China’s largest river in recovery due to 10-year fishing ban

(CN) — The Yangtze River stretches across the southeast quarter of China and is the nation’s longest. It was, up until very recently, one of the most polluted waterways in the world, overtaxed and overfished, leading to biological degradation.

But with a 10-year commercial fishing ban aimed to halt the decline taking effect in 2021, the early results of ecological restoration look promising.

New research published Thursday in the journal Science found some fish populations have doubled, and several endangered species have rebounded — including the critically endangered freshwater Yangtze finless porpoise, whose numbers dipped down from approximately 1,200 porpoises twenty years ago to just 445 in 2017, researchers say.

“The implementation of the 10-year full fishing ban in 2021 has turned the Yangtze River into an ideal natural laboratory to test the effectiveness of this large-scale river restoration on biodiversity recovery,” scientists say.

Researchers at the Institute of Hydrobiology at the Chinese Academy of Sciences in Wuhan report the unprecedented ban with strict enforcement is proving essential to the health of riparian and aquatic habitats of the region.

Since the 1950s, China’s freshwater biodiversity has been in decline, due to the erosion of its water quality. Rapid and widespread commercial fishing, with few regulations, and mass pollution are also responsible for the decreasing populations.

Some species have not survived to see the rebound, including the Yangtze River dolphin, or baiji, which went extinct in 2002, and the Chinese paddlefish, a large ray-finned fish similar to a swordfish, that was last seen in 2003.

The study assessed the biodiversity before the ban, from 2018 to 2020, and three years into the ban 2021 to 2023, from collected data at 57 river sites.

Not only did the absence of fishing relieve the pressure on the ecosystem, it allowed for improved water quality, due to fewer vessels in water, and less disturbance in fish nurseries, according to researchers.

“The results reported in this study … provide hope that in an era of global biodiversity decline, ambitious political decisions that support large-scale restoration efforts can help reverse the ecosystem damages of the past and lead to a brighter future,” lead author and researcher at the Chinese Academy of Sciences Fangyuan Xiong and her team said.

The researchers are cautiously optimistic and said the ban and restoration plan could be replicated for other rivers in need of recovery, such as the Mekong River — which flows through China, Laos, Thailand, Cambodia and Vietnam — and the world’s largest river, the Amazon.  

The authors said it remains to be seen what will happen when commercial fishing is allowed after the ban lifts.

“We also caution that this progress could easily be reversed by reinitiating commercial fishing operations or in response to continuing stressors that compromise habitat condition, connectivity, water quality, and the flow regimes upon which fish species depend,” they said.  “The 10-year full fishing ban provides a hopeful example of the potential effectiveness of large-scale biodiversity conservation to meet the goals of the United Nations Decade on Ecosystem Restoration.”

But, the authors noted, while commercial fishing plays a large role in river’s health, it isn’t the only issue, citing other human-made problems that effect the river’s recovery.

“Despite the trajectory toward initial biodiversity recovery, the future of the Yangtze River biodiversity remains uncertain and sensitive to emerging threats, such as changes in water management and dam infrastructure, which are imminent with mounting pressures associated with ongoing climate change.”