20% increase. If $C^*$ is the preliminary advice and $C_{2026}$ is the agreed previous advice value, the 2027 value before rounding for those CMPs is

\[ C_{2027} = \max\left(0.85C_{2026}, \min\left(C^*,1.20C_{2026}\right)\right). \]

MP43 and MP44 instead allow a 20% decrease and a 15% increase:

\[ C_{2027} = \max\left(0.80C_{2026}, \min\left(C^*,1.15C_{2026}\right)\right). \]

These two cases were retuned after changing the annual limits. Under reference OM11, their mean probabilities of being in the dynamic Kobe green zone over 2041–2050 were 0.606 for MP43 and 0.603 for MP44, within the 0.01 tuning tolerance around the 0.60 objective.

The value 1385 appears as the initial value in the simulation controls. It should not automatically be treated as $C_{2026}$. The operational specification must say whether the annual limit is based on the previous TAC, the previous CMP recommendation, or another approved quantity.

6 Worked retrospective: 2025 advice using data through 2024

For this retrospective, the advice year is labelled as the year immediately after the last data year: 2024 observations produce illustrative 2025 advice. This simply backs the calendar labels up one year while retaining the candidate index calculations, harvest rules, and initial comparison value of 1385.

This remains an illustration rather than advice adopted by SPRFMO. The result is a total catch quantity in the analysis units, before an approved rounding rule or allocation among fisheries.

6.1 Historical inputs

The table contains the observations from the updated assessment data associated with input/0.15.dat. The two Peruvian series are retained separately as Peru_Artis and Peru_Ind. Each reference mean is calculated over the available observations in 2019–2023. The northern acoustic series has no 2022 value.

Table 1: Historical observations used for the retrospective calculation. A dash means that no value is stored.

	Series	2019–2023 mean	2022	2023	2024	2025
1	Chile_AcousN	1896.963	—	2502.157	2788.465	3058.843
2	Chile_CPUE	96.249	90.157	98.162	82.478	97.287
4	Peru_Artis	0.507	0.571	0.617	0.672	0.495
5	Peru_Ind	0.686	0.736	0.683	0.656	0.630
3	Offshore_CPUE	937.613	1339.693	1169.402	428.054	—

6.2 Indicators for the 2025 calculation

The all-index annual values are 1.141 for 2022, 1.159 for 2023, and 1.013 for 2024. Their three-year mean is 1.104. The corresponding CPUE/fishery-index mean is 1.053. MP23 uses five years and has an indicator of 1.039.

Table 2: Relative-index values supplied to the candidate harvest rules for the retrospective 2025 calculation.

Used by	Index set	Years averaged	Indicator
MP18, MP24, MP29, MP31, MP32, MP43, MP44	All five indices	2022–2024	1.104
MP23	All five indices	2020–2024	1.039
MP35, MP36	Four CPUE/fishery indices	2022–2024	1.053

6.3 Turn the indicator into preliminary advice

The indicator is a relative measure, not a catch quantity. A value of 1 means that the recent indices are, on average, equal to their 2019–2023 reference levels. A value above 1 means they are higher; a value below 1 means they are lower.

Each candidate then puts its indicator into its own harvest-control rule. The rule converts the relative indicator into a catch quantity. Because the candidates have different limits, triggers, targets, and rule shapes, the same indicator can produce different preliminary advice.

We write this preliminary catch advice as $C^*$. Here, $C$ means catch advice and the star means provisional: it is the harvest-control-rule result before the annual change limit is applied. The star is not another calculation.

The table shows the substitution explicitly. Values displayed in the calculation are rounded to three decimal places; the code uses the unrounded values.

Table 3: How each candidate converts its indicator into preliminary catch advice (C*).

