Basics of Sharks

  • Sharks have roamed our seas for more than 400 million years, which means they inhabited the earth for nearly 200 million years before dinosaurs.
  • Sharks are fish with skeletons made of cartilage instead of bone, but sharks’ slow growth and late maturity mean they have more in common with sea turtles and marine mammals than bony fish such as flounder or tuna.
  • Sharks are a remarkably diverse group of fish. They range from less than a metre to 20 metres in length; they are found in most coastal regions but also in the deep ocean and even in fresh water. Some sharks lay eggs, but most give birth to live young. Most are top predators while a few feed on plankton. Sharks in turn are preyed upon by other sharks and sometimes killer whales.
  • The term ‘shark’ often refers not only to shark species but also to the closely related rays and skates, as well as the oft-overlooked chimaeras (rat, rabbit and elephant fish).Collectively these cartilaginous species are known as chondrichthyan fish (forming Class Chondrichthyes).

Sharks are different with other fishes

  • Sharks and rays do not have true bones like other fishes. They have cartilage instead which is lighter and much more elastic and allows them to bend in very tight circles.

  • Sharks do not have swim bladders. A swim bladder is a gas filled sack inside the body of bony fishes that allows them to stay still without sinking. Sharks compensate by having a very big liver that is filled with oil. Even so, sharks sink unless they keep swimming forward. The exception is the Sandtiger Shark which swallows air to make itself more buoyant.

  • A shark’s upper jaw is not fused to its skull like most animals. When a shark bites a large object, it is able to move its upper and lower jaw forward in order to take a bigger bite.

  • Unlike other fishes, sharks are able to replace their teeth constantly. New teeth grow from the inner surface of the jaw and rotate forward when the old teeth get worn out or lost during feeding.

  • Sharks and rays do not reproduce like other fishes. Most fish release clouds of sperm and eggs into the water column where they mix together. The fertilized eggs then float around until the fish larvae hatch and form schools of tiny fish. Male sharks have two organs called claspers attached to their anal fins. They insert one of these into the female shark’s cloaca (the entrance to the uterus) to transfer sperm (just like in mammals). Some sharks and rays incubate the eggs in their uteruses until the baby sharks are ready to be born. Other sharks and rays (i.e. skates) lay eggs and attach them to the reef.

  • Sharks have between 5 and 7 gill slits on each side of their body in front of their pectoral fins. Bony fishes only have one pair. Having many exposed gill slits probably helps transfer more oxygen into their blood faster which allows them to swim very fast when they need to.

  • Most shark’s skin is covered in small denticles instead of scales. Denticles are a lot like teeth. They have dentine in the centre and enamel on the surface. This makes shark’s skin very tough and abrasive like sandpaper. The shape and position of some shark’s denticles also helps reduce friction so that they can slip through the water easier.

  • Sharks have an extra sense that is able to detect tiny electric fields. They can use this to find food that is buried or to search for animals to eat in the dark or in turbid water.

  • Sharks and rays make up the sub-class of fishes called elasmobranches. This sub-class is part of a class of cartilaginous fishes called Chondrichthyes which also includes chimaeras (ratfishes).

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SOS attend international conference in Brussels

Following its acceptance of membership to the recently formed Shark Alliance, Save Our Sharks (SOS) attended the first anniversary and inaugural meeting of the Shark Alliance member groups in Brussels.
Around 35 delegates from 6 countries, U.K, France, Italy, Germany, Switzerland and Holland attended plus the directors and staff from the Pew Charitable Trusts, who financed the meeting.

Save Our Sharks were represented by Nigel Proctor (on behalf of the SOS committee) who met up at Brussels airport with the Sea Anglers Conservation Network (Scotland) representative, and SOS liaison officer Denis Kelly.

“Fins On”

One of the principal proposals that came out the conference is to be headed “Fins On” where the aim is to have sharks landed whole. There will be a drive to raise public awareness of the issue, and we will try to capitalise on the IUCN red listing, and create further publicity.

“Shark Week”

Another proposal is to hold a “Shark Week” in each member country, where each country’s members create a project to involve the community, schools, museums, aquariums and the like to raise awareness of shark issues.

There will be more to follow on the above shortly

There were many other issues and points made, however, these are the principal ones

• Strive to raise public awareness of shark related issues,
• Create adequate publicity and maintain the pressure,
• Educate journalists away from ‘sensationalism’ without portraying sharks as an animal they clearly are not, they are apex predators, not cuddly, loveable ‘toys’,
• Pre-influence the journalist way of thinking prior to ‘shark week’ and Ocean Day,
• Feed the media with facts and data to ‘force’ the attention on sharks prior to EU discussions on shark management,
• Similarly with CITES,
• Important to maintain ‘shark friendly’ states and get them to lobby less friendly countries,
• Lobby the UK to dispense with its ‘special permits’,
• Ensure that the Shark Alliance has a high profile at the release and showing of the new shark film,
• Don’t alienate the fishing industry,
• Work with fishermen, more is likely to be achieved at a faster rate,

Denis and Nigel were made extremely welcome and clearly treated as being amongst equals, if but a little less experienced in the ways of policy and lobbying. Nigel stated after the meeting that, “We have made significant moves along the pathway of shark conservation and have little to fear in the future, in terms of acceptability, we have a lot to offer and should not be afraid to push forward with our objectives, we can gain a great deal from liaison with the other member groups of the Shark Alliance, however, we also have a great deal to offer as well”.

