Distribution and abundance of Hector's dolphins (Cephalorhynchus hectori) off Kaikoura, New Zealand

Abstract

Boat-based surveys of Hector's dolphins (Cephalorhynchus hectori) were conducted throughout 2013 to evaluate their distribution and abundance off Kaikoura. We conducted a total of 48 surveys and encountered 164 groups of Hector's dolphins. This study showed that Hector's dolphins off Kaikoura preferred areas of shallow, nearshore waters with poor water clarity and that there were more sightings to the north of the Kaikoura Peninsula than to the south. Using photo-identification techniques we identified 47 distinct individuals within the study area and these known individuals were only sighted either north or south of the Kaikoura Canyon. This study, combined with opportunistic sightings data collected from 2005–2013, improves our understanding of habitat use within the Kaikoura area by Hector's dolphins. These data suggest that the canyon area, characterised by very deep waters, could act as a natural barrier dividing the Hector's dolphins off Kaikoura into two separate groups.