Modelling the movements of flapper skate (Dipturus intermedius) in relation to a Scottish Marine Protected Area

Abstract

1. Movement shapes the lives of animals and their interactions with human activities. In recent decades, the emergence of movement ecology as a discipline and developments in electronic tagging and tracking have led to substantial improvements in our understanding of animal movement and its implications for species conservation. Yet while research has burgeoned for many taxa, including sharks, other groups in aquatic ecosystems, such as skate (Rajidae), remain comparatively understudied.

2. The flapper skate (Dipturus intermedius) is a large, Critically Endangered elasmobranch. The species has been extirpated from much of its former range, but individuals are still found off west Scotland where the Loch Sunart to the Sound of Jura Marine Protected Area (MPA) has been designated for flapper skate conservation. However, skate movements within and around the MPA remain poorly understood.

3. This thesis investigates the movements of flapper skate in relation to the MPA using electronic tagging and tracking data from passive acoustic telemetry, archival (depth and temperature) tags and mark-recapture angling. Objectives include the examination of site affinity, vertical movements and responses to disturbance. Research in these areas motivates the development of a flexible, mechanistic modelling framework for passive acoustic telemetry systems.

4. For flapper skate, the key finding is the prevalence of site affinity to the MPA. Vertical movements are shaped by depth-specific periodic behaviours and individual variation. These movements can be perturbed by angling, but on the whole skate appear to be behaviourally resilient to this practice.

5. Beyond flapper skate, this thesis highlights multifarious uses of electronic tagging and tracking data, brings underutilised analytical methods to the attention of the movement ecology community and establishes a holistic framework for movement modelling in passive acoustic telemetry systems. This work demonstrates the wide-ranging contributions of species-specific studies in the fields of movement ecology and conservation.