The estimation of growth parameters influenced by gill net selectivity for half-fin anchovy (Setipinna taty!Valenciennes, 1948)in the southern Kinmen waters

• Main Authors: WENG, WEN-SHUENN, 翁文舜
• Other Authors: LEE YING-CHOU
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/55236188533415766026

碩士 === 國立臺灣大學 === 漁業科學研究所 === 85 === The age of Setipinna taty in the southern Kinmen waters was determined byvertebral ring-count, and its von Bertalanffy''s growth equation was estimated by nonlinear regression. Furthermore, the mesh selectivity of gill net was estimated by modified Holt''s method (1963), and used to discuss the influences on the estimation of growth parameters. The results were as follows: 1. Observed length frequency distribution ranged from 8.1 to 17.8cm as well as it showed bimodal. The main mode was at 15.25cm, and the second at 12.25cm. 2. The annulus of vertebrae was formed annually, and the period was between winter and spring. 3. The von Bertalanffy''s equation of fork length (cm) was estimated Lt＝23.45{1－exp[-0.40(t+0.37)]} 4. The optimum selection lengths (lm) and selection factors (k) of three meshes, i.e., 4.00cm(A), 4.29cm(B), and 5.00cm( C) were as follows: (a) When fork length of specimens>14.0cm, Alm=14.8cm, Blm=15.5cm, Clm=15.8cm, and kA=3.71, kB=3.62, kC=3.17. (b) When fork length of specimens <14.0cm: Alm=11.7cm, Blm=11.4 cm, Clm=12.3cm, and kA=2.94, kB=2.66, kC=2.46. 5. The optimum selection length increased with mesh sizes when specimens were caught by the wedged pattern, but it didn''t showed same trend when specimens were caught by the tangled pattern. 6. The mesh selectivity of gill net indeed affects the estimation of growth parameters.