Searching for accurate and convenient body measurements for estimating the body length and weight of the blue shark (Prionace glauca)

• Published in: Aquaculture Science Vol. 70; no. 2; pp. 169 - 177
• Main Authors: Yamamoto, Atsuya, Shibano, Ayumi, Fujinami, Yuki, Semba, Yasuko, Hiraoka, Yuko, Kanaiwa, Minoru
• Format: Journal Article
• Language: English; Japanese
• Published: Tsu Japanese Society for Aquaculture Science 01.01.2022; Japan Science and Technology Agency
• Subjects: Blue shark; Body length; Body measurements; Conversion factors; Fins; Length frequency; Length-length relationship; Length-weight relationship; Length-weight relationships; Linear regression; Marine fishes; Prionace glauca; Sharks; Stock assessment
• ISSN: 0371-4217; 2185-0194
• DOI: 10.11233/aquaculturesci.70.169

Blue sharks (Prionace glauca) are caught in many countries, but the body measurements data collected vary among countries and institutions. This paper examined if the logarithmic value model or the real value model is more suitable for estimating the body lengths of blue sharks caught in the northwestern Pacific Ocean, using the conversion factors from linear regressions between various body measurements. In addition, we identified suitable body measurements that can be used to estimate body lengths, which is important for stock assessment, based on their accuracy and convenience of measurement. Generally, the linear models using log-transformed numbers outperformed those that used real numbers. We considered the performance of each conversion factor and port sampling situation, and suggested that the pectoral fin anterior margin and length between the prior base from the 1st to 2nd dorsal fins were the optimal body measurements to measure. The findings of the present study can help incorporate the length and weight data of various body measurements and increase the amount of length frequency data available for stock assessments of this species.