New Zealand Dolphin Facts and Habitat Explained

New Zealand is home to several dolphin species, but did you know that the most common one is the bottlenose dolphin? They can be found in the country's coastal waters, particularly in the Hauraki Gulf.

The bottlenose dolphin is a social creature, often swimming in groups of up to 100 individuals. These groups are usually led by a dominant male.

These dolphins are known for their intelligence and have been observed using tools to help them hunt for food. They've even been seen working together to herd fish into tight groups, making it easier to catch them.

In New Zealand, bottlenose dolphins can be found in both the North and South Islands, with the majority residing in the Hauraki Gulf.

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Hector's dolphin is the smallest dolphin species, with mature adults reaching a total length of 1.2-1.6 meters and weighing 40-60 kilograms.

Their body shape is stocky, with no discernible beak, and the most distinctive feature is the rounded dorsal fin with a convex trailing edge and undercut rear margin.

At birth, Hector's dolphin calves have a total length of 60-80 centimeters and weigh 8-10 kilograms, with a coloration similar to adults but with a darker grey hue.

Newborn Hector's dolphins have distinct fetal fold marks on their flanks that cause a change in coloration pattern of the skin, which are visible for approximately six months and consist of four to six vertical light grey stripes against darker grey skin.

Hector's dolphins live to around 20-25 years old, which is similar to humans living until we are 85-90 years old.

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Hector's dolphin is the smallest dolphin species, with mature adults reaching a total length of 1.2–1.6 m (3 ft 11 in – 5 ft 3 in) and weighing 40–60 kg (88–132 lb).

The species is sexually dimorphic, with females being about 5–7% longer than males.

Their body shape is stocky, with no discernible beak.

The most distinctive feature is the rounded dorsal fin, with a convex trailing edge and undercut rear margin.

At birth, Hector's dolphin calves have a total length of 60–80 cm (24–31 in) and weigh 8–10 kg (18–22 lb).

Hector's dolphins spend their day between feeding and play, and love to surf on waves, play with seaweed, and are incredibly friendly and inquisitive creatures.

They make frequent short dives to find food, such as flounder, red cod, crabs, kahawai, mackerel, and squid.

Their rounded black dorsal fin is shaped like a Mickey Mouse ear, and their bodies are a distinctive grey colour, with white and black markings.

Hector's dolphins are classed as “nationally endangered” with their population thought to be around 10,000.

Their lifespan is around 20-25 years old, similar to humans living until we are 85-90 years old.

Hector's dolphins use high-frequency echolocation clicks, which are similar to those used by the hourglass dolphin.

These clicks are produced at a lower source level due to the crowded environment, which limits the distance they can spot prey to half that of an hourglass dolphin.

The species has a very simple repertoire with few types of clicks, as well as little audible signals in addition to these clicks.

In fact, more complex clicks are only observed in large groups of Hector's dolphins.

Hector's dolphins can be found in murky coastal waters out to 100 m depth, though most sightings are in waters shallower than 50 m.

They display a seasonal inshore-offshore movement, favouring shallow coastal waters during spring and summer, and moving offshore into deeper waters during autumn and winter.

Their inshore-offshore movement is thought to relate to seasonal patterns of turbidity and the inshore movements of prey species during spring and summer.

Hector's dolphins are most abundant off the East Coast and West Coast of the South Island, particularly around Banks Peninsula, with smaller populations scattered around the island.

The estimated total population size of Hector's dolphins in the South Island is 14,849, almost twice the previous estimate.

Māui dolphins, on the other hand, are typically found on the west coast of the North Island between Maunganui Bluff and Whanganui, with an estimated population of just 54 individuals aged 1 year or older.

Akaroa Harbour is a must-visit destination for wildlife enthusiasts, with a high success rate of spotting Hector's dolphins.

Located in a prime location for spotting Hector's dolphins, Akaroa Harbour is a great place to observe these marine animals.

White-flippered penguins and New Zealand fur seals can also be found in the harbour, making it a great spot for a variety of wildlife sightings.

Orcas, humpback whales, and other dolphin species can occasionally be spotted in the harbour, thanks to its position on a migration route.

You can't guarantee a sighting, but the harbour's unique location makes it an ideal spot for dolphin watching.

Hector's dolphins can be found in murky coastal waters, extending as deep as 100 meters, but most sightings are in waters shallower than 50 meters.

They prefer shallow coastal waters during the spring and summer months.

Their favorite habitats are shallow coastal waters, where they can be found during the warmer seasons.

In the autumn and winter, they move offshore into deeper waters.

They tend to return to the same location during consecutive summers, showing a strong preference for familiar foraging sites.

Their inshore-offshore movement is thought to be linked to seasonal patterns of turbidity and the inshore movements of prey species during the spring and summer.

Hector's and Māui dolphins are endemic to the coastal regions of New Zealand, with Hector's dolphins being most abundant in high turbidity areas around the South Island.

The Hector's dolphin sub-species is found in discontinuous regions off the East Coast and West Coast, particularly around Banks Peninsula. Smaller populations are scattered around the South Island, including Cook Strait, Kaikōura, Catlins, and Otago coasts.

Māui dolphins are typically found on the west coast of the North Island between Maunganui Bluff and Whanganui.

An aerial survey of South Island Hector's dolphin abundance estimated a total population size of 14,849 dolphins, which is almost twice the previous estimate.

The estimated population size of Māui dolphins is a staggering 54 individuals aged 1 year or older.

