WCPFC Harvest Strategy and Reference Points

Harvest Strategy CMM - 2014-06  

WCPFC11 agreed to Conservation and Management Measures to develop and implement a harvest strategy approach for key fisheries and stocks in the WCPO (326.23 KB)  The objective of CMM 2014-06 is "To agree that the Commission shall develop and implement a harvest strategy approach for each of the key fisheries or stocks under the purview of the Commission according to the process set out in CMM 2014-06."

Pursuant to paragraph 13 of CMM 2014-06, WCPFC12 agreed a workplan for adoption of Harvest Strategies under CMM 2014-06 Workplan for the adoption of Harvest Strategies under CMM 2014-06 (506.05 KB) An updated workplan was agreed at WCPFC13 and records as an annex the Harvest Strategy-related outcomes from WCPFC13 Updated workplan on Harvest Strategies 2016 - 2019 and record of outcomes from WCPFC13 (240.6 KB)

Limit reference points (LRPs)

WCPFC8 approved a number of SC7 recommendations related to limit reference points

1. The agreed working definition for LRPs is to be based on the following principles:

  • they define a state of the fishery that is considered to be undesirable and which management action should avoid;
  • the probability of breaching an LRP should be very low;
  • management actions should be taken before the fishery falls below or is at risk of falling below an LRP.

 

2. The hierarchical approach (as outlined in SC7-MI-WP-03) to identify key LRPs for key target species in the WCPFC is as follows:

Level

Condition

LRPs

Level 1

A reliable estimate of steepness is available

FMSY and BMSY

Level 2

Steepness is not known well, if at all, but the key biological  (natural mortality, maturity) and fishery (selectivity) variables  are reasonably well estimated.

FX%SPRo and either

X%SBo or

X%SBcurrent,F=0

Level 3

The key biological and fishery variables are not well estimated or understood.

X%SBo or

X%SBcurrent,F=0

Bigeye: the LRP set at Level 2 with regard to the biomass-based LRP of 20%SBrecent,F=0, with deferral of a recommendation on the value of X% in the Level 2 fishing mortality-based LRP of Fx%SPR to SC9 (SC8 recommendation)

Yellowfin: the LRP set at Level 2 with regard to the biomass-based LRP of 20%SBrecent,F=0, with deferral of a recommendation on the value of X% in the Level 2 fishing mortality-based LRP of Fx%SPR to SC9 (SC8 recommendation)

South Pacific albacore: the LRP set at Level 2 with regard to the biomass-based LRP of 20%SBrecent,F=0, with deferral of a recommendation on the value of X% in the Level 2 fishing mortality-based LRP of Fx%SPR to SC9 (SC8 recommendation)

Skipjack: the LRP for skipjack is set at Level 3, 20%SBrecent,F=0.  (SC8 recommendation)

(note that SPR refers to the spawning-potential-per-recruit and SBrecent,F=0 refers to the estimated average spawning biomass over a recent period in the absence of fishing). 

WCPFC10 endorsed that the time window to be used in the LRP 20%SBF=0,t1-t2 satisfy the following criteria:

  1. have a length of 10 years;
  2. be based on the years t1=ylast-10 to t2=ylast-1 where ylast is the last year used in the assessment; and
  3. the approach used for calculating the unfished biomass levels be based on scaled estimates of recruitment according to the stock recruitment relationship.

Acceptable Risk Level of exceeding LRP

At WCPFC12, the Commission noted that SC10 had considered levels of risk associated with breaching the LRP within the range 5-20% and that the identification of acceptable risk is a management issue.  The Commission agreed to identify the level of acceptable risk which should be applied to breaching a LRP for the key target species, noting that the UN Fish Stocks Agreement states that the risk of exceeding LRPs should be very low.

At WCPFC13, the Commission agreed to:

i)         not specify, at this time, acceptable levels of risk of breaching the limit reference point for each stock;

ii)         consider any risk level greater than 20 percent to be inconsistent with the LRP related principle in UNFSA  (as referenced in Article 6 of the Convention) including that the risk of breaching limit reference points be very low; and

iii)        determine the acceptability of potential HCRs where the estimated risk of breaching the limit reference point is between 0 and 20%.

(Ref: WCPFC13 Summary Report, paragraph 296)

Target Reference Point for Skipjack

WCPFC12 agreed to CMM 2015-06 (363.05 KB) which establishes a target reference point for the WCPO skipjack tuna stock shall initially be 50 per cent of the estimated recent average spawning biomass in the absence of fishing, (SBF=0, t1-t2) calculated in a manner consistent with that detailed above for the LRP. This target reference point shall be an interim target reference point until it is reviewed in accordance with paragraph 8 of CMM 2015-06.  

