Timeline of Harvest Strategy Development for Four Tuna Stocks in the WCPO

Year

Progress Summary (Reference)

2015

1. Agreed to harvest strategy workplan for the adoption of harvest strategies under CMM 2014-06 (WCPFC12 Summary Report, Att. Y)
2. The Commission adopted CMM 2015-06 establishing a TRP for skipjack tuna. (WCPFC12 Summary Report, Att. G)

2016

1. Agreed to determine the acceptability of potential HCRs where the estimated risk of breaching the LRP is between 0 and 20%. (WCPFC13 Summary Report, Para 296)
2. Accepted the initial list of performance indicators for tropical purse seine fisheries for the purpose of the evaluation of harvest control rules (WCPFC13 Summary Report, Att. M)
3. Agreed to a refined workplan for the adoption of harvest strategies under CMM 2014-06 (WCPFC13 Summary Report, Att. N.)
4. Agreed to an interim timeframe of up to ten years for rebuilding the bigeye tuna stock to the agreed Limit Reference Point of 0.2SBF=0 (WCPFC13 Summary Report, para 305)

2017

1. Noted candidate performance indicators for the Southern Longline Fishery and the Tropical Longline fishery to evaluate harvest control rules. (WCPFC14 Summary Report, Attachment K, Table 1 and 2)
2. Agreed on actions to prioritise the development and adoption of a Target Reference Point for south Pacific albacore at WCPFC15. (WCPFC14 Summary Report, para 188)
3. Tasked the Secretariat to develop a dedicated space on the WCPFC website for publishing harvest strategies, including interim harvest strategies, agreed to by the Commission. (WCPFC14 Summary Report, para 208)
4. Agreed to reprioritise as needed the annual agenda of the Commission and Scientific Committee to allow sufficient additional time for consideration of harvest strategy issues. In addition, WCPFC recognised that there may also be a need for a dedicated science/management dialogue. (WCPFC14 Summary Report, para 215)

2018

1. Agreed to hold a 6-day annual meeting in 2019 with additional time devoted for the Commission to discuss harvest strategies.  (WCPFC15 Summary Report, para 328)
   1. adopted the Updated Workplan for the Adoption of Harvest Strategies under CMM 2014-06. (WCPFC15 Summary Report, Att. I)
      1. Agreed on an interim TRP for South Pacific albacore at 0.56SBF=0 with the objective of achieving an 8% increase in CPUE for the southern longline fishery as compared to 2013 levels. The TRP shall be reviewed every 3 years, consistent with the SP albacore assessment schedule, and the timeline for achieving the interim TRP shall be no later than 20 years. (WCPFC15 Summary Report, paras 207-212)

2019

1. No need to review the Management Objectives on an annual basis. (WCPFC16 Summary Report, para 170)
2. Important to consider economic indicators based on economic and other data. (WCPFC16 Summary Report, para 181)
3. Agreed to progress work on a multispecies approach and to report back to the Commission. (WCPFC16 Summary Report, para 195)
4. Continue to build CCM’s capacity on harvest strategies. (WCPFC16 Summary Report, para 207)
5. Adopted the Updated Indicative Workplan for the Adoption of Harvest Strategies. (WCPFC16 Summary Report, Att. H)
6. SC to provide advice on the formulation of TRPs for skipjack tuna and effort creep estimated in relation to the TRPs. (WCPFC16 Summary Report, para 258).
7. Revise WCPFC16-2019-15 (Minimum TRPs for WCPO yellowfin and bigeye tuna consistent with alternative LRP risk levels, and multispecies implications) using candidate revised interim skipjack TRPs of 42%,44%, 46%, 48% and 50% of SB/SBF=0. (WCPFC16 Summary Report, para 259).
8. Requested SC to provide advice on the formulation of TRPs for bigeye and yellowfin tuna for other candidate TRP indicators other than depletion ratio, such as longline CPUE. (WCPFC16 Summary Report, para 273)
9. Requested the SSP to conduct an analysis for bigeye and yellowfin tuna similar to that undertaken in WCPFC16-2019-14 (Current and projected stock status of WCPO skipjack tuna to inform consideration of an updated target reference point). (WCPFC16 Summary Report, para 274)
10. Agreed that the interim paragraphs 12 and 14 of CMM 2018-01 be retained and tasked SC and SSP to explore potential candidate TRPs for the two stocks. (WCPFC16 Summary Report, para 275)