CMP	Indicator	Rule	Substitute the indicator in the rule	C* before annual limit
MP29	1.104	Hockeystick	270.000 + (1.104 − 0.100) × (2000.000 − 270.000) ÷ (2.125 − 0.100)	1128.100
MP43	1.104	Hockeystick	270.000 + (1.104 − 0.100) × (2000.000 − 270.000) ÷ (3.062 − 0.100)	856.550
MP32	1.104	Power ramp	x = (1.104 − 0.100) ÷ (1.422 − 0.100) = 0.760; 270.000 + (1500.000 − 270.000) × x raised to 2.5	889.044
MP44	1.104	Power ramp	x = (1.104 − 0.100) ÷ (1.914 − 0.100) = 0.554; 270.000 + (1500.000 − 270.000) × x raised to 2.5	550.587
MP18	1.104	Hockeystick	0.000 + (1.104 − 0.000) × (5000.000 − 0.000) ÷ (5.797 − 0.000)	952.603
MP24	1.104	Hockeystick	0.000 + (1.104 − 0.000) × (1750.000 − 0.000) ÷ (1.512 − 0.000)	1277.846
MP31	1.104	Hockeystick	270.000 + (1.104 − 0.300) × (2000.000 − 270.000) ÷ (1.984 − 0.300)	1096.213
MP23	1.039	Straight slope	821.875 × 1.039	854.254
MP35	1.053	Power ramp	x = (1.053 − 0.100) ÷ (1.492 − 0.100) = 0.685; 270.000 + (1500.000 − 270.000) × x raised to 2.5	746.909
MP36	1.053	Hockeystick	270.000 + (1.053 − 0.100) × (2000.000 − 270.000) ÷ (2.219 − 0.100)	1048.173

For example, MP29 uses the hockeystick rule:

\[ C^* = 270 + \frac{(1.104-0.100)(2000-270)} {(2.125-0.100)} = 1128.10. \]

The value 1128.10 is therefore MP29’s harvest-rule result. It is not yet the final value because the annual change limit must still be applied.

6.4 Apply the annual change limit

With 1385 as the initial comparison value, the original annual limits give a range from 0.85 × 1385 = 1177.25 to 1.20 × 1385 = 1662.00. MP43 and MP44 instead use a range from 0.80 × 1385 = 1108.00 to 1.15 × 1385 = 1592.75. The table applies the appropriate range to each candidate. MP24’s preliminary result is already within its allowed range.

Table 4: Illustrative 2025 total catch advice using observations through 2024 and an initial comparison value of 1385.

CMP	Index years	Indicator	C* before annual limit	Adjustment	Result after annual limit
MP29	2022–2024	1.104	1128.100	15% decrease floor	1177.250
MP43	2022–2024	1.104	856.550	20% decrease floor	1108.000
MP32	2022–2024	1.104	889.044	15% decrease floor	1177.250
MP44	2022–2024	1.104	550.587	20% decrease floor	1108.000
MP18	2022–2024	1.104	952.603	15% decrease floor	1177.250
MP24	2022–2024	1.104	1277.846	None	1277.846
MP31	2022–2024	1.104	1096.213	15% decrease floor	1177.250
MP23	2020–2024	1.039	854.254	15% decrease floor	1177.250
MP35	2022–2024	1.053	746.909	15% decrease floor	1177.250
MP36	2022–2024	1.053	1048.173	15% decrease floor	1177.250

These values should not be interpreted as ten equally supported recommendations: MP29 and MP32 are the advanced candidates, while the other eight are comparison cases. MP43 and MP44 specifically test a different pair of annual change limits after retuning. The table is useful for checking that every rule can be reproduced from one shared set of observations.

7 Why this example stops with 2024 observations

The updated data contain both Peruvian series through 2025, but the 2025 offshore CPUE is absent. Rather than silently omit that series or invent a replacement, the worked calculation backs off one year and uses the complete set available through 2024. Once the missing-data rule and 2025 offshore CPUE status are settled, the same calculation can be advanced one year to produce an illustrative 2026 result.

8 Complete and record the recommendation

For each CMP, save:

the original data files and their units;
the 2019–2023 average for each index;
every annual relative index $R_{j,y}$;
the combined annual indices $A_y$;
the recent-year indicator $I$;
the preliminary harvest-rule result $C^*$;
the previous-advice value and annual-change adjustment;
the unrounded and rounded total recommendation;
any allocation calculation; and
all missing-data, revision, or exceptional-circumstances warnings.

The current simulations divide the total catch among fisheries using their average catch shares over the previous five years. The Scientific Committee should confirm whether that calculation is part of the CMP or a separate allocation decision.

