Jun 22
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Endangered Species of the Week: Leaf-scaled sea snake

Photo of leaf-scaled sea snake

Leaf-scaled sea snake (Aipysurus foliosquama)

Species: Leaf-scaled sea snake (Aipysurus foliosquama)

Status: Critically Endangered (CR)

Interesting Fact: The leaf-scaled sea snake is able to remain underwater for up to two hours before resurfacing for air.

Named for the characteristic leaf-like shape of its scales, the leaf-scaled sea snake is a relatively small snake which spends its entire life at sea. Like other sea snakes, it shows a number of adaptations to its aquatic lifestyle, including a flattened, paddle-like tail for swimming, valves in the nostrils which prevent water entering the lung, and a gland under the tongue which excretes excess salt from the body. The leaf-scaled sea snake lives in shallow waters and gives birth to live young. It feeds on small coral reef fish, which it immobilises with its venom.

The leaf-scaled sea snake has one of the most restricted ranges of any sea snake, occurring in just two reefs in the Timor Sea, and occasionally being seen off the northwest coast of Australia. This species was once one of the most commonly seen sea snakes in its range, but has not been recorded in surveys since 2001. The exact reasons for this are unclear, but could be to do with rising sea temperatures and the degradation of its reef habitat, which in turn reduces prey availability. All sea snakes are legally protected in Australia, and measures are underway to monitor and reduce any impacts of fisheries on sea snake species. One of the reefs the leaf-scaled sea snake inhabits is a nature reserve, but unfortunately none of the habitat management plans for this area specifically target this rare marine reptile.

 

Find out more about sea snakes at IUCN – Sea snakes.

See images of the leaf-scaled sea snake on ARKive.

Find out more about other sea snake species on ARKive.

Liz Shaw, ARKive Text Author

Jun 18
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In the field: The Manta Trust

Manta ray photoWhile the oceans of our planet cover more than 70% of the Earth’s surface, we still know so little about what goes on beneath the waves.  There are vast areas, great depths and even hundreds or perhaps thousands of species that we still barely understand.  Manta rays can certainly be classed as one such species that we know little about and that is why in January 2012, The Manta Trust came into being; a UK registered charity aiming to improve our understanding of these animals and promote their long-term conservation.

What is the Manta Trust?

Manta Trust LogoThe Manta Trust is a growing group of scientists, photographers, film-makers, conservations and advocacy experts who have joined forces to co-ordinate global research and conservation efforts for both manta rays and their close cousin’s, the mobula rays.

Manta ray photoThese rays are among the most charismatic creatures that inhabit our oceans. With the largest brain of all fish, their intelligence and curiosity is often compared to that of a large mammal, making encounters with them a truly unforgettable experience.

However, despite their popularity with divers and snorkelers many aspects of these creature’s lives remain a mystery, with only snippets of their life history currently understood. More worryingly, in recent years a targeted fishery for these animals has developed, causing devastating declines in global manta ray populations.

The Manta Trust brings together a number of research projects from around the globe. By conducting long-term, robust studies into manta populations in these varying locations, we aim to build the solid foundations upon which governments, NGOs and conservationists can make informed and effective decisions to ensure the long term survival of these animals and their habitat. By coupling this research with educational programmes and raising awareness, we hope to be able to make a lasting difference to the future of our oceans.

What are manta rays?

Manta and mobula rays are cartilaginous elasmobranch fishes. Like other rays this means they are a close relative of the shark. However, unlike most rays which spend at least a portion of their lives hugging the seabed, mobulids live pelagic existences – meaning they spend their time swimming in open water.

They’re also completely harmless to humans, feeding on zooplankton, the often microscopic animals which live in the water column and are the base of many ocean food chains.  This food source means that these amazing rays are at the mercy of the oceans, often migrating thousands of kilometres to track down their next meal!

Manta ray photo

Manta rays are also the largest rays in the world.  There are two species of manta, the reef mantas and the larger oceanic mantas that grow to over 7m diameter from wingtip to wingtip.

We believe manta rays to be incredibly long lived, probably living to at least 50 years old or possibly longer! This characteristic, coupled with the fact that they mature late, reproduce infrequently and give birth usually to a single pup at a time, make them very vulnerable to exploitation by fisheries.

Are there any threats to mantas?

Gill plate photoUnfortunately yes, manta and mobula rays are fished for their gill plates, the intricate apparatus which helps them to both breathe underwater and to strain their microscopic planktonic food from the water.

This fishery is quite a recent development, with the gill plates being sold in Asian markets where they are prepared as a tonic to treat a variety of ailments.

Due to the vulnerable nature of these animals this has the potential to have catastrophic implications for their fragile populations.  In fact populations in some areas have already seen declines of up to 86% due to fisheries.

Where does the Manta Trust work?

One of the main aims of the Manta Trust is to unite and co-ordinate work being undertaken with these rays in all corners of the globe.  So far we are working in 17 countries!  By co-ordinating our research in this way the hope is that we can share in each other’s successes (and failures), learning what works and what doesn’t, ultimately achieving global successes for these species.

What does the Manta Trust want to achieve?

Our vision is “A sustainable future for the oceans where manta rays thrive in healthy, diverse marine ecosystems.”  We’d like to achieve this by conducting robust scientific research whilst educating and raising awareness of the issues which face these animals.

We know that good conservation requires a holistic approach. Therefore the Manta Trust researchers and volunteers work closely with tourists, local communities, businesses and governments to ensure the preservation of these amazing animals through a combination of good science, education, community based initiatives and government legislation. As the scope of the Trust’s work continues to grow our goal is to keep expanding these efforts globally.

In March 2013, the Manta Trust was part of a consortium of NGOs behind the successful listing of both species of manta ray on Appendix II of CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora).  This listing means trade in manta ray parts between the 178 signatory nations will be closely controlled and restricted when this legislation comes into force in September 2014.

Manta Trust photo

This is a huge victory, however much still needs to be achieved for these animals until this legislation comes into force, especially to aid those in the involved fishing industry to transition to more sustainable futures.

How can you help The Manta Trust?

Manta ray photoOne of the best ways you can help is to swim with mantas! By showing governments that manta-based tourism is important and that it provides a sustainable long term industry in which people can earn a living whilst co-existing with these animals, we will be taking positive steps towards long-term solutions for these rays.

If you’ve been lucky enough to swim with mantas why not send us your pictures?  Each manta is uniquely identifiable by the pattern of spots on their ventral (belly) surface.  We are collating manta images from around the world as part of our global IDtheManta database.

You can learn more about it here.  By collecting this information on a global scale we hope to learn more about these amazing and mysterious animals.

We also accept volunteers! Check out our Volunteer page on The Manta Trust website and follow us on Facebook to see the latest opportunities as they are announced. In fact following our work on our blog, website, Facebook and Twitter pages and sharing what we do with your friends is also an amazing way to spread the manta message!

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

Jun 10
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In the News: Mexico takes a positive step towards saving world’s rarest marine mammal

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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