ABSTRACT: Modelling has predicted that reductions in ocean pH and increases in temperature will reduce vital rates (survival and growth) of North Pacific crab stocks and hence the target levels of fishing mortality consistent with sustainable harvesting. However, these predictions have been based on best estimates of the effects of changes in ocean pH and temperature on vital rates. The effects of sources of uncertainty (in the relationship between ocean pH/temperature and vital rates, in economic parameters, whether prices and costs are non-linear functions of catches and effort, and that associated with the population dynamics model used to predict optimal fishing mortality rates) are quantified for red king crab and southern Tanner crab in Alaska. This shows that uncertainty related to the effects of ocean pH and temperature on vital rates and which Earth System Model / future emission scenario best reflects reality are the dominant sources of uncertainty. We then evaluate how additional experiments to explore the relationship between changes in ocean pH/temperature and vital rates (additional replicates and a wider range of levels of pH and temperature) could reduce the uncertainty in estimates of future time-trajectories of target fishing mortality rates.