Trace DNA reveals critically endangered Chinese bahaba in Hong Kong after decade without records
The Chinese bahaba (Bahaba taipingensis), a marine fish species endemic to the Chinese coast and known as the "Panda of the Sea," is critically endangered and one of the few marine fish listed as a first-class ...
The Chinese bahaba (Bahaba taipingensis), a marine fish species endemic to the Chinese coast and known as the "Panda of the Sea," is critically endangered and one of the few marine fish listed as a first-class protected wild animal in China. Collaborative research led by the Division of Science at Lingnan University has developed a cost-effective environmental DNA (eDNA) monitoring qPCR approach specifically designed for the Chinese bahaba.
Using the new technology, researchers detected traces of the species in western Hong Kong SAR waters, marking the first scientific discovery of the fish in the city in more than a decade.
The researchers highlight that the technology enables experts to monitor the species noninvasively and evaluate conservation outcomes without capturing or disturbing rare marine animals, providing important scientific evidence to assist in marine conservation planning in China.
The work has been published on the preprint server bioRxiv.
A vanished fish and a new test
The Chinese bahaba is the largest member of the croaker family found in the South China Sea and can grow up to 2 meters (6.6 feet) in length. It was abundant in the estuarine waters around Tai O, Hong Kong SAR, during the 20th century and known locally as the "Tai O fish." Owing to the medicinal value of its swim bladder, the species has been heavily overfished, resulting in a dramatic decline in its wild population and making it extremely difficult to monitor.
To address this issue, the research team analyzed its mitochondrial genome sequences and developed a highly sensitive genetic identification technology capable of detecting eDNA, including traces from mucus and feces left behind in seawater.
Computational analysis and laboratory validation confirmed that the technology can accurately identify the Chinese bahaba without confusing it with DNA from other fish species, even when only trace amounts of eDNA are present in seawater samples.
Where traces were found
Using this new technology, the research team carried out surveys at 23 sites throughout western Hong Kong SAR waters, including areas near the Mai Po Nature Reserve, the Sha Chau and Lung Kwu Chau Marine Park, The Brothers Marine Park and the Southwest Lantau Marine Park, between January and September 2025.
At each site, three 1-liter seawater samples were collected, resulting in a total of 414 natural seawater samples. Sterile distilled water was also used as a control throughout the sampling and testing process to ensure that the results were not affected by contamination from external DNA.
Analysis showed that eDNA from the Chinese bahaba was detected in seawater samples collected at four survey sites in September 2025: Tai O; Sha Chau and Lung Kwu Chau Marine Park; the Southwest Lantau Marine Park; and Sunny Bay, near The Brothers Marine Park.
Among these, Tai O recorded the highest frequency and concentration of eDNA. This coincides with a stock enhancement release of approximately 1,300 hatchery-reared juvenile Chinese bahaba into the Pearl River Estuary in August 2025, suggesting that some of the released juveniles may have entered western Hong Kong SAR waters.
eDNA's edge over trawling
Jack Ip Chi-ho, assistant professor (Presidential Early Career Scholar) in the Division of Science at Lingnan University, said, "There has been no recorded occurrence of the Chinese bahaba in Hong Kong SAR waters for more than a decade.
"Given the species' extreme rarity, the chance of encountering it through conventional survey methods is exceptionally low, making it difficult to understand its distribution. Reliable advanced monitoring technology is essential for effectively tracking wild populations and evaluating the survival and adaptation of released juveniles in their natural habitats.
"The new detection technology developed by our research team is highly sensitive, and if a fish has passed through an area and left behind even a tiny amount of eDNA, its presence can be accurately determined, enabling researchers to monitor the movement of released fish populations without the need for capture."
Ip added that conventional marine fish surveys rely heavily on trawling or capture methods, which require skilled manpower and substantial financial resources while also damaging seabed habitats and posing a risk to nontarget species.
Ip explained, "The greatest advantage of eDNA technology lies in its noninvasive nature. It enables scientists to confirm the presence of a species without capturing or disturbing individual fish. Researchers simply need to collect seawater samples to conduct large-scale marine surveys within a short period of time, significantly reducing sampling efforts.
"The technology also provides conservation organizations with an effective tool to evaluate the outcomes of juvenile fish release programs. Beyond long-term monitoring of the Chinese bahaba in the Pearl River Estuary and nearby waters, the technology can also be integrated with other eDNA approaches to support biodiversity monitoring and provide valuable reference data for conservation planning across the Guangdong-Hong Kong-Macao Greater Bay Area."
The study was led by Ip, assistant professor (Presidential Early Career Scholar) in the Division of Science (DoS) at Lingnan University, and Junjie Wang of South China Normal University.
Publication details
Yuzhuo Liao et al, Tracing the 'Panda of the Sea': Species-Specific qPCR Assays for eDNA Monitoring of Critically Endangered Bahaba taipingensis in the Pearl River Estuary, bioRxiv (2026). DOI: 10.64898/2026.07.20.739478
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Citation: Trace DNA reveals critically endangered Chinese bahaba in Hong Kong after decade without records (2026, July 23) retrieved 23 July 2026 from https://phys.org/news/2026-07-dna-reveals-critically-endangered-chinese.html
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