Scientists turn to the most unusual source to study endangered Yangtze Porpoise — ancient Chinese poems

Mysteries and folklore about ancient creatures are what tie generations together. The tales that echoed in the ears of our forefathers are passed down to us generation after generation. However, some stories and their elements get lost in translation — from ancient mystical creatures like dragons to scientifically proven ones like dinosaurs, we know too little about what is already gone. The Yangtze Porpoise is one such being. A report by Scientific American talks about the study of this rare creature, but the source of this information is not what you might have expected.

The Yangtze Porpoise is an endangered subspecies found specifically in China. It is the only freshwater porpoise in the world whose existence is limited to the Yangtze River — also known as the Chang Jiang — located in China. Due to its rapid decline, scientists are now researching their existence and history. At one point, the river used to brim with these creatures, whose numbers are now limited to only 1,250. A video posted by New China TV on YouTube will give you a better insight into the story. 

Around 1765, a Chinese emperor and poet, named Qianlong, was sailing on the Yangtze River, heading towards the eastern city of Zhenjiang. He was dumbstruck by what he saw next: a group of Yangtze finless porpoises (Neophocaena asiaeorientalis), surfacing from the river. The beautiful sight inspired him to write a poem, which was later published in the “Imperial Collection of Poems, Volume II.” It read, “Porpoises chased moonlight on silvered tides, as dragons summoned storm-clouds loom in sight.” As surprising as it may sound, 300 years later, the poems form the fundamental data that scientists are referring to when studying the Yangtze porpoise. An article published by Current Biology shared that 724 poems mentioned the subspecies, and some of them even helped scientists understand where the species had been spotted in the past. In-depth research has revealed that their population has declined by about 65 percent over 1,400 years, with a more rapid decline in the last century. Their existence was also marked in the tributaries and adjoining lakes, which has now declined by about 91 percent.

“Having access to past data allows us to detect when declines began and correlate those changes with potential threats like habitat destruction, climate change, overhunting, disease or the introduction of invasive species,” says Yaoyao Zhang, an ecologist at the Institute of Hydrobiology, Chinese Academy of Sciences. “We searched for various historical names of the Yangtze finless porpoise across dynastic poetry, manually verifying each mention to ensure it referred to the porpoise and no other animals.” She adds, “The poets vividly described the actual behaviors of the porpoises [using language] such as ‘blowing waves...,’ ‘surging waves…,’ and ‘bowing to the wind.’”

Jens-Christian Svenning, a macroecologist at Aarhus University in Denmark, says that the study “builds on many prior examples on how historical texts of various kinds can help understand past species distributions and human-caused biodiversity losses.” Zhang and her coworkers will further refer to the poems to study “what the river looked like in the past, how big the groups of porpoises used to be, and how they might have behaved before their numbers dwindled.”