Akaroa Harbour is well known for playing host to the beautiful Hector’s dolphins. They are among the world’s smallest marine dolphins and extensive conservation work is being carried out to protect these fantastic creatures, which are found only in the inshore waters of New Zealand.
Two sub-species of Hector’s dolphins exist: the South Island Hector’s dolphin which is found around the South Island of New Zealand, and the Maui’s dolphin which is found off the west coast of the North Island.
What do they look like?
They are the only dolphins in New Zealand with a wellrounded black dorsal fin. Their bodies are a distinctive grey, with white and black markings and a short snout.
Adult South Island Hector’s dolphins don’t often exceed 1.5 metres in length and weigh between 40 and 60 kg. Males are slightly smaller and lighter than females.
Where are they found?
Hector’s dolphins are found around the coast of the South Island but distribution is patchy. Populations are concentrated between Haast and Farewell Spit in the west, around Banks Peninsula in the east, and Te Waewae Bay and Porpoise Bay/Te whanaga aihe in the south.
- Hector’s dolphins are known to live to a maximum of about 20 years.
- Like other dolphins, Hector’s use echolocation to find their food. They send out high frequency ‘clicks’ that bounce off surrounding objects and fish, giving the dolphins a detailed picture of their surroundings. This sonar is not used all the time, which may be one of the reasons why the dolphins get caught in nets.
- Females reach sexual maturity between seven to nine years of age. They produce just one calf every two to three years, making population increase a very slow process.
- Most females only have four or five calves in a lifetime. Calving usually occurs between November and mid-February, and calves stay with their mothers for up to two years.
- Traditionally, Māori watched dolphin movements to predict the weather.
- Hector’s dolphins are the smallest and one of the rarest marine dolphins in the world.
- A marine mammal, they live in the sea but breathe air.
- The Hector’s dolphin was named after Sir James Hector, who was the curator of the Colonial Museum in Wellington (now Te Papa). He examined the first specimen found of the dolphin. Sir James lived from 1834 to 1907. He was the most influential New Zealand scientist of his time.
- They swim in pairs, or in groups of up to 12.
- Once distributed in waters all around the New Zealand coast line, these very special animals have now declined to just above 7000 individuals and have been fragmented to a degree that threatens their survival.
- Both the South Island Hector’s dolphin and the North Island Maui’s dolphin are listed internationally as Species Threatened with Extinction. Maui’s dolphin are listed as “Critically Endangered”, as there are only an estimated 55 individuals left!
- They prefer shallow water (usually less than 100m) and usually stay within a home range of about 30 km of coastline all their lives.
- They feed on fish throughout the water column, including fish that dwell near the seafloor in shallow, often sandy bottomed waters, making frequent short dives to find food, such as flounder, red cod, mackerel, crabs and squid.
- Hector’s dolphins are similar to the endangered parrot the kakapo, in that they do not breed very often, which causes problems for the species’ survival. Female dolphins only produce one calf every 2-4 years and do not start breeding until they are seven to nine years old. This slow rate of reproduction makes Hector’s dolphin populations particularly vulnerable to deaths caused by human activities such as fishing.
- The single biggest threat to Hectors dolphins is gill nets. Dolphins are accidentally caught in nets and drown.
- The lungs of Hector’s dolphin are small, only about the size of human lungs, so they drown in about the same period of time a human would if they get tangled in set nets.
- Hector’s dolphin deaths from fishing must be zero to ensure the species’ survival. Set nets are banned or heavily restricted in many countries worldwide, including Australia, the UK and USA
Many thanks to Forest & Bird and the Department of Conservation for their continued efforts to protect Hector’s dolphins and for the information provided above. Please visit their websites to find out more about these special animals and for details about the best ways to safely enjoy seeing them whilst in Akaroa.