| Summary: | 碩士 === 國立臺灣海洋大學 === 海洋事務與資源管理研究所 === 104 === Fisheries biology of Upeneus japonicus in surrounding waters of Three Northern Islet of Taiwan was examined based on samples collected between Aug. 2004 and Jun. 2016. In total, 1157 fishes including 459 males, and 648 females, as well as 50 undifferentiated individuals were collected. There was no difference found in body weight – fork length relationships for both sexes. The combined equation is BW=0.023FL2.8972. The formation of annuli for the species was found between December and January. The maximum ages for male and female fishes were estimated to be 7 and 5. The von Bertalanffy growth equations in fork length (cm) and weight (g) estimated by non-liner method were FLt = 23.2491 (1-e-0.1282(t+2.7089)) (for female) and FLt = 13.1104 (1-e-0.6314(t+0.5923)) (for male), and Wt=209.16(1-e-0.1282(t+2.7089))2.8972 (for female), Wt = 39.78(1-e-0.6314 (t+0.5923))2.8972 (for male). Females matured at age 2.2 and males at age 2. The spawning season was from March to October, and the size at first maturity for females was 10.5 cm, and 9.6 cm for males. Asynchronous ovarian development type was identified for the species, and the fecundity was estimated to be ranged from 13,819 to 320,336. There was no difference found in sex ratio for most months except for period between Aug. and Oct. and Dec. of 2014, Jan. Mar. and Nov. of 2015, and Feb. of 2016. The condition factor (CF) for both sexes started increase after winter, and reached the highest value in May-June period before it dropped to low value again. The seasonal variations in hepatosomatic index (HSI) and visceral index (VI) were less evident for males, but were significantly higher during the spawning season for females. The feeding conditions showed that this species may also increase feeding activity during the spawning season. These results indicated that energy required for spawning in U. japonicus may be fueled partially by the reserves in muscle, liver and visceral, and partially from continuous feeding.
|
|---|
