T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Dolphin (Common) Tursiops truncatus

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Infraorder: Cetacea
Family: Delphinidae
Genus: Tursiops
Species: T. truncatus
Binomial name: Tursiops truncatus
Synonyms: Tursiops gephyreus, Tursiops gilli, Tursiops nuuanu
Common names: Common Bottlenose Dolphin, Bottle-nosed Dolphin, Bottlenosed Dolphin, Bottlenose Dolphin 

Tursiops truncatus is the most common members of the family Delphinidae, the family of oceanic dolphin are widely distributed throughout the world in cold temperate and tropical seas. They generally do not range poleward of 45°. New Zealand is therefore at the southernmost point of their range.
In New Zealand, there are three main coastal populations. In the north from Doubtless Bay to Tauranga the are about 450 individuals. There is a Westcoast group that range from Marlborough Sounds to Westport. There is a third group of approximately 65 that that lives in Doubtful and Fiordland.

Tursiops truncatus is a large dolphin growing up to 4 m long, with a dark to light grey back that fades to white on its underside and a dark stripe from eye to flipper. The colour and shape can be variable. It has a pronounced snout and the lower jaw protrudes in front of the upper. It has a prominent tall dorsal fin that is backwards-curving. There are between 18 - 26 pairs of large teeth in each jaw. Each dolphin appears to have its own distinctive whistle used to communicate information to other dolphins. They also use click-like pulses produced by nasal sacs in the forehead for echolocation.
They feed on fish, invertebrates and oceanic squid. The maximum time they spend underwater is about 7 minutes. Individual feeding appears to be the most prevalent foraging method but they also work together to herd schools of fish. Bottlenose dolphins are commonly seen feeding with pilot whales, rough-toothed and Risso’s dolphins, and whales.
Bottlenose dolphins can live up to 50 years of age. Females breed every 3-5 years and calves suckle for around 2-3 years.

Sharks are probably the most important predators of bottlenose dolphins with the numerous shark-bite scars found on as many as half of all bottlenose dolphins providing evidence of such encounters. Killer whales are also likely to be one of the main predators. Due to their coastal nature in New Zealand, the main adverse effects of human is tourism. The close presence of boats interfere with dolphins’ normal behaviour and boat strike in areas of high boating activity is always a threat.
Common sense rules should, therefore, apply when boating around dolphins to reduce stress on the animals. 

The rules listed below are from the Marine Mammal Protection Regulations (1992).

Special conditions applying to dolphins or seals
In addition to complying with the conditions set out in regulation 18, any commercial operation and any person coming into contact with dolphins or seals shall also comply with the following conditions:
(a) no vessel shall proceed through a pod of dolphins:
(b) persons may swim with dolphins and seals but not with juvenile dolphins or a pod of dolphins that includes juvenile dolphins:
(c) commercial operators may use an airhorn to call swimmers back to the boat or to the shore:
(d) except as provided in paragraph (c), no person shall make any loud or disturbing noise near dolphins or seals:
(e) no vessel or aircraft shall approach within 300 metres (1 000 feet) of any pod of dolphins or herd of seals for the purpose of enabling passengers to watch the dolphins or seals, if the number of vessels or aircraft, or both, already positioned to enable passengers to watch that pod or herd is 3 or more:
(f) where 2 or more vessels or aircraft approach an unaccompanied dolphin or seal, the masters concerned shall coordinate their approach and manoeuvres, and the pilots concerned shall coordinate their approach and manoeuvres: 
(g) a vessel shall approach a dolphin from a direction that is parallel to the dolphin and slightly to the rear of the dolphin.



 


Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0/