University of Wollongong Research Online Faculty of Science, Medicine & Health - Honours Theses University of Wollongong Thesis Collections 2019 The use of unmanned aerial vehicles to assess the spatial and temporal dynamics of seals at Martin Islet (NSW) L Esteban Follow this and additional works at: https://ro.uow.edu.au/thsci University of Wollongong Copyright Warning You may print or download ONE copy of this document for the purpose of your own research or study. The University does not authorise you to copy, communicate or otherwise make available electronically to any other person any copyright material contained on this site. You are reminded of the following: This work is copyright. Apart from any use permitted under the Copyright Act 1968, no part of this work may be reproduced by any process, nor may any other exclusive right be exercised, without the permission of the author. Copyright owners are entitled to take legal action against persons who infringe their copyright. 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For further information contact the UOW Library: [email protected] The use of unmanned aerial vehicles to assess the spatial and temporal dynamics of seals at Martin Islet (NSW) Abstract The increasing anthropogenic influence on natural ecosystems has led to shifts in species geographic range, dispersal patterns and livelihood, thus providing significant challenges for environmental managers. Unmanned aerial vehicles (UAVs) show a unique potential for achieving non-disruptive surveys of marine mammal populations on offshore islands. This technology allows scientists to access and collect information in coastal environments that would otherwise not be possible. UAVs capture quick and continuous high-resolution data across the entirety of a site, often at a reduced cost and risk compared to light aircraft and satellite technologies. Situated 1.35 km off the coast of Port Kembla, Martin Islet is a haul-out site for the vulnerable Australian and Long-nosed fur seals. Haul-out sites are important for these species as they allow seals to rest when foraging and avoid predation. This study aimed to investigate temporal variation, spatial distribution and habitat suitability of the fur seal population at Martin Islet. UAV and boat surveys were completed each month from March to August, with additional, more frequent, aerial surveys conducted every two hours to investigate diurnal haul-out behaviour. An evaluation of in-situ and aerial techniques for surveying seals was conducted to determine the most appropriate methodology for Martin Islet. To statistically evaluate the uncertainty associated with counting seals from visual RGB images and thermal infrared images, seal counts were made by two groups of volunteers on an RGB and thermal image respectively. The results of this study provide the first empirical videncee of fur seal haul-out behaviour at Martin Islet, revealing temporal seasonal similarities to other haul-out sites within NSW (e.g. Montague Island and Steamers Head). The study found that the seal population at Martin Islet increased in size from a few individuals in March to a peak of approximately 103 seals in late July. A notable increase in observed seal numbers in July and August corresponded with a decrease in seawater temperatures to approximately 16.7°C. This correlates with favoured foraging conditions of the Australian fur seal in the literature. On a diurnal scale, seals hauled out in greatest numbers around midday, while the number of seals in the water peaked at sunrise and decreased over the course of the day. As a methodological approach to population assessment, our results suggest that UAV-based surveys are more accurate in identifying seals on Martin Islet, particularly as the number of seals hauled out increases. During July and August where the UAV surveys saw a large increase in seal numbers, the boat- based approach recorded just 52% and 37% of the seals observed using a UAV. The variable topography of Martin Islet resulted in a greater degree of uncertainty when identifying seals using thermal imagery compared to RGB imagery. The observer’s ability to distinguish seals from the surrounding landscape was hindered due to the rocky surfaces of the islet heating up in the sun and emitting thermal signals that were often similar in shape to the seals. The range in the number of seals estimated was substantially higher among participants analysing the thermal image (226) compared to the RGB image (29). The spatial distribution of seals across Martin Islet displayed positive spatial autocorrelation and appears to depend primarily on the topographic characteristics of the islet (R2 = 0.77). Throughout the study, fur seals tended to haul out in groups, favouring the southern coastline of Martin Islet, on relatively uniform areas of low elevation that are easily accessible from the water. Most of the seals hauled out on rock platforms with elevations below 4 meters and within 12 meters of the shore. Three major zones, consisting of statistically significant spatial clusters of seal observations, were identified through the hot spot analysis, covering a combined area of 2016 m2. These zones are situated in the southern corners and north-west portion of Martin Islet. It is hoped that the maps developed in this study are used to guide conservation and help assess potential human and environmental impacts on the islet’s seal population. Degree Type Thesis Degree Name BEnviSci Hons Department School of Earth, Atmospheric & Life Sciences Advisor(s) Sarah Hamylton Keywords Arctocepjalis Pusillus doriferus, A. forsteri, haul-out, thermal, Five Islands Nature Reserve This thesis is available at Research Online: https://ro.uow.edu.au/thsci/175 The use of unmanned aerial vehicles to assess the spatial and temporal dynamics of seals at Martin Islet (NSW) Luis Esteban (Photograph credit: Victor Hawk) A thesis submitted in partial fulfilment of the requirements for the award of the Degree of Bachelor of Environmental Science (Honours) in the School of Earth, Atmospheric and Life Sciences, Faculty of Science, Medicine and Health, University of Wollongong 2019. 22 October 2019 1 The information in this thesis is entirely the result of investigations conducted by the author unless otherwise acknowledged, and has not been submitted in part, or otherwise, for any other degree or qualification. Luis Esteban 22 October 2019 2 Acknowledgements Firstly, I would like to acknowledge the Dharawal people as the traditional custodians of the Five Islands where I conducted fieldwork that formed the basis of this study. I would like to thank my supervisor, Sarah Hamylton, for her guidance and feedback throughout this project. Your expertise and knowledge in the fields of GIS and remote sensing have provided me with great skills and opportunities moving forward. I would like to thank Rowena Morris for not only sharing her passion for the Five Islands and the environment but also for helping organise crucial boat trips to the study site and allowing me to perform an overnight stay to ensure I collected the data I desired. Her enthusiasm and willingness to help, despite a chaotic schedule, was admirable and ensured the overnight surveys and project as a whole was thoroughly enjoyable. Thank you, Heidi Brown, for your technical support and assistance with all things GIS, and to Marina McGlinn for supporting myself and all honours students. I would also like to thank my friends and family for their support throughout this year, especially in the final stages. In particular, I want to thank Nicholas Keatley, Reid Formosa and Kegan Cook for their willingness to help me in the field. Finally, to Emma, thank you for believing in me and for encouraging me when I needed it most. 3 Abstract The increasing anthropogenic influence on natural ecosystems has led to shifts in species geographic range, dispersal patterns and livelihood, thus providing significant challenges for environmental managers. Unmanned aerial vehicles (UAVs) show a unique potential for achieving non-disruptive surveys of marine mammal populations on offshore islands. This technology allows scientists to access and collect information in coastal environments that would otherwise not be possible. UAVs capture quick and continuous high-resolution data across the entirety of a site, often at a reduced cost and risk compared to light aircraft and satellite technologies. Situated 1.35 km off the coast of Port Kembla, Martin Islet is a haul-out site for the vulnerable Australian and Long-nosed fur seals. Haul-out sites are important for these species as they allow seals to rest when foraging and avoid predation. This study aimed to investigate temporal variation, spatial distribution and habitat suitability of the fur seal population at Martin Islet. UAV and boat surveys were completed each month from March to August, with additional, more frequent, aerial surveys conducted every two hours to investigate diurnal haul-out behaviour. An evaluation of in-situ and aerial techniques for surveying seals was conducted to determine the most appropriate methodology for Martin Islet. To statistically evaluate the uncertainty associated with counting seals from visual RGB images and thermal infrared images, seal counts were made by two groups of volunteers on an RGB and thermal image respectively.