An updated checklist of fishes of Dongsha Island, Taiwan, northern South China Sea

Study Extent

Our study used two distinct datasets: occurrence records from the literature on coral and seagrass-associated shallow-water fishes and newly collected occurrence data from deep-water fishes sampled via commercial bottom trawlers. Both datasets represent different ecological settings with distinct sampling techniques. For the former, we reviewed existing literature and validated nomenclatures.

Sampling

Commercial bottom trawlers operated in the waters off Dongsha Island at depths of around 300 to 600 meters (coordinates 18°49' to 20°45'N and 112°46 to 116°15'E). From February to early July each year from 2021 to 2024, we obtained frozen samples from fishermen at Zhengbin fish port in Keelung, Taiwan. These samples mainly consisted of fishes and other invertebrates and weighed approximately 30 kg each. The total samples (n = 198) we processed collectively weighed over 5,000 kg.

Method steps

1. Our samplings were conducted bi-monthly, and selections were made to represent as diverse a range as possible of the catch. These samples were then transferred to our lab and defrosted sequentially. These otoliths were coated with a thin layer of gold using an ion sputter machine (MCM-100P, Sec, South Korea) to enhance the visibility of the sulcus. Additionally, for small-sized otoliths, images were captured using a scanning electron microscope (JSM-7100FLV, Jeol, Japan). Otoliths were archived at the marine paleontology lab, Biodiversity Research Center, Academia Sinica, registered under the code CHLOL.

We updated the new occurrences of 137 species belonging to 90 families, including potentially undescribed species.

1. Chondrichthyes
   rank: class
2. Actinopterygii
   rank: class
3. Myxini
   rank: class
4. Elasmobranchii
   rank: class

Dongsha Island (also known as Dongsha Atoll or Pratas Island) is situated on the northern margin of the South China Sea; it is located at the midpoint between Taiwan, Hong Kong, and Luzon.