Length–weight relationships of 17 noncommercial fish species (Actinopterygii) sampled through bottom trawling in the waters of southwestern Taiwan

Although noncommercial species are generally smaller in body size, they hold considerable ecological value. Because they are often discarded at sea or cannot be collected, basic data on their biological features remain limited. In this study, we explored the length–weight relationships of 17 noncommercial fish species sampled through bottom trawling (16 trawling hauls) in the waters of southwestern Taiwan between 2019 and 2023. Sampling was performed using a bottom trawl with a net opening height of 2.5 m and a width of 30 m; the codend mesh size was 2 × 2 cm. Fork length and body weight measurements were obtained from randomly selected subsamples of the total catch. Twelve species exhibited isometric growth: Ariosoma dolichopterum Karmovskaya, 2015, Crossorhombus kanekonis (Tanaka, 1918), Suezichthys gracilis (Steindachner et Döderlein, 1887), Jaydia truncata (Bleeker, 1855), Lepidotrigla punctipectoralis Fowler, 1938, Ophidion asiro (Jordan et Fowler, 1902), Ostorhinchus kiensis (Jordan et Snyder, 1901), Parapercis sexfasciata (Temminck et Schlegel, 1843), Rogadius asper (Cuvier, 1829), Synodus binotatus Schultz, 1953, Synodus fuscus Tanaka, 1917, and Synodus taiwanensis Chen, Ho et Shao, 2007. Four species exhibited positive allometry— Bleekeria mitsukurii Jordan et Evermann, 1902, Gonorynchus abbreviatus Temminck et Schlegel, 1846, Synodus tectus Cressey, 1981, and Trachinocephalus trachinus (Temminck et Schlegel, 1846), whereas one species exhibited negative allometry— Ratabulus megacephalus (Tanaka, 1917). Overall, this study provides updated insights into the length–weight relationships of data-poor fish species. Our findings may guide studies determining resource status and investigating ecological dynamics in marine ecosystems.