Integrating climate change and management scenarios in population models to guide the conservation of marine turtles

Michael P. Jensen, Tomoharu Eguchi, Nancy N. FitzSimmons*, Michael A. McCarthy, Mariana M.P.B. Fuentes, Mark Hamann, Colin J. Limpus, Ian P. Bell, Mark A. Read


Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

8 Citationer (Scopus)


The globally significant green turtle (Chelonia mydas) population in the northern Great Barrier Reef is threatened by anthropogenic pressures, including climate change, habitat degradation, and indigenous harvest. Evidence suggesting the population is producing an extreme proportion of females due to increasing temperatures, coupled with temperature-dependent sex determination, is concerning. In response, and to explore management options, we developed two density-independent, stochastic stagestructured metapopulation models: a "Moderate Climate Model"and an "Extreme Climate Model". The models differ based on climate change projections by incorporating increased female hatchling sex ratios due to global warming and loss of nesting habitat due to sea level rise. The models were based on demographic data from field studies at major rookeries and regional foraging grounds and allowed for variation in operational sex ratios, management actions, and levels of indigenous harvest. Under the Moderate Climate Model, population size increased but could be vulnerable to overharvest of adult females. If overharvest was indicated, the harvest of a proportion of subadults rather than only adult females reduced population declines. Under the Extreme Climate Model, there was a steep population decline even without any harvest and harvesting subadults accelerated population decline due to the inclusion of subadult males. In the Extreme Climate Model, reversal of population decline depended on male turtles mating with an increased number of females, or management actions to substantially increase the number of male hatchlings produced.

TidsskriftBulletin of Marine Science
Udgave nummer2
Sider (fra-til)131-154
Antal sider24
StatusUdgivet - apr. 2022

Bibliografisk note

Funding Information:
This project was made possible through the efforts of countless volunteers over four decades. Volunteers of the Queensland Turtle Research Project collected data on nesting females at Milman Island, Bramble Cay, Raine Island, Moulter Cay, and surrounding sand cays, and foraging turtles at Clack Reef, Green Island, the Howick Group reefs, Repulse Bay, and Shoalwater Bay. We thank the Torres Strait Regional Authority and the Torres Strait rangers who collected the data from the Bramble Cay and Dauarowar Island rookeries and the Torres Strait foraging ground. Raine Island, Moulter Cay, and MacLennan Cay are managed under an Indigenous Land Use Agreement (ILUA) with the Wuthathi people of Cape York and the Erubam Le, Meriam Le, and Ugarem Le of the Torres Strait, and Bramble Cay and Dauar Island are traditional lands of Erubam Le and Meriam Le in Torres Strait and we acknowledge these traditional owners. Funding for this project was gratefully provided by the Great Barrier Reef Marine Park Authority. This paper benefitted greatly from the constructive comments of anonymous reviewers who we thank.

Publisher Copyright:
© 2022 Rosenstiel School of Marine & Atmospheric Science of the University of Miami.


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