Developing the climate test: robustness trials for climate-ready management procedures

The research on climate change impacts on pelagic fish species was reviewed and organized into the theoretical linkages between climatological processes, oceanographic properties affecting habitat, mechanisms of impact and relevant operating model dynamics. The most cited impacts on species biology, ecology and behaviour related to spatial distribution, larval survival, range contraction, adult survival and condition factor. Since few quantitative predictions of climate impacts have been made with regard to these aspects, expert judgement was used to specify proof-of-concept climate tests that included moderate and extreme cases of declining somatic growth, condition factor, adult survival and mean recruitment strength. A range of management procedure (MP) archetypes were tested for their robustness to the climate scenarios including empirical index-target and index-ratio MPs, and model-based stock assessment MPs with and without harvest control rules. MPs that specified effort controls or size limits provided more robust conservation performance for climate tests than their equivalents providing catch advice. Stock assessment model MPs providing catch advice were substantially more robust to declining survival and recruitment when also incorporating a harvest control rule. In general, the most challenging climate tests involved declining survival and recruitment with these leading to larger impacts on yield outcomes than biomass outcomes.