Developing the climate test: performance metrics of climate robustness

Operating models were developed from the 2021 stock assessment of bigeye tuna. Four types of projected climate impact were simulated: increasing natural mortality rate, and decreases in recruitment strength, somatic growth and condition factor. Defining a robustness threshold enabled the calculation of a performance metric of climate robustness that was calculated for each type of climate impact for three management procedure (MP) archetypes and two MP derivatives. Shifting the focus away from establishing defensible climate forecasts and towards climate robustness performance metrics, provided information that could support the selection of MPs accounting for climate impacts. It was not necessary to know the exact type of impact or the exact level of forecasted impact to identify an MP that clearly and consistently outperformed the rest in terms of climate robustness.