Squatina squatina ZBK (Linnaeus, 1758)
Istanbul Fish Market : 1700-30 (1 spc.), 1981 .
- Nurettin Meriç, Lütfiye Eryilmaz, Müfit Özulug (2007): A catalogue of the fishes held in the Istanbul University, Science Faculty, Hydrobiology Museum. Zootaxa 1472, 29-54: 32-32, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:428F3980-C1B8-45FF-812E-0F4847AF6786
Habitat and Ecology
Most life history data were provided by Capape et al. (1990) for the Mediterranean. Females reach maturity at 128 to 169 cm, and males at 80 to 132 cm (Lipej et al. 2004), with maximum sizes of 183 cm and possibly up to 244 cm (Compagno 1984, in prep.), with estimates of less than 240 cm in the Mediterranean Sea (Tortonese 1956). Age at maturity and longevity are unknown. This shark is ovoviviparous, with both ovaries functional. It has moderate-sized litters of 7 to 25 young which vary according to the size of the female (Tortonese 1956, Bini 1967, Capapé et al. 1990, Compagno in prep). Records of size at birth are 24 to 30 cm (Compagno in prep.) and 24 cm (Tortonese 1956, Bini 1967). Gestation period is 8 to 10 months (Capapé et al. 1990, Compagno in prep.), born in December to February in the Mediterranean but apparently later in northern parts of its range (July in England). Reproductive age and periodicity, rate of population increase and mortality are unknown.
The angelshark feeds primarily on bony fishes, especially flatfishes (Ellis et al. 1996) but also other demersal fishes and skates, crustaceans and molluscs. Specific items include hake (Merlucius merlucius, Merluciidae), sparids (Pagellus erythrinus, Sparidae), grunts (Pomadasys sp., Haemulidae) flatfish (Bothus sp., Bothidae, Citharus linguatula, Citharidae), sole (Solea solea, Soleidae), squid (Loligo vulgaris), cuttlefish (Sepia officinalis, Sepiola spp.), and crustaceans (Dorippe lanata, Geryon tridens, Dromia vulgaris, Goneplax rhomboides, Macropipus corregatus, Atelecyclus rotundatus). It occasionally swallows odd items, including eelgrass and seabirds (a cormorant was once recorded) (Compagno in prep.).
Water temperature and chemistry ranges based on 1 sample.
Depth range (m): 0 - 146
Temperature range (°C): 16.273 - 16.273
Nitrate (umol/L): 11.916 - 11.916
Salinity (PPS): 36.219 - 36.219
Oxygen (ml/l): 3.476 - 3.476
Phosphate (umol/l): 0.711 - 0.711
Silicate (umol/l): 4.349 - 4.349
Depth range (m): 0 - 146
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.
Recorded at 150 meters.
Life History and Behavior
Molecular Biology and Genetics
Barcode data: Squatina squatina
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Squatina squatina
Public Records: 27
Specimens with Barcodes: 27
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
In 2012, Squatina squatina was included among the world's 100 most threatened species, in a report by the IUCN Species Survival Commission and the Zoological Society of London.
Vacchi et al. (2002) reported the dramatic decline in the elasmobranch catch of a tuna trap operating in Baratti (Northern Tyrrhenian Sea) between 1898 and 1922. For the genus Squatina, catches decreased from an average of 134 specimens from the period 1898 to 1905, to 95 between 1906 and 1913, and down to 15 between 1914 and 1922.
Declines have also been reported from studies off the Balearic Islands where this species, previously relatively frequent, may now be absent. Off the Balearic Islands Squatina squatina was historically documented in checklists (Delaroche 1809, Ramis 1814, Barceló I Combis 1868, Fage 1907, De Buen 1935). Captures of S. squatina spp. were relatively frequent until the 1970s, becoming increasingly sporadic during the 1980s in coastal artisanal fisheries (trammel nets and gillnets), lobster tanglenets, trawls and bottom longline fisheries. Since the mid 1990s no reports of Squatina spp. have been reported in the area (Gabriel Morey, pers. comm). Recently, Massutí and Moranta (2003) reported no captures of Squatina spp. from four bottom trawl fishing surveys (131 hauls, at a depth range of 46 to 1,800 m) carried out between 1996 and 2001 around the Balearic Islands. In addition, the likely low interaction with stocks from other areas further affects the already low recovery capacity of isolated populations such as those around the Balearics.
