Marine Ecology Progress Series
MEPS is a leading hybrid research journal on all aspects of marine, coastal and estuarine ecology. Priority is given to outstanding research that advances our ecological understanding.
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DOI: https://doi.org/10.3354/meps13763
copiedProjected impacts of climate change, bycatch, harvesting, and predation on the Aotearoa New Zealand tītī Ardenna grisea population
- David Fletcher
- Jamie Newman
- Sam McKechnie
- Corey Bragg
- Peter Dillingham
- Rosemary Clucas
- Darren Scott
- Sebastian Uhlmann
- Phil O’B. Lyver
- Andrew M. Gormley
- Stewart Bull
- Kayne Davis
- Renata Davis
- Riki Davis
- Tane Davis
- Lania Edwards
- Jane Kitson
- Tina Nixon
- Michael Skerrett
- Henrik Moller
ABSTRACT: Many factors have contributed to a decline in the tītī (sooty shearwater) Ardenna grisea population in Aotearoa New Zealand since at least the 1960s. The relative impacts of Southern Oscillation Index (SOI) variation, bycatch, predation, and traditional harvesting by Rakiura Māori were recently estimated in a study fitting population models to data from the period 1976-2005. Annual mean SOI was related to both adult survival and fecundity. We used the results from that study to project abundance of tītī under a range of management strategies and future SOI scenarios, based on 41 climate models. Projections over the period 2019-2070 showed marked variation across the climate models. When the proportion of chicks harvested and the level of depredation by weka Gallirallus australis were set at their historical means and the proportion of birds killed in bycatch was set at an upper bound based on current estimates, the probability of a decline ranged from 0.30 to 1.00, across all climate models. When both bycatch and depredation by weka were set to zero, the probability of a decline ranged from 0.11 to 1.00, across all climate models. Our results suggest that future abundance of tītī in Aotearoa New Zealand will depend to a large extent on SOI conditions over the coming decades. As climate-model uncertainty makes reliable prediction of future SOI conditions difficult, adaptive management is likely to be the best option for Rakiura Māori, the kaitiaki (environmental guardians) of the Rakiura Tītī Islands, to maintain sustainable tītī harvests.
KEYWORDS
David Fletcher (Corresponding Author)
- David Fletcher Consulting Limited, Karitane 9471, Aotearoa New Zealand
Jamie Newman (Co-author)
- Department of Zoology, University of Otago, PO Box 56, Dunedin 9054, Aotearoa New Zealand
Sam McKechnie (Co-author)
- Department of Zoology, University of Otago, PO Box 56, Dunedin 9054, Aotearoa New Zealand
Corey Bragg (Co-author)
- Tokona te Ao - Tribal Economies, Te Rūnanga o Ngāi Tahu, 25 College Street, Dunedin 9012, Aotearoa New Zealand
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Peter Dillingham (Co-author)
- Department of Mathematics and Statistics, University of Otago, PO Box 56, Dunedin 9054, Aotearoa New Zealand
Rosemary Clucas (Co-author)
- Department of Zoology, University of Otago, PO Box 56, Dunedin 9054, Aotearoa New Zealand
Darren Scott (Co-author)
- Department of Zoology, University of Otago, PO Box 56, Dunedin 9054, Aotearoa New Zealand
Sebastian Uhlmann (Co-author)
- Department of Zoology, University of Otago, PO Box 56, Dunedin 9054, Aotearoa New Zealand
Phil O’B. Lyver (Co-author)
- Manaaki Whenua Landcare Research, PO Box 69040, Lincoln 7640, Aotearoa New Zealand
Andrew M. Gormley (Co-author)
- Manaaki Whenua Landcare Research, PO Box 69040, Lincoln 7640, Aotearoa New Zealand
Stewart Bull (Co-author)
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Kayne Davis (Co-author)
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Renata Davis (Co-author)
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Riki Davis (Co-author)
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Tane Davis (Co-author)
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Lania Edwards (Co-author)
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Jane Kitson (Co-author)
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Tina Nixon (Co-author)
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Michael Skerrett (Co-author)
- Rakiura Tītī Islands Administering Body, PO Box 316, Invercargill 9840, Aotearoa New Zealand
Henrik Moller (Co-author)
- Centre for Sustainability, University of Otago, PO Box 56, Dunedin 9054, Aotearoa New Zealand