2020

1. Requested SPC to update the skipjack TRP work by including additional candidates, including 36%, 38% and 40% in the median depletion table. (WCPFC18 Summary Report, para 159)
2. Noted the results of analyses on candidate TRPs for bigeye and yellowfin (WCPFC17-2020-12). (WCPFC18 Summary Report, para 165; WCPFC17-2020-12 (SC16-requested analyses to inform WCPFC17 discussions on candidate target reference points for WCPO bigeye and yellowfin tuna)

*  The SSP has made substantial technical progress during 2020, notably on MSE for South Pacific albacore and skipjack.

2021

1. Noted advice on possible formulations of a TRP for skipjack tuna. (WCPFC18 Summary Report, para 100)
2. Noted the results of analyses on candidate TRPs for bigeye and yellowfin. (WCPFC18 Summary Report, para 107)
3. Noted the importance of agreeing on TRP for bigeye and yellowfin and agreed to progress this work in 2022. (WCPFC18 Summary Report, para 108)
4. Agreed to defer consideration of MPs for skipjack until 2022. (WCPFC18 Summary Report, para 111)
5. Noted the advice related to a recalibration of the interim TRP for the SP albacore. (WCPFC18 Summary Report, para 171)
6. Adopted the updated Indicative Workplan for the Adoption of Harvest Strategies under CMM 2014-06. (WCPFC18 Summary Report, para 256; Att. I)
7. The Commission agreed to have the first Science-Management Dialogue, on a trial basis, back-to-back with SC18 in 2022, with a list of proposed areas of focus. (WCPFC18 Summary Report, para 271-272)

2022

1. Noted the presentation on the TRP for skipjack tuna. (WCPFC19 Summary Report, para 145)
2. Adopted CMM 2022-01 Conservation and Management Measure on a Management Procedure for WCPO Skipjack Tuna (WCPFC19 Summary Report, para 152, Att. G)
3. Noted TRPs for bigeye and yellowfin tuna, and agreed on the need for further work prior to considering TRPs for bigeye and yellowfin tuna. (WCPFC19 Summary Report, para 156; WCPFC19-2022-12 (WCPO bigeye and yellowfin TRP evaluations (with updated 2022 skipjack assessment results))
4. Noted on South Pacific albacore objectives and the TRP. (WCPFC19 Summary Report, para 212; WCPFC19-2022-15 (Further analyses to inform discussions on South Pacific albacore objectives and the TRP)
5. Noted the additional work tasked by SMD01 to support decision-making on MPs for South Pacific albacore (WCPFC19-2022-16). (WCPFC19 Summary Report, para 222; WCPFC19-2022-16 (Updates on MP evaluations for south Pacific albacore since SMD01)
6. Adopted CMM 2022-03 CMM on Establishing a Harvest Strategy for key fisheries and stocks in the WCPO. (WCPFC19 Summary Report, para 270)
7. Adopted the updated Indicative Workplan for the Adoption of Harvest Strategies under CMM 2014-06. (WCPFC19 Summary Report, para 277; Att. L)

8. Given the heavy workload in 2023, agreed not to hold an SMD in 2023 and agreed to assess the need to hold an SMD in 2024. (WCPFC19 Summary Report, para 291))

   * First Science Management Dialogue held in August 2022. (SMD01 Outcomes Document: WCPFC19-2022-SMD01-01)

