Jun 15
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Endangered Species of the Week: Hector’s dolphin

Photo of Hector's dolphin pod

Hector’s dolphin (Cephalorhynchus hectori)

Species: Hector’s dolphin (Cephalorhynchus hectori)

Status: Endangered (EN)

Interesting Fact: Hector’s dolphin produces high-frequency clicks, but unlike many other dolphins it does not whistle.

Found only in New Zealand, Hector’s dolphin is one of the smallest and rarest of all marine dolphins. This species is generally light grey with darker stripes, and has a black tail, flippers and rounded dorsal fin. Females tend to be slightly larger than males. Hector’s dolphin usually occurs in small groups of up to ten individuals, but these may sometimes join together into larger aggregations. This small dolphin is found in shallow coastal waters where it feeds on fish and squid. It has one of the most restricted distributions of any cetacean, occurring mostly around the South Island of New Zealand, with a subspecies, Maui’s dolphin, found only off the west coast of the North Island.

The major threat to Hector’s dolphin comes from accidental capture in gillnets. Its coastal habitat also makes it vulnerable to other human impacts, including pollution, boat strikes and habitat modification. The South Island population of Hector’s dolphin numbers just over 7,000 individuals, but Maui’s dolphin is down to only around 55 adults, and is classified as Critically Endangered. The New Zealand government has created two protected areas for Hector’s dolphin, where the use of nets is restricted, and a management plan is in place which outlines measures to reduce the threats to this tiny cetacean.

 

Find out more about Hector’s dolphin at the New Zealand Department of Conservation, WWF New Zealand and the New Zealand Whale and Dolphin Trust.

See images and videos of Hector’s dolphin on ARKive.

Liz Shaw, ARKive Text Author

Jun 12
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ARKive’s Top Ten Whales and Dolphins

Last weekend marked World Oceans Day, a day dedicated to celebrating the beauty and bounty that our oceans provide, and raising awareness of the importance of protecting them. Here at ARKive, we’ve been inspired by the watery realm, and thought we’d honour our fellow mammals by submerging ourselves in the wonderful world of whales and dolphins.

Winged whale

Humpback whale image

An instantly recognisable species, the humpback whale is named for the distinctive ‘hump’ formed by its back as it prepares to dive. Its long flippers, another characteristic feature, can grow up to five metres in length, and contribute to this vocal cetacean’s scientific name, Megaptera novaeangliae, which means ‘big-winged New Englander’.

Marine misnomer

Orca image

Orcas are easily distinguishable by their striking black and white markings and their imposing, triangular dorsal fin. Interestingly, these fascinating marine mammals have a rather misleading alternative name – killer whales. While they are certainly efficient predators, they are not whales and are, in fact, the largest members of the dolphin family. Orcas usually hunt in pods, although individuals from some populations are known to deliberately beach themselves in order to snatch sea lions resting on the beach before wriggling back to sea with their prey.

Social cetacean

Dusky dolphin image

The charismatic dusky dolphin is a highly social species, sometimes being found in pods of over 1,000 individuals and frequently associating with other cetacean species. This beautiful marine mammal is said to be one of the most acrobatic of all dolphins, often making energetic leaps out of the water and performing impressive tumbles in the air.

Underwater unicorn

Narwhal image

There’s no mistaking the unique narwhal, a species famed for the hugely elongated tooth or ‘tusk’ which protrudes from its upper lip. The longest of these incredible appendages was recorded at over 2.5 metres in length, and the males use these bodily weapons in jousting bouts. The narwhal is found throughout the waters of the Arctic, as well as in the northern Atlantic Ocean, and it tends to stay close to pack ice.

Cerebral cetaceans

Bottlenose dolphin image

Quite possibly the most famous of all cetaceans, the bottlenose dolphin is much-loved by many. This extremely intelligent species is highly social, and uses a wide range of clicks and whistles to communicate with other members of its pod. Like some other species of cetacean, the bottlenose dolphin seeks out prey using echolocation, and individuals in a pod will work together as a team to round up schools of fish into tight balls upon which the dolphins can feed. When not chasing prey or performing impressive leaps, dolphins are able to rest one side of their brain at a time. This allows them to sleep while remaining conscious enough to surface and breathe.

Moby Dick

Sperm whale image

The strange-looking sperm whale can be forgiven for having such a bulbous head, given that it has the largest and heaviest brain of any living animal! And its record-breaking statistics don’t stop there – capable of diving for up to two hours at a time, the sperm whale can dive to depths of 3,000 metres, making it the deepest-diving mammal. The largest of the toothed whales, the sperm whale is famed in literature as Herman Melville’s Moby Dick, but sadly it is classified as Vulnerable on the IUCN Red List, primarily as a result of historic and present-day hunting.