Rebuilding timelines for Bigeye to [or above] its LRP

At WCPFC13, the Commission 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.  The Commission shall use this timeframe in its development and evaluation of strategies and conservation and management measures relevant to the rebuilding of bigeye tuna. Amongst other matters, the Commission will consider the probability of the bigeye stock being at or above the limit reference point at the end of the rebuilding timeframe.  (Ref: WCPFC13 Summary Report, paragraphs 304 – 306)

Agreed interim performance indicators to evaluate Harvest Control Rules

At WCPFC13, the Commission accepted the suggested initial list of performance indicators for tropical purse-seine fisheries as developed by the Small Working Group on Management Objectives at WCPFC13 for the purpose of the evaluation of harvest control rules (This list is attached at WCPFC13 Summary Report Attachment M: WCPFC13 Att M (109.82 KB) )  (Ref: WCPFC13 Summary Report, paragraph 286)

Links to WCPFC MOW and HSW workshop materials and outcomes

Four WCPFC workshops have been held on Management Objectives and Harvest Strategies from 2012 - 2014.  These workshops were held as informal meetings of stakeholders with an interest in WCPO tuna fisheries, that were convened by the Commission to facilitate and support the development of harvest strategies by Commission Members.  Links to the relevant meeting pages and reports: 

Northern Stocks

Interim Harvest Strategy for North Pacific Albacore Fishery

 

Introduction

At the Sixth Regular Session of the Northern Committee, and consistent with Article VI of the WCPFC Convention, Canada submitted a paper (WCPFC-NC6-DP02) on the development of a precautionary approach based fishery management regime for the northern stocks. Building on this paper, the Seventh Regular Session of the Northern Committee (NC7) agreed to a three-year work programme to develop a precautionary approach based management framework for North Pacific albacore.

The NC9 determined that it was best to delay discussions on the framework until the completion of the 2014 North Pacific albacore stock assessment. In July 2014, the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (ISC) concluded that the North Pacific albacore stock is “healthy and that current productivity is sufficient to sustain recent exploitation levels, assuming average historical recruitment in both the short and long term”. The ISC also provided further advice regarding candidate limit and target reference points.

Based on the advice from the ISC, NC10 recommended and the 11th regular session of the Commission (WCPFC11) adopted the Precautionary Management Framework for North Pacific Albacore. In December 2017, the Commission (WCPFC14) adopted the Interim Harvest Strategy for North Pacific Albacore Fishery as recommedned by NC13, which replaces the Precautionary Management Framework for North Pacific Albacore.

1. Interim management objective

The management objective for the North Pacific albacore fishery is to maintain the biomass, with reasonable variability, around its current level in order to allow recent exploitation levels to continue and with a low risk of breaching the limit reference point.

2. Biological reference points

Based on ISC’s stock assessment advice and following the hierarchical approach adopted by the Commission, North Pacific albacore is to be treated as a Level 2 stock. The following is based on an average recruitment scenario:

  • The limit reference point (LRP) for this stock is established at 20%SSBcurrent F=0. This LRP is consistent with the Annex II of the UN Fish Stocks Agreement (UNFSA) and recent WCPFC decisions on LRPs for the three tropical tuna species and South Pacific albacore, where 20%SSBcurrent F=0 was adopted. If this point is breached, management actions will be taken to return the stock to a predetermined level as outlined in the subsequent section on Decision Rules.

  • The target reference point (TRP) for this stock will be determined following a comprehensive analysis under a management strategy evaluation (MSE) approach as outlined in section 4 on “Future Work”. Historical fishing activity, anticipated fishing activity, and the source of increased fishing mortality will also be considered when evaluating a suitable TRP. Socioeconomic factors, as per UNFSA Article 6.3.c., will be further considered. The existing conservation and management measure (CMM) for the stock (WCPFC 2005-03) establishes through limits on current effort an overall management regime for the stock. 

3. Decision rules

NC recommends a management strategy for the stock that ensures that the risk of the biomass decreasing below the LRP is low.

LRP rule: In the event that, based on information from ISC, the spawning stock size decreases below the LRP at any time, NC will, at its next regular session or intersessionally if warranted, adopt a reasonable timeline, but no longer than 10 years, for rebuilding the spawning stock to at least the LRP and recommend a CMM that can be expected to achieve such rebuilding within that timeline. NC will take into account historical fishing activity and the source of increased fishing mortality when developing management strategies to rebuild the stock, including in establishing effort reductions. NC will further consider socioeconomic factors, as per UNFSA Article 6.3.c., as well as which NC members, if any, contributed to exceeding the LRP.

