2.1 Sample collection
A total of 300 specimens of L. spadiceus were obtained from eight geographic locations, including Beihai (BH), Zhanjiang (ZJ), Leizhou (LZ), Danzhou (DZ), Dongfang (DF), Maoming (MM), Shanwei (SW), and Zhangzhou (ZZ) in the South China Sea (Figure 1, Table 1). All L. spadiceus Specimens were collected from bottom trawl surveys within the period of April 2022 to April 2023. A morphological analysis was used to identify species (head, dorsal surface, and ventral surface are covered with small spines, the dorsal side of the body is brownish-yellow or yellow-green, caudal fin is white at the upper and lower tips) (Liu et al., 2016; Chen & Zhang, 2015). Fishes were given access to muscle tissue, which were then stored in 1.5 ml vials with 95% ethanol at -20°C until genomic extraction. Experimental procedures concerning fish were performed following the Experimental Animal Administration Regulations.