Exploitation rate of cutlassfish (Trichiurus japonicus) in the waters around Taiwan

Chih-Yu Lin ； Wen-Qi Xu ； Sheng-Ping Wang

《臺灣水產學會刊》 49卷1期_特刊 (2022/03) Pp. 23-31

https://doi.org/10.29822/JFST.202203/SP_49(1).0003

摘要

Trichiurus japonicus is one of the economically important fish species in offshore and coastal fisheries around Taiwan. Due to the absence of reliable and long-term catch statistics for the Trichiurus fishery in the waters around Taiwan, conventional stock assessment approaches cannot be used to assess the stock. In this study, we estimate mortality rates based on a large amount of catch-to-size data and evaluated the exploitation of T. japonicas in the waters around Taiwan. The length data for T. japonicas were collected by observers of Taiwanese coastal and offshore fisheries from 2019 to 2021. In addition, the lengths of the catches were also measured through photos using scientific software to increase the sample size of the length data. The results showed that natural mortality (M) ranged from 0.176 to 0.410 year^(-1), total mortality (Z) ranged from 0.569 to 1.430 year^(-1) and fishing mortality (F) ranged from 0.159 to 1.254 year^(-1). Based on estimated mortality values, the current exploitation rate (E) of T. japonicas ranged from 0.4 to 0.8, indicating that the stock was at an optimal higher level of exploitation.

關鍵字

Trichiurus japonicus ； natural mortality ； fishing mortality ； total mortality ； exploitation rate