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Endangered Species Research

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ESR 50:209-215 (2023)  -  DOI: https://doi.org/10.3354/esr01228

Apparent survival probability and abundance of juvenile green turtles in the foraging ground at Kuroshima Island, Ryukyu Archipelago

Kazunari Kameda1,*, Motoki Wakatsuki1, Mai Takase2, Yu Nakanishi1, Naoki Kamezaki3

1Kuroshima Research Station, Sea Turtle Association of Japan, 136 Kuroshima Taketomi-cho, 907-1311 Okinawa Prefecture, Japan
2The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, 113-0033 Tokyo, Japan
3Okayama University of Science, Faculty of Biosphere-Geosphere Science, 1-1 Ridai-cho, Okayama City, 700-0005 Okayama Prefecture, Japan
*Corresponding author:

ABSTRACT: An understanding of the survival probability and abundance of endangered species is critical for their effective conservation and management. In this study, long-term capture-mark-recapture data were used to estimate the apparent survival probability and abundance of green turtles Chelonia mydas at Kuroshima Island in the Yaeyama Islands, Japan. A total of 453 turtles were captured from 2009 to 2020 using entangling nets. All captured turtles were juveniles and subadults; no adult turtles were captured during this study. The estimated apparent survival rate of this aggregation was 0.82 (95% CI = 0.76-0.86) using the Cormack-Jolly-Seber model, which accounts for both permanent emigration and death. Annual abundance was estimated using the Horvitz-Thompson estimator. Estimated abundance increased from 234 (95% CI = 182-286) in 2009 to 418 (95% CI = 325-510) in 2020. This trend in abundance for green turtles in the foraging ground may result from the increasing nesting population in this region. Our study provides information for understanding the life cycle of green turtles in the Yaeyama Islands and for the conservation and management of marine ecosystems in this region.


KEY WORDS: Chelonia mydas · Abundance trend · Cormack-Jolly-Seber model · Capture-mark-recapture · Japan


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Cite this article as: Kameda K, Wakatsuki M, Takase M, Nakanishi Y, Kamezaki N (2023) Apparent survival probability and abundance of juvenile green turtles in the foraging ground at Kuroshima Island, Ryukyu Archipelago. Endang Species Res 50:209-215. https://doi.org/10.3354/esr01228

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