A preliminary study of the movement patterns of false killer whales (Pseudorca crassidens) in coastal and pelagic waters of the Northern Territory, Australia

Abstract

The false killer whale (Pseudorca crassidens) is regarded as Data Deficient globally and in Australia. In most parts of its range, there is little information on its social behaviour, dispersal or ecology. The present study is the first assessment of its movement patterns in Australian waters, on the basis of satellite tracking of four individuals, in the Arafura and Timor Seas from late March to early July 2014. When initially tagged, the four individuals occurred in a single group; they then showed generally similar movement patterns and regularly re-associated. Total distance travelled by tagged individuals ranged from 5161km (over a 54-day period) to 7577km (104 days). Distance from land varied from 100m to 188km (median distance 24km). Individual minimum convex polygons covered an area of 72368 to 86252km2, with a total overlap of 64038km2. Water depths varied from 0.3 to 118m (median 36m). In total, 15% of records were in waters shallower than 10m, and 26% of records were within 10km of land. The present study indicated that false killer whales appear to regularly use coastal and pelagic waters in this region and, hence, should be afforded more conservation attention.