Investigating the drivers of vertical movement patterns in predatory pelagic fishes

Large fishes of the epipelagic zone of the oceans and coastal seas display a variety of patterns of vertical movement. This thesis aims to improve our understanding of the underlying factors structuring these movement behaviours using data from recovered biologging and satellite tags at both fine- and large-scales. I argue that characteristic patterns of vertical movement, particularly oscillatory descents and ascents, result from the need for gill-breathing animals to move continuously in a three-dimensional environment whilst optimising food encounter rates, energy expenditure, and remaining within the limits imposed by the physical environment on their physiology.