"Understanding how fishing pressure and climate-driven ocean warming affect productivity is important for fisheries sustainability and food security.

"It is often difficult to estimate the direct causal effect of different drivers on the decline of fish stocks, and this study uses a data-driven dynamic model to find the causal drivers of stock productivity.

"The study finds that harvest rates are the most important driver of stock productivity, while changes in sea surface temperature also had a significant impact. The impact of ocean warming is found to be predominantly negative and intensifying over time, suggesting that the adverse effects of ocean warming poses a growing threat to fisheries sustainability.

"These are important findings for New Zealand’s Quota Management System, which at its inception was designed with the assumption that fish stocks were relatively stable over time. New Zealand’s fisheries management addresses climate change through research and adaptation planning policy, but more explicit legal provisions may be required in future."