Figure 1: (a) Time-depth series of 12 February 2009 recorded with a standard rate X-Tag attached to a bull shark in Fiji (F14 in [14]). Each dot (96 in total corresponding to four Argos messages each containing 24 pressure readings = the full dataset for that day) indicates a depth value at 15 minute intervals. Green dots denote actual pressure readings whereas all other colours denote values transmitted as the difference between that time and the measurement made 60 minutes before. Blue dots denote delta limited descents (meaning that the bull shark likely was deeper), and yellow dots denote delta limited ascents (meaning that the bull shark likely was less deep). Excluding delta limited values, the red shaded area denotes the vertical niche calculated from archived data; the green shaded area denotes the vertical niche calculated using minimum/maximum depth values recorded at 2 minute intervals. The entire time-depth series of tag F14 (7 -16 February 2009) is shown in (b); red lines denote the time-depth series including delta limited values and daily minimum/maximum depths calculated from archived data; green lines denote the time-depth series excluding delta limited values and daily minimum/ maximum depths calculated from 2 minute sensor readings.