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Doctoral defence in biology - Jed Macdonald

Thu, 03/10/2019 - 13:00 to 14:30



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Ph.D. student: Jed Macdonald

Dissertation title: Uniting models and otoliths to explore migration, connectivity and space use in marine fishes

Opponents: Dr. Audrey Geffen, Professor at theUniversity of Bergen, Norway
Dr. Pierre Petitgas, IFREMER, Nantes, France.

Advisor: Dr.Guðrún Marteinsdóttir, Professor at the Faculty of Life and Environmental Sciences,University of Iceland.

Also in the doctoral committee: 

Mr. Þorsteinn Sigurðsson, Director at the Marine and Freshwater Research Institute, Reykjavík, Iceland
Dr. Geir Huse, Director at the Marine Research Institute, Bergen, Norway.

Chair of Ceremony:  Dr. Snæbjörn Pálsson, Professor at the Faculty of Life and Environmental Sciences.


Movements of animals en masse are impressive phenomena that continue to fascinate scientists of all persuasions. Fishes display some of the most striking examples, and an extensive literature has explored the subject in marine species with long histories of commercial harvest, and/or strong, enduring cultural values. Yet, as recognition of the cognitive capacity of fishes grows, and strong inter-individual variability in behavioural traits among sympatric conspecifics is revealed as the norm, fundamental questions on the drivers underpinning both large-scale migrations, and the spatial outcomes of such moves require re-examination.

This thesis comprises five papers that focus broadly on understanding the factors that shape movement decisions, distribution patterns and connectivity in schooling marine fishes. Using Atlantic herring (Clupea harengus L.) in Iceland, and striped red mullet (Mullus surmuletus L.) in the North Sea and Eastern English Channel for illustration, the work combines new Bayesian modelling approaches with analyses of otolith (ear stone) chemistry to test the role of intrinsic (i.e. collective behaviour, demographic traits, ontogeny) and extrinsic (i.e. the environment, fishing pressure, prey availability) factors in influencing the spatial dynamics of these commercially-important species.

The outcomes highlight the natural synergy between model-based and empirical approaches in addressing questions on the movements of group-living fishes, and demonstrate how these can be integrated to guide fishery-management decisions, both under present conditions, and under future scenarios of environmental change.

About the doctoral candidate:

Jed grew up in Melbourne, Australia, his parents instilling a strong love of the ocean and fishing from an early age. After finishing high school in Melbourne, Jed moved south to Tasmania to indulge these passions further, pursuing a Bachelor of Science degree in ecology at the University of Tasmania.

This led on to a Masters in fish ecology, also at the University of Tasmania, where Jed shifted focus to rivers, exploring different options for improving the upstream passage of migrating diadromous fish in streams affected by dams and man-made barriers.

After several years working in freshwater fish research in Australia, the UK and South America, Jed made a decision to return to the marine realm and undertake a PhD at the University of Iceland. He now lives in New Caledonia, where he works on questions relating to tuna ecology and biology in the Pacific, and consumes large amounts of sustainable sashimi and French butter on a daily basis!

Jed Macdonald

Doctoral defence in biology - Jed Macdonald