Length–weight relations of underutilized nine fish species (Actinopterygii) from set-net fishery, Mie, Japan

Abstract

Bycatch, the unintentional capture of non-target species, poses a significant challenge in fisheries management worldwide. Underutilized bycatch species often lack biological information, hindering the assessment of their stock status and the implementation of appropriate management strategies. This study investigated the length–weight relations (LWRs) of 9 of 14 underutilized bycatch fish species collected from set-net fisheries in Nishiki, Mie Prefecture, Japan, during the 2018–2020 fishing seasons. The following fish species were studied: Hyperoglyphe japonica (Döderlein, 1884); Labracoglossa argenteiventris Peters, 1866; Macroramphosus sagifue Jordan et Starks, 1902; Microcanthus strigatus (Cuvier, 1831); Ostorhinchus semilineatus (Temminck et Schlegel, 1843); Parapriacanthus ransonneti Steindachner, 1870; Rexea prometheoides (Bleeker, 1856); Siganus fuscescens (Houttuyn, 1782); Upeneus japonicus (Houttuyn, 1782). A total of 251 fishing operations were conducted, and the collected fish specimens were measured for length (fork length) and wet weight. Simple regression analysis was performed on the logarithm of length and weight data to estimate the LWR parameters (a, b, and R2) for each species. The estimated values of the relative growth coefficient (b) ranged from 2.862 to 3.311, and the coefficients of determination (R2) were above 0.8 for all species, indicating robust LWR estimations. Notably, five species were not previously listed or credibly described in FishBase, and four were new records for the Japanese coast. This study provides new biological information on LWRs for underutilized bycatch fish species, contributing to our understanding of their population dynamics and supporting future management efforts for sustainable fisheries and biodiversity conservation.