Using daily growth increments in otoliths to age juvenile fourfinger threadfin (Eleutheronema rhadinum) in waters off western Taiwan

• Main Authors: Lu, Yi-Sin, 呂繹昕
• Other Authors: Su, Nan-Jay
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/b97rsa

碩士 === 國立臺灣海洋大學 === 環境生物與漁業科學學系 === 105 === Daily growth increments in otoliths were used to age juveniles of East Asian fourfinger threadfin, Eleutheronema rhadinum, in waters off western Taiwan. A total of 915 samples with fork length (FL) ranging from 11.5 to 80.0 cm and body weight from 29 to 8100 g were collected at fishing ports in Yunlin, Taichung, Miaoli and New Taipei during January 2015 to December 2016 in this study. There is no significant difference in the relationship of body weight and fork length between sexes. Daily periodicity of microincrement formation in otoliths was further validated based on studies for E. tetradactylum. Results indicated that daily increments could be used as age determination tools for fish smaller than 50 cm in FL. The East Asian fourfinger threadfin were aged from 87 to 326 days in this study, with a reading precision of 2.36% in average percent error (APE) and 3.16% in coefficients of variation (CV). The growth of the East Asian fourfinger threadfin juveniles can be best described using a linear function of length (FL) = 58.097 × Age (t). As a fast growing species, fourfinger threadfin juveniles can reach more than 50 cm in FL, with daily growth rates consistent among individuals. The relationship between daily age and otolith radius (OR): Daily age = 39.258 OR + 16.261 could be considered a convenient approach to age juvenile fourfinger threadfin in waters off western Taiwan as suggested in this study.