How climate change could derail fish farmers

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Aquaculture, the cultivation of fish and other aquatic species, is the world’s fastest growing food sector, but preparing for climate change is vital for future generations of aquafarmers to succeed, according to new research.

The study explores how climate change could affect marine aquaculture production, specifically of finfish and bivalves (such as oysters), around the world. The findings reveal that climate change is not only a threat to global production in the future, but affects producers today.

“Climate change is impacting marine aquatic farmers now, and it’s likely to get worse for most of the world if we don’t take mitigating measures,” says Halley Froehlich, a postdoctoral researcher at the National Center for Ecological Analysis and Synthesis at the University of California, Santa Barbara and lead author of the paper, which appears in Nature Ecology & Evolution.

The new analysis reports an important and previously missing piece of the puzzle in understanding how climate change will affect the future of global food security and provides an essential first step toward helping ocean farmers and coastal countries prepare for the coming changes to ensure sustainable seafood production worldwide.

Winners and losers

According to the newest State of World Fisheries and Aquaculture report by the United Nations’ Food and Agriculture Organization (FAO), aquaculture’s contribution to global seafood production now surpasses that of wild-caught fisheries. The sector is gaining increasing attention globally as important for achieving not just food security but also sustainable development goals.

“There’s a lot of push for ‘blue growth’ in aquaculture in both developing and developed regions, but less effort has gone into how to develop adaptive measures under climate change, mostly because we do not have a good sense of the level or location of impacts,” Froehlich says. “Our study begins to shed light on these unknowns.”

Coastal countries should expect their overall potential for aquaculture production to decline over time, as water temperatures rise and oceans undergo other shifts due to a changing climate, the researchers found.

What’s more, the region that currently accounts for 90 percent of the world’s total production—Indo-Pacific countries such as China, Bangladesh, and Indonesia—will likely feel the biggest impacts. Without intervention, by midcentury declines in finfish could be as high as 30 percent in some areas, and there is even the risk of a complete loss of suitable waters for bivalves.

Such declines would harm not only the global availability of farmed seafood but also the lives of Indo-Pacific people, who depend more heavily on seafood for sustenance and farming for livelihoods than the rest of the world.

“Climate change will likely have highly inequitable consequences among ocean farmers.”

“The issue is less about whether or not we will be able to grow enough fish in the ocean under a changing climate globally—we can—and instead about who wins and who loses, and by how much,” says coauthor Ben Halpern, director of NCEAS and a professor at UCSB. “Climate change will likely have highly inequitable consequences among ocean farmers.”

There will be some “winning” patches of ocean, however, where aquaculture production could fare well or better under climate change. For example, rising water temperatures will make sub-polar waters, such as those near Norway, hospitable for finfish farming.

Even so, there are no absolute winners or losers among countries that are farming or could farm the ocean, according to the study. Rather, production levels worldwide will be patchy due to variable ocean conditions, even within the same country.

Shifting conditions

The authors looked specifically at three ocean scenarios that are among the most important for supporting aquaculture production: warming sea surface temperatures, ocean acidification, and changes in algae, a primary food source for oysters and other bivalves.

The patchiness in future production potential will matter when it comes to preparing ocean farmers for climate change or mitigating its impacts—and is part of what gives Froehlich hope.

One strategy to help ocean farmers adapt will be to move or place farms in more favorable ocean patches, a measure the FAO highlighted in another recent report. Good planning now could help marine aquaculture adapt to the changing conditions while enabling ocean planners to balance aquatic farming with the many other uses of oceans, such as wind energy and conservation, Froelich says.

“The industry is still in its growing phase, and that allows some flexibility,” she says.

This flexibility is particularly advantageous for countries with large Exclusive Economic Zones (EEZs), such as the United States or Australia, since having more ocean space to move farms could alleviate much of the threat. Already, there are reports of salmon farmers in Australia relocating their pens because waters are getting too warm, and US oyster farmers are moving their hatcheries away from the acidified waters of the Pacific Northwest.

“If you were a land farmer, would you want to buy property that will be plagued by drought in 15 years?”

“Aquatic farmers are on the frontlines of climate change. Some are already seeing the effects and know they need to be prepared for what’s to come. But that’s going to take planning by not only the farmers, but governments, too,” Froehlich says.

While countries with more winning patches may be able to pick up the slack where others fall short, local planning will be essential to support small-scale farmers, the current majority of producers, who lease ocean plots or specialize in a particular species, as it may be harder for them to move their farms or switch species.

The new findings offer a blueprint for long-term planning for ocean farming, Halpern says.

“Governments provide permits and leases for growing different species, and setting those locations now with the future in mind will help avoid putting things in riskier places. If you were a land farmer, would you want to buy property that will be plagued by drought in 15 years? I doubt it. The same thinking should be applied to ocean farming.”

The Zegar Family Foundation supported the study.

Source: UC Santa Barbara