The habits and biology of Hector's dolphin have been well studied in the last couple of decades, and this is undoubtedly the best-known species of the genus (Dawson 2002). It is found in shallow coastal waters, almost always within about 15 km of shore and <100 m deep, strongly concentrated in shallow, turbid waters close to shore in summer months and dispersing more widely in winter (Slooten et al. 2006a). Photo-identification studies have demonstrated that at least some individuals are resident in small areas (about 30 km of coastline) year-round (Slooten et al. 1993). No two sightings of an individual have been more than 106 km apart (Bräger et al. 2002).

Hector's dolphins feed on several species of small fish and squid (Dawson 2002). The diet is more varied on the east coast of the South Island (8 species make up 80% of the diet) than on the west coast (only 4 species make up 80%).

Hector’s Dolphin is endemic to New Zealand, and it has one of the most restricted distributions of any cetacean (Dawson and Slooten 1988; Dawson 2002). They are most common off the South Island and the west coast of the North Island. There are at least three genetically separate populations in the South Island, and a single small North Island population (C. h. maui - Baker et al. 2002).

The map shows where the species may occur based on oceanography. The species has not been recorded for all the states within the hypothetical range as shown on the map. States for which confirmed records of the species exist are included in the list of native range states.

The species is listed in CITES Appendix II.

The entire range is within New Zealand waters, and therefore national conservation measures are discussed here. The New Zealand Government has created two protected areas to promote the conservation of C. hectori, and it is thought that these areas have contributed to reduced mortality in recent years. The Banks Peninsula Marine Mammal Sanctuary was established in 1988 under the Marine Mammals Protection Act to protect Hector’s dolphins. The 1,170 km² sanctuary extends 70 nautical miles alongshore around the Banks Peninsula to the Rakaia River and out to 4 nautical miles offshore (Dawson and Slooten 2005). Its effectiveness has been compromised by the interests of sports and commercial fishermen and by the fact that the dolphins’ offshore distribution extends beyond the protected area (Dawson and Slooten 1993). At Banks Peninsula the dolphins are found further offshore than elsewhere, probably because the bathymetry there slopes more gradually. Up to 65% of the dolphins in the area occur outside the sanctuary boundaries in winter months (Slooten et al. 2006a).

The protected area established for Maui’s dolphins stretches for 210 nautical miles along the west coast of the North Island out to 4 nautical miles offshore. Although this area was closed to gillnetting under the Fisheries Act in 2003, gillnetting has continued inside the harbors, and trawling is restricted only within the first nautical mile offshore (Slooten et al. 2006b).

Discussions between the Ministry of Fisheries and Department of Conservation are currently (early 2008) underway to develop a more comprehensive management plan. A continuing high level of bycatch mortality indicates that stronger protection from entanglement in commercial and recreational fisheries is needed. Protected areas, reduced gillnet fishing effort and changes in fishing methods have been recommended as necessary to ensure the species’ long-term persistence (e.g. Martien et al. 1999, Burkhart and Slooten 2003, Slooten 2007; DOC and Mfish 2007). Meetings of stakeholders have concluded that fishery mortality must be reduced to zero to allow the North Island subspecies to recover (Dawson et al. 2001; Slooten et al. 2006a). Several other small subpopulations (100 individuals or fewer) are at a similar risk from entanglement (Burkhart and Slooten 2003; Slooten 2005). Recent surveys (Dawson et al. 2004, Slooten 2005, Slooten et al. 2006a,b) indicate that restricting gillnet fisheries to waters >100 m deep would have a major benefit in terms of reducing bycatch. In waters <100 m deep it would also be advisable to institute observer programs on any trawl fisheries that operate in Hector’s dolphin habitat.