2023

SPALB TRP

1. Agreed on an interim target reference point (iTRP) for south Pacific albacore specified as (0.96 SB2017- 2019/SBF=0)[1]. (WCPFC20 Summary Report (Rev1), Para. 238)
2. The iTRP for SPALB this iTRP shall be subject for review following the 2024 stock assessment and further development of candidate MPs. (WCPFC20 Summary Report (Rev1), Para. 241)
3. Tasked the SSP to undertake additional evaluations on selected candidate MPs and alternative candidate TRPs for SPALB. (WCPFC20 Summary Report (Rev1), Para. 242)

SPALB Management Procedure

4. Agreed to hold a Science-Management Dialogue in 2024 (SMD-02) focused on:

5. South Pacific albacore MPs (including review of the iTRP);

6. Development of BET and YFT TRPs;

7. Issues pertaining to the application of the SKJ management procedure, and

8. Harvest strategy capacity-building for CCMs (SPC-facilitated). (WCPFC20 Summary Report (Rev1), Para. 264)

9. Noted the importance of applying compatible measures between WCPFC and IATTC, the Commission tasked the Secretariat to strengthen its relations with the IATTC in the development of the MSE and MPs for South Pacific albacore. (WCPFC20 Summary Report (Rev1), Para. 268-270)

SKJ Management Procedure

6. Noted the successful running of the skipjack MP and the need to re-evaluate the skipjack estimation method prior to the next implementation of the MP. (WCPFC20 Summary Report (Rev1), Para. 301-302)

SKJ Monitoring Strategy

7. Noted a need for intercessional work, led by the SC and TCC Chairs, to facilitate the development by SSP of a monitoring strategy for adoption at WCPFC21. (WCPFC20 Summary Report (Rev1), Para. 301-313)

Mixed Fishery MSE

8. Noted the progress to date on the development of the mixed fishery MSE framework. (WCPFC20 Summary Report (Rev1), para 337)

2024

SKJ Management Procedure

1. SC20 recommended that the SSP evaluate the following potential approaches to modify the estimation method for the WCPO skipjack interim MP, using the current OM grid and HCR, to evaluate whether the performance of the MP would change if the EM were revised, and report back to SC21 on outcomes and recommendations:

   1. Modification of tropical CPUE abundance indices in the existing estimation method along the lines of the approach taken using unassociated set purse seine CPUE data by the 2022 stock assessment.

   2. Further investigation of alternative stock assessment platforms and modelling approaches. (SC20 Outcomes Document, Para. 98)

2. SC20 further recommended that SC21 review the outputs from the re-evaluation and provide recommendations to WCPFC22 regarding the potential need to revise the current interim skipjack MP (CMM 2022-01). (SC20 Outcomes Document, Para. 100)

SKJ Monitoring Strategy

3. SC20 requested that the SSP conduct the following analyses related to the monitoring strategy for skipjack:
   1. Evaluate whether changes in the FAD closure duration (as adopted in CMM 2023-01) will affect the performance of the interim MP;
   2. Representativeness and appropriateness of candidate CPUEs for use in MP. (SC20 Outcomes Document, Para. 101)
4. SC20 recommended that in years when an assessment is not conducted, the monitoring strategy could be reviewed by SC and feedback provided through the Online Discussion Forum. (SC20 Outcomes Document, Para. 102)
5. SC20 recommended the monitoring strategy be forwarded to the SMD, TCC and the Commission for their consideration. (SC20 Outcomes Document, para 104)

SPALB Target Reference Point

6. SC20 recommended the Commission note that the biomass depletion associated with the adopted iTRP has been re-estimated to be 50% based on the 2024 assessment, which was 47% based on the 2021 assessment. (SC20 Outcomes Document, Para. 105)
7. SC20 recommended that both catch numbers and weight be used for projections. SC20 further recommended that SSP present trends in vulnerable biomass among specific WCPFC-CA longline fleets, and for WCPFC-CA catch levels to be related to 2017-2019 levels. (SC20 Outcomes Document, para 107)
8. SC20 recommended including more scenarios for projections by fixing EPO catch at 2017-2019 levels and using multiple catch levels in the WCPFC-CA related to 2017-2019 levels. (SC20 Outcomes Document, para 108)

