Oral Presentation Australian Society for Fish Biology Conference 2017

Vertical Migrations in fishes: how novel sensors elucidate the drivers of daily migrations in freshwater and marine environments (#78)

Adrian Gleiss 1 , Stephen Beatty 1 , Brad Norman 1 , David Morgan 1
  1. Centre for Fish and Fisheries, Murdoch University, Murdoch, WA, Australia

Diel Vertical Migrations (DVM) are phenomena that occur throughout the world’s aquatic ecosystems, where the transition from day to night results in drastic shits in the vertical distribution of organisms, from zooplankton to marine vertebrates. Current thought suggests that visual predation pressure drives prey species to depth, where darkness provides cover and foraging occurs during the day in surface waters. Despite this widely held believe, many of these ideas have rarely been tested in fishes, because quantifying the behaviour of individuals on a diel scale has remained challenging. Here we show how the use of accelerometers in animal tags can address how animal behaviour changes in relation to diel changes in depth. Moreover, we show how changing abiotic conditions can have contrasting impacts on DVMs and circadian rhythms, using examples such as estuarine black bream, epipelagic whale sharks and freshwater sawfish. Overall, the drivers behind DVMs represent a highly flexible response to diel changes in the biotic and abiotic environment and in many cases do not solely reflect a simple response to sheltering from predation.