9 What can be concluded from the currently reported value

The approximately 630 kt acoustic estimate alone is not sufficient to calculate a TAC:

it is outside the tested data window for a 2027 recommendation;
it must be expressed relative to the 2019–2023 average for the same survey;
the other required indices are needed for the all-index CMPs; and
MP35 and MP36 do not use the acoustic survey.

Once the complete annual data table and the agreed previous-advice value are available, the calculations above can be run side by side to show the recommendation produced by every candidate.

10 Implementation basis

This calculation plan is based on the controls saved by the jmMSE candidate runner on branch devel, commit 278c309. The historical index extract used in the worked calculation is saved as cmp-historical-indices.csv. It was extracted from the updated h1_0.16 assessment output associated with input/0.15.dat, retaining both Peruvian index series. The main implementation sources are run_candidate_mps.R and tune_candidate_change_limits.R. If the data delays, recent-year windows, combined-index calculation, or annual change rule are revised, this page and the MSE tests must be updated together.

--- title: "Illustrative 2027 TAC calculation" --- {{< include ../_includes/sprfmo-banner.qmd >}} <div class="paper-title">How the Candidate Procedures Would Produce 2027 Advice</div> ::: {.status-note} **This is a calculation plan, not a 2027 TAC recommendation.** None of the candidate management procedures (CMPs) has been adopted. A numerical recommendation cannot be produced until the complete annual index data, the previous catch-advice value, and the rules for data timing, missing values, rounding, and allocation have been confirmed. ::: This page shows how the data available for the 2027 decision would be passed through each CMP. It also identifies where the approximately 630 kt estimate from the 2026 northern Chile acoustic survey could, and could not, be used. ## First settle which data year applies The current MSE runs use a one-year data delay and a one-year management delay. Under that tested timing: 1. the CMP calculation made in 2026 produces catch advice for 2027; 2. the most recent observations used are from 2025; 3. the three-year CMPs use 2023–2025 data; and 4. MP23 uses 2021–2025 data because its current comparison run has a five-year averaging window. The 2026 northern Chile acoustic estimate therefore **does not enter the 2027 calculation as it was tested in the MSE**. It would first enter the following annual calculation, for 2028 advice. Using observations from 2026 for the 2027 TAC would require a same-year data rule. That would change the timing assumed in the tested CMP and should be specified, coded, and checked before it is used. Under such a revised rule, the three-year window would be 2024–2026 and the MP23 window would be 2022–2026. ## Data required Eight CMPs use all five indices. Two use the four CPUE and fishery indices and exclude the acoustic survey. | CMPs | Annual series required | Is the northern Chile acoustic survey used? | |---|---|---| | MP18, MP23, MP24, MP29, MP31, MP32, MP43, MP44 | Northern Chile acoustic survey (`Chile_AcousN`), Chile CPUE, Peru artisanal index, Peru industrial index, and offshore CPUE | Yes, when its data year falls within the approved window | | MP35, MP36 | Chile CPUE, Peru artisanal index, Peru industrial index, and offshore CPUE | No | For every series, retain the value, unit, survey or fleet coverage, source, revision status, and date received. Values must be comparable with those used in the 2019–2023 reference period. ## Turn the observations into the CMP indicator The raw indices are on different scales, so they cannot be averaged directly. The current procedure performs the following calculation. ### Express each series relative to its reference-period average For index $j$ in year $y$, $$ R_{j,y} = \frac{\text{index }j\text{ in year }y} {\text{mean of index }j\text{ over 2019--2023}}. $$ A value of 1 means that the observation equals its own 2019–2023 average. A value of 1.25 means it is 25% above that average. The reported acoustic estimate of about 630 kt cannot be entered directly into the harvest rule. If its year is