4. Future work

This framework may be periodically reviewed and revised. To support such revisions, NC endorses the ongoing development and implementation of  an MSE for the stock and fishery, which would yield new information that would enhance the robustness of this framework.

 

Harvest Strategy for Pacific Bluefin Tuna Fisheries

 

Introduction and scope

This harvest strategy has been prepared in accordance with the Commission’s Conservation and Management Measure on Establishing a Harvest Strategy for Key Fisheries and Stocks in the Western and Central Pacific Ocean.

Although the provisions of this harvest strategy are expressed in terms of a single stock, they may be applied to multiple stocks as appropriate and as determined by the Northern Committee.

1.  Management objectives

The management objectives are, first, to support thriving Pacific bluefin tuna fisheries across the Pacific Ocean while recognizing that the management objectives of the WCPFC are to maintain or restore the stock at levels capable of producing maximum sustainable yield, second, to maintain an equitable balance of fishing privileges among CCMs and, third, to seek cooperation with IATTC to find an equitable balance between the fisheries in the western and central Pacific Ocean (WCPO) and those in the eastern Pacific Ocean (EPO).

2.  Reference points

Because steepness in the stock-recruitment relationship is not well known but the key biological and fishery variables are reasonably well estimated,[1] the stock of PBF is to be treated as a Level 2 stock under the Commission’s hierarchical approach for setting biological limit reference points.

2.1  Rebuilding targets

Initial rebuilding target:  The initial rebuilding target for the PBF stock size is the median SSB estimated for the period 1952 through 2014, to be reached by 2024 with at least 60% probability.

Recruitment scenario during initial rebuilding period:  The low recruitment scenario (resampling from the relatively low recruitment period (1980-1989)) or the recent recruitment scenario (resampling from the last 10 years), whichever is lower, will be used for the ISC’s SSB projections until 2024 or until the SSB reaches the initial rebuilding target, whichever is earlier.

The ISC is requested to periodically evaluate whether the recruitment scenario used during the initial rebuilding period is reasonable given current conditions, and to make recommendations on whether a different scenario should be used.  If ISC recommends a different scenario, this will be considered by the NC.

Second rebuilding target:  The second rebuilding target for the PBF stock size is 20%SSBF=0[2], to be reached by 2034, or 10 years after reaching the initial rebuilding target, whichever is earlier, with at least 60% probability.

However, if: (1) the SSB reaches the initial rebuilding target earlier than 2024; (2) ISC recommends a recruitment scenario lower than the average recruitment scenario; and (3) the SSB projections indicate that the second rebuilding target will not be achieved on this schedule, the deadline for rebuilding may be extended to 2034 at the latest.

Also, if there is a recommendation from the Northern Committee that 20%SSBF=0 is not appropriate as the second rebuilding target, taking into account consideration from IATTC, scientific advice from ISC, IATTC or WCPFC SC, and socioeconomic factors, another objective may be established.

Recruitment scenario during second rebuilding period:  After the initial rebuilding target is reached and until the second rebuilding target is reached, the recruitment scenario to be used for the SSB projections will tentatively be the average recruitment scenario (resampling from the entire recruitment period).

The ISC is requested to periodically evaluate whether the recruitment scenario used during the second rebuilding period is reasonable given current conditions, and to make recommendations on whether a different scenario should be used.  If ISC recommends a different scenario, this will be considered by the NC.

2.2  Development of reference points

The Northern Committee will develop more refined management objectives as well as limit reference point(s) and target reference point(s) through MSE process specified in Section 6.

3.  Acceptable levels of risk

Until the stock is rebuilt, the Northern Committee will recommend conservation and management measures as needed to ensure rebuilding in accordance with the probabilities specified in sections 2.1 and 5 for each of the two rebuilding targets.

Once the stock is rebuilt, in accordance with Article 6.1(a) of the Convention, the Northern Committee will recommend conservation and management measures as needed to ensure that any target reference point(s) (once adopted) are achieved on average in the long term, and ensure that the risk of the stock size declining below the B-limit (once adopted) is very low.[3]

4.  Monitoring strategy

The ISC will periodically evaluate the stock size and exploitation rate with respect to the established reference points and the report will be presented to the Scientific Committee.  Until 2024, while the MSE is being developed (see section 6), the ISC is requested to conduct stock assessments in 2018, 2020 and 2022.

