Chinese scientist’s marathon quest to prove existence of new species
Chen Xiaoyong has just published research naming a new species of catfish found in the mountains of southwest China after years of painstaking work and arduous expeditions in inhospitable terrain. He spoke to Stephen Chen about his passion for biology and the excitement of scientific discovery
Chen Xiaoyong remembers the thrill when he discovered a fish that later proved to be a new species, even though the memory stretches back more than 14 years.
Then an assistant researcher at the Kunming Institute of Zoology in Yunnan province, Chen was part of a China-US expedition to the Gaoligong, a forbidding mountain range dividing China and northern Myanmar.
After days of trudging through dense forest, he and his colleagues came across a wild stream with water gushing through boulders and small stones slippery with algae.
“I was having a struggle to get a foothold,” Chen said, recalling the moment in 2003 when he spotted the catfish taking a rest, a suction cup on its belly attached firmly to a rock.
The fish’s head and back was grey, it was blunt around the mouth and with a pair of short barbels, or whiskers.
“I knew it could be a new species. It looked different from other catfishes. We were gripped with joy and excitement,” Chen said.
What he did not foresee at the time was that it would take him nearly a decade and a half to gather enough evidence to prove his find.
It involved painstaking investigation spanning continents during a period of rapid environmental change and rising awareness of biodiversity protection in China.
Chen and his colleagues later obtained more samples of the fish in follow-up expeditions.
Some were found and bought from village fishermen casting nets over tributaries of the Salween River, with the specimens included adults and juveniles.
To confirm and name a new species, scientists must show new features not found on specimens described in previous collections. As a result, Chen had to check specimens from the Gaoligong which had previously been sent to fish experts at the California Academy of Sciences in San Francisco for further study.
Western explorers and naturalists collected large numbers of animals and plants during 19th and 20th century along the Salween River, which originates on the Tibetan Plateau and flows all the way to the Andaman Sea in Southeast Asia.
With the help of American colleagues, Chen studied nearly all the related Southeast Asian catfish specimens that could be found, but the work proved difficult.
“The skin had decayed on specimens to something as thin as tissue paper and with muscles contracted or fragmented some labels did not name the exact location of discovery,” he said.
When Chen started his career studying fish as a scientist, the construction of dams in China was at a historical peak. The barriers created along the Yangtze, Yellow and Yarlung Tsangpo (Brahmaputra) rivers led to concerns among environmentalists in China and around the world about the impact they would have on fish populations.
The Salween became the only major river in China without a dam on its main course and Chen was caught in a race with dam builders to study and protect fish species in the region before some disappeared.
“Many fish species in the Salween are unique. They cannot be found anywhere else in the world,” he said.
Over the past decade, he has taken the lead in at least 10 research projects on fish diversity and conservation in southern China and Southeast Asia.
Although the main Salween River still flows freely, nearly all of its tributaries have been dammed and this poses a threat to fish numbers.
“Some species lived in the main river, but laid eggs in tributaries. Now access to tributaries was mostly blocked, they had no place to mate and produce offspring,” Chen said.
Over the years, Chen also continued his work to prove the catfish he found in the Gaoligong Mountains was a new species.
He and colleagues were able to rule out that numerous similar-looking species were the same, but one type of fish they had to check proved more elusive.
The species – Exostoma vinciguerrae – was found across the border in Myanmar, but getting there to look for it would prove difficult.
“We couldn’t just cross the border and go fishing,” said Chen. “There are many militants on the other side [of the border]. Even if we found the fish, we couldn’t ship the specimen out of the country without going through a pile of paperwork,” he said.
Chen finally got his chance two years ago.
As part of China’s “Belt and Road” international trade initiative, the Chinese Academy of Sciences set up the Southeast Asia Biodiversity Research Institute in Myanmar.
The facility had a state-of-the-art laboratory and it organised expeditions for scientists from China and other countries to explore for flora and fauna.
Chen finally found two types of fish he needed to rule out and so confirm that his was a new species. In one, the barbels of the Myanmar fish were significantly longer than the species he found in China.
After the painstaking work, Chen was at long last able to prove his was a new species and he published his findings in the academic journal Zoological Research last month.
Chen and his colleagues named the fish Exostoma gaoligongse, a tribute to the location where it was first found.
“For a biologist, discovering and naming a species is the biggest reward,” said Chen.
“The laboratory work can grow tiresome, field trips are full of hardship and danger, but when we discover something out of the boundary of human knowledge, the excitement will wash out all the pain and agony and the joy will accompany you for a lifetime,” he said.