At the conference Nigel reiterated the high level of importance UK anglers attached to sharks, skates and rays, making the point that the bad old days of trophy fish were long gone. He finished off by indicating our commitment and referencing the prohibition on the landing of tope along the English east coast (c 200 miles of coastline) which to the best of our knowledge is the first full protection, and or prohibition on the landing of any shark species in European waters. This brought about a warm and consensual round of applause, which probably indicates that we are not outcasts any more, but highly regarded and welcome members of an important Shark Alliance.

Well done to Nigel and Denis for helping to put recreational shark fishing on the front-line of European shark conservation

The next few months

We are in for a quiet time in Scotland until after the elections but there is much to do, in England and Europe. We will be writing to our members shortly with more details, please get involved.

• Liaise with the Shark Trust to organise a “Shark Week” to raise public awareness with the overall goal of banning the removing of fins at sea.

• Lobby Defra to stop handing out special permits which allows finning on Porbeagles. Both of the above are part of the “Fins On” campaign.

• Keep pressure on Defra to announce the results of the tope consultation.

• Build up a case to take to the EU to implement tope management across Europe.

• Remind Defra of their intention to implement a maximum landing size on rays, skate and spurdog.

• Keep pressure on the Scottish Exec. to have the Firth of Lorne, Sound of Mull and surrounding lochs and waters designated as a Spurdog nursery area.

• Lobby the EU to have the 25 per cent by catch on rays implemented in all UK waters.

• Continue with the red tape to get SOS listed for charitable status. Once achieved we can apply for grants to help with the campaigning and administrative costs.

A STING IN THE TALE FOR SHARKS AND RAYS

Expert findings show sharks and rays are now amongst Europe’s most threatened animals as more are added to the IUCN Red List of Threatened Species

Gland, Switzerland, 20 February 2006 (IUCN)  The number of species of sharks and rays on the IUCN Red List of Threatened Species will increase based on the findings of a three-day expert workshop, hosted by the Joint Nature Conservation Committee (JNCC), that examined the conservation status of the species in the Northeast Atlantic and Mediterranean waters.

The workshop confirms the widely-accepted notion that slow-growing sharks and rays are exceptionally vulnerable to over-fishing, and that deep-water species are being depleted at an alarming rate. Some formerly important commercial species are now so rare that they are no longer being sought by fishermen, but their risk of extinction is still rising because of continued incidental capture in fisheries for more abundant species. This situation is exacerbated by the lack of shark fisheries management in European waters.

“Sharks and rays are amongst the most threatened animal groups in the UK today. I welcome the development of a Red List baseline, against which to monitor the hoped-for changes in their status that should arise from increased awareness of their plight,” said Dr Malcolm Vincent, JNCC’s Director of Science.

Nearly 100 species of sharks and rays were evaluated against the IUCN Red List Categories and Criteria. Categories range from Extinct to Least Concern and Data Deficient. Species deemed Vulnerable, Endangered or Critically Endangered are considered threatened with extinction and are added to the global IUCN Red List of Threatened Species. The IUCN Shark Specialist Group, which convened the meeting, will compile these assessments for a regional report that will include recommendations for conservation action.

Proposed additions to the Red List include three species of angel sharks, two species of skates, and several species of deep-water sharks, all of which are considered Critically Endangered in the region, as well as two species of coastal ray, now considered Endangered. The species found to be at lowest risk were generally small and fast-growing coastal species, like cuckoo ray and lesser-spotted catshark, and very deep ocean species that are still beyond the reach of today’s fishing fleets.

Angel sharks, formerly abundant large coastal sharks, were once a common sight in fish markets, but have largely vanished, almost unnoticed, from the European seas that are their world stronghold.

Now officially declared extinct in the North Sea by the International Council for the Exploration of the Sea (fisheries advisers to European countries), the angel shark was nominated in 2001 for strict legal protection in British waters, but we are still waiting for government action on this proposal, said Sarah Fowler, Co-Chair of the Shark Specialist Group. Workshop participants emphasised the urgency of protecting this, and many other imperilled species.

Three species of deep-water sharks, taken as incidental catch in fisheries and increasingly targeted for their meat and rich liver oil, were assessed as threatened. A population decline of 80-95% prompted a Critically Endangered classification for the region’s deep-water gulper shark.

These exceptionally slow-growing sharks are simply not biologically equipped to withstand such intense fishing pressure, said Tom Blasdale, Marine Species Adviser at the JNCC. We welcome recent European Union action to manage deep-water gillnet fisheries, but similar measures are still urgently needed to protect deep-water sharks taken by trawls and longlines.

The shortfin mako shark, a favourite target of commercial and recreational fishermen around the world, was proposed as Vulnerable in the Northeast Atlantic and Critically Endangered in the Mediterranean Sea.