In order to cope with the adverse effects on the rebuilding of the stock due to drastic drops of recruitment: (1) all the available data and information will be reviewed annually, including recruitment data provided by the ISC and in National Reports; and (2) the ISC is requested to conduct in 2019, and periodically thereafter as resources permit and if drops in recruitment are detected, projections to see if any additional measure is necessary to achieve the initial rebuilding target by 2024 with at least 60% probability.

5.  Decision rules

Harvest controls rules during initial rebuilding period:  The interim harvest control rules below will be applied based on the results of stock assessments and SSB projections to be conducted by ISC.

(a)        If the SSB projection indicates that the probability of achieving the initial rebuilding target by 2024 is less than 60%, management measures will be modified to increase it to at least 60%.  Modification of management measures may be (1) a reduction (in %) in the catch limit for fish smaller than 30 kg (hereinafter called “small fish”) or (2) a transfer of part of the catch limit for small fish to the catch limit for fish 30 kg or larger (hereinafter called “large fish”).  For this purpose, ISC will be requested, if necessary, to provide different combinations of these two measures so as to achieve 60% probability. 

(b)        If the SSB projection indicates that the probability of achieving the initial rebuilding target by 2024 is at 75% or larger, the WCPFC may increase their catch limits as long as the probability is maintained at 70% or larger, and the probability of reaching the second rebuilding target by the agreed deadline remains at least 60%.  For this purpose, ISC will be requested, if necessary, to provide relevant information on potential catch limit increases.

Harvest controls rules during second rebuilding period:  Harvest control rules to be applied during the second rebuilding period will be decided, taking into account the implementation of the interim harvest control rules applied during the initial rebuilding period.

The Northern Committee will, through MSE development process, develop decision rules related to the limit reference points once adopted including for the case of their being breached.

6.  Performance evaluation

Until the stock is rebuilt, the Northern Committee will work with the ISC and the Scientific Committee and consult with the IATTC to identify and evaluate the performance of candidate rebuilding strategies with respect to the rebuilding targets, schedules, and probabilities.

The ISC is requested to start the work to develop a management strategy evaluation (MSE) for Pacific bluefin tuna fisheries in 2019 and have a goal of completing it by 2024.

To support development of the MSE, ISC is encouraged to identify at least two experts and NC members are encouraged to provide additional funds for the ISC’s work on the MSE.

The Joint WG will start to discuss in 2018, and aim to finalize no later than 2019, guidelines for the MSE, including at least one candidate long-term target reference point (TRP), two candidate limit reference points (LRPs) and candidate harvest control rules (HCRs), which will be provided to the ISC. Those candidate TRPs, LRPs and HCRs will be tested and changed if appropriate during the MSE development process.

In preparation for the Joint WG meeting in 2019, the ISC is requested to organize workshops in early 2018 and 2019 to support the identification of specific management objectives, including level of risks and timelines.  The workshops will include managers, scientists and stakeholders, taking into account any recommendations of the Joint WG, and the number of representatives should be relatively small, as it was for the MSE workshop for North Pacific albacore.

In evaluating the performance of candidate target reference points, limit reference points, and harvest control rules, the Northern Committee, in consultation with the ISC and the Scientific Committee, should consider the following criteria:

  1. Probability of achieving each of the rebuilding targets within each of the rebuilding periods (if applicable).
  2. Time expected to achieve each of the rebuilding targets (if applicable).
  3. Expected annual yield, by fishery.
  4. Expected annual fishing effort, by PBF-directed fishery.
  5. Inter-annual variability in yield and fishing effort, by fishery.
  6. Probabilities of SSB falling below the B-limit and the historical lowest level.
  7. Probability of fishing mortality exceeding FMSY or an appropriate proxy, and other relevant benchmarks.
  8. Expected proportional fishery impact on SSB, by fishery and by WCPO fisheries and EPO fisheries.

Recognizing that developing the operating model and other aspects of the MSE will take time and additional resources, and might require further dialogue between the Northern Committee, the ISC, and the IATTC, while the MSE is in development the ISC is requested to perform this work using the best means at its disposal.

 

[1] See the information provided by the International Scientific Committee for Tuna and Tuna-like Species in the North Pacific Ocean (WCPFC-NC9-2013/IP-03) in response to a request made by the Northern Committee at its Eighth Regular Session (Attachment F of the report of NC8).

[2] SSBF=0 is the expected spawning stock biomass under average recruitment conditions without fishing.

[3] WCPFC13 agreed that any risk level greater than 20 percent to be inconsistent with the limit reference point related principles in UNFSA (as references in Article 6 of the Convention) including that the risk of breaching limit reference points be very low.

 

Key documents

 

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