Catch data for this species in the north Mediterranean exist for the period from 1985 to 1999, when two major trawl surveys were carried out: the Mediterranean International Trawl Survey (MEDITS) and the Italian National Project (National Group for Demersal Resource Evaluation (GRUND)).
During the MEDITS program (1995-1999), a broad scale survey of the north Mediterranean coastline from west Morocco to the Aegean Sea in depths of 10 to 800 m, S. squatina appeared in only two of a total of 9,095 tows, at a depth range of 50 to 100 m, resulting in an estimated standing biomass of 14 t throughout the survey area (Baino et al. 2001), which equates to 1,400 individuals assuming an average individual weight of 10 kg.
In the Italian survey, captures of S. squatina were reported in only 0.41% of 9,281 hauls (Relini et al. 2000). Squatina squatina was reported from trawl surveys carried out in the Adriatic Sea in 1948, but MEDITS trawls in 1998 indicated this species may now be absent from this area (Jukic-Peladic et al. 2001). Indeed, evidence points to angel sharks being absent nowadays from most of the northern Mediterranean coastline.
Landings in the Northeast Atlantic compiled by WGEF (2004) from 1978 to 2002 for all ICES Areas are variable because of recent misreporting of other species (primarily Lophius) as this non-quota species. After deleting these records, landings have declined from 15 to 20 t in the 1980s, to 1 to 2 t in the 1990s, with the last reported landing in 1998.
Tunisia reported small catches of this species during the past decade (10 to 53 t), with the 1997 catch at 37 t; other Mediterranean countries that report 'angelsharks' to FAO with this species as part of the catch include Albania, Turkey, Malta and France. Landings in the Northeast Atlantic collated by WGEF (ICES 2004) may include some misreporting of other (quota) species (e.g., Lophius) as angel shark is a non-quota species, but otherwise landings have declined from an average of 17 t/annum in the 1980s, to 1 to 2 t in the 1990s.
There is an urgent need to confirm the status of this species in the southern Mediterranean, Canary Islands and other areas where populations may still persist. If so appropriate conservation measures are needed to protect this species there.
Relevance to Humans and Ecosystems
Squatina squatina, the angelshark or monkfish, is a species of shark in the family Squatinidae (known generally also as angel sharks), once widespread in the coastal waters of the northeastern Atlantic Ocean. Well-adapted for camouflaging itself on the sea floor, the angelshark has a flattened form with enlarged pectoral and pelvic fins, giving it a superficial resemblance to a ray. This species can be identified by its broad and stout body, conical barbels, thornless back (in larger individuals), and grayish or brownish dorsal coloration with a pattern of numerous small light and dark markings (that is more vivid in juveniles). It measures up to 2.4 m (7.9 ft) long.
Like other members of its family, the angelshark is a nocturnal ambush predator that buries itself in sediment and waits for passing prey, mostly benthic bony fishes but also skates and invertebrates. An aplacental viviparous species, females bear litters of 7–25 pups every other year. The angelshark normally poses little danger to humans, though if provoked it is quick to bite. Caught for food since at least Ancient Greece, this shark was often sold on European markets under the name "monkfish". Since the mid-20th century, intense commercial fishing across the angelshark's range have decimated its population via bycatch – it is now locally extinct or nearly so across most of its northern range, and the prospects of the remaining fragmented subpopulations are made more precarious by its slow rate of reproduction. As a result, the International Union for Conservation of Nature (IUCN) has assessed this species as Critically Endangered.
Taxonomy and phylogeny
The angelshark was originally described by the Swedish natural historian Carl Linnaeus, known as the "father of taxonomy", in the 1758 tenth edition of Systema Naturae as Squalus squatina. He did not designate a type specimen. The word squatina is the angelshark's name in Latin, derived from the word for skate; it was made the genus name for all angel sharks by the French zoologist André Duméril in 1806. Other common names used for this species include angel, angel fiddle fish, angel puffy fish, angel ray, angelfish, escat jueu, fiddle fish, monk, and monkfish. Stelbrink and colleagues (2010) conducted a phylogenetic study based on mitochondrial DNA, and found that the sister species of the angelshark is the sawback angelshark (S. aculeata). The two species formed a clade with a number of Asian angelshark species.
One of the largest members of its family, female angelsharks can attain a length of 2.4 m (7.9