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Conservation efforts are crucial for the New Zealand dolphin population. The New Zealand Whale and Dolphin Trust has been instrumental in continuing a long-term research program on the Doubtful Sound dolphins.

Researchers have been studying the dolphins' habitat use, ecology, behavior, and population trends for over 20 years. The population has experienced periods of decline, including in the early 2000s.

A sudden change in calf survival in 2002 halved the population's growth rate and has stayed low ever since. This decline is attributed to potential impacts from tourism, long-term fishing, and freshwater discharge from the Manapouri power station.

Tourism can affect the dolphins' behavior, especially when tour boats approach them at speed or head-on. Thankfully, vessel behavior has improved, and tourism companies follow a code of practice to reduce impacts.

The Manapouri power station's freshwater discharge can be a challenge for the dolphins, especially during winter and spring when the water temperature is cold. This can stress the dolphins, especially the females and their calves.

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Human impacts are a serious concern for New Zealand's dolphin populations. The use of gillnets, in particular, poses a significant threat to their survival.

Any threat to Māui dolphins is of serious concern due to their small population size. Increased fishing activities, diseases, oil and gas exploration, boat strike, seabed mining, coastal development, tourism, and noise are all potential hazards.

Fishing restrictions have been implemented to help mitigate these threats. For example, commercial gill-netting was effectively prohibited out to 4 nautical miles offshore in the Banks Peninsula Marine Protected Area, established in 1988.

Human impacts have a significant effect on coastal areas, particularly for marine life like Hector's and Māui dolphins.

Increased risk from fishing, especially the use of gillnets, poses a serious threat to these dolphin populations.

Other human activities like oil and gas exploration, boat strike, seabed mining, coastal development, tourism, and noise also contribute to the decline of these dolphin populations.

Any threat to these dolphins is of serious concern, given their small population size.

Fishing restrictions have been put in place to protect Hector's and Māui dolphins, including the prohibition of commercial gill-netting in some areas and seasonal restrictions on recreational gill-netting.

These restrictions have been implemented in various marine protected areas (MPAs) and sanctuaries, such as the Banks Peninsula Marine Mammal Sanctuary, which was expanded in 2020 to include restrictions on seismic surveying and seabed mining.

Hector's dolphins have a few main predators that we know about. The broadnose sevengill shark is considered their main predator, and their remains have been found in the stomachs of these sharks.

Great white sharks and blue sharks are also known to prey on Hector's dolphins, with their remains often discovered in the stomachs of these sharks.

Unconfirmed predators of Hector's and Māui dolphins include killer whales, mako sharks, and bronze whaler shark, but more research is needed to confirm this.

The New Zealand dolphin has some close relatives in the ocean. The most similar species to the New Zealand dolphin is the Commerson's dolphin, which is also a small dolphin that inhabits the coastal waters of the southern hemisphere.

The Commerson's dolphin, like the New Zealand dolphin, is known for its distinctive coloration and social behavior. They are both highly social animals that live in large groups and have been observed playing and interacting with each other in the wild.

In terms of physical characteristics, the Commerson's dolphin is slightly smaller than the New Zealand dolphin, but they share many similarities in their body shape and dorsal fin.

Hector's and Māui dolphins have a unique feature in common - a rounded black dorsal fin. This distinctive fin is a key characteristic of both species.

They also share a similar way of communicating, using short ultra-high-frequency clicks and other methods like touching, visual clues, slapping their tail on the water, or leaping into the air.

Both species are revered as a taonga to Māori and are known by a variety of names, including tutumairekurai, papakanua, upokohue, tukuperu, tūpoupou, pahu, pōpoto, and hopuhopu.

Bottlenose dolphins are closely related to other dolphin species, including the Atlantic spotted dolphin and the Indo-Pacific bottlenose dolphin. They share similar physical characteristics, such as their distinctive dorsal fin and curved beak.

One of the most notable similarities between bottlenose dolphins and the Atlantic spotted dolphin is their social behavior. Both species are known to form long-lasting social groups.

Bottlenose dolphins are also similar to the Indo-Pacific bottlenose dolphin in their diet, primarily consisting of fish, squid, and crustaceans. They have been observed using complex hunting strategies to catch their prey.

Their intelligence and ability to communicate with each other are also traits shared with the Indo-Pacific bottlenose dolphin.

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Māui dolphins are the smallest and rarest dolphins in the world, with only 63 individuals over 1 year old remaining.

They have a unique dorsal fin, which is rounded and black, unlike the curved and pointed fin of other dolphin species.

Māui dolphins don't start breeding until they're at least 6 years old and may only produce one calf every 2-3 years, resulting in a population growth rate of only about 2% a year.

Their lifespan is relatively short, typically lasting only 20 years.

Māui dolphins are often slightly smaller than Hector's dolphins, and have larger skulls and a longer, wider rostrum.

They're found on the upper west coast of the North Island, whereas Hector's dolphins are found almost exclusively around the coast of the South Island.

Let's talk about the other species of dolphins that can be found in New Zealand's waters. There are 15 other species recorded around the coast, including the bottlenose and common dolphins.

The dusky dolphin is one of the most commonly seen species, and it's known for its distinctive rounded forehead. Another large dolphin species is the orca, also known as the killer whale, which is actually a member of the dolphin family despite its name.

Pilot whales are also found in New Zealand waters and are known for their social behavior, often swimming in large groups.

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