Apr 23
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Guest Blog: British Freshwater Fish – Jack Perks

It’s a well-known fact that Britain is a nation of animal lovers and is particularly obsessed with its wildlife. However, there is one group which often gets overlooked – our piscatorial friends the freshwater fish. Currently there are 54 species of freshwater fish swimming around the United Kingdom, including species like the mullet and flounder which, despite just visiting the estuarine parts of rivers, can be found surprisingly far up from the sea! Non-native species such as the wels catfish, which resembles a giant tadpole, and the topmouth gudgeon are also present in the UK. Despite the UK not suffering from the presence of non-native species as much as other countries such as Spain, the tiny topmouth gudgeon does still cause big problems by outcompeting native fish and spreading disease.

The topmouth gudgeon has been described as Europe’s most invasive fish species

In recent years, the number of native European eels has declined by around 95%. However, 2013 was recorded as one of the best elver runs in recent years, with millions making their way up the Severn. Whilst many may think that floods are not good for fish, flooding helps the European eels get into ponds and lakes where they can grow before returning to the Sargasso Sea with the next floods.

European eel image

The European eel is very long-lived, potentially reaching an impressive 85 years old

There are many other native freshwater fish species which are less well known to the general public and even wildlife enthusiasts (I bet most birders in the UK have never heard of a spined loach or allis shad, for example). One such species is the Arctic charr, a cousin of the trout, which lives in deep glacial lakes mostly in the Lake District and Scottish Lochs. The Arctic charr can also be found in Iceland where it reaches much larger sizes of up to 20lb and, unlike the British populations, goes out to sea like a salmon.

Male and female Arctic charr

So next time you’re walking by your local canal or river, take a look and see what you can spot -  you’ll be surprised by the wealth of fish life beneath the waterline in British waterways.

Video showing 28 species filmed by me: http://www.youtube.com/watch?v=mjAIUKfYtHA

Jack Perks Photography – Underwater & Wildlife Photographer

Website – http://www.jackperksphotography.com and http://www.btwlfishproject.com/
Twitter – @JackPerksPhoto

Jan 23
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In the News: One quarter of sharks and rays threatened with extinction

A shocking one quarter of all shark and ray species are threatened with extinction, according to the results of a new study.

Great white shark image

The great white shark is classified as Vulnerable on the IUCN Red List

Threat analysis

The paper, published this week in the open-access journal eLife, analysed the threat and conservation status of an impressive 1,041 species of chondrichthyans, a fascinating group of fish species including sharks, rays, skates and chimaeras whose skeletons are made of cartilage rather than bone. The results were rather alarming, revealing that this group is among the most threatened in the animal kingdom.

The paper is the result of collaboration between more than 300 experts from 64 countries, and reports that, while no species has yet been driven to global extinction, at least 28 populations of skates, sawfishes and angel sharks are now locally or regionally extinct. In addition, several shark species have not been seen for several decades.

Reef manta ray image

Reef manta ray parts are highly valued in traditional medicine, posing a threat to this majestic species

Threat hotspots

The study highlights two areas which are currently experiencing a higher than expected level of threat: the Red Sea and the Indo-Pacific Biodiversity Triangle. The latter is considered to be among the most biologically and culturally diverse regions on the planet, yet unfortunately it is also one of the least regulated.

The authors of the paper explain that, “The Indo-Pacific Biodiversity Triangle, particularly the Gulf of Thailand, and the islands of Sumatra, Java, Borneo, and Sulawesi, is a hotspot of greatest residual threat, especially for coastal sharks and rays with 76 threatened species.”

It is feared that, should no national or international action be taken, these species could rapidly become extinct.

Shark finning image

Finning was revealed to be a major threat to many shark species

Major threats

The results of the study revealed that the main threat to chondrichthyans is overexploitation through targeted fisheries and incidental catches. Of particular concern for the future of sharks, wedgefishes and sawfishes is the process of ‘finning’, which is driven by the huge market demand for shark fin soup, a highly sought-after delicacy in China.

The authors of the new research paper state that, “Fins, in particular, have become one of the most valuable seafood commodities. It is estimated that the fins of between 26 and 73 million individuals, worth US$400-550 million, are traded each year.”

Habitat loss is a further threat to chondrichthyans, with 22 species being threatened by the destruction of estuaries and river systems for the purposes of residential and commercial development, and 12 species being placed at risk due to the conversion of mangroves into shrimp farms. In addition, pollution and climate change have been identified as major threats to sharks, rays and their relatives.

Scalloped hammerhead shark image

The scalloped hammerhead shark is classified as Endangered on the IUCN Red List

Additional factors

As well as providing a vital insight into the type and extent of threats to chondrichthyans, the paper also revealed other interesting factors which come into play. It was found that large body size and occurrence in shallow habitat are the biggest factors determining a species’ likelihood of being threatened. The results showed that with every 10-centimetre increase in a species’ maximum body length came a 1.2-percent increase in the probability that the species would be threatened. Dwellers of deep water appear to fare better than their shallow-water relatives, with a 10.3-percent decrease in the probability of being threatened for every 50-metre increase in the minimum depth limit of the species.

