Zoological Studies

Vol. 58, 2019

(update: 2019.06.19; 08.01)

Using Programming Languages and Geographic Information System to Determine Spatial and Temporal Variability in a Green Turtle Foraging Population on Liuchiu Island, Taiwan

Wan-hwa Cheng1, Ying-Tin Chan2, Haisen Hong2, Benjamin Johnson3, and I-Jiunn Cheng2,*


1The Masters of Advanced Study in Geographic Information Systems, Arizona State University, Tempe Campus, Arizona, 85281, USA
2Institute of Marine Biology, National Taiwan Ocean University, Keelung 202-24, Taiwan
3Department of Geographic Information Science and Cartography, University of Maryland, College Park, Maryland, 20724, USA. *Correspondence: E-mail: b0107@mail.ntou.edu.tw

Received 8 January 2019 / Accepted 11 June 2019
Communicated by Benny K.K. Chan

Facial photo identification (ID) has proven to be a non-invasive method for identifying individual wild animals, and in recent years it has been effective on megafauna such as sea turtles. However, when processing hundreds of photos over a long period of time, variation in facial scale patterns makes identifying individuals complicated. This means that there is a high possibility that the individual is misidentified, which results in incorrectly determining population sizes. This study used the programming languages Python and SQL to determine green turtle foraging population size in the nearshore waters of a coral island, Liuchiu Island, from 2011 to 2017. The programs determined that the foraging population was 432 turtles, approximately 90% of which resided there one year or less and selected only one foraging site. Those that stayed for more than two years selected two foraging sites. Less than 3% stayed throughout the 7 years. The core residence area was from Beauty Cave to Vase Rock. This study found that the nearshore waters of Liuchiu Island are a temporary development/foraging site for immature green turtles. This is the first study to use Python analysis to determine a foraging sea turtle population in the field.

Key words: Green sea turtles, Liuchiu Island, Foraging population size, Spatial and temporal distribution, Python, GIS.

Citation: Cheng Wh, Chan YT, Hong H, Johnson B, Cheng IJ. 2019. Using programming languages and geographic information system to determine spatial and temporal variability in a green turtle foraging population on Liuchiu Island, Taiwan. Zool Stud 58:18. doi:10.6620/ZS.2019.58-18.