Through the Looking-Glass: Marine mammal monitoring in a changing world
Hoekendijk, J.P.A. (2024). Through the Looking-Glass: Marine mammal monitoring in a changing world. PhD Thesis. [S.n.]: Wageningen. ISBN 978-94-6447-176-2. 1-160 pp.
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| Abstract |
The Arctic climate is changing extremely fast: as soon as 2035, the Arctic Ocean is predicted to be nearly ice-free. This is particularly problematic for Arctic pinnipeds (true seals, eared seals and walruses) that are dependent on the sea-ice for instance to rest and breed. How these animals will respond to these rapidly changing conditions, remains unclear and is highly unpredictable. Therefore, aerial and ship-based surveys might soon prove insufficient to monitor pinnipeds in the remote and vast Arctic. This thesis aims to develop and apply methodologies for marine mammal monitoring, that can aid with studying distribution and range shifts. Data-rich marine mammal populations in the southern North Sea are used as ‘model organisms’ to test these new methods. The thesis addresses the following research questions: RQ 1. Which changes in migration timing or distribution do Arctic migratory vertebrates exhibit in response to global warming? RQ 2. How can opportunistically collected data contribute to a better understanding of range shifts in marine mammals? A bottlenose dolphin case study. RQ 3. How can image-level annotations be leveraged to train a deep learning model to count pinnipeds from aerial imagery, and what is the accuracy of this approach? A grey and harbour seal case study. RQ 4. How can fine-scale spatial haul-out patterns in pinniped haul-out sites be used as a tool to differentiate between sympatric species, when using low-resolution remote sensing imagery? |
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