Chinese aquaculture can tip the balance in world fish supplies

China's booming aquaculture industry relies increasingly on fishmeal made from wild-caught fish. This practice risks depleting wild fish stocks and strains fragile ocean ecosystems, but a new FSE-led study offers a more sustainable path.

In a new paper in Science, a research team led by Stanford postdoctoral scholar Ling Cao and professor Rosamond Naylor offers the clearest picture to date of China’s enormous impact on wild fisheries. The study also presents a more sustainable alternative to the current practice of using wild-caught fish to feed farm-raised fish.

China is the world's leading producer, consumer and processor of fish, contributing one-third of the global supply. China’s fish production has tripled in the past 20 years, and about three-quarters of its supply now comes from fish farms. Yet the industry still places huge pressure on wild fisheries through its demand for fishmeal and fish oil made from wild-caught species. How China develops its aquaculture and aquafeeds sector can thus tip the balance of global seafood availability.

“There is a clear opportunity for positive change, but the economic and regulatory incentives for such change are not yet in place,” said Naylor, the William Wrigley Professor in Earth Science at Stanford University and director of the Center on Food Security and the Environment.

Fishing in the coastal waters of China is poorly-regulated and often indiscriminant. The result is large volumes of assorted “trash fish” – species that are undesirable for human consumption - that end up in animal feeds, including in fishmeal that is fed to farm-raised fish. Many of the species of wild fish used for feeds have been fully exploited or overexploited, and reducing their demand can help protect fragile ocean ecosystems.

One promising solution is to recycle the waste by-products from seafood processing plants across China. This waste, which can be 30-70% of the incoming volume of fish, is often discarded or discharged into nearby waters.

The team’s analysis shows that these processing wastes could satisfy between half and two-thirds of the current volume of fishmeal used by Chinese fish farmers, replacing much of the wild fish currently used in feeds.

Quality and food safety are two potential barriers to replacing wild-caught fish with fish processing wastes. The waste is lower in protein than wild-caught fish, but this can be overcome by adding plant-based protein sources to the fishmeal, like algae or ethanol yeast. The use of processing waste also raises concerns about contamination and disease transmission, which the researchers say can be addressed through better research on the safety risks, and through tighter regulations.

"It's time to make serious decisions about managing and protecting ocean fisheries, and China will play a pivotal role in this process," said Naylor. “Collecting good data from China is an important starting point. But we also need a clear path toward more sustainable fisheries and aquaculture management, and that’s what we present in this paper.”

"This is a critical juncture for China," said lead author Ling Cao, a postdoctoral scholar at the Center on Food Security and the Environment at Stanford University. "If the country makes proactive reforms to its aquaculture sector, like using fish processing wastes instead of wild fish, and generally reducing the amount of fishmeal in aquafeeds, it can greatly improve the sustainability of the industry. If not, the consequences for the entire global seafood supply chain are going to be really serious."

The team’s research was supported by funding from the Lenfest Ocean Program of The Pew Charitable Trusts, the China Fund of the Freeman Spogli Institute for International Studies at Stanford University, the EU-FP7 Sustaining Ethical Aquaculture Trade (SEAT) project and the David and Lucile Packard Foundation.

This research, led by Ling Cao and Rosamond Naylor at Stanford University, was supported by a consortium of researchers from around the world, including Patrik Henriksson of Leiden University, the Netherlands; Duncan Leadbitter of the University of Wollongong, Australia; Wenbo Zhang of the University of Stirling, Scotland; Max Troell of Stockholm University; and Marc Metian of Stockholm University.

Laura Seaman is Communications and External Relations Manager for the Center on Food Security and the Environment, a joint effort of the Freeman Spogli Institute for International Studies and the Stanford Woods Institute for the Environment.

Contact:

Rosamond Naylor: roz@stanford.edu

Ling Cao: caoling@stanford.edu

Special Notes to Reporters:

More information, including a copy of the paper, can be found online at the Science press package at http://www.eurekalert.org/jrnls/sci. You will need your user ID and password to access this information. 

Several co-authors are available to give interviews in languages other than English. These include Mandarin, French, Dutch and Swedish. Press releases are also available in these languages. Please contact Laura Seaman at lseaman@stanford.edu.