The Yangtze Finless Porpoise (Neophocaena asiaeorientalis) is a freshwater cetacean known as the “smiling angel” due to its visible grin and lack of a dorsal fin. Endemic to the middle and lower reaches of the Yangtze River, this mammal indicates the ecosystem’s health. Following the extinction of the Baiji dolphin, the porpoise became the river’s last surviving cetacean, facing a population crisis that prompted major conservation efforts.
Defining the Yangtze Finless Porpoise and Its Home
The Yangtze Finless Porpoise is the only porpoise species that lives exclusively in freshwater habitats, distinguishing it from its marine relatives. Instead of a dorsal fin, it possesses a low, narrow ridge along its back, covered in rows of tiny structures called tubercles. This trait, along with its steep forehead and lack of a beak, contributes to its streamlined appearance in the turbid river environment.
Porpoises rely on high-frequency echolocation clicks to navigate and hunt fish, shrimp, and cephalopods in the murky water. Their habitat is restricted to the main channel of the Yangtze River and its two largest connecting lakes, Poyang and Dongting. This limited geographical range makes the population vulnerable to localized threats.
The Critical Causes of Population Collapse
The decline was driven by human activity that fundamentally altered the river system. Habitat fragmentation from infrastructure projects, such as dams and sluice gates, isolated porpoise groups and cut off access to feeding and breeding grounds. These barriers also disrupted the natural flow and sediment patterns of the river, degrading the habitat structure.
Commercial vessel traffic led to direct mortality and acoustic stress. Porpoises were frequently struck by propellers, and constant underwater noise pollution interfered with their echolocation system, impairing their ability to navigate, communicate, and locate prey. This acoustic interference reduced the functional size of their habitat.
Environmental degradation compounded these issues, notably from industrial discharge and agricultural runoff introducing pollutants. Chemical contamination impacts the porpoises’ health and reproductive success while also reducing prey abundance. Accidental entanglement in fishing gear, particularly gillnets, was a major cause of accidental death, known as bycatch.
Conservation and Recovery Methods
Conservationists developed a multi-pronged strategy to safeguard the species. A cornerstone was the establishment of ex-situ conservation reserves, such as the Tian’e-zhou Oxbow Nature Reserve. Relocating porpoises to these protected oxbow lakes created a secure environment for a self-sustaining population, shielded from the threats of the main river channel.
A significant regulatory action was the implementation of a 10-year fishing moratorium across the Yangtze River and its connecting lakes, beginning in January 2021. This measure aimed to reduce accidental mortality from fishing gear and allow fish stocks, the porpoises’ primary food source, to recover. The fishing ban was supported by programs offering alternative livelihoods and compensation to former fishers.
Conservation efforts also focused on habitat restoration, including reconnecting floodplain lakes with the main river to improve water flow and expand foraging area. Strict controls were placed on sand mining and dredging operations, which had previously destabilized the riverbed and destroyed porpoise habitats. Technological monitoring, such as passive acoustic surveillance, was deployed to track porpoise movements and understand their distribution, guiding protection efforts.
Current Population Trends and Long-Term Goals
Conservation efforts have yielded positive results, evidenced by recent population assessments. A census conducted in 2022 estimated the total population at 1,249 individuals, marking an increase of 23.42 percent from the 2017 estimate of 1,012. This rebound suggests that protective measures, especially the fishing moratorium and the success of the oxbow reserves, are stabilizing the population trend.
The long-term strategy centers on achieving a self-sustaining population that can thrive in the main river system without constant intervention. Conservationists aim to increase the population, including a target to double the number of porpoises in key protected areas by 2030. Securing the future of the Yangtze Finless Porpoise requires maintaining the health of the entire river ecosystem, ensuring the main channel and its connected lakes remain habitable, pollution-free, and acoustically undisturbed.