Analyzing 109 well-sampled stocks from all oceans, we show that current practices may attain 55% recovery on average...
Rebuilding global fisheries under uncertainty
UNITED STATES
Tuesday, July 23, 2019, 17:50 (GMT + 9)
Many fisheries that have been historically overexploited are now considered to be rebuilding, with a hope that current best practices could ensure the recovery of most overfished species by mid century. Our analysis suggests this optimism may be premature, as current projections typically assume managers can have perfect measurements of current stock sizes. We demonstrate how such an assumption can undermine rebuilding efforts under current best practices and even drive unintentional stock declines. By borrowing novel decision methods from the field of robotics, we also show how stock rebuilding can be achieved in the face of measurement and environmental uncertainty, while also achieving higher economic returns than expected under current approaches.
"More than 867 million fishing records have been compiled into a single harmonised view and mapped down to tiny spatial cells, so we can see where fishing has been happening and how it’s changed over time" (Professor Reg Watson)
Abstract
Current and future prospects for successfully rebuilding global fisheries remain debated due to uncertain stock status, variable management success, and disruptive environmental change. While scientists routinely account for some of this uncertainty in population models, the mechanisms by which this translates into decision-making and policy are problematic and can lead to unintentional overexploitation. Here, we explicitly track the role of measurement uncertainty and environmental variation in the decision-making process for setting catch quotas. Analyzing 109 well-sampled stocks from all oceans, we show that current practices may attain 55% recovery on average, while richer decision methods borrowed from robotics yield 85% recovery of global stocks by midcentury, higher economic returns, and greater robustness to environmental surprises. These results challenge the consensus that global fisheries can be rebuilt by existing approaches alone, while also underscoring that rebuilding stocks may still be achieved by improved decision-making tools that optimally manage this uncertainty.
Authors: Milad Memarzadeh, Gregory L. Britten, Boris Worm, and Carl Boettiger
Published By: National Academy of Sciences
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