SPALB Operating Model

9. SC20 adopted the operating model (OM) reference set, together with the proposed robustness set (Table 2, SC20-MI-WP-04), for the evaluation of candidate SPALB MPs. (SC20 Outcomes Document para 109)
10. SC20 recommended that future work to elaborate the OM sets be conducted through the monitoring strategy and could include:
    1. development of scenarios for the impacts of climate change
    2. consideration of potential effects of effort creep and/or hyperstability in CPUE
    3. development of models that address uncertainties around stock structure to the robustness set. (SC20 Outcomes Document, para 110)
11. SC20 recommended that simulations be conducted to explore the implications of assuming a single stock OM when there could be multiple stocks. If ongoing genetics work confirms the presence of multiple-stocks and the simulations indicate that the single-stock assumption made in the OMs is problematic, then exceptional circumstances should be considered and the OM sets should be revised to account for multiple reproductive stocks in the South Pacific. (SC20 Outcomes Document, para 111)

SPALB Management Procedure

12. SC20 recommended that SSP focus primarily on the following two ASPM-derived estimators with a view to having a robust estimator, without obvious future data vulnerabilities:
    1. A direct biomass depletion approach using mean SB/SBF=0 of the last three years; and
    2. A ratio approach that uses Mean SB/SBF=0 of the last three year (same as in 1.a) relative to 2017-2019. (SC20 Outcomes Document, para 112)
13. SC20 noted that there was bias in estimation model performance at low predicted stock sizes. SC20 recommended that this bias be addressed through the design of the HCR and its significance or otherwise will be evaluated through evaluation of candidate MPs. Should the estimation model bias become problematic in the MP design context, then steps will need to be taken to address that issue. (SC20 Outcomes Document, para 113)
14. SC20 recommended that SSP conduct a Management Strategy Evaluation of a range of candidate MPs, using updated estimators together with HCR and maximum change metarule specifications similar to those presented at SC19 (SC19-MI-WP-06). (SC20 Outcomes Document, para 114)
15. SC20 recommended that SSP, in addition to running projections assuming a single baseline for all fisheries within the Management Procedure evaluations, explore the potential implications of using different reference periods for different fisheries and gears within the MP. (SC20 Outcomes Document, para 115)
16. SC20 recommended that EPO catches be assumed to remain constant at recent levels but with an exploration of a case where the EPO is subject to MP controls (in a similar way to SC20-MI-WP-03). (SC20 Outcomes Document, para 116)
17. SC20 noted that it was desirable to constrain the number of candidate MPs evaluated for consideration and recommended that steps be taken to manage this, including using one-off variations from a base-case scenario, rather than a full factorial grid of options. (SC20 Outcomes Document, para 117-118)

BET and YFT Target Reference Points

18. SC20 recommended that the SSP include the following updates to SC20-MI-WP-07 for presentation to the Commission:
    1. Update tables 2-7 with the equivalent depletion levels for South Pacific albacore based on the 2024 South Pacific albacore stock assessment;
    2. Include additional columns in the evaluation of candidate TRPs for YFT and BET which provide the impact on vulnerable biomass within the tropical longline fishery and the southern longline fishery. (SC20 Outcomes Document, Para. 119)
19. SC20 recommended that the SMD and Commission take into account the analysis contained in xvSC20-MI-WP-07 including the following when considering TRPs for bigeye and yellowfin tuna:
    1. Based on the 2023 stock assessment for yellowfin, the miscellaneous fisheries are estimated to account for approximately 37% of the impact on the spawning potential over the period 2016-2018 , but recent catch for yellowfin is higher.
    2. Based on the analysis in SC20-MI-WP-07, the CMM 2023-01 objectives for yellowfin and bigeye tuna cannot both be met simultaneously. (SC20 Outcomes Document, Para. 120)
20. SC20 recommended that an additional working paper be submitted to WCPFC21, which will include a re-evaluation of the candidate yellowfin and bigeye tuna TRPs using more recent fishing conditions for the domestic fisheries of Indonesia, Philippines, and Vietnam. The 2016-18 average catches are significantly lower than the recent fishing level, likely leading to a more optimistic projected stock status for yellowfin tuna. (SC20 Outcomes Document, Para. 121)

