(van Beneden, 1881) - Hector's dolphin
Distinctive Characteristics
The typical robust Cephalorhynchus body shape is evident in this species. The head is blunt, the dorsal fin is low and rounded, and the flippers are rounded at the tips.
The predominant colour of Hector's dolphin is light grey. The dorsal fin, flukes, flippers, area around the blowhole, and much of the face are dark grey to black. Ventrally, the animals are largely white. The lower part of the head, starting just behind the black lower jaw tip is white, as is the area from just behind the flippers to the urogenital area. Arms of white from this patch also extend part way up the sides. The white ventral patches can be invaded by black between the flippers, or can be completely separated by a continuous black area. There are also small white axillary and dark grey urogenital patches (the latter are smaller and not apparent in some females).
The mouth of a Hector's dolphin contains 24 to 31 fine pointed teeth in each row.
Can be confused with
Other dolphins (common, dusky, bottlenose, etc.) are found around New Zealand, but should be easy to distinguish from the small Hector's dolphin, largely on the basis of size and dorsal-fin shape.
Size
Hector's dolphin adults reach lengths of 1.5 m (females are slightly larger than males), and newborns are about 60 to 70 cm long. Weights of up to 57 kg have been reported.
Geographical Distribution
This dolphin is endemic to New Zealand. They are found in shallow coastal waters, and are most common off South Island and the west coast of North Island.
Biology and Behaviour
The habits and biology of Hector's dolphin have been well studied only in the last few years. They live in groups of 2 to 8 individuals. Larger aggregations of up to 50 can be seen at times. These are active, acrobatic dolphins, and they are known to engage in bowriding activity. Photo-identification studies have demonstrated that at least some individuals are resident in small areas year-round.
The calving season is in the spring through early summer.
Hector's dolphins engage in opportunistic feeding on several species of small fish and squid.
Exploitation
The catch of large numbers of Hector's dolphins in coastal gillnets, many of them used by recreational fishermen, has been documented in recent years. Due to evidence that the catches were seriously threatening the estimated 3,000 to 4,000 Hector's dolphins around New Zealand, the government of that country created a marine mammal sanctuary in 1989 to protect them.
IUCN Status
Indeterminate.