 

Read more on this story at Mongabay.com – One quarter of sharks and rays threatened with extinction.

View photos and videos of chondrichthyans on ARKive.

Read more about shark conservation and conservation in the Indo-Pacific Region.

 

Kathryn Pintus, ARKive Content and Outreach Officer

 

Oct 5
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Endangered Species of the Week: Barndoor skate

Photo of barndoor skate

Barndoor skate (Dipturus laevis)

Species: Barndoor skate (Dipturus laevis)

Status: Endangered (EN)

Interesting Fact: Adult male barndoor skates have widely spaced teeth with sharply pointed cusps, but females have close-set teeth with rounded cusps.

More information:

The largest skate in the Northwest Atlantic Ocean, the barndoor skate can grow up to about 1.5 metres in length. Like other skates, this species has a flattened body which is fused to the expanded pectoral fins to form a broad disc. Its snout is pointed and its tail bears three rows of spines as well as two small dorsal fins. The barndoor skate grows slowly, taking at least 6 to 7 years to reach maturity, and can potentially live for up to 18 years. Its diet consists mainly of bottom-dwelling prey such as fish, squid, crustaceans, bivalves and worms. The eggs of the barndoor skate are laid in smooth, rectangular capsules and hatch after about 11 to 16 months.

Although not specifically targeted by fisheries, the barndoor skate has often been taken as accidental bycatch, and has been part of a group of several skates fished in U.S. waters which are not recorded by species. The flesh of this and other skates has been used as lobster bait, fish meal, pet food and seafood. The slow growth, late maturity and low reproductive rate of this species make it vulnerable to overfishing, and its population has undergone a dramatic decline. Possession of the barndoor skate in U.S. waters is now banned, and ‘no-take’ zones in areas such as Georges Bank have decreased mortality of this species and increased the number of juveniles being produced. A reduction in fishing effort is thought to have allowed the barndoor skate population to start recovering, but if fishing was to increase again the skate would be likely to decline once more.

 

Find out more about the barndoor skate at the Ichthyology Department of the Florida Museum of Natural History.

You can also find out more about the conservation of skates, rays and sharks at:

See more images of the barndoor skate on ARKive.

Liz Shaw, ARKive Text Author

Sep 13
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In the News: Blobfish claims landslide victory as world’s ugliest animal

Its grouchy face and slimy, gelatinous body have won the blobfish the honour of becoming the official mascot of the Ugly Animal Preservation Society, as well as the unofficial title of world’s ugliest animal.

Public vote

First taking form as a science-themed comedy night, the society launched a campaign urging members of the public to vote for its mascot from a pool of ‘aesthetically challenged’ threatened species. The main aim of the campaign, which was run in conjunction with the National Science and Engineering Competition, was to draw attention to the threats facing these bizarre and often ignored creatures.

Our traditional approach to conservation is egotistical,” said biologist and TV presenter Simon Watt, president of the Ugly Animal Preservation Society. “We only protect the animals that we relate to because they’re cute, like pandas. If extinction threats are as bad as they seem, then focusing just on very charismatic megafauna is completely missing the point.”

The campaign featured eleven ‘ugly’ species, each of which was championed by a comedian and was promoted via a special YouTube video message before the public was asked to vote for their favourite. “I have nothing against pandas,” added Watt, “but they have their supporters. These species need help.”

Proboscis monkey image

Proboscis monkey males have enlarged noses

Blobfish emerges victorious

After around 88,000 video views and more than 3,000 votes, the campaign came to its conclusion at the British Science Festival in Newcastle with the announcement of the blobfish as the winner. Supported by comedian Paul Foot, this species received a whopping 795 votes and will now become the official mascot of the Ugly Animal Preservation Society.

Some would describe it as a bit ugly, but I think the sad face of the blobfish belies a kind and very wise little brain in there,” said Foot of his chosen species.

A strange, gelatinous creature, the blobfish lives off the coast of south-eastern Australia and Tasmania, where it lives at depths of between 600 and 1,200 metres and is rarely seen. Incredibly, the blobfish is able to thrive at these depths, despite the pressure being several dozen times higher than at the surface. With its body being just slightly denser than water, the blobfish spends its life bobbing around in the ocean, feeding on crabs and lobsters. However, fishing trawlers pose a significant threat to this aesthetically challenged species, as it becomes caught up in their nets.

