Figure 1.
Mapping of blows by a pod of humpback whales.
A: Whale blow locations (triangles) relative to the (moving) ship (ship is at center of concentric circles). B: Map of corresponding geo-referenced ship positions (dots) and blow locations (triangles). Color indicates time after first detection.D.
Figure 2.
Night-time thermographic video snippets (at 0.2 s resolution) of whale blows:
A) 24.03.2012 00:07; 61.11°S 56.36°W; Twater = 1.3°C; Tair = −1.7°C; r = 3608 m; B) 28.03.2012 03:27; 61.88°S 60.29°W; Twater = 1.4°C; Tair = 2.3°C; r = 3608 m; C) 29.12.2011 01:06; 56.49°S 00.00°E; Twater = −0.8°C; Tair = −0.5°C; r = 1116 m; D) 01.01.2012 02:38; 43.96°S 07.44°E; Twater = 8.8°C; Tair = 8.7°C; r = 879 m; Figure 2E: Day-time thermographic (top) and visual (bottom) video snippets of an automatically detected whale blow: 28.12.2011 14:41; 58.65°S 0.02°E; Twater = −1.5°C; Tair = −0.6°C; r = 1072 m;
Figure 3.
Detection performance and efficiency.
A: Cue-based classifier ROC curves for training, testing and two (day and night) validation datasets. AUC values: Training: 0.99; Testing: 0.98; Validation day: 0.90; Validation night: 0.98. B: Lines with error bars: Proportion of successful automatic detections of all visually detected blows (black), and proportion of visually detected blows of all automatic detections (grey) versus distance (bin width of 1 km). Errorbars give the standard error. Bar plot: Number of automatic (black) and visual (grey) detections versus distance.
Figure 4.
Probability of a whale being at the surface within a detection radius r before it is within the exclusion zone (radius 500 m, acoustic source towed 500 m behind the ship, see Figure S3) as a function of diving time. Ship speed is assumed to be 4.5 knots. Colored areas indicate different maximum radii over which whales can be reliably detected (1, 3 and 5 km). Upper limits of filled areas correspond to the maximum, lower limits to the minimum known surface times. Mean values for various whale species are indicated by letters: A = Arnoux’s beaked whale, B = Blainville’s beaked whale, b = blue whale, C = Cuvier’s beaked whale, f = fin whale, h = humpback whale, k = killer whale, m = minke whale, n = northern bottlenose whale, p = pilot whale, r = right whale, s = sei whale, sp = sperm whale. Letters are only displayed for a detection radius of 1 km. Within in the blue (3 km) area, circles and dots vertically aligned with letters indicate whether the underlying data represents single measurements (dots) or group averages (circles). Light grey symbols represent odontocetes, black symbols mysticetes.