Sea scars

Risso's dolphin image

A somewhat unusual-looking mammal, Risso’s dolphin can be identified by its long, pointed flippers, bulbous, beakless head, and the conspicuous scars present all over its body. These markings are thought to be caused by bites from other individuals of its kind during playing or fighting, but some scars could be the result of squid bites.

White whale

Beluga whale image

Although it is also known as the white whale, the beluga whale is actually born with dark grey to bluish- or brownish-grey colouration, only achieving the striking white hue as it matures. It is one of just a few cetaceans with a flexible neck, and it is capable of pursing its lips to suck up prey. The beluga whale is sometimes referred to as the sea canary because of the high-pitched twittering noises it produces.

On the brink

Baiji image

The baiji, or Yangtze River dolphin, is a very shy and graceful freshwater dolphin species with a very long, narrow, slightly upturned beak and small eyes placed high on the face. Sadly, it is thought that the Critically Endangered baiji could actually now be extinct. In 1999, only four individuals of its kind were observed, and an intensive search of its range in 2006 resulted in none being seen. The major threats to the baiji are considered to be illegal fishing using electricity, and being caught as bycatch in fishing nets.

Ocean giant

Blue whale image

We couldn’t possibly finish this round-up of ten incredible cetaceans without including the biggest of them all – the blue whale! The biggest animal to have ever lived, the blue whale has a heart the size of a small car and is capable of eating more than 4 tonnes of krill per day during the summer months. Whereas some cetacean species communicate using a series of high-pitched clicks and whistles, the blue whale produces a variety of low-frequency sounds, which may also serve the purpose of sensing the environment and detecting prey.

Is your favourite whale or dolphin not featured here? Then why not comment below to let us know what it is and why you love it!

If you’re looking for a fun challenge, check out ARKive’s ocean-themed scavenger hunt – there may well be a few cetaceans hidden in there!

Find out more about whale and dolphin conservation:

Kathryn Pintus, ARKive Text Author

Mar 28
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In the News: Survival of rare dolphin boosted by Marine Protected Area

Hector’s dolphins living off the coast of Christchurch, New Zealand, have benefitted from the designation of a Marine Protected Area, according to scientists.

Photo of Hector's dolphins

Sliding towards extinction

One of the world’s smallest dolphin species, Hector’s dolphin is also one of the most highly endangered, with fewer than 7,500 individuals remaining. Found only in waters around New Zealand, the species is gradually sliding towards extinction, due mainly to entanglement in fishing nets.

A subspecies from New Zealand’s North Island, known as Maui’s dolphin, is particularly endangered, with recent figures suggesting it is down to just 55 mature individuals.

Increased survival rates

The Banks Peninsula Marine Mammal Sanctuary was established in 1988 in an attempt to protect the dolphins from fatalities associated with the fishing industry. Researchers who have studied the dolphins in the area for 21 years found that their survival rate has increased by 5.4% since the sanctuary was declared.

This is the first evidence that Marine Protected Areas can be effective for marine mammals. We found a significant improvement in the survival rate,” said Dr Liz Slooten, one of the researchers.

Photo of Hector's dolphin

The team of scientists used regular photo identification of Hector’s dolphins in the Marine Mammal Sanctuary to monitor their population, starting two years before the area was officially protected. The results of the research are published in the Journal of Applied Ecology.

Estimating population changes in marine mammals is challenging, often requiring many years of research to produce data accurate enough to detect these kinds of biological changes,” said Dr Slooten. “It seems to take a long time for a dolphin population to respond to protection, and therefore a long-term study to detect [any] improvement.”

Good news and bad news

Unfortunately, although the increased survival rate of the dolphins is a positive step, the researchers were surprised that it had not increased further.

Once the Banks Peninsula area was protected, we had expected the problem to be solved and the population to be healthy and recovering,” said Dr Slooten.

Instead, the team found that the dolphins were not spending the whole year in the protected area, with some moving up to 16 nautical miles outside of the area in winter. Continuing mortality in fishing nets means that the species as a whole is still on course to becoming extinct.

Photo of Hector's dolphin in typical habitat

According to Dr Slooten, “The good news is that the situation has improved. The population was doing a nose-dive, declining at 6% per year, and now it’s only declining slowly [at] about 1% per year.”

The bad news is that the protected area is still too small. It would need to be extended further offshore to allow the population to stop declining and better still to grow and recover towards its original population size.”

Step in the right direction

Although the Marine Protected Area has not yet ensured the long-term survival of Hector’s dolphin, it is thought to be a major step in the right direction. The New Zealand government is now considering whether to extend Marine Protected Areas where Hector’s dolphins are found.

Photo of Hector's dolphin leaping

Speaking about the findings of the research, Dr Barbara Maas, Head of Endangered Species Conservation at NABU-International – Foundation for Nature, said, “This is excellent news because it proves that the removal of fishing nets from their habitat benefits threatened marine mammals. However, it also shows that unless a Protected Area is large enough, this positive influence cannot compensate for mortality caused by fishing. The net effect is continued decline.”

Conservationists are calling for a ban on all gillnet and trawl fishing throughout the entire range of Hector’s dolphin.

Read more on this story at the BBC and Hector’s and Maui’s Dolphin SOS.

View photos and videos of dolphin species on ARKive.

Liz Shaw, ARKive Species Text Author

Mar 22
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The ARKive Team’s Favourite Species – Ellie Dart

Last time Liana proved her passion for plant-life, but will this week’s ARKive team member believe botany is best or animals are awesome?

Ellie Dart – Online Outreach Manager

Favourite species? Dusky dolphin

Why? The dusky dolphin stole my heart when I was in New Zealand eight years ago. I love the dusky dolphin’s playful character, its social nature and its ability to put on an impromptu acrobatics show.

It was a cold snowy morning when a group of 100 or more dolphins started swimming alongside our boat. I’d never seen so many dolphins at one time. Wetsuits on, we jumped into the sea with them. I think my heart actually skipped a couple of beats – perhaps it was the shock of the ice cold water, or perhaps it was their power that took my breath away.

They were bigger up close than they looked from the boat, and the speed at which they moved was to begin with, verging on terrifying, as they rocketed towards us, before playfully curving around. But within seconds, I felt at home with them, splashing around in the water (though my movements were significantly less graceful than theirs). Everywhere I looked there were dolphins – twirling to the side of me, diving underneath me and shooting out of the water and over my head. These dolphins know how to have fun and showed me a truly unforgettable morning.

Favourite dusky dolphin image(s) on ARKive:

Dusky dolphin imageDusky dolphin image

 

 

 

 

 

 

 

 

The dusky dolphin is classified as Data Deficient on the IUCN Red List. Threats to this species are thought to include entanglement in gillnets and illegal harpooning for meat.

See more photos and videos of the dusky dolphin.

Sep 30
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In the News: Endangered dolphin sliding towards extinction

One of the world’s most endangered dolphin species is sliding towards extinction due to damaging fishing methods, experts have warned.

Photo of Hector's dolphin pod

Hector’s dolphins

Also one of the world’s smallest marine dolphins, Hector’s dolphin lives only in waters around New Zealand, where its population has fallen from 30,000 to around 7,000 individuals since nylon fishing nets came into use in the 1970s.

A subspecies from New Zealand’s North Island, known as Maui’s dolphin, is particularly threatened. Classified by the IUCN as Critically Endangered, its population now numbers fewer than 100 individuals.

Photo of Hector's dolphins porpoising

Unsustainable dolphin mortality

According to research conducted by Dr Liz Slooten of the University of Otago in New Zealand, commercial gillnets (long nets set vertically in the water to entangle fish) are drowning around 23 Hector’s dolphins each year along the east coast of New Zealand’s South Island.

With the sustainable limit for dolphin bycatch in the area estimated at just one dolphin a year, the current levels of dolphin mortality would reduce the Hector’s dolphin population by at least a further 14% by 2050.

Photo of pair of Hector's dolphins

Hector’s dolphin is also threatened by other fishing methods, including trawl nets, which are likely to kill just as many individuals as gillnets. This brings the number of dolphin deaths due to fisheries to at least 46 a year along the east coast.

Dr Barbara Maas, head of endangered species conservation for NABU International – Foundation for Nature, said, “An annual loss of this size will wipe out 62% of the population by 2050. Only a scattering of animals will survive, potentially pushing the population beyond the point of no return.”

As a coastal species, Hector’s dolphin is also highly vulnerable to a range of other threats, including pollution, boat strikes and marine mining.

Photo of Hector's dolphins in typical habitat

Hector’s dolphins in typical habitat

More selective fishing methods needed

Although bans on gillnetting are already in force in some parts of New Zealand, the continuing high levels of dolphin mortality indicate that more work is needed to protect this rare species from extinction.

Dr Mass, who has been speaking at the World Conference on Marine Biodiversity in Aberdeen this week, recommended that the only way to prevent the demise of Hector’s dolphin would be “absolute protection against commercial and recreational gill-netting and trawling.”

She urges the New Zealand government to ban these fishing methods in waters up to 100 metres deep, and suggests that more selective fishing methods which do not catch dolphins, such as hook and line fishing and fish traps, should be used instead.

Read more on this story at the Guardian – Endangered dolphins near extinction.

Find out more about the World Conference on Marine Biodiversity.

View photos and videos of Hector’s dolphin on ARKive.

Liz Shaw, ARKive Species Text Author

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