2025

SKJ Management Procedure

1. SC21 supported the continued application of the interim skipjack MP for the next implementation cycle, while also emphasizing the importance of further development of alternative indices in advance of the third implementation of the MP. This work should be conducted as part of the scheduled MSE review in 2028 (or potentially, 2029). SC21 further noted that changes to the tuning indices used by the MP may require reconditioning of the OMs and retesting of the MP, which is a considerable undertaking. (SC21 Outcomes Document, Para. 131)

SKJ Monitoring Strategy

2. Based on the discussion and information available, including the 2025 SKJ stock assessment, SC21 made updates to the skipjack monitoring strategy table as shown in Attachment 5 of the SC21 Outcomes Document. (SC21 Outcomes Document, Para. 132)

SPALB Management Procedure

3. Regarding changes of management area south of 10°S and a reduced set of MPs with different MP conditions, SC21 encouraged the SSP to provide sufficient explanation and additional information as necessary to the SPAMWS01 (Sept 2025) and to WCPFC22 to assist decision makers. (SC21 Outcomes Document, Para. 133)
4. SC21 requested WCPFC22 to consider developing a mechanism to provide timely feedback for MSE development to achieve the timelines detailed in the harvest strategy workplan. (SC21 Outcomes Document, Para. 134)
5. SC21 recommended the continued application of the Estimation Method, which does not include a troll index, as presented to WCPFC21 in WCPFC21-2024-30_Rev01. (SC21 Outcomes Document, Para. 137)
6. For the four candidate MPs provided, SC21 draws the attention of the Commission to the following:

   • All the MPs perform well in terms of biological risk to the stock, with the risk of breaching the limit reference point below the specified 20% threshold, and only HCR 10 shows a greater than 5% risk of breaching this threshold.

   • The candidate MPs have different outcomes in terms of the trade-off between catches and catch rates. 

   • Sensitivity tests were conducted, which evaluated the performance of the MPs when catches in the two areas outside of the MP were set to higher levels (EPO excluding the overlap area at 22,500 mt, and the WCPFC-CA between 0° and 10°S at 12,000 mt), which appears below. These tests showed that the performance of the candidate MPs was not strongly affected by the alternative catch assumptions examined. (SC21 Outcomes Document, Para. 138)

7. SC21 noted that it is desirable to constrain the number of candidate MPs evaluated to a manageable level. SC21 recommended that, in addition to the results presented in SC21-MI-WP-04, three additional MPs be developed for the Commission's consideration that more fully explore EPO (excluding overlap area) catch consequences as well as the use of a fixed effort assumption in the WCPFC-CA area equator to 10°S. 

• EPO (excluding the overlap area) set to 22,500 mt (being the approximate average of catches in the years 2021-22), WCPFC-CA 0-10°S set to 9,000t (being the approximate average in the period 2014-2023), using a catch control HCR “tuned” to achieve the adopted iTRP. 

• EPO (excluding the overlap area) set to 13,500 mt (being the approximate catch in the year 2020), WCPFC-CA 0-10°S set to 9,000 t (being the approximate average in the period 2014–2023), using a catch control HCR “tuned” to achieve the adopted iTRP. 

