May 28, 2019 — With a growing consensus that climate change is causing drastic transformations of marine ecosystems and fish stock dynamics, two recent studies have addressed the importance of taking a more adaptive and responsive approach to their management.
The first study, published in the ICES Journal of Marine Science, shows that adjusting fishing levels when fish populations change is key to making global fisheries more climate-resilient. The result of making this shift would be healthier oceans and a more stable supply of fish for consumption, according to scientists at the Environmental Defense Fund and the University of California, Santa Barbara.
Their paper outlines the fact that many commercially important fish stocks are vulnerable to the effects of climate change, and that managing those stocks sustainably in the future will be a large and growing challenge for fisheries scientists and managers. The paper recommends responsive harvest control rules (HCRs) that automatically reduce catch percentages when decreases in biomass are detected, and increases when biomass increases. By adopting HCRs, “inherent resilience” could be introduced into the system, reducing the adverse effects of climate change while longer-term solutions are sought to better address the negative impacts of global warming.
“Using the right harvest-control rule is like having adaptive cruise control for your fishery,” said Jake Kritzer, a senior director of Environmental Defense Fund’s Oceans program and lead author of the paper. “When you need to slow down, the system can automatically adjust to the right level. Then, when the road ahead is clear, it allows you to return to a higher level.”
Warmer waters caused by climate change are resulting in lower reproduction rates in fish and forcing them to migrate out of their natural ranges. The current system for managing fish catches is often not adaptive enough to respond to these dynamics, the report noted. In addition, current catch levels are being calculated on biomass that may be incorrect as a result of these large-scale changes, the report found.