A global analysis led by the University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS) has revealed that fishery stock assessments have systematically overstated the health of fish populations—particularly for the most depleted stocks. The study, published in Science, examined 230 fisheries worldwide, comparing older and more recent assessments for the same years. Results showed that initial estimates of fish biomass were, on average, 11.5% too high, especially in stocks already under pressure.

This overestimation has significant implications for sustainable fisheries management, as it can delay necessary actions like reducing catch limits to allow for recovery. The researchers found that even when catch restrictions were introduced, overfished populations often failed to recover at the rates predicted, suggesting flaws in current assessment models. Stocks with low economic value were also more prone to inaccurate estimates due to limited scientific data.

The study calls for more precautionary approaches, improved independent monitoring, and changes to assessment protocols—such as including ‘red teams’ to challenge optimistic projections and consider worst-case scenarios. According to lead author Professor Graham Edgar, increased transparency and realism in fisheries science is essential for food security, job sustainability, and healthy oceans.

The full University of Tasmania article is available here: https://www.utas.edu.au/about/news-and-stories/articles/2024/taking-stock-of-assessments-for-sustainable-fisheries