5 mai 2022
It’s been over a decade since ICCAT began implementing science-based quotas to help recover Atlantic bluefin, the largest of the tuna species. It now appears that the species is on the verge of locking in those gains using one of the most effective forms of management – a harvest strategy. Next week’s Panel 2 meeting, to be held on 9-10 May 2022, offers a tremendous opportunity to make progress. Finalization of the management strategy evaluation (MSE), the simulation-based modelling tool that informs harvest strategy selection, is on track for completion by the 2022 Commission meeting. While the scientific work is largely complete after eight years in development, critical management decisions remain. The scientists will rely on these decision points as they continue their work, making it imperative that this upcoming dialogue proves fruitful and yields concrete outcomes that can be immediately fed into the MSE.
Most importantly, managers will be asked to operationalize management objectives by agreeing on the risk tolerances and associated timeframes that a harvest strategy must meet. First adopted in 2018, the initial conceptual management objectives include clauses that range from concurrently avoiding overfishing and the state of being overfished to limiting the percent change in catch quotas between management periods. Now it’s time to fill in the blanks of Resolution 18-03. To ensure an abundant future for both the species and fisheries, precautionary objectives would include a high probability (e.g., ≥70%) of achieving a healthy stock and a low probability (e.g., ≤10%) of reaching a dangerously small stock size (known as Blim).
In addition to objectives, managers must approve a path forward for narrowing down the current list of candidate harvest strategies, including so-called “tuning.” Tuning levels the playing field and allows an MSE to compare apples to apples. It requires all candidate harvest strategies to achieve a common performance level for one management objective, and then relative performance against other objectives can be compared. For example, in the case of the Atlantic bluefin MSE, all candidates must achieve a certain population size in 30 years relative to the population size that can produce maximum sustainable yield. Once they are “tuned” to achieve that level, one can compare relative catches and stability in catches of the harvest strategy options. For a common population status, ICCAT might opt to cull a candidate harvest strategy that has the lowest catch, for example.
While the main decision points for next week include endorsing tuning processes and operationalizing management objectives, the meeting will also touch on other necessary discussions surrounding the harvest strategy framework and path forward.
It’s a tall order for a two-day meeting, but the scientists have done an extraordinary job updating the MSE and preparing comprehensive results for review by managers. Now, it’s up to the managers to make the necessary decisions that will allow the development process to progress, ensuring that this precedent-setting harvest strategy will be adopted for Eastern and Western Atlantic bluefin tuna at ICCAT in 2022. At a recent webinar on harvest strategies at ICCAT, 100% of participants agreed that ICCAT should prioritize the implementation of the bluefin tuna harvest strategy at its upcoming Commission meeting. ICCAT and Panel 2 must heed this call, echoed from many others, managers, scientists, and stakeholders alike, and continue development without delay.