Reproductive biology of the codlet Bregmaceros lanceolatus inthe coastal waters off southwestern Taiwan

• Main Authors: Lin Ge-Wen, 林智文
• Other Authors: Chiou Wann-Duen
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/10155040737395138239

碩士 === 國立高雄海洋科技大學 === 漁業生產與管理研究所 === 95 === This study is aimed to investigate the reproductive biology of codlet, Bregmaceros lanceolatus, in the coastal waters off southwestern Taiwan. A total of 2,143 specimens (1,606 females and 537 males) were collected monthly for October 2005 to September 2006, from the landings of trawlers returned to Jhong-Yun fishing port in Linyuan, Taiwan. By means of histological examination, the oocyte development can be clearly categorized into eight stages while the ovary development is four stages. Based on the macroscopic appearance, histological examination of ovary, estimations of gonadosomatic index and group maturity rate, it suggests that spawning of this species occurs throughout the year and has peaks in November and June-July. Mean fecundity and mean batch fecundity of this species were estimated as 6,218±2,684 and 2,750±1,257, respectively. The fecundity of female codlet increased with increasing body weight . The relationships between fecundity (F), batch fecundity (BF) and body weight (BW) were obtained as the follows：F=2080×BW＋648(n=117；r2=0.62) and BF=605×BW＋1087(n=34；r2=0.31). The sex ratio (females/total) for all specimens combined data was 0.75 (1,606/2,143), which was significantly difference from 1.0 (p＜0.05). Size at maturity of female and male estimated from the Logistic model were 68.34 mm and 55.90 mm, respectively.