Table 1.
Satellite tag deployment details and movement descriptors from the filtered Argos location data.
Figure 1.
Filtered satellite tag derived locations of pygmy blue whales (n = 11) by month.
Individuals were tagged in March (2011: n = 7) and April (2009: n = 3; 2011: n = 1) in the Perth Canyon. The northern terminus of migration occurred in Indonesia. A single whale was tracked intermittently until February 2012 at which time it was located in the subtropical frontal zone.
Figure 2.
Pygmy blue whale migration (n = 11) towards Indonesia in relation to 2° bins of latitude.
a) Distance to coastline (km), b) bathymetric depth (m) and c) distance travelled per day (km). All bars represent mean values with 95% confidence intervals. Map of Australia is included to indicate the position of each longitudinal bin in relation to the Australian and Indonesian coastline.
Figure 3.
Positional information for pygmy blue whales.
Catches (x), sightings (○), strandings (Δ), acoustic recordings (□) and discovery marks (∇) collected up to and including 1973 when whaling stopped (red) and after 1973 (blue). Modified from [4].
Figure 4.
Gridded measures of time spent and occupancy for satellite tagged pygmy blue whales (n = 11).
a) Total time spent, b) number of whales, c) measure of occupancy 1: proportion of time spent per grid square per individual summed across all individuals and d) measure of occupancy 2: sum of individual time spent per grid square adjusted by the contribution to total time spent by all individuals for all pygmy blue whales throughout the tracking period. Four regions of potentially higher occupancy are indentified in Fig. 4d): A. Indonesia, B. Ningaloo Reef, C. Perth Canyon/Naturaliste Plateau and D. Subtropical frontal zone. The grid presented is 100 km×100 km. GEBCO bathymetry is also shown.
Figure 5.
Boxplots describing the oceanographic characteristics of the four regions of potentially higher occupancy as identified in Fig. 4d.
A. Indonesia (n = 324), B. Ningaloo Reef (n = 106), C. Perth Canyon/Naturaliste Plateau (n = 396) and D. Subtropical frontal zone (n = 78): a) bathymetric depth (m), b) sea surface temperature (°C) and c) chlorophyll a concentration (mg m−3).