Relationship between post-nesting migrations of green turtles (Chelonia mydas) and the currents in Taiwan Strait and in South China Sea

• Main Authors: Ya-Ru Cai, 蔡雅如
• Other Authors: I. J. Cheng
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/94199927019235983935

碩士 === 國立臺灣海洋大學 === 海洋生物研究所 === 93 === The post-nesting migration of green turtles at Wan-An Island, Penghu Archipelago since 1994 and in 2000 Taiping Islands of Nansha Archipelago. The study found that the turtles left Wan-An would move toward N、NW、NE and S directions. The turtles left Taiping Islands would move toward NE、N、SE and S directions. The relevant studies in the past would mislead the conclusion, because the current models only use the mean current speed over large areas, thus did not considered the variability in the currents. In this study, the simultaneously current speed was calculated from the current model and compared to the migration speed derived from the Argos positions.Then, one can determine the effect of current on the migration behavior of different turtles in the same Ocean basin, and in the different ocean basins. In Taiwan straits,when the turtle moved toward N and NW, because current speed is equal to the net-turtle speed, the current can increase the migration speed. When the turtle moved toward S in Taiwan straits, the northward current speed was smaller than the net migration speed, then the current can not influence both the turtle’s migration speed and direction. The turtles in the South China Sea swam in the same direction as the current. However because the current speed was smaller than net-turtle speed, it can not change the migration behavior. In conclusion, when the current speed is equal the net-turtle speed, current can influence the migration speed of turtles. However, when current speed is smaller then net-turtle speed, no matter where turtles are they will not be changed their migration speeds and directions.