| 英文摘要 |
The aims of this project include (1) collect of age characters and ring-reading (2) to estimate the growth parameters using length-frequency data (3) conversion between length and age for albacore caught by Taiwanese longliners in Indian (4) CPUE standardization of Indian albacore. About the collect of age characters and ring-reading, a total of 154 spines and vertebrae have been collected, which their ring-reading are conducting. The age characters have been collecting continuously. About the estimation of growth parameter based on length frequency, length frequency data recorded by shipmen and by observers were analysed using Multifan program. The growth parameters estimated by data recorded by shipmen are k=0.088yr-1,L∞=158.9 cm; and the growth parameters estimated by data recorded by observers are k=0.191yr-1,L∞=136.2cm respectively. About the conversion between length and age for albacore caught by Taiwanese longliners in Indian from 1980 to 2013, the VBGEs described in this study (by Multifan), Lee and Liu (1992) and Wells (2013) were used with Knife-edge cutting method, moreover, Lee and Liu (1992) was used to constitute the Age-length key then convert the length composition into age composition. The results indicate that, in the Knife-edge cutting method, there are similar mode of age composition on 3 VBGE aforementioned, and age 5 has the most ratio, but above age 12, the ratio based on Wells (2013) was higher apparently than others. As the Age-length key method, based on Lee and Liu (1992), although age 5 has the most ratio that is similar to Knife-edge cutting method using the growth equation Lee and Liu (1992) , the age composition adapted Knife-edge cutting method is more fit in with normal distribution. Then, the factors including year, quarter, subarea, bycatch were used to standardize the CPUEs of albacore caught by Taiwan longliners in Indian whole area and core area for 1980-2013 from Generalized Linear Model (GLM). In whole area, the yearly CPUE trend of Indian albacore thus obtained indicated that the values of CPUEs have decreased rapidly from early 1980s to 1990 while the values between 1991 and 2005 were decreased moderate and the values of standardized CPUE varied between 0.8 and 1.3. In 2007, the CPUE reached the lowest value from 2011 but no longer decrease, just like the beginning of a new cycle. In core area, the CPUE oscillated from 1980 to 1988, then decreased sharply to the historic lowest value in 1990. In 1990s, there were two times increased by a wide margin, particularly in 1997 and 1998 years. However, the CPUE decreased sharply in 1999 but was steady to 2013. |