eligible, it must first be checked against the same northern Chile acoustic series and converted to $$ R_{\text{acoustic},2026} = \frac{630\text{ kt}} {\text{mean northern Chile acoustic biomass over 2019--2023}}. $$ The reference-period mean is not recorded on this site, so this contribution cannot yet be calculated here. ### Combine the available series within each year For each year, average the relative values for the indices required by the CMP. This gives one combined annual index $A_y$. The analysis code averages the non-missing series. Before an operational calculation, the Scientific Committee should decide whether a missing required series may be omitted or whether it stops the calculation. A missing value should never be omitted without being reported. ### Average across the recent years The indicator supplied to the harvest rule is: $$ I = \text{mean of the combined annual indices over the approved recent years}. $$ For the tested 2027 timing, use 2023–2025 for all CMPs except MP23, which uses 2021–2025. Calculate two versions of $I$: an all-index value for MP18, MP23, MP24, MP29, MP31, MP32, MP43, and MP44, and a CPUE/fishery-index value for MP35 and MP36. ## Apply each harvest rule The table gives the current settings. Catch quantities use the units of the `jmMSE` analysis; those units and the final rounding convention must be confirmed before providing formal advice. | CMP | Information | Rule | Minimum | Limit | Trigger | Target or slope | |---|---|---|---:|---:|---:|---:| | MP18 | All five indices, 3 years | Hockeystick | 0 | 0 | 5.796875 | Target 5000 | | MP23 | All five indices, 5 years | Straight slope | 0 | 0 | — | Slope 821.875 | | MP24 | All five indices, 3 years | Hockeystick | 0 | 0 | 1.5125 | Target 1750 | | MP29 | All five indices, 3 years | Hockeystick | 270 | 0.1 | 2.125 | Target 2000 | | MP43 | All five indices, 3 years | Hockeystick | 270 | 0.1 | 3.0625 | Target 2000 | | MP31 | All five indices, 3 years | Hockeystick | 270 | 0.3 | 1.984375 | Target 2000 | | MP32 | All five indices, 3 years | Power ramp | 270 | 0.1 | 1.421875 | Target 1500 | | MP44 | All five indices, 3 years | Power ramp | 270 | 0.1 | 1.9140625 | Target 1500 | | MP35 | Four CPUE/fishery indices, 3 years | Power ramp | 270 | 0.1 | 1.4921875 | Target 1500 | | MP36 | Four CPUE/fishery indices, 3 years | Hockeystick | 270 | 0.1 | 2.21875 | Target 2000 | For a hockeystick CMP, the preliminary catch advice is the minimum at or below the limit, rises in a straight line between the limit and trigger, and equals the target at or above the trigger. For MP23, the preliminary advice is $821.875 \times I$ when $I$ is above zero. For MP32, MP35, and MP44, let $$ x = \frac{I-\text{limit}}{\text{trigger}-\text{limit}}. $$ The preliminary advice is the minimum when $I$ is at or below the limit. It is $$ \text{minimum} + (\text{target}-\text{minimum})x^{2.5} $$ between the limit and trigger, and $$ \text{target}(0.2+0.8x)^{0.6} $$ at or above the trigger. Unlike the hockeystick, the power-ramp advice can continue to rise above its stated target. ## Apply the annual change limit MP18, MP23, MP24, MP29, MP31, MP32, MP35, and MP36 limit the change from the previous year's catch advice to a 15% decrease or a 20% increase. If $C^*$ is the preliminary advice and $C_{2026}$ is the agreed previous advice value, the 2027 value before rounding for those CMPs is $$ C_{2027} = \max\left(0.85C_{2026}, \min\left(C^*,1.20C_{2026}\right)\right). $$ MP43 and MP44 instead allow a 20% decrease and a 15% increase: $$ C_{2027} = \max\left(0.80C_{2026}, \min\left(C^*,1.15C_{2026}\right)\right). $$ These two cases were retuned after changing the annual limits. Under reference OM11, their mean probabilities of being in the dynamic Kobe green zone over 2041–2050 were 0.606 for MP43 and 0.603 for MP44, within the 0.01 tuning tolerance around the 0.60 objective. The value 1385 appears as the initial value in the simulation controls. It should not automatically be treated as $C_{2026}$. The operational specification must say whether the annual limit is based on the previous TAC, the previous CMP recommendation, or another approved quantity. ## Worked retrospective: 2025 advice using data through 2024 For this retrospective, the