Movements of Antarctic blue whales derived from Discovery tag, photo-ID, and satellite tag data
Paula A. Olson, Virginia Andrews-Goff, Michael C. Double, Koji Matsuoka, Luis A. Pastene
Whether the population structure of Antarctic blue whales consists of one or multiple populations is unresolved. A dataset combining Discovery tag (45) and photo-ID (17) inter-seasonal recaptures was examined for ocean basin fidelity and evidence of separate populations. The majority of Antarctic blue whales were recaptured within the ocean basin where they were marked (50-79%) except for the eastern Indian Ocean sector where only 20% of marked whales were recaptured. Six of seven whales with locations north of 60?S were marked and recaptured in the same ocean basin. Four of seven whales with both intra- and inter-seasonal recaptures were always recaptured within the same ocean basin as the original mark. The Antarctic Peninsula may represent a barrier of some sort in the movement patterns of blue whales south of 60?S, based on the shortest distance between mark and recapture points. The mark-recapture distances for individual Antarctic blue whales on the summer feeding grounds were highly variable. Both short and long distances between locations were exhibited by intra-seasonal recaptures. Two satellite tagged whales moved extensively during the summer season, despite periods of area-restricted search behavior assumed to be foraging. Overall, while there was a trend for ocean basin fidelity, due to small sample size these results do not discriminate between a single or multiple population structure for Antarctic blue whales.