China has banned all fishing to save the Yangtze River. This “nuclear” option appears to be working.

China’s Yangtze River has shown signs of recovery since a 10-year commercial fishing ban was introduced in 2021. The number of large fish is increasing and endangered animals such as the Yangtze sturgeon (Sinosturia dabryanus) and the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) are also recovering, a new study finds.

“These results show that restoring biodiversity requires strong political decisions,” Sébastien Bross, an ecologist at the University of Toulouse in France and co-author of the new study, told LiveScience in an email. “This is a reassuring message, as biodiversity loss is often considered irreversible.” The Yangtze River is China’s longest and largest river. Approximately 30% of China’s population lives within the basin, and the 11 provinces and municipalities that make up the Yangtze River Economic Belt generate approximately 47% of China’s total gross domestic product.

But rapid urban development since the 1950s, the construction of dams, and decades of overfishing, pollution, and habitat degradation have all contributed to declining water quality and a biodiversity crisis. The Yangtze River dolphin (Lipotes vexillifer) and the bluefin fish (Psephurus gladius) have become extinct, and 135 species of fish found in historical surveys have disappeared.

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This decline continued despite more than $300 billion in investments in establishing protected area networks and water quality management and improvement. In response, China took drastic measures. The country imposed a 10-year fishing ban across the Yangtze River basin in 2021, used river police to impose tough penalties, and continued extensive environmental controls.

To assess the impact of the fishing ban, Yushun Chen, an aquatic biologist at the Chinese Academy of Sciences in Wuhan, China, and colleagues used data from 2018 to 2023 to assess the health of fish communities in the Yangtze River before and after the ban went into effect.

They found that, overall, the total mass of fish collected in the samples more than doubled between these dates, and the number of species in the samples increased by 13%.

Although the overall number of fish remained about the same, larger fish species higher up the food web, such as the economically valuable black-eared mulefish (Megalobrama terminis) and white-faced mulefish (Parabramis pekinensis), increased and contributed more biomass. However, the total mass of small species sampled decreased by 18%.

The team’s findings, published in the journal Science on Thursday, February 12, also included positive signs for migratory birds and endangered species. For example, the population of narrow-tongued flounder (Cynoglossus gracilis) increased after the ban, and its freshwater migration expanded further upstream. Endangered fish species such as the sturgeon, Chinese sturgeon (Myxocyprinus asiaticus) and tubefish (Ochetobius elongatus) are also showing signs of recovery.

Another notable positive was the increase in the number of the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), the only remaining freshwater mammal in the Yangtze, whose population increased by one-third from 445 in 2017 to 595 in 2022. This increase may be the result of larger fish becoming available for consumption. Reduced deaths related to vessel collisions and fishing bycatch. And the researchers also suggested a reduction in other stressors, such as underwater noise from ship propellers.

“At a time of unprecedented biodiversity loss and decline, especially in freshwater systems, this study offers a glimpse of hope for the future of biodiversity,” said Lise Conte, a conservation ecologist at California-based Conservation Science Partners.

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“This shows that bold conservation and restoration strategies can be effective in slowing and even reversing human impacts on ecological communities,” she told Live Science via email.

Chen and his colleagues are still monitoring biodiversity in the Yangtze River, and said recovery is continuing. But they warned that this progress could easily be reversed if commercial fishing resumed, and that sustainable recovery of biodiversity would depend on sustainable management that addresses all human pressures on river systems.

They also suggested that similar conservation measures could help rivers such as the Mekong and Amazon.

However, the Yangtze fishing ban came at significant human and financial costs, as it included the recall of 111,000 fishing vessels, the relocation of 231,000 fishermen, and more than $2.74 billion in investments in the Yangtze River Economic Belt.

“The promising findings demonstrate the resilience of these systems, but they are also a case study for an approach that we hope does not need to be replicated elsewhere,” co-author Stephen Cook, a professor of biology at Carleton University in Ottawa, Canada, told Live Science in an email. “Closing all fisheries in a river basin has significant socio-economic implications. Fishermen and those working in related industries often relocate, forever changing their communities. It is always preferable to manage fisheries in a way that does not require such ‘nuclear’ options.”

A better approach involves continually assessing fish populations. Science-based fisheries management. He also added the study of watersheds as integrated systems that connect people, water, and fish.