37% of fish stocks straddling the high seas and economic zones will likely shift distribution by 2030
American Association for the Advancement of Science (AAAS)Even under the most conservative climate projection scenario, 37% of fisheries’ straddling stocks – fish populations that are not contained to either the high seas or specific exclusive economic zones (EEZs) – are likely to undergo distribution shifts by 2030 thanks to climate change, new research suggests. The projections spotlight an urgent issue that fisheries management and governance officials must address as global warming accelerates. “Incorporating climate change into ocean management plans aimed at protecting biodiversity, rebuilding overfished stocks, and governing fisheries, including those targeting transboundary [stocks], will be key to effectively respond to the impacts of climate change on marine ecosystems,” Juliano Palacios-Abrantes and colleagues write. Human-driven climate change is altering ocean habitats, forcing fish stocks to adapt and shift in their historic movement patterns. This problem is especially challenging for straddling stocks, which move throughout the high seas and EEZs, the latter of which generally extend 200 nautical miles from a nation’s coastline and grant exclusive sovereign rights to the resources contained therein. Palacios-Abrantes et al. analyzed 6 preexisting observational datasets to map the current distribution of 347 straddling stocks belonging to 67 species, including highly migratory and less mobile ones. They used these data to derive share stock ratios between EEZs and the high seas. The findings showed that straddling stocks dominated EEZs in the temperate North Atlantic, the central Indo-Pacific, and temperate Australasia – with highly mobile tunas and billfishes as the most shared group among regional EEZs. Other mobile and present species included silky sharks, blue sharks, wahoos, skipjack tuna, and yellowfin tuna. Next, the team modeled how stock distributions may shift by 2030 and by 2050. Overall, 123 straddling stocks globally are likely to shift between the high seas and EEZs by 2030 under the most conservative climate emissions scenario, SSP1-2.6. Under SSP1-2.6, 54% of stocks are predicted to shift by 2050. Most straddling stocks are likely to shift in distribution towards the high seas and many across Regional Fisheries Management Organizations, according to the predictions.
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- Science Advances