Reproductive biology of bluefin tuna, Thunnun thynnus, from southwestern North Pacific.

• Main Authors: Kuo-Shu Chen, 陳國書
• Other Authors: Chien-Chung Hsu
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/47714922501381863959

碩士 === 國立臺灣大學 === 海洋研究所 === 88 === The investigation of reproductive biology of bluefin tuna, Thunnus thynnus, from the southwestern North Pacific has been pursued based on macroscopic and microscopic examination of ovaries and oocytes. Ovaries were collected from fish caught by longline vessels fishing on the spawning ground during May and June, 1999. The results are: (1) abundant northern bluefin tuna occurred in the southeastern waters off Taiwan and northeastern waters off Philippines during late April and middle June; (2) sex ratio of spawning stock (172-252 cm) was 1:1; (3) the spawning stock included almost giant fish (99% fish＞190 cm), and a few medium fish; (4) the length and gutted weight of about 50% fish were located at 208-219 cm and 161-194 kg, respectively; (5) the minimum length of spawning stock found in the landings was 165 cm; (6) The batch fecundity was estimated based on 11 ovaries with hydrated oocytes, then a linear relationship between batch fecundity (BF) and fork length (FL) was derived as: BF = (4.3952×10^5)FL－7.58×10^7　(r2 = 0.793, p＜0.01); (7) The mean relative batch fecundity (±95% CI) was 89 ( ±18.3) oocytes per gram of gutted weight.