• EPO (excluding the overlap area) set to 18,000 mt (being the approximate average for the period 2014-2023), WCPFC-CA 0-10°S set to average effort levels in the period 2014-2023, using a catch control HCR “tuned” to achieve the adopted iTRP. (SC21 Outcomes Document, Para. 139)

8. SC21 recommended that, to the extent possible, the results of this expanded set of seven candidate MP evaluations and all candidate MP evaluations in WCPFC21-2024-30 (those applied to longline and troll fisheries operating in the WCPFC-CA, south of the equator) be provided to the SPAMWS01 in September 2025 and to the Commission for their consideration and decision. (SC21 Outcomes Document, Para. 140)
9. SC21 also requested that the SSP report the median time series of vulnerable biomass from the OMs for the historical period and to develop a table with the average nominal CPUE (kg/100 hooks) for the reference period (2020–2022) by CCMs with SPA catches. (SC21 Outcomes Document, Para. 141)

BET Operating Models

10. SC21 supported the use of the proposed reference set of 24 OMs for the bigeye tuna as a basis for further development. However, SC21 recommended that work should continue to promptly refine and expand the OM reference set to include alternative assumptions as listed below in Table MI-01 (in the SC21 Outcomes Document) as much as practicable, with a view to the formal adoption of the OM reference set in 2026. SC21 noted that assumptions around the purse seine FAD closure period may not need to be included in the OM reference set, but rather that those assumptions can be addressed through specific MP design and sensitivity analysis. (SC21 Outcomes Document, Para. 144)

BET TRPs and Performance Evaluation of Candidate Management Procedures   

11. SC21 noted that the MP controls only a fraction of the BET catch (27% over the period 2020-2022) and stressed the importance of considering the dynamics of other fisheries that catch BET that are either managed under an MP (same or separate) or require assumptions about their management. SC21 also noted that specific settings within the BET MSE remained to be defined by the Commission. (SC21 Outcomes Document, Para. 147)
12. A variety of alternatives for MP design settings were suggested by CCMs. Those need to be carefully considered by the Commission so that plausible assumptions are properly covered in the MSE testing. SC21 also draws the Commission’s attention to the fact that the order of MP and MSE application under the mixed fishery harvest strategy framework (i.e., which species’ MP goes first) could affect the performance across the individual MPs, and that this order of MP application has not yet been formally agreed upon. (SC21 Outcomes Document, Para. 148)
13. SC21 recommended that WCPFC22 review the current proposed BET MSE framework and provide guidance on BET MP settings and assumptions. (SC21 Outcomes Document, Para. 149)
14. SC21 considered that the six proposed performance indicators should be included in future presentations and encouraged the SSP to consider further options to help inform management decision-making, including through feedback from WCPFC22. (SC21 Outcomes Document, Para. 150)

Progress of the WCPFC Harvest Strategy Work Plan 

15. SC21 recommended that the Commission support a one-time extension of the current skipjack MP application period from 3 to 4 years. SC21 noted that such a change would need to be reflected in an amendment to CMM 2022-01. SC21 recommended that SC21-MI-WP-10 be provided to WCPFC22. (SC21 Outcomes Document, Para. 155)
16. MSE analyses for three stocks (SKJ, SPA, BET) were presented to SC21 this year and represented a significant body of work for the SC’s consideration. SC21 noted that, as the development and implementation of the harvest strategy approach progresses under the milestones within the WCPFC harvest strategy work plan, it is critical to receive timely guidance and instruction from the Commission on key aspects of this work. The workplan anticipates the adoption of multiple MPs in the near future, and it is important that the Commission provide guidance in relation to the implementation of the mixed fishery approach. (SC21 Outcomes Document, Para. 157)
17. SC21 noted that for complex fisheries management, such as that required for WCPFC key tuna stocks, the development and simultaneous application of species-specific MPs, as in WCPFC, is a reasonable approach due to the difficulty in developing fully integrated multi-stocks approaches. When developing species-specific MPs in this approach, settings must be agreed not just for individual MPs but also for how those individual MPs should interact. These would include, but are not limited to: 

18. How each fishery is to be managed (catch or effort).

19. What catch or effort levels in fisheries not managed by the MP should be considered.

20. The scope of candidate MPs in terms of their spatial extent and the fisheries to be managed.

21. Management objectives for fisheries and, in particular, TRP options to consider.

22. How the stock status of individual species may trigger Exceptional Circumstances in other species MPs.

Order of MP application (SC21 Outcomes Document, Para. 158)