advice year is labelled as the year immediately after the last data year: 2024 observations produce illustrative 2025 advice. This simply backs the calendar labels up one year while retaining the candidate index calculations, harvest rules, and initial comparison value of 1385. This remains an illustration rather than advice adopted by SPRFMO. The result is a total catch quantity in the analysis units, before an approved rounding rule or allocation among fisheries. ```{r} #| label: worked-calculation-setup #| include: false historical_indices <- read.csv( "../data/cmp-historical-indices.csv", na.strings = c("", "NA"), check.names = FALSE ) all_indices <- c( "Chile_AcousN", "Chile_CPUE", "Peru_Artis", "Peru_Ind", "Offshore_CPUE" ) cpue_indices <- setdiff(all_indices, "Chile_AcousN") reference_means <- aggregate( value ~ index, historical_indices[historical_indices$year %in% 2019:2023, ], function(x) mean(x, na.rm = TRUE) ) names(reference_means)[2] <- "reference_mean" relative_indices <- merge( historical_indices, reference_means, by = "index", all.x = TRUE ) relative_indices$relative <- relative_indices$value / relative_indices$reference_mean annual_relative <- function(indices) { selected <- relative_indices[relative_indices$index %in% indices, ] annual <- aggregate( relative ~ year, selected, function(x) mean(x, na.rm = TRUE) ) annual$n_available <- vapply(annual$year, function(y) { sum(selected$year == y & !is.na(selected$value)) }, integer(1)) annual } recent_indicator <- function(end_year, n_years, indices) { annual <- annual_relative(indices) years <- seq(end_year - n_years + 1, end_year) mean(annual$relative[annual$year %in% years]) } controls <- read.csv("../tuns_ctrl.csv", check.names = FALSE) selected_mps <- c( "MP29", "MP43", "MP32", "MP44", "MP18", "MP24", "MP31", "MP23", "MP35", "MP36" ) controls <- controls[match(selected_mps, controls$label), ] calculate_advice <- function(control_row, end_year, previous = 1385) { indices <- if (control_row$estimator == "all.idx") { all_indices } else { cpue_indices } n_years <- if (control_row$label == "MP23") 5 else 3 indicator <- recent_indicator(end_year, n_years, indices) if (control_row$hcr == "hockeystick") { preliminary <- if (indicator <= control_row$lim) { control_row$min } else if (indicator < control_row$trigger) { control_row$min + (indicator - control_row$lim) * (control_row$target - control_row$min) / (control_row$trigger - control_row$lim) } else { control_row$target } } else if (control_row$hcr == "slope") { preliminary <- if (indicator <= control_row$lim) { control_row$min } else { indicator * control_row$slope } } else if (control_row$hcr == "powerramp") { x <- (indicator - control_row$lim) / (control_row$trigger - control_row$lim) preliminary <- if (indicator <= control_row$lim) { control_row$min } else if (indicator < control_row$trigger) { control_row$min + (control_row$target - control_row$min) * x^2.5 } else { control_row$target * (0.2 + 0.8 * x)^0.6 } } lower <- control_row$dlow * previous upper <- control_row$dupp * previous adjusted <- max(lower, min(preliminary, upper)) adjustment <- if (preliminary < lower) { paste0(round(100 * (1 - control_row$dlow)), "% decrease floor") } else if (preliminary > upper) { paste0(round(100 * (control_row$dupp - 1)), "% increase ceiling") } else { "None" } data.frame( CMP = control_row$label, `Index years` = paste0(end_year - n_years + 1, "–", end_year), Indicator = indicator, `C* before annual limit` = preliminary, Adjustment = adjustment, `Result after annual limit` = adjusted, check.names = FALSE ) } advice_for_year <- function(end_year) { do.call(rbind, lapply(seq_len(nrow(controls)), function(i) { calculate_advice(controls[i, ], end_year = end_year) })) } advice_2024 <- advice_for_year(2024) calculation_text <- function(control_row, indicator) { fmt <- function(x) formatC(x, digits = 3, format = "f") if (control_row$hcr == "slope") { return(paste0( fmt(control_row$slope), " × ", fmt(indicator) )) } if (indicator <= control_row$lim) { return(paste0( "Indicator is at or below the limit; use minimum ", fmt(control_row$min) )) } if (control_row$hcr == "hockeystick") { if (indicator >= control_row$trigger) { return(paste0( "Indicator is at or above the trigger; use target ", fmt(control_row$target) )) } return(paste0( fmt(control_row$min), " + (", fmt(indicator), " − ", fmt(control_row$lim), ") × (", fmt(control_row$target), " − ", fmt(control_row$min), ") ÷ (", fmt(control_row$trigger), " − ", fmt(control_row$lim), ")" )) } x <- (indicator - control_row$lim) / (control_row$trigger - control_row$lim) if (indicator < control_row$trigger) { return(paste0( "x = (", fmt(indicator), " − ", fmt(control_row$lim), ") ÷ (", fmt(control_row$trigger), " − ", fmt(control_row$lim), ") = ", fmt(x), "; ", fmt(control_row$min), " + (", fmt(control_row$target), " − ", fmt(control_row$min), ") × x raised to 2.5" )) } paste0( "x = (", fmt(indicator), " − ", fmt(control_row$lim), ") ÷ (", fmt(control_row$trigger), " − ", fmt(control_row$lim), ") = ", fmt(x), "; ", fmt(control_row$target), " × (0.2 + 0.8 × x) raised to 0.6" ) } rule_names <- c( hockeystick = "Hockeystick", slope = "Straight slope", powerramp = "Power ramp" ) conversion_table <- do.call(rbind, lapply(seq_len(nrow(controls)), function(i) { data.frame( CMP = controls$label[i], Indicator = advice_2024$Indicator[i], Rule = unname(rule_names[controls$hcr[i]]), `Substitute the indicator in the rule` = calculation_text(controls[i, ], advice_2024$Indicator[i]), `C* before annual limit` = advice_2024$`C* before annual limit`[i], check.names = FALSE ) })) ``` ### Historical inputs The table contains the observations from the updated assessment data associated with `input/0.15.dat`. The two Peruvian series are retained separately as `Peru_Artis` and `Peru_Ind`. Each reference mean is calculated over the available observations in 2019–2023. The northern acoustic series has no 2022 value. ```{r} #| label: tbl-retrospective-inputs #| tbl-cap: "Historical observations used for the retrospective calculation. A dash means that no value is stored." #| echo: false recent_inputs <- historical_indices[ historical_indices$year %in% 2022:2025, ] wide_inputs <- reshape( recent_inputs, idvar = "index", timevar = "year", direction = "wide" ) names(wide_inputs) <- sub("^value\\.", "", names(wide_inputs)) input_table <- merge(reference_means, wide_inputs, by = "index", all.x = TRUE) input_table <- input_table[ match(all_indices, input_table$index), c("index", "reference_mean", "2022", "2023", "2024", "2025") ] names(input_table) <- c( "Series", "2019–2023 mean", "2022", "2023", "2024", "2025" ) old_na <- getOption("knitr.kable.NA") options(knitr.kable.NA = "—") knitr::kable(input_table, digits = 3) options(knitr.kable.NA = old_na) ``` ### Indicators for the 2025 calculation The all-index annual values are 1.141 for 2022, 1.159 for 2023, and 1.013 for 2024. Their three-year mean is 1.104. The corresponding CPUE/fishery-index mean is 1.053. MP23 uses five years and has an indicator of 1.039. ```{r} #| label: tbl-retrospective-indicators #| tbl-cap: "Relative-index values supplied to the candidate harvest rules for the retrospective 2025 calculation." #| echo: false indicator_table <- data.frame( `Used by` = c( "MP18, MP24, MP29, MP31, MP32, MP43, MP44", "MP23", "MP35, MP36" ), `Index set` = c( "All five indices", "All five indices", "Four CPUE/fishery indices" ), `Years averaged` = c("2022–2024", "2020–2024", "2022–2024"), Indicator = c( recent_indicator(2024, 3, all_indices), recent_indicator(2024, 5, all_indices), recent_indicator(2024, 3, cpue_indices) ), check.names = FALSE ) knitr::kable(indicator_table, digits = 3) ``` ### Turn the indicator into preliminary advice The indicator is a relative measure, not a catch quantity. A value of 1 means that the recent indices are, on average, equal to their 2019–2023 reference levels. A value above 1 means they are higher; a value below 1 means they are lower. Each candidate then puts its indicator into its own harvest-control rule. The rule converts the relative indicator into a catch quantity. Because the candidates have different limits, triggers, targets, and rule shapes, the same indicator can produce different preliminary advice. We write this preliminary catch advice as $C^*$. Here, $C$ means catch advice and the star means **provisional**: it is the harvest-control-rule result before the annual change limit is applied. The star is not another calculation. The table shows the substitution