This wide-ranging species is increasingly the target of fisheries and yet lacks any type of protective measures in this region, warned Alen Soldo of the Institute of Oceanography and Fisheries in Croatia. Of particular concern are mako sharks in the Mediterranean, where our findings revealed ongoing fishing pressure well beyond the reproductive capacity of the species.

In contrast to similar workshops held in North America, South Africa, and Australia, the workshop yielded little if any good news, due largely to the lack of shark and ray conservation measures in this region. Protection is granted by just a handful of European countries for the three largest species (basking shark, devil ray, and great white shark). The few European shark and ray quotas in place are routinely set far in excess of actual catches and therefore do not limit fishing pressure. They also cover only part of these stocks. Scientists advice for zero catch of many depleted shark and ray species has been ignored. There are no international limits on shark catch, even as fisheries for wide-ranging shark species (such as mako and blue sharks) expand and evidence of their declines mounts.

Scientists from government agencies, universities, and private institutions participated in the workshop including authors of published papers on shark and skate population status and experts who develop advice on shark quotas for European and international fisheries of the Northeast Atlantic. Experts from England, Scotland, Ireland, Italy, Spain, Portugal, Croatia, Russia, Sweden, Canada, and the USA took part.

The IUCN Red List of Threatened Species is the world’s most authoritative guide to the status of biological diversity. The workshop was the eighth in a global series to assess all of the world’s shark and ray species and develop regional conservation priorities. Resulting Red List proposals are preliminary until accepted by the global Shark Specialist Group network.

Big sharks are disappearing

he rapid decline of great sharks in the world’s oceans is disrupting the marine ecosystem by allowing more lowly fish to thrive, scientists warn today.
Overfishing of the ancient predators has lead to a sudden uprising of species they prey on, causing an abundance of skates, rays and smaller sharks, which are steadily devastating populations of shellfish, including scallops, oysters and clams, the researchers claim.
The findings suggest that the demise of the great sharks, whose primitive ancestors cruised the seas long before the rise and fall of the dinosaurs, may have unforeseen knock-on effects on marine life lower down the food chain.
Records from fisheries and research vessels dating from the 1970s to 2005 have revealed a dramatic nosedive in great shark populations. Tiger sharks and scalloped hammerheads may have declined more than 97% since the mid-1980s, while numbers of smooth hammerheads and bull sharks are believed to have fallen by 99% off the east coast of the US.
Writing in the journal Science, a team of marine biologists led by Ran Myers at Dalhousie University in Halifax, Nova Scotia, analyse fish research surveys over the past 16 to 35 years. The records show that while the abundance of 11 great shark species fell dramatically over the past 35 years, 12 of the 14 fish species they prey on had increased sharply.
In the waters along the US Atlantic coast, numbers of cownose rays, a staple of the great shark diet that can grow to four feet across, jumped 8% a year to an estimated population of around 40 million.
The explosion of the cownose population coincides with an almost complete collapse of scallops in the waters, leaving only those protected behind marine fences for local fisheries to take.
Without sharks to keep their numbers in check, researchers fear the migrating rays will drive down shellfish populations as they swim through, to the point where they are unable to recover .
Julia Baum, a co-author of the paper, said: “With fewer sharks around, the species they prey upon, like cownose rays, have increased in numbers, and in turn, hordes of cownose rays dining on scallops, have wiped the scallops out.”
Sharks are targeted by fisheries for their fins and meat, but are also taken as by-catch by fleets fishing for tuna and swordfish. As many as 73 million sharks are killed each year around the globe for the finning trade.
Ellen Pikitch, executive director of the Pew Institute for Ocean Science in Miami, said: “This is the first published field experiment to demonstrate that the loss of sharks is cascading through ocean ecosystems and inflicting collateral damage on food fisheries such as scallops. These unforeseen and devastating impacts underscore the need to take a more holistic, ecosystem-based approach to fisheries management.”
Charles Peterson, a researcher on the paper and marine biologist at the University of North Carolina in Chapel Hill, said the study highlighted the importance of maintaining populations of the ocean’s top predators. “Despite the vastness of the oceans, its organisms are interconnected, meaning that changes at one level have implications several steps removed. Through our work, the ocean is not so unfathomable, and we know better now why sharks matter,” he added.
In British waters, historic overfishing has seen the common ray decline to the point that surveys in the western channel have failed to spot any since the 1930s. More recently, numbers of blue and porbeagle sharks are believed to have fallen. The porbeagles are believed to be taken by Danish and French fleets, while Spanish long-line vessels take blue sharks migrating into British waters.
Last year, a team lead by David Sims of the Marine Biological Association in Plymouth tagged six blue sharks off the coast of Portugal to investigate their fate. Two were landed by fisheries within three months. “The ones that get here may be the survivors,” he said.
Dr Sims said the lack of hard data makes it extremely difficult to produce reliable assessments of fish populations, adding that many predators have such varied diets that cascade effects through ecosystems are complex and often difficult to pinpoint.
“There’s no doubt the fisheries are having an impact on the big shark populations, but what we really don’t know is what the ecosystem effects of that will be. There could be other factors involved that haven’t been measured,” he added.