- Title
- Foraging behaviour of the Sooty Albatross in relation to climatic variability and fisheries
- Creator
- Banda, Shamiso
- Subject
- Spatial behavior in animals
- Subject
- Conservation of natural resources --South Africa
- Date Issued
- 2022-04
- Date
- 2022-04
- Type
- Master's theses
- Type
- text
- Identifier
- http://hdl.handle.net/10948/55632
- Identifier
- vital:53383
- Description
- As top predators, seabirds occupy the upper trophic level of marine ecosystems. They are consequently important for the maintenance of ecosystem structure and function, while also possessing characteristics which are useful for identifying climate-driven changes in oceanography at all trophic levels. This important faunal group is one of the most threatened, with climate change and fisheries bycatch mortality being the primary drivers of population declines. Understanding these threats is important for the management of threatened seabird populations. One impact of climate change and variability in climate occurs through changes in prey availability. As central place foragers, breeding seabirds have trip duration constraints due to the obligation of nest duties. This makes them particularly vulnerable to changes in prey availability within their foraging ranges. The ability to adjust foraging behaviour during environmental conditions which alter prey availability is an important attribute which can contribute to breeding success. Thus, investigating for this foraging behavioural plasticity during different breeding stages provides insights into how a species is likely to be impacted by climate change. The sooty albatross population on Marion Island was studied and displayed a degree of foraging behavioural plasticity during the five-year period of pronounced climatic variability studied. Incubating birds mainly foraged in the subtropical convergence zone (STCZ), the Sub Antarctic Front (SAF) and Subtropical Front (STF) which border it, and the region north of the STF. Brooding birds mainly used the SAF and Polar Frontal Zone (PFZ). Significantly different areas were used between years during both breeding stages. This population showed a lack of consistent habitat preferences which may offer resilience to progressive climatic variability and change. Interactions of sooty albatrosses, as well as white-chinned petrels for comparative purposes, with fisheries were also assessed. The two species were compared to shed light on possible explanations for differences in seabird-fishery interactions between the species. The impact of fisheries-related mortality (bycatch) is dependent on exposure to fishing activity and attraction to fishing boats encountered while foraging. Bycatch mortality has previously been proposed as the main cause of this sooty albatross population’s decline. Exposure and 6 attraction to fishing boats was found to be lower than that of white-chinned petrels which are bycatch prone. However, the current level of attraction exhibited by this sooty albatross population may expose a significant fraction of the population to bycatch risk due to its small population size. Additionally, all fishing boats were encountered north of the STF where non breeding individuals are now known to be distributed. Thus, the impact of fisheries on this population may mainly be mediated by more bycatch prone non-breeding individuals. Overall, the relative impact of fisheries bycatch mortality is suggested to be higher than that of climatic impacts on the sooty albatross population on Marion Island. However, this study did not incorporate dietary and demographic information which would reveal whether there are nutritional differences between years that may impact on breeding success. An integrated rather than independent assessment of foraging behavioural responses to climatic variability and fishing activity is recommended for improving our understanding of current and future conservation priorities.
- Description
- Thesis (MSc) -- Faculty of Science, Zoology , 2021
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (112 pages)
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
- Rights
- All Rights Reserved
- Rights
- Open Access
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | SBanda_MSc_Dec2021_Final.pdf | 3 MB | Adobe Acrobat PDF | View Details Download |