ROME, Italy (Thomson Reuters Foundation) — Fish farmers in China have been increasingly harvesting wild stocks to feed their caged varieties, which is putting new strains on the world’s oceans, said new research from scientists at Stanford University.
China is the world’s largest producer and consumer of fish, contributing about one-third of the global supply.
Its production has tripled in the last 20 years, with about 75 percent coming from fish farms, according to a study published in the journal Science.
It said aquaculture could become more sustainable if the industry fed farmed fish with more waste from caught fish, along with plant proteins such as algae and ethanol yeast.
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“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,” said Ling Cao of Stanford’s Center on Food Security and the Environment.
“If not, the consequences for the entire global seafood supply chain are going to be really serious.”
Global fish farming has been growing by five to eight percent a year for the last two decades, said Jogeir Toppe of the UN’s Food and Agriculture Organization.
He expects the rapid growth to continue as catches of wild fish plateau and demand increases.
“China has been the main driver of this growth,” Toppe said.
“This is expected to continue.”
Toppe said the fast growth comes with concerns over environmental sustainability and human health because farmed fish are often fed large amounts of antibiotics and other chemicals.
Aquaculture companies in China have made progress in reducing the amount of wild fish fed to captured stock by using waste from other processing plants or algae, the study said.
However, farms often use “trash fish,” which are less valuable, small breeds caught in the wild, to feed bigger, more expensive varieties such as carp or tilapia.
Waste byproducts from seafood processing plants are often discarded or dumped into nearby waterways.
