|Abstract: ||本研究針對台灣北部沿岸海域所產之嘉?魚(Pagrus major)進行漁業生物學研究，採樣期間自2007年10月至2008年12月止，共計採得樣本數380尾，含雄魚120尾、雌魚202尾以及無法分辨雌雄之個體58尾。樣本體長範圍在13.7~86.0cm之間，體重在37.5~8640.0g之間，全長(TL)體重(BW)關係式經變積分析檢定後無顯著差異，故合併後之關係式可以BW=0.02905TL^2.79926表示。本種耳石輪紋形成期約在每年的4~6月間，雌、雄魚之輪紋數最高可分別讀至16輪及8輪；而非線性法所估算而得之von Bertalanffy成長方程式以全長(cm)表示為Lt=125.4(1-exp(-0.0791(t+0.3656)))(1 ~ 8歲)及Lt=110.5(1-exp(-0.0944(t+0.2779))) (1 ~ 16歲)，而以體重(g)表示為Wt=21,718.33(1-exp(-0.0791(t+0.3656)))^2.79926 (1 ~ 8歲)及Wt=15,242.23(1-exp(-0.0944 (t+0.2779)))^2.79926 (1 ~ 16歲)；本種達性成熟年齡雄魚約4.8歲、雌魚則約為4.1歲，而生殖期在每年的1~4月間，最小性成熟體長雄魚約42.0 cm (TL)、雌魚約37.0 cm (TL)，嘉?魚雌魚有多於雄魚的現象，可能與本種之性轉變有關。此外，本種無論雌雄肥滿度均在秋末開始下降，並於3 ~ 4月達全年最低，而9至10月為最高值。肝臟和內臟指數則無論雌雄均以3月份為全年最低值，並於5月達高峰後開始下降，顯示本種生殖期間能量的來源可能主要係來自肌肉，而部份來自肝臟與內臟。本種主要攝食節肢動物、棘皮動物、軟體動物以及硬骨魚類，其中又以螃蟹、蝦、海膽、章魚、烏賊以及魚類為主。本研究結果也與不同年代及日本水域所得之結果做一比較，以了解長期漁業開發及地理差異所造成之可能影響。|
Fisheries biology of Pagrus major in waters off northern coast of Taiwan was examined based on samples collected between Oct. 2007 and Dec. 2008. In total, 380 fishes including 120 males, and 202 females, as well as 58 undifferentiated individuals were collected. Size of fishes ranged from 13.7 cm to 86.0 cm in length, and 37.5g to 8640.0g in weight were recorded. There was no difference found in body weight – total length relationships for both sexes. The combined equation is BW=0.02905TL2.79926. The formation of annuli for the species was found between April and June. The maximum ages for male and female fishes were estimated to be about 8 and 16, respectively. The von Bertalanffy growth equations in length (cm) and weight (g) estimated by non-liner method were Lt=125.4(1-exp(-0.0791 (t+0.3656))) (for ages 1 ~ 8) and Lt=110.5(1-exp(-0.0944 (t+0.2779))) (for ages 1 ~ 16), and Wt=21,718.33(1-exp(-0.0791 (t+0.3656)))^2.79926 (for ages 1 ~ 8), Wt=15,242.23 (1-exp(-0.0944(t+0.2779))^2.79926 (for ages 1 ~ 16). Males matured at age 4.8 and female at age 4.1. Spawning season of the species was between January and April. The size at first maturity for male fish was 42.0cm (TL), and was 37.0cm (TL) for female. Female fish was also more abundant than male, possibly related to the sex reversal reported for the species. The condition factor (CF) for both sexes start decrease after fall, and reached the lowest value in March-April period before it increase again on May. The hepatosomatic index (HSI) and visceral index (VI) of the species were the lowest on Mar. after peak spawning, and maintained at relative high after spawning. These results indicated that Pagrus major may use energy reserved mainly in the muscle, and partially in the liver and visceral for spawning. P. major feed mainly on Arthropoda, (i.e., crabs and shrimps) Echinodermata, (i.e., sea urchin) Molluscan (i.e., cuttlefish and Octopus) and Teleostean (i.e., fishes). The results of this study are also compared with reports from early years and from Japan to understand potential impacts of fishery, and influences of geographical differences.