Summer and autumn movements of white whales Delphinapterus leucas in Svalbard, Norway

Abstract

Fifteen adult white whales Delphinapterus leucas were fitted with satellite relay data loggers (SRDLs) in order to study their distribution and movement patterns in Svalbard. A total of 844 d of tracking data was recorded. The average longevity of the SRDLs was 56 ± 30 (SD) d (range 7 to 120 d). The tracking data were analysed using a computer visualisation system, which allowed the movement patterns to be animated against a background map of the study area. This enabled classification of the whales' tracking data into 4 major activity patterns: (1) glacier front stationary (55.6 % of the time), (2) in-fjord movements (10.6 % of the time), (3) coastal movements (26.0 % of the time), and (4) coastal stationary (7.8 % of the time). The whales spent most of their time relatively stationary, close to different glacier fronts in the area. These areas are known to have a high abundance of potential prey species for white whales, so foraging is the probable reason for this behaviour. When the whales changed location, they did so in an apparently directed and rapid manner. Average horizontal swimming speed was at least 6 km h-1 during long-distance movements. Movements between glacier fronts were extremely coastal in nature and took place in shallow waters. This behaviour has probably developed as a means of avoiding predators.