The First Record of the Non-Native West African Lungfish, Protopterus annectens (Owen, 1839), in Poyang Lake, China

Fish sampling in Poyang Lake was conducted quarterly between January 2010 to October 2019. We implemented 40 surveys in Poyang Lake using dip nets (0.5 m in diameter, mesh size 1 mm), gill nets (20 × 10 m, mesh-size 5 mm) and electroshocking (CWB-2000 P, 12V, 250 Hz). In wetlands, fish sampled by two individuals using a dip net about 15 min. In lake periphery and bays, fish sampled by gillnet with about 12 h (from 18:00 to 6:00). In wetlands and lake periphery, fish sampled by electroshock fishing techniques about 15 min. For a detailed description of our sampling methods see Xiong et al. (2015b, 2017b). The fish sampled were identified according to morphology, and West African lungfish were identified with Kottelat et al. (1993) and Lerssutthichawal (2005). We caught a small patch of pectoral fin and stored in 95% alcohol, mitochondrial COI genes were sequenced in two individuals of fish sample specimens collected from Poyang Lake and base pairs were collected, molecular sequencing (COI) were conducted in laboratory (Valdez-Moreno et al., 2009).

Two West African lungfish were collected in Poyang county (N28.925457, E116.382135). It has an elongate body, filamentous paired fins, and external gills located behind the gill slits and above the pectoral fins (Fig. 1). The morphometric and meristic characteristics of our specimens are shown in Table I. The molecular sequences were checked and matched 100% on NCBI database (Fig. 2).

TL, total length; SL, standard length; BW, body weight.

This collection is the first record of the species in a natural environment in China. During our survey in 2018 and 2019, about twenty individuals (about 500mm total length) of this species were observed in the weedy littoral areas of the lake preying on small endemic and endangered fishes, such as Pseudorasbora elongata, Luciobrama macrocephalus and Oryzias latipes, whish were listed in the China Species Red List (Wang and Xie, 2004). Frequent catches (one to four individuals catght in a month) of West African lungfish (about 20-700 mm total length) in Poyang Lake were mentioned by some local fishermen in the past three years (personal communication with local fisherman).

Some researchers have investigated fish biodiversity in Poyang Lake, the West African lungfish was not reported from Poyang Lake until 2015 (Huang et al., 2013; Zeng, 2014). This non-native fish was likely introduced between 2015 and 2019, and could potentially establish a feral population in Poyang Lake.

China is threatened by aquatic non-native species, with a great number of non-native fishes introduced for use in the ornamental fish trade (Xiong et al., 2015a, 2017a; Wang et al., 2016). No-native species are one of the greatest threats to Chinese freshwater biodiversity (Xiong et al., 2018b, 2019), particularly in the Yangtze River watershed.

Although West African lungfish have been introduced into China for many years in the ornamental fish trade (Xiong et al., 2015a), there have been no previous reports of its having escaped and established populations elsewhere in China (Xiong et al., 2015a). Recently, we observed this species being sold in some aquarium stores of big cities around Poyang Lake such as Nanchang and Jiujiang. Non-native ornamental fish often dive in sewage pipes and eventually escape into natural waterbodies by uninternationally escaped (Bueno et al., 2021). Thus, this study is the first record that West African lungfish occurred in the wild environment of China.

The Poyang Lake is an important region of Chinese freshwater fish biodiversity (Huang et al., 2013), including over 200 fish species, of which 131 are endemic (Huang et al., 2013). Many native fishes are threatened by the loss of wetland habitat caused by some large water conservancy projects (such as the Three Gorges Dam, the Gezhou Dam), drought, and global warming (Mei et al., 2015; Liu et al., 2020). West African lungfish can survive for long periods in dry environments by encasing their bodies in a thin layer of slime (Okeyo, 1998), which possibly enables the species to survive and successfully invade in the drought-prone environment of the Poyang Lake (Okeyo, 1998). West African lungfish prey on small fish, crustaceans, insects, mollusks and plants (Dankwa et al., 1999). In field investigations, we observed that West African lungfish are active predators on native locally endangered fish, such as Oryzias latipes (Wang and Xie, 2004). Therefore, we appeal to local government, fishermen and environmental protection organizations to work together to mitigate the potential risk of West African lungfish.

Special thanks to three anonymous reviewers whose comments greatly improved the manuscript. Thanks are also due to Professor Peter A Bowler who improved our manuscript.

This research was supported by the project (LFBC1004) of Key Lab of Freshwater Biodiversity Conservation Ministry of Agriculture and Rural Affairs of China,Yangtze River Fisheries Research Institute and the project ‘The investigation and protection research on the resources and spawning grounds of Coilia nasus in the Poyang Lake of Jiujiang City.

The Tab of Animal Experimental Ethical Inspection of Laboratory Animal Centre, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences approved the study.

This research was conducted in accordance with ethics committee procedures of animal experiments.

All necessary permits for sampling and observational field studies have been obtained by the authors from the competent authorities and are mentioned in the acknowledgements, if applicable.

All data generated or analyzed during this study are included in this article.

The authors have declared no conflict of interest.