What are harvest strategies?
Harvest strategies provide a more predictable approach than the traditional use of stock assessments to provide management advice. The effectiveness of harvest strategies relies on a set of agreed management objectives for the fishery and the stock, and then using management strategy evaluations (MSE, also known as management procedures, MP) to select the Harvest Control Rule (HCR) that is most likely to achieve these goals.
As the HCR is used to set the harvest rate (i.e., the annual catch limit), harvest strategies provide a structured framework for determining the scientific management advice. This approach allows managers to identify the most important management objectives, that are then used to determine the most effective HCR to meet these objectives. See https://ofp-sam.shinyapps.io/AMPLE-intro-hcr/_w_5d6010bd/tutorials/intro_hcr.html for an introductory tutorial on HCRs developed by SPC for the WCPFC using the AMPLE package. Other similar on-line apps include;
- WCPFC South Pacific Albacore (https://ofp-sam.shinyapps.io/spample/),
- New England Groundfish (https://jjesse.shinyapps.io/hcr_app/), and
- the MSE Game for EPO Bigeye tuna (https://valeromaspez.shinyapps.io/tunamse_epo_eng/).
Harvest strategies use a pre-agreed framework for making fisheries management decisions, and includes the following core elements:
- A monitoring programme (e.g., CPUE, surveys, and/or age composition data).
- An approach to estimate stock status (e.g., a stock assessment).
- Reference points.
- An HCR evaluated using MSE.
MSE is a tool or procedure that uses simulation models to help compare the expected performance of different HCRs and guides the process of harvest strategy development (Figure 1).
Figure 1: Conceptual overview of the management strategy evaluation modelling process (Figure 1 in Punt et al. 2016).
Harvest Strategies development in SIOFA
In 2023, the Eight Annual Meeting of the SIOFA Scientific Committee (SC8) formulated a series of recommendations for harvest strategies, stemming from the SIOFA Workshop on Harvest Strategy pre-assessment (WSHSPA-2023). Later in 2023, the Tenth Annual SIOFA Meeting of Parties (MoP10) discussed the recommendations of the SC and agreed on interim stock-specific reference points for orange roughy, alfonsino, and toothfish in the SIOFA Area (MoP10 report, paragraphs 77-78) and interim Harvest Control Rules (HCRs) for the management for all its stocks (MoP10 report, paragraph 79), with the main objective of preserving the status quo.
The SIOFA MoP agreed to further establish a continued dialogue with the SIOFA SC on the development of Harvest Strategies and to prioritize orange roughy and toothfish as a first step, with alfonsino and other primary species to be developed subsequently.
The SIOFA SC was tasked to evaluate different stock assessment options, based on the level of data available, for all species that are potential candidates for harvest strategies. scientific uncertainty, relative costs, and applicability by stock/fishery of the various options.
The SIOFA SC was also requested to develop develop interim ad-hoc harvest control rules that could be used for managing stocks, including for example, harvest control rules that adjust any future catch limits based on trends in CPUE or other stock status indicators.
In general, the SIOFA SC was requested provide advice based on the objectives set by the MoP, including on potential performance indicators for each of the management objectives decided by the MoP
The joint SIOFA MoP-SC intersessional workshop to define management objectives (WS2023-HSMO) was held in 2023 and aimed to define Management Objectives for the development of Harvest Strategies for selected SIOFA stocks. To do so, WS2023-HSMO developed management objective categories and, within these, preliminary management objectives in the development of harvest strategies, focused on specific management objectives for the development of harvest strategies for orange roughy and toothfish, identifying any other relevant management objectives, for example bycatch objectives, ecosystem objectives, and fishery impact objectives for harvest strategies for orange roughy and toothfish. WS2023-HSMO also identified potential responses to exceptional circumstances, such as dropout or breakout rules, in the implementation of harvest strategies that should be considered by the Scientific Committee.
Key steps for the future development of Harvest Strategies in SIOFA
In 2023, the SIOFA MoP endorsed a timeline for the development of harvest strategies, including preassessments, assessments, management objectives and implementation of harvest strategies (MoP10 report, paragraph 87). This timeline is composed by 6 steps (Annex G of the SC8 report):
Step 1: Define management objectives.
Step 2: Determine appropriate fisheries monitoring regime.
Step 3 Develop candidate HCRs.
Step 4: Test HCRs with MSE.
Step 5: Implement the harvest strategy.
Step 6: Improve assessment and harvest strategy.
The SIOFA MoP agreed to have a specific agenda meeting on Harvest Strategies at its next annual meeting, in 2024 (MoP11) and the discussion will continue thereafter.
At the SIOFA SC meeting in 2026 (SC11), the SIOFA SC aims to formally propose final Harvest Strategies to the SIOFA MoP. If adopted by the SIOFA MoP in 2026, the Harvest Strategies could be used for formulating the SIOFA SC scientific advice from 2027 onwards.