Titicaca water frog image

The Critically Endangered Titicaca water frog

Daily extinctions

With an estimated 200 species going extinct each day, the Ugly Animal Preservation Society is keen to promote the conservation of less well known or less adored species, and Watt is pleased with the success of the campaign, saying, “We’ve needed an ugly face for endangered animals for a long time and I’ve been amazed by the public’s reaction.”

Watt also hopes that the attention given to these animals has brought a lighter side to conservation, and that it has highlighted the importance of habitat conservation.

Carly Waterman, from the Zoological Society of London’s EDGE of Existence programme which aims to highlight and conserve evolutionarily distinct, ‘one-of-a-kind’ species, praised the efforts of the campaign, saying, “A large proportion of the world’s biodiversity is being overlooked, so flying the flag for these species is a really positive thing.”

Axolotl image

The axolotl, an unusual amphibian

Other contenders

A whole host of fascinating creatures were in line for the title of world’s ugliest animal, including the flightless dung beetle, the European eel and the dromedary jumping-slug. In addition to the blobfish, the other four species in the top five following the public vote were the:

Read more on this story at BBC News – Blobfish wins ugliest animal vote and The Guardian – Blobfish voted world’s ugliest animal.

Watch Paul Foot’s acceptance speech on behalf of the blobfish.

Kathryn Pintus, ARKive Text Author

Aug 6
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ARKive’s Top Ten Shark Videos

As most of people don’t have enough spare time to watch the 8,522 videos currently on ARKive (although you may wish you did), we thought we’d give you a helping hand by choosing what we considered to be the top ten videos of one of the world’s most endearing animals: the shark. After perusing all of the magnificent shark footage on ARKive we managed to whittle them down to just ten terrifying, awe-inspiring and bizarre videos.

Gentle giants

The whale shark is the biggest fish in the world, measuring as much as twelve metres and weighing up to 12,500 kilograms. It is a fairly docile species and feeds mostly on plankton and small fish, actively sucking in prey through its large mouth. Its sheer size can be acknowledged when compared with the diver in this video:

Whale shark with snorkeler

It’s fin may cut the surface of the water in a way which could instil fear into the most courageous humans, but the basking shark is more interested in devouring microscopic prey. The basking shark is the second largest fish in the world and has a mouth that can measure up to a metre across when fully open. See it feeding in this fascinating footage:

Basking shark feeding

Out of the ordinary

The mysterious megamouth shark was only described as recently as 1976 and is so genetically different from other sharks that it was placed in its own family. It can reach over five metres in length and its oversized mouth has over 50 rows of tiny, hooked teeth. See this strange species in action in this video:

Megamouth shark

Friends with benefits

The Greenland shark is one of the largest sharks in the world, measuring up to seven metres. Almost all Greenland sharks are parasitized by a minute crustacean which attaches itself to the shark’s cornea and gradually destroys the host’s eyesight. It is thought to be a mutually beneficial relationship as the crustacean may act as a lure for fish, although this is unconfirmed. See it in action here:

Greenland shark with parasitic copepod

The strange-looking scalloped hammerhead has a mutually beneficial relationship with cleaner wrasse. This helpful fish eats parasites from the skin and mouth of the scalloped hammerhead shark, as well as cleaning any wounds, as shown in this video:

Barber fish cleaning scalloped hammerhead

Remarkable reproduction

Most sharks are ovoviviparous, with the young developing within eggs in the body of the female. The eggs then hatch inside the female, who then gives birth to the well-developed young. However, the lemon shark, similarly to humans, is viviparous and the young develop inside the female, while receiving nutrients from an internal placenta and the female then gives birth to live young. See this extraordinary event unfold here:

Newborn lemon shark pup

Expensive taste

The salmon shark, as its name suggests is thought to be one of the main predators of Pacific salmon. It is similar in appearance to the great white shark and shares its excellent predatory skills. The salmon shark may have the highest body temperature of any shark, which allows them to maintain warm muscles and organs, so they are still able to hunt in the ice cold waters of the North Pacific Ocean. See this giant in its habitat here:

Salmon shark

Quick off the mark

The shortfin mako is thought to be the fastest shark species and is capable of reaching speeds of up to 35 kilometres per hour. Its high tail and efficient heat exchange system enable it to quickly pursue its prey, as shown in this video:

Shortfin mako

Fearsome fish

No list about sharks would be complete without mentioning the formidable great white shark. A tremendously skilled predator, it is at the top of the marine food chain and is known to hunt fish, turtles, molluscs, dolphins, porpoises and seals. Their powerful bodies enable them to leap from the water in pursuit of prey, as shown in this video:

Great white shark breaching

Fighting back

The tiger shark is one of the largest shark species and is known for its voracious appetite, eating anything from fish to car license plates. Although the inanimate objects it predates on are unlikely to fight back, its more alive prey may create more problems, much like the loggerhead turtle in this video:

Tiger shark feeding on fish carcass

Hannah Mulvany, ARKive Species Text Author Intern

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