Table 1.
Summary of tag deployments on 20 tiger sharks off northeastern Brazil.
Figure 1.
Vertical profile of the seawater temperature.
Depth-and-temperature data sampled by tiger sharks off northeastern Brazil. Colors represent months of the year to depict temperature seasonality in the mixed surface layer, which extends to about the 60-m isobath.
Table 2.
Summary of depths and temperatures experienced by tiger sharks.
Figure 2.
Representative tracks depicting the diving behavior of tiger sharks (A: T3, B: T5, C: T6, D: T7, E: T8, F: T11, G: T13, H: T15, I: T18, J: T20) off northeastern Brazil. The horizontal dashed line represents the 60-m isobath of the shelf break. The color scale represents water temperature (°C).
Figure 3.
Tiger shark vertical habitat use.
Representative tracks depicting depth use in tiger sharks (A: T3, B: T5, C: T6, D: T7, E: T8, F: T11, G: T13, H: T15, I: T18, J: T20) off northeastern Brazil. The proportion of time spent at each depth stratum is informed by the color scale; however, note the different sizes of depth strata, usually larger at greater depths.
Table 3.
Tiger shark vertical habitat use.
Table 4.
Tiger shark thermal preferences.
Figure 4.
Diel variability in vertical habitat use.
Diel behavioral shift in tiger shark depth use, as the proportion of time spent at each depth stratum, with sharks spending more time at the surface during the night time (solid bars) and more time between the 20- and 60-m isobaths during the daytime (blank bars). The error bars represent standard deviations.
Figure 5.
Lunar variability in vertical habitat use.
Tiger shark depth use, as the proportion of time spent at each depth stratum, across the four moon phases (new moon, first quarter, full moon and last quarter) of the lunar cycle. The error bars represent standard deviations.
Figure 6.
Influence of shark size on diving behavior.
Boxplots depicting the distribution of maximum diving depth (top panel) and minimum diving temperature (bottom panel) across three size-classes (large, medium and small) of juvenile tiger sharks. The box represents the first and third quartiles and the bold horizontal bar represents the median, whereas circles represent outliers. The box width is proportional to the logarithm of sample size. A total of 3169 samples were used.
Figure 7.
Influence of shark size on depth and temperature use.
Cumulative plots of the percentage of time spent by juvenile tiger sharks across consecutive depth (top panel) and temperature (bottom panel) intervals. The separation in blue (for small-sized sharks), red (for medium-sized sharks) and black (for large-sized sharks) points out to an ontogenetic shift in vertical habitat use, with larger sharks spending more time in deeper, colder waters.
Figure 8.
Generalized linear models showing the effects of shark length (top panel), diel phase (middle panel) and sex (bottom panel) on the maximum diving depth of juvenile tiger sharks. Note the different scales on the y-axes.
Figure 9.
Minimum diving temperature models.
Generalized linear models showing the effects of shark length (top-left panel), moon phase (top-right panel), diel phase (bottom-left panel) and sex (bottom-right panel) on the minimum diving temperature of juvenile tiger sharks. Note the different scales on the y-axes.
Figure 10.
Ontogenetic variability in shallow habitat use.
Generalized linear models showing the effect of shark length on the proportion of time spent by tiger sharks in surface waters. Surface waters were defined as the water layer between the sea surface and a given isobath. These isobaths were set to (A) 10 m, (B) 20 m, (C) 40 m, (D) 60 m, (E) 100 m and (F) 150 m. The 5-m isobath was not included because shark length had no significant effect on the time spent above such depth. The black dots represent the empirical data. Note the different scales on the y-axes.