Editor’s note: This article was updated on May 26, 2022, to clarify that the study examined only the potential for fisheries reforms to reduce the effects of climate change on seafood production.
Climate change has done significant harm to the world’s fish populations: Warming ocean waters have reduced fish productivity, killed off their sources of food, and dramatically altered their distributions. These developments have strained seafood production, with humans relying heavily on oceans to meet increasing food demands.
Yet management reforms can help ensure continued and sustainable seafood harvests.
Chris Free, a quantitative ecologist at the University of California Santa Barbara, led a study—published in Nature in April and co-written with Jim Palardy from The Pew Charitable Trusts—intended to identify whether various fisheries and aquaculture reforms could increase seafood production despite climate change. What the team found was promising: that oceans could produce more food through swift and ambitious action that reduces emissions, reforms fisheries, and expands sustainable ocean aquaculture operations.
This interview with Free has been edited for clarity and length.
Millions of people around the world depend on seafood as a source of nutrition and income. Understanding how to help the ocean continue to provide those important services to people during climate change is a really important global challenge for the future.
Seafood generally has a lower environmental footprint than land-based sources of protein. That gets measured in a variety of ways: Seafood can have a lower carbon footprint, lower water demand, and a lower land conversion footprint (the degree to which a natural area is disrupted for food production). Also, seafood represents a healthy alternative to eating some land-based sources of protein; it's rich in omega-3 fatty acids and other critical micronutrients. So increased production of seafood could lead not only to lower environmental impacts, but also to healthier diets.
We look at two sectors of seafood supply in our paper. One is wild capture fisheries—fish and invertebrates that are caught out in the ocean through fishing. The other is ocean aquaculture—fish and shellfish that are farmed. Climate change is affecting wild fisheries by changing their productivity and shifting where fish live out in the ocean. Among other factors, these characteristics determine how much we can sustainably harvest. What we expect to happen is that fisheries will shift toward the poles to track the fishes’ preferred temperatures.
The impacts on ocean aquaculture are somewhat similar. Changing ocean conditions will change where aquaculture will be feasible to operate. And warming waters may also introduce new risks, such as harmful algae blooms that produce toxins that are a threat to people when consumed in high doses.
There’s some cause for optimism, yes. We found that while even the best reforms in wild fisheries management won’t be sufficient to maintain food for people all around the world, expansions in sustainable ocean aquaculture could actually offset those losses and increase the amount of seafood available to everyone on the planet.
Despite climate change. So that’s a really encouraging finding, especially given how we anticipate climate change will impact all other food systems.
We need to end overfishing, which would allow us to gain more catch from currently overfished populations. We need to do this in a way that’s responsive to fish shifting where they live as a result of climate change. That requires data-sharing across international boundaries and sustainable practices across different management jurisdictions.
We need continued technological advancements that reduce the need for fish caught in the wild as feed for farmed fish. That would raise the ceiling on how much farmed fish we can produce. And we also need to see careful site selection and identification of aquaculture species that are suitable for production in water with changing conditions.
Most importantly, however, we need to make sure that the growth of aquaculture is sustainable by working to implement best practices which limit harm to the environment and to other maritime industries. The good news is we find that aquaculture expansion consistent with those best practices is sufficient to maintain seafood availability for a growing population.
Tropical developing countries are expected to be the hardest hit by climate change and among the most vulnerable to climate-driven losses in fisheries productivity. Their populations are among the world’s most dependent on fisheries as a source of food, and they also don't have the same history of data collection and management capacity as places like the U.S. do. Addressing these problems requires a much different set of solutions than the aforementioned reforms, which might include conservation and economic incentives for communities of fishers living in the same area to band together to manage their local fisheries. The solutions might also include investments from foreign governments to help set up the institutions that developing countries need to manage fisheries more sustainably or to develop the skills for conducting aquaculture.
I think the rapid growth that we’ve seen in aquaculture has stirred up a lot of enthusiasm for continuing that growth in a sustainable way and with a reduction in harmful practices. In places like the U.S., where there’s been a lot of precautions surrounding aquaculture development, we’re starting to see government-led strategies for thinking about how to expand aquaculture smartly and sustainably.