| 英文摘要 |
The aim of this project is try to investigate the catch data and some biological information to establish the database for the whale shark, Rhincodon typus. Meanwhile, the satellite telemetry technique is also introduced to study the movement and migration of the whale shark around Taiwan waters.
A total of 60 whale sharks were landed in Taiwan during January and July 2006. The majority of them were caught by set net that occupied 41.7% of all catches. Only 11.7% were caught by spears this year due to the arrival of the allowance capture in July, but the spear fishery prevails in colder seasons. By comparison with landed areas, east coast still had the highest landed amount of the whale shark that occupied 61.7% of whole amount this year. From analyzing body length of 60 individuals, the highest peak was still at the 4.0-4.5 m length interval (40.0%). However, there were 12 individuals shorter than 4.0 m TL, and not any mature specimen (8.0 m TL at least) was caught this year.
Two whale sharks were released with PAT4 tags in 2005, and the tags popped-off last September and this January, respectively. Both of them have successfully recorded vertical movement data. They often occupied the depth 5-10 m where the water temperature was between 23 and 26 °C and between 15 and 20 °C. In addition, the whale shark migrates to different depth intervals more frequently in fall and winter.
According to age and total length data, parameters of the VBGE (sex combined) were estimated as L∞=16.570 m, K=0.036 yr-1, and t0=-1.295 yr, respectively, suggest that whale shark is a slow-growth species. |