Fish Migrating to Cooler Waters Will Affect Economies

A new international study published in Nature Sustainability concludes that nations in the tropics, especially Northwest African nations, are vulnerable to potential species loss due to climate change.

Not only are tropical countries at risk of loss of fish stocks, as fish migrate to cooler waters to maintain their preferred thermal environment, but there are not currently any adequate policy interventions to help mitigate affected countries’ potential losses.
Researchers from the Universities of Delaware, California Santa Barbara and Hokkaido collaborated on the study, which was reported at EurekAlert, the online publication of the American Association for the Advancement of Science.

When researchers looked at international agreements, including the UN Convention on the Law of the Sea, they found no specific text for what happens when fish leave a country’s exclusive economic zone, a zone established to give a country national jurisdiction over a fishery resource. That means countries could be vulnerable to economic losses, and those potential losses could make the fish populations themselves vulnerable as well, the study said.

The researchers used previously projected change in the distribution range of 779 commercial fish species to estimate the number of species exiting national jurisdiction under contrasting emissions scenarios up to 2100.

They said tropical nations in particular stand to lose the most species because there are few if any stocks to replace those leaving. Under a moderate emissions scenario, the research showed that by the year 2100 the average tropical nation could lose 7 percent of the species that were present in 2012.

While the exit of stocks from national fisheries is inevitable, carefully designed international cooperation could ease that impact on individual nations while preserving the resource for others, they said.

Researchers also examined 127 international fisheries agreements, looking at the large, regional ones as well as smaller bilateral agreements. They found none of them have language to prepare countries for the exit of stock, climate change or range shifts.
Traditional fisheries management assumes that fish are a renewable natural resource and that so long as their geographic range is static they will remain plentiful in the absence of overfishing. But with long term migration of a species out of a country due to climate change fish stocks may not always be renewable on the level of a given jurisdiction, even if they remain renewable on an international scale, researchers said.

Policy makers need to think about how those countries could be compensated for loss of fish stocks due to climate change, which might help prevent countries from overfishing stocks before they exit their EEZs, they said. International agreements regarding climate change have mechanisms to consider compensation for losses, and that policy avenue may work better than the scores of fisheries agreements not set up to wrestle with the question at all, they said.