This PhD project will investigate killer whale predation of harbour seals with the ultimate goal to inform their conservation. The key objectives are to 1) provide age stage-specific (e.g. adult/pup) estimates of grey and harbour seal consumption by killer whales in coastal waters of Scotland, 2) quantify spatial and temporal variation in seal predation, and 3) investigate whether predation rates could lead to observed declines in harbour seal population numbers.
The project will take a bioenergetics approach1–3 with a focus on integrating and modelling existing datasets, but which can be supplemented by new field data. Available datasets include: citizen science sighting databases, concurrent killer whale sightings and tagged seal movement data, passive acoustic monitoring data, and overhead video of killer whale foraging behaviour. There is also scope to work with individual photo-identification data. The student will be expected to contribute towards the design and collection of field data in Shetland.
Foraging animals make decisions about where, when, and what to eat, the outcome of which can be critical to determine their fitness. Animals that are prey to others must also balance foraging benefits and safety from predation. Responses such as fleeing to a refuge can cost prey time and energy but ensure their survival4,5. Predators, in turn, must respond strategically to prey behaviour to maximise their foraging success. Predator-prey interactions provide a mechanistic basis to predict food web structure and understand the dynamics and resilience of ecological communities6.
Harbour (Phoca vitulina) and grey (Halichoerus grypus) seals are closely related species with overlapping distributions in the UK. Killer whale (Orcinus orca) predation of both species is frequently observed in some parts of Scotland; however, the scale of predation is largely unknown7,8. In contrast to sub-populations of Pacific killer whales (‘ecotypes’), killer whales in the Atlantic may feed on both mammal and fish prey9–11. Their prey selection is likely to be influenced by both prey availability (distribution and abundance) and traits (e.g., age class, body size). For example, grey seals are larger in size and are more abundant than harbour seals in Scotland but tend to forage further offshore12.
The project will provide the PhD student with training in both empirical and theoretical approaches to behavioural ecology and energetics, with a strong emphasis on quantitative methods. While the project is partly motivated by the need to inform harbour seal population management13, the student will also have freedom to pursue related fundamental scientific questions. The existing datasets can be used to address questions such as: to what extent can acoustic detection play a role in the interaction? Do seals exhibit anti-predator behaviour in their movements? How much energy do killer whales spend capturing seals? How does killer whale predation risk vary in space and time?
The student will be part a growing network of high calibre environmental scientists through the SUPER doctoral training partnership (https://superdtp.st-andrews.ac.uk/
). SUPER provides students with inter-institutional support and shared training opportunities. All students will participate in two main cohort-building events per year; the Annual Science Meeting and the Annual Retreat. Students are also registered for the SUPER Post Graduate Certificate in Researcher Professional Development.
Applicants should have a degree in biology or a related subject. A quantitative background is desirable, and relevant analysis skills (e.g. acoustic data processing) and field experience would be an advantage. Please provide a cover letter, a scientific writing sample (e.g., extract from thesis; max 1000 words excluding bibliography), CV, and two references. In your cover letter, please describe, with examples, your 1) ability to work effectively in a team and liaise with a range of stakeholders, 2) willingness to work outdoors and in sometimes remote & challenging conditions, 3) ability to integrate and critically analyse different sources of information or data, and 4) motivation and suitability for the project, including desired training. Please also ensure your academic history (grades, thesis work, any publications or prizes) are clearly presented in the CV.
This PhD will be supervised by Saana Isojunno, Gordon Hastie and Peter Tyack (SMRU, SOI, University of St Andrews), Ross Culloch (Marine Scotland Science) and Karen Hall (Scottish Natural Heritage). For more information about the project please visit https://ecopreds.wordpress.com
. Informal enquiries should be directed to Isojunno ([email protected]
Studentships commence: 27 September 2020.
We are unlikely to be able to consider any international (non-EU) applications. SUPER has a cap of 10% for international recruitment and is generally reserved to cases when there are few qualified applicants.
1. Williams, T. M., Estes, J. A., Doak, D. F. & Springer, A. M. Killer appetites: assessing the role of predators in ecological communities. Ecology 85, 3373–3384 (2004).
2. Testa, J. W. et al. Agent-based modeling of the dynamics of mammal-eating killer whales and their prey. Mar. Ecol. Prog. Ser. 466, 275–291 (2012).
3. Noren, D. P. Estimated field metabolic rates and prey requirements of resident killer whales. Mar. Mammal Sci. 27, 60–77 (2011).
4. Brown, J. S., Laundré, J. W. & Gurung, M. The Ecology of Fear : Optimal Foraging , Game Theory , and Trophic Interactions. J. Mammal. 80, 385–399 (1999).
5. Brown, J. S. & Kotler, B. P. Hazardous duty pay and the foraging cost of predation. Ecol. Lett. 7, 999–1014 (2004).
6. Portalier, S. M. J., Fussmann, G. F., Loreau, M. & Cherif, M. The mechanics of predator–prey interactions: First principles of physics predict predator–prey size ratios. Funct. Ecol. 33, 323–334 (2019).
7. Bolt, H. E., V, H. P., Laura, M. & Foote, A. Occurrence of killer whales in Scottish inshore waters: temporal and spatial patterns relative to the distribution of declining harbour seal populations. Aquat. Conserv. Mar. Freshw. Ecosyst. 19, 671–675 (2009).
8. Deecke, V. B., Nykänen, M., Foote, A. D. & Janik, V. M. Vocal behaviour and feeding ecology of killer whales orcinus orca around Shetland, UK. Aquat. Biol. 13, 79–88 (2011).
9. Foote, A. D., Kuningas, S. & Samarra, F. I. P. North Atlantic killer whale research; past, present and future. J. Mar. Biol. Assoc. United Kingdom 94, 1245–1252 (2014).
10. Samarra, F. I. P. et al. Prey of killer whales (Orcinus orca) in Iceland. PLoS One 13, e0207287 (2018).
11. Jourdain, E. et al. North Atlantic killer whale Orcinus orca populations: a review of current knowledge and threats to conservation. Mamm. Rev. 49, 1–17 (2019).
12. Thompson, P. M., Mcconnell, B. J., Tollit, D. J., Mackay, A. & Racey, P. A. Comparative Distribution , Movements and Diet of Harbour and Grey Seals from Moray Firth. J. Appl. Ecol. 33, 1572–1584 (1996).
13. SCOS. Scientific advice on matters related to the menagement of seal populations: 2017. Scientific Advice on Matters Related to the Managment of Seal Populations: 2015 (2017). doi:10.1038/213644a0