Hector's dolphin (C. hectori) is endemic to
waters (Dawson and Slooten 1988). The North Island subpopulation (C. h. maui) is currently restricted to the west coast of the North Island of New Zealand, between Taranaki and Ninety Mile Beach (Russell 1999; Baker et al. 2002; Slooten et al. 2005, 2006). The range of the subspecies has undergone a marked reduction (Dawson et al. 2001; Slooten et al. 2005). Previous sightings off the east coast of the North Island (e.g., Russell 1999) suggest either that there used to be a much larger contiguous population or that a separate subpopulation on the New Zealand North Island has already become extinct.