Twenty-eight years of decline: Nesting population demographics and trajectory of the north-east Queensland endangered hawksbill turtle (Eretmochelys imbricata)

I P Bell; Justin J Meager; T Eguchi; K A Dobbs; J D Miller; Christine A Madden Hof

doi:10.1016/j.biocon.2019.108376

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Twenty-eight years of decline: Nesting population demographics and trajectory of the north-east Queensland endangered hawksbill turtle (Eretmochelys imbricata)

Journal article

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Twenty-eight years of decline: Nesting population demographics and trajectory of the north-east Queensland endangered hawksbill turtle (Eretmochelys imbricata)

I P Bell, Justin J Meager, T Eguchi, K A Dobbs, J D Miller and Christine A Madden Hof

Biological Conservation, Vol.241, 108376

2020

DOI: https://doi.org/10.1016/j.biocon.2019.108376

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Abstract

Hawksbill turtle

Eretmochelys imbricata

Population abundance

Tortoiseshell

Great barrier reef

Capture-mark-recapture

Globally, hawksbill turtles (Eretmochelys imbricata) are listed as Critically Endangered, the cause of which is largely attributed to excessive historical take by the tortoiseshell industry. Yet few long-term data analyses describing population trend or survivorship exist. Here we analyse a long-term dataset for a globally significant western Pacific E. imbricata nesting population on Milman Island, northern Great Barrier Reef. Three demographic indicators were used: (1) number of egg clutches laid, (2) nester abundance and survival, and (3) the body-size distribution of nesters (curved carapace length, CCL). Models were developed for a time series from the 1990-91 to 2016-17 nesting season that included 21 years of sampling, with predicted trends evaluated against samples from the 2017-18 nesting season. The number of clutches laid and nester abundance rate of decline varied over the study period, but the decline was markedly similar with a 58 and 57% overall reduction, respectively. Annual survival rate was high (0.972, 95% CI = 0.965 to 0.977), but was not estimated separately for all years. Models predicted that the current rate of decline would lead to nesting extirpation by 2036 (95% CI: 2026-2058) and 2032-2037 (95% CI: from 2020 to increasing), for the models of nester abundance and number of eggs laid, respectively; and aligned with the observed values for the test dataset (2017-18 season). The rate of decline of E. imbricata nesting at Milman Island highlights the urgency to understand and mitigate risks faced by this endangered population and more broadly across the western Pacific.

Details

Title: Twenty-eight years of decline: Nesting population demographics and trajectory of the north-east Queensland endangered hawksbill turtle (Eretmochelys imbricata)
Authors: I P Bell (Author)
Justin J Meager (Author)
T Eguchi (Author)
K A Dobbs (Author)
J D Miller (Author)
Christine A Madden Hof (Author) - University of the Sunshine Coast
Publication details: Biological Conservation, Vol.241, 108376
Publisher: Elsevier BV
Date published: 2020
DOI: 10.1016/j.biocon.2019.108376
ISSN: 0006-3207
Organisation Unit: University of the Sunshine Coast, Queensland; School of Science, Technology and Engineering
Language: English
Record Identifier: 99450962202621
Output Type: Journal article

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Collaboration types: Domestic collaboration; International collaboration
Web Of Science research areas: Biodiversity Conservation; Ecology; Environmental Sciences

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