Yangtze River Fishing Ban Shows Fish Biomass More Than Doubling in Four Years

Seventy years of freshwater biodiversity loss is not an easy trend to reverse. The Yangtze River - the longest and most ecologically significant river in China - had been in continuous ecological decline since the 1950s, when rapid industrialization began reshaping the basin. Decades of overfishing, dam construction, pollution, and habitat degradation had depleted fish populations to a fraction of historic levels. Several species were edging toward extinction despite large-scale conservation investments.

In 2021, China enacted a response proportionate to the scale of the problem: a complete 10-year commercial fishing ban across the entire Yangtze basin, backed by the Yangtze River Protection Law and strict enforcement mechanisms. No comparable freshwater fishing prohibition had ever been attempted at this scale anywhere in the world.

A study by Fangyuan Xiong and colleagues, published in Science on February 12, presents the first systematic analysis of what four years of that ban have produced.

Fish biomass more than doubled

The research drew on monitoring data collected from 2018 through 2023, spanning both the period before full ban enforcement and the first two years under it. Researchers examined fish communities across the Yangtze's main channel, measuring biomass, body condition, species diversity, and the presence of threatened and migratory species.

The most striking finding was biomass. Fish biomass more than doubled relative to pre-ban levels - a rapid and substantial increase that reflects relief from the most direct pressure on fish populations. Species richness increased modestly, a more gradual indicator that reflects the slower process of range expansion and population rebuilding by less common species.

The recovery was most pronounced among larger-bodied, higher-trophic-level species. These are the fish most heavily targeted by commercial fishing: slow to mature, slow to reproduce, and therefore most vulnerable to sustained harvest. Their disproportionate response to the ban's removal of fishing pressure is consistent with what population biology predicts and confirms that the ban's effects are reaching the top of the food web.

Porpoise and endangered species rebound

The Yangtze finless porpoise - the last freshwater cetacean in the river after the Yangtze river dolphin was declared functionally extinct - numbered 445 individuals in 2017. By 2022, population surveys counted 595, a gain of 33% in five years. The porpoise's recovery reflects both the direct reduction in boat traffic and entanglement risk from fishing, and the broader improvement in prey availability as fish populations rebuild.

Several endangered fish species also showed initial signs of recovery. The Yangtze sturgeon, Chinese sucker, and tube fish are still rare, but their populations have stabilized or edged upward. The fate of the Chinese sturgeon, Acipenser sinensis, remains uncertain - its population was so reduced before the ban that recovery may require decades and targeted interventions beyond fishing prohibitions alone.

Isolating what drove the change

The Yangtze basin saw multiple concurrent interventions during the study period: reduced commercial vessel traffic, improved riparian vegetation management, and continued water quality monitoring. Attributing biological recovery to the fishing ban specifically - rather than these other factors - required statistical modeling.

Using Generalized Least-Squares-based Structural Equation Models, Xiong and colleagues found that the fishing ban was the primary driver, with vessel traffic reductions, vegetation buffers, and water quality improvements contributing secondarily. "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," the authors write.

What the short timeframe cannot tell us

The authors are explicit about the limits of four years of data. Ecosystem recovery is not a linear process, and the current trajectory may slow as the easiest gains are made and harder challenges - rebuilding populations of long-lived, slow-reproducing species - remain. Climate change, altered hydrological regimes from upstream dams, and ongoing land-use pressure continue to affect the basin. The fishing ban has addressed one major stressor; sustaining the recovery requires addressing the others in parallel.

The ban runs through 2030. Whether the biological gains of its first years persist and compound, or plateau as other stressors dominate, will determine whether the experiment ultimately serves as a model for freshwater restoration elsewhere.