Squatina squatina
Length:
Mature females can be 128-169 cm long, while males can grow to 80-132 cm.
Weight:
up to 80kg
Max Depth:
400 m
Feeding habits:
The angel shark spends its days lying buried in the mud or sand with just its eyes protruding. From this position it can ambush its prey and burst out at a startling speed to engulf flatfishes, skates, crustaceans or molluscs.
Habitat:
Angel sharks of the European and North African continental shelves can be found from the subtidal zone down to at least 150 m depth. They prefer mud or sandy bottom and may penetrate estuaries and brackish water.
Distinctive characteristics:
With a flat body and large pectoral fins, the angel shark resembles a large ray more than a shark. Its skin is grey to reddish or greenish brown, scattered with small white spots and blackish dots. Young angel sharks may also have white net-like markings and large, dark blotches, while adults are plainer. Whisker-like projections near the nostrils are used to taste and feel.
Population trend:
Reported as common in many areas during the 19th and early 20th century. Steep population declines have now been reported from several parts of this species’ range, including in the North Sea, British coastal waters, the French coast and large areas of the Mediterranean Sea. Fragmentation of the species range has also occurred, causing populations to become isolated from one another.
Main threats:
Spending much time resting on the seabed, angel sharks are particularly vulnerable to bottom trawls, which have become an increasingly widespread fishing technique. Touristic developments in the shark’s range have degraded the quality of its coastal habitat.
Status (IUCN):
Prionace glauca
Length:
The blue shark reaches a maximum lengbout 380 cm. About 50% of males in the Atlantic are sexually mature by 218 cm, although some may reach maturity being as small as 182 cm. Females are considered sub-adult from 173 to 221 cm and fully mature from 221 cm.
Weight:
From 27 to 55 kg in males and from 93 to 182 kg in females.
Max Depth:
1100 m
Feeding habits:
Feeding throughout the 24 hour period, but being most active at night, the blue sharks eat mainly small pelagic fish and cephalopods, particularly squids. However, invertebrates (mainly pelagic crustaceans), small sharks, cetaceans (possibly carrion) and seabirds are also taken.
Habitat:
Blue sharks are highly migratory, with complex movement patterns and spatial structure related to reproduction and the distribution of prey. They are found in a range of habitat types throughout migration.
Distinctive characteristics:
Blue sharks are light-bodied, with long pectoral fins. The top of the body is deep blue, lighter on the sides, and the underside is white.
Population trend:
Current population trend is unknown. Limited information comes from fishery assessments, which show no evidence of a declining trend in catch rates of blue sharks in the Atlantic or Indian Oceans. However, a 20% decrease was evident in the North Pacific between the periods of 1971-1982 and 1983-1993.
Main threats:
An estimated 20 million individuals annually are caught as bycatch from other fisheries. Blue sharks are also taken by sport fishermen, particularly in the United States, Europe and Australia.
Status (IUCN):
Alopias superciliosus
Length:
3.3 – 4.0 m
Weight:
160 kg
Max Depth:
500 m
Feeding habits:
Diet consists mainly of pelagic bony fishes and cephalopods. The shark uses its tail to stun the pelagic fishes on which it feeds.
Habitat:
Ranges from the surface and the intertidal to at least 500 m deep (has been recorded 723 m deep). Found both in coastal waters and the high seas.
Distinctive characteristics:
Up to half of the body length is taken by the long upper lobe of the caudal fin. The body has a deep, metallic violet to purplish brown color above and creamy white below. The shark has huge, bulbous eyes up to 10 cm across.
Population trend:
Declining globally.
Main threats:
The species struggles to recover from moderate levels of exploitation. Occasionally targeted for its fin (2-3% of the fins auctioned in Hong Kong are from this species). Bycatch is another threat to bigeye thresher sharks, with many fishing gear types catching them accidentally.
Status (IUCN):
Cetorhinus maximus
Length:
Males become sexually mature at a length of 5-7 m, females are mature at 8.1-9.8 m. There are unconfirmed measurements of individuals that reached 12.76 m.
