| 英文摘要 |
Bigeye tuna is a species of high economical value and contributed more than 40,000 tonnes of catch to the Taiwan’s fisheries annually from the Indian Ocean in recent years. Owing to the importance of Indian bigeye tuna resources to Taiwanese fisheries, this study is aiming to investigate the age and growth of this species based on their length frequencies and otoliths, attempting to provide to the basis of further studies, such as population structure changes and ASPM surplus production analysis.
Length measurements and otolith samples of the Indian bigeye tuna were collected by assisstants worked on board from April to December in 2006. The sample sizes of length frequencies and otoliths were 5,540 and 218, respectively. The Multifan program was applied to estimate the von Bertalanffy’s growth equation of the bigeye tuna and the K and L∞ were then obtained as 0.147yr-1 and 202.5cm. Among the otoliths collected, 100 of them have been examined after preliminary treatments, such as cleaning, embedding and grinding, in order to cross check the results of length frequency analyses. The APE value of two blindly reading on the same otolith was 2.2%, showing high precision in the ring identification. For those otoliths with different counts of ring between two readings, the third reading was then made for further confirmation of ring count. The results of otolith reading were compared with the growth equation derived from length frequency analysis, in an attempts to confirm the age and growth of Indian bigeye tuna. |