Studies on the reproductive biology of Auxis thazard in the waters off Taiwan

• Main Authors: Chen, ShengWen, 陳聖玟
• Other Authors: Chiou, WannDuen
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/89908331376590569439

碩士 === 國立高雄海洋科技大學 === 漁業生產與管理研究所 === 99 === The aim of this study is to investigate the reproductive biology of Auxis thazard from the specimen which were caught in the coastal waters off Taiwan between 1996 and 2007. With the ANOVA analysis, it is found that there is no significant difference between body weight (BW) and fork length (FL) for both sexes. The BW-FL relationship equation can be described as BW=3×10^-5 FL2.93. The sex ratio (female/male) for specimen in 1996 is not significant from 0.5 according to the result of Chi-squared test (χ2=0.78, P＞0.05), while the sex ratio is 0.39 (152/390) for specimen in 2007 which indicates that the number of male is outnumbered female (χ2=104.51, P＜0.05). Based on the macroscopic appearance and gonadosomatic index, the spawning season is estimated between March and August for Year 1996. With the results of histological examination characteristics of ovary, the spawning season is also estimated between March and August for Year 2007. For samples in Year 1996, the size at first maturity for male is 304.7 mm FL and for female is 355.7 mm FL. For samples in Year 2007, the size at first maturity for male is 372.7mm FL and for female is 350.9mm FL. The size at 50% maturity for male is 380.9 mm FL and 389.7 mm FL is for female. Based on the results of this study, it suggests that there are no appeared miniaturized fish in this species. The spawning type of this species is belonged to Asynchronous. The spawning fraction is 0.69, and spawning frequency is 1.45 for one day in this study.