Weight:
2,200 kg
Max Depth:
1000 m
Feeding habits:
Passive feeder, filtering zooplankton, small fish and invertebrates from the surface water. Basking sharks filter up to 2,000 tons of water per hour. They do not seek prey actively, but possess a large olfactory bulb which presumably guides them towards prey rich regions.
Habitat:
The basking shark is a coastal-pelagic animal, found worldwide in boreal to warm-temperate waters around the continental shelves and entering into brackish waters on occasions. It prefers temperatures of 8 to 14.5°C, but has been confirmed to cross much warmer waters at the equator.
Distinctive characteristics:
Basking sharks possess a cavernous jaw, up to 1 m wide and gill slits which almost encircle the head. Colouration varies from dark brown to black on the dorsal surface and white underside.
Population trend:
Decreasing.
Main threats:
Basking sharks have been exploited for several centuries to supply liver oil for lighting and industrial use, skin for leather and flesh for food or fishmeal. Modern fisheries yield liver oil, fins, meat and cartilage. Basking shark fins are very valuable in East Asian markets, meaning the species is often targeted for this reason, as well as caught as bycatch.
Status (IUCN):
Isurus oxyrinchus
Length:
3.2 m, but the largest verified individual was 4.45 m long.
Weight:
Typically between 60 and 135 kg, but individuals weighing up to 600 kg have been recorded.
Max Depth:
500 m
Feeding habits:
This species feeds mainly on cephalopods and bony fish, but it may also eat other sharks, porpoises, sea turtles and seabirds. It hunts by lunging vertically up and tearing off chunks of flanks and fins of its prey.
Habitat:
The shortfin mako inhabits temperate and tropical seas worldwide. It is a pelagic species that can be found from the surface to the depths of 150 m, normally far from land. Rarely found in water cooler than 16˚C.
Distinctive characteristics:
Cylindrical body shape, with a vertically elongated tail. This species exhibits countershading, with brilliant metallic blue coloration dorsally and white ventrally. The juvenile mako has a clear blackish stain on the tip of the snout. Shortfin makos are also reported to have one of the biggest brains – body size ratios show the potential to learn remarkably quickly.
Population trend:
Strong evidence of decline.
Main threats:
Shortfin mako is an important target species, a bycatch in tuna and billfish longline and driftnet fisheries. It is also targeted by recreational fishermen.
Status (IUCN):
Carcharodon carcharias
Length:
6.4 m with some records claiming lengths of 8 m.
Weight:
up to 3,324 kg
Max Depth:
1200 m
Feeding habits:
Marine mammals, seabirds and large fish. Can exert a bite force of 18,216 newtons. When the shark bites, it shakes its head side-to-side, helping the teeth saw off large chunks of flesh.
Habitat:
Great white sharks live in almost all coastal and offshore waters which have the temperature between 12 and 24°C. Bigger concentrations are found in the United States (northeast and California), South Africa, Japan, Oceania, Chile, and the Mediterranean. Although it has been considered an entirely coastal species, individuals were found at depths of 1,200 m.
Distinctive characteristics:
The great white shark has a robust, large, conical snout. Countershading with white underside and grey dorsal area. Great white sharks, like many other sharks, have rows of serrated teeth behind the main ones, ready to replace any that break off.
Population trend:
Unknown
Main threats:
Often persecuted due to its (somewhat exaggerated) image as a threat to human safety. This negative image also makes it an over targeted species by recreational trophy fishermen. The great white falls victim to fishing gear such as gillnets, longlines and trawl nets designed to catch other species. Coastal developments and pollution degrade important nursery habitat areas. Directed fishery exploitation of great white sharks is primarily undertaken with the aim of trading their teeth and jaws as trophies and their fins for the oriental fin trade.
Status (IUCN):
Lamna nasus
Length:
2.5 m
Weight:
135 kg
Max Depth:
1300 m
Feeding habits:
Opportunistic hunter that preys mainly on bony fishes and cephalopods throughout the water column.