explicitly. Values displayed in the calculation are rounded to three decimal places; the code uses the unrounded values. ```{r} #| label: tbl-indicator-to-advice #| tbl-cap: "How each candidate converts its indicator into preliminary catch advice (C*)." #| echo: false knitr::kable(conversion_table, digits = 3) ``` For example, MP29 uses the hockeystick rule: $$ C^* = 270 + \frac{(1.104-0.100)(2000-270)} {(2.125-0.100)} = 1128.10. $$ The value 1128.10 is therefore MP29's harvest-rule result. It is not yet the final value because the annual change limit must still be applied. ### Apply the annual change limit With 1385 as the initial comparison value, the original annual limits give a range from 0.85 × 1385 = 1177.25 to 1.20 × 1385 = 1662.00. MP43 and MP44 instead use a range from 0.80 × 1385 = 1108.00 to 1.15 × 1385 = 1592.75. The table applies the appropriate range to each candidate. MP24's preliminary result is already within its allowed range. ```{r} #| label: tbl-retrospective-advice #| tbl-cap: "Illustrative 2025 total catch advice using observations through 2024 and an initial comparison value of 1385." #| echo: false knitr::kable(advice_2024, digits = 3) ``` These values should not be interpreted as ten equally supported recommendations: MP29 and MP32 are the advanced candidates, while the other eight are comparison cases. MP43 and MP44 specifically test a different pair of annual change limits after retuning. The table is useful for checking that every rule can be reproduced from one shared set of observations. ## Why this example stops with 2024 observations The updated data contain both Peruvian series through 2025, but the 2025 offshore CPUE is absent. Rather than silently omit that series or invent a replacement, the worked calculation backs off one year and uses the complete set available through 2024. Once the missing-data rule and 2025 offshore CPUE status are settled, the same calculation can be advanced one year to produce an illustrative 2026 result. ## Complete and record the recommendation For each CMP, save: 1. the original data files and their units; 2. the 2019–2023 average for each index; 3. every annual relative index $R_{j,y}$; 4. the combined annual indices $A_y$; 5. the recent-year indicator $I$; 6. the preliminary harvest-rule result $C^*$; 7. the previous-advice value and annual-change adjustment; 8. the unrounded and rounded total recommendation; 9. any allocation calculation; and 10. all missing-data, revision, or exceptional-circumstances warnings. The current simulations divide the total catch among fisheries using their average catch shares over the previous five years. The Scientific Committee should confirm whether that calculation is part of the CMP or a separate allocation decision. ## What can be concluded from the currently reported value The approximately 630 kt acoustic estimate alone is not sufficient to calculate a TAC: - it is outside the tested data window for a 2027 recommendation; - it must be expressed relative to the 2019–2023 average for the same survey; - the other required indices are needed for the all-index CMPs; and - MP35 and MP36 do not use the acoustic survey. Once the complete annual data table and the agreed previous-advice value are available, the calculations above can be run side by side to show the recommendation produced by every candidate. ## Implementation basis This calculation plan is based on the controls saved by the `jmMSE` candidate runner on branch `devel`, commit [`278c309`](https://github.com/SPRFMO/jmMSE/commit/278c309888c03d241c0aa42967200351ffaa3b05). The historical index extract used in the worked calculation is saved as [`cmp-historical-indices.csv`](../data/cmp-historical-indices.csv). It was extracted from the updated `h1_0.16` assessment output associated with `input/0.15.dat`, retaining both Peruvian index series. The main implementation sources are [`run_candidate_mps.R`](https://github.com/SPRFMO/jmMSE/blob/devel/run_candidate_mps.R) and [`tune_candidate_change_limits.R`](https://github.com/SPRFMO/jmMSE/blob/devel/tune_candidate_change_limits.R). If the data delays, recent-year windows, combined-index calculation, or annual change rule are revised, this page and the MSE tests must be updated together.