Zoological Studies

Vol. 58, 2019

(update: 2019.12.6; 12.19)

Twenty-three Years of Sea Turtle Stranding/bycatch Research in Taiwan

I-Jiunn Cheng*, Hua-Yan Wang, Wen-Yi Hsieh, and Yin-Ting Chan


Institute of Marine Biology, National Taiwan Ocean University, Keelung 20224, Taiwan. *Correspondence: b0107@mail.ntou.edu.tw

Received 30 April 2019 / Accepted 4 December 2019
Communicated by Benny K.K. Chan

Coastal sea turtle stranding and bycatch are common phenomena worldwide and have received more attention in recent years. They are caused by both natural and anthropogenic factors. One thousand and seventy-two turtles were reported to be victims of these phenomena from March 1997 to November 2019 in Taiwan. Number of stranding/bycatch were variable and infrequent for the first 14 years, but increased
each year after 2012 and peaked in 2019 with 217 cases. Most turtles were juveniles to subadults. All five of Taiwan’s species were reported in stranding and bycatch records, and the green turtle was reported the most common. The main reported seasons lasted from winter to spring, when the weather changes dramatically. The sex ratio (female: male) ranged from 7 in the hawksbill turtle to 0.7 in the olive ridley, with
an average of 2.4 for all species. Green turtles were the dominant stranded species, and more loggerhead turtles were by-caught. The hotspots were the towns of Dougou and Tochen in Yilan County, and Gongliao District in New Taipei City, located in NE coast of Taiwan respectively. Stranding was the more common of the two phenomena reported, and 80% of all stranded turtles were subadult green turtles. Eighty percent
of all stranded/bycaught turtles were dead. Pond-nets were the fishing gear that accounted for the most bycatch, and captured mainly living young and subadult green turtles as well as subadult loggerhead turtles. The hotspots for bycatch were the towns of Dongou and Tochen in Yilan County. The Coast Guard and concerned citizen were the main sources of reports. This is the first study to analyze the long-term stranding/bycatch of sea turtles in Taiwan.

Key words: Stranding and bycatch, Green turtle, Temporal and spatial distribution, Report type, Bycatch type, Gender, Juvenile to subadult turtles.

Citation: Cheng CI, Wang HY, Hsieh WY, Chan YT. 2019. Twenty-three years of sea turtle stranding/bycatch research in Taiwan. Zool Stud 58:44. doi:10.6620/ZS.2019.58-44.

Supplementary Materials: Table S1 | Table S2