Habitat:
Distributed widely in cold and temperate marine waters of the North Atlantic and the Southern Hemisphere.
Distinctive characteristics:
Gray above and white below, the porbeagle has a very stout midsection that tapers towards the long, pointed snout and the narrow base of the tail. It has large pectoral and first dorsal fins, tiny pelvic, second dorsal, and anal fins, as well as a crescent-shaped caudal fin.
Population trend:
Decreasing
Main threats:
Targeted both as a game species by recreational fishermen and for its valuable meat on larger commercial scales. Often caught as bycatch, but meat and fins are still sold even in such cases. Slow life history traits mean recovery of stocks is unlikely.
Status (IUCN):
Hexanchus nakamurai
Length:
4.8 m
Weight:
Up to 590 kg
Max Depth:
1100 m
Feeding habits:
The bluntnose sixgill shark commonly feeds upon a variety of prey including other sharks, skates and rays, many kinds of large bony fish, and invertebrates including squid, crabs, sea cucumbers, and shrimp
Habitat:
The bluntnose sixgill shark is found in temperate waters off of the continental shelf.
Distinctive characteristics:
While most shark species have five gills, the bluntnose sixgill species has six. The bluntnose sixgill shark also has six rows of teeth.
Population trend:
Data deficiency
Main threats:
Threatened by bycatch.
Status (IUCN):
Near threatened
Threats
1.Bycatch
Bycatch, the capture of species other than those being targeted, is the biggest threat to the survival of shark populations in Greece. Intense fishing efforts in the Mediterranean are causing a drastic decline in shark populations and as efforts increase with demand, the number of sharks being impacted is increasing tenfold. Different fishing methods such as longline, trawlers, and nets can have profound effects on species depletion. Trawlers account for only 10% of the total fishing fleet in the Mediterranean, but half of its total bycatch. However, data on shark landings due to bycatch are largely inaccurate, with over 50% going unrecorded. Many species are classified under the same common name (galeos) or individuals are returned to the sea before being recorded, making it difficult to calculate the true extent of species decline. As a result, species depletion can continue to go unnoticed and if these practices continue, it may be too late to reverse the damage and decline of this charismatic species.
2.Targeted Fishing Practices
Sharks in the Mediterranean Sea are also threatened by targeted fishing practices as fishermen are becoming aware of their commercial value. As fish stocks begin to decline due to overfishing, sharks are often substituted for more commercial species. In some countries within the Mediterranean, it is reported that fishermen are targeting sharks to be sold instead of other more commercially valuable species. Shortfin mako is marketed as swordfish in cases of seafood fraud due to the resemblance of the meat. One study in Italy found 20% of commercially sold swordfish to actually be shark meat.
3.Shark finning
Shark fins are globally in demand and have led to the practice of shark finning, where valuable fins are removed, and the less valuable carcass is thrown overboard. In 2005, the practice of shark finning was banned in the Mediterranean but the removal of fins at sea was not prohibited. This loophole led to the practice of cutting the fins off sharks too large to bring aboard. Sharks must swim continuously to prevent drowning, but when their fins are severed they unable to do so, and drown.
4.Pollution
The bioaccumulation of pollutants through the food chain threatens the survival of sharks. As sharks occupy the highest trophic level, bioaccumulation leads to high concentrations of dangerous pollutants in their tissue. Heavy metals are highly toxic in animal tissues, even at low concentrations. Additionally, every year approximately 8 million tons of plastic ends up in our oceans, not only disrupting ecosystem health, but also increasing the possibility of species ingesting debris, suffocating, or becoming entangled. Fisheries-related pollution such as ghost nets that are left or lost at sea pose a major threat and have the potential to entangle marine life such as sharks.
5.Climate change
Climate change has been shown to affect prey distribution and ocean currents. This affects the abundance and distribution of sharks, often limiting the habitats they are able to survive in. With climate change causing the oceans to warm at rates unseen before, the effects on marine ecosystems and species are not entirely known, but are likely to be detrimental.