台灣東部海域白皮旗魚之年齡與成長研究

Abstract

本研究以背鰭第三硬棘，做為白皮旗魚年齡查定之形質，以估計台灣東部海域白皮旗魚的年齡與成長。自2004年7月至2006年4月於台東成功新港魚市場總共量測4,521尾白皮旗魚體長資料，其中雄魚586尾，雌魚3,799尾，性別不明的136尾，下顎至尾叉體長範圍為147.1至368.2公分。 分析各項量測資料，經檢定後發現雌雄間之下顎尾叉長與眼後眶尾叉長關係，及下顎尾叉長與體重關係在雌雄間均有差異。背鰭硬棘切片樣本合計923個，其中874個完成判讀與測量，判讀率為94.7%。以邊緣成長率來分析背鰭硬棘輪紋形成期及一年所形成之輪紋數，結果顯示雌性白皮旗魚之背鰭硬棘在每年的二月至四月間形成一輪，而由於雄魚無完整一年之月別資料，因此無法進一步以邊緣成長率來判定其輪紋形成期。 成長參數的推估以Fraser-Lee’s法與Monastyrsky法估算白皮旗魚各年齡之平均逆算體長，分別套入standard von Bertalanffy成長方程式以非線性迴歸法及Ford-Walford定差圖法估算成長參數，以及套入generalized von Bertalanffy成長方程式以非線性迴歸法估算成長參數，結果顯示以Monastyrsky法估算之平均逆算體長套適standard von Bertalanffy成長方程式所推估之成長參數最為適當，而所推估雄性白皮旗魚之成長方程式為Lt = 305.8〔1 – e-0.125 (t +2.274)〕；雌性白皮旗魚成長方程式為Lt =396.7〔1 – e-0.094 (t + 1.825)〕，樣本中雄魚最大判讀年齡為5歲，雌魚最大判讀年齡為11歲。另外以殘差平方分析法比較雌雄別白皮旗魚之成長參數，結果顯示雌雄別成長參數有差異。因此，在進行白皮旗魚漁業資源分析及評估時應將雌雄分別處理以獲得較正確的結果。

Age and growth of black marlin (Makaira indica) in the waters off eastern Taiwan were studied from counts of growth bands on cross sections of the third spine of the first dorsal fin. Length and weight data and the dorsal fin spines were collected monthly at the fishing port of Shinkang (southeast of Taiwan) from July 2004 to April 2006. In total, 923 dorsal fins were collected, of which 874 (95%)(187 males and 687 females) were aged successfully. Trends in the monthly mean marginal increment ratio indicated that growth bands formed once a year. Two methods were used to back-calculated the length of presumed ages, and growth was described by using the standard von Bertalanffy growth function and the Richards function. The most reasonable and conservative description of growth assumes that length-at-age follows the standard von Bertalanffy function and that the relationship between spine radius and lower jaw fork length (LJFL) follows a power function. Growth differed significantly between the sexes; females grew faster and reached larger sizes than did males. The maximum sizes in our samples were 368.2 cm LJFL for females and 261.5 cm LJFL for males.