Jun 15
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

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

Jun 10

The Mexican government has approved an important measure which aims to protect the vaquita, a porpoise species thought to be the world’s rarest and most threatened marine mammal.

Vaquita image

The vaquita is classified as Critically Endangered on the IUCN Red List

Critically Endangered

The vaquita is the smallest porpoise species in the world, reaching a maximum length of just 1.5 metres, and is the only cetacean endemic to Mexico, being found only in the upper Gulf of California.

Sadly, it also has the unfortunate distinction of being the most threatened marine mammal. Classified as Critically Endangered on the IUCN Red List of Threatened Species, the vaquita is struggling for survival as a result of becoming entangled in gill nets and trawl nets cast by commercial and artisanal fisheries to catch shrimps and fish, including sharks. It is estimated that between 39 and 84 vaquitas drown as bycatch every year, which is a worryingly high number given that, in 2007, only an estimated 150 individuals of this species remained.

Positive action

Fortunately, according to WWF-Mexico, positive action is now being taken to promote sustainable fisheries in the vaquita’s range, in measures which will benefit the species as well as fishermen and their families. A new regulation will establish shrimping standards in Mexico, and will define the types of fishing gear permitted in different zones of the country.

Vaquita image

Drowning in fishing nets is the main threat to the vaquita

An official norm

The new regulation, known as an ‘official norm’, has come into play as a result of a WWF petition to Mexico’s President Enrique Peña Nieto. Signed by an impressive 38,000 people from 127 countries, the petition requested that measures be established to protect the vaquita whilst also ensuring that fishermen can continue to earn a living through sustainable fishing.

With this norm, drift gillnets – one of the nets used in artisanal shrimping operations in which vaquitas die incidentally – will be gradually substituted, during a three year period, for selective fishing gears that do not kill this porpoise, but that allow fishers to keep earning their livelihoods,” said Omar Vidal, WWF-Mexico’s Director General.

The effective application of the norm requires the participation and commitment of local fishermen. The optimal use of the net requires the development of particular skills; therefore, the support of the government and other organizations through training and temporary compensation programs will be essential along the fisher’s learning curve.”

This positive action represents a major opportunity to promote sustainable fisheries in the Gulf of California region, whilst simultaneously protecting an endemic threatened species.

View more photos of the vaquita on ARKive.

To learn more about protecting our marine environment, visit the World Oceans Day page or take part in ARKive’s ocean-themed virtual scavenger hunt.

 

Kathryn Pintus, ARKive Text Author

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