New Techniques for Underwater Video Photography of Line Fishing and Their Application in Shark Depredation Studies

There is an increasing need to understand the interaction of marine fauna with line fishing, both recreational and commercial, particularly in regions where shark depredation has become an increasing issue. The dynamic nature of the fishing requires underwater filming techniques that can move with the fishing activity and capture high-resolution footage enabling the identification of fauna species. In the case of shark depredation, the development of deterrent devices specifically designed for use while line fishing will require underwater footage to determine the effectiveness of those devices designed to invoke avoidance behaviours in sharks that approach hooked fish. Two new and inexpensive mounting systems were developed, enabling a range of “action” cameras to be attached to fishing lines to capture underwater footage while line fishing. Using these mounting systems with GoProTM cameras, high-resolution video was obtained during line fishing trials in which the effectiveness of shark deterrents was investigated. The video footage enabled the identification of fish and shark species and recorded any avoidance behaviours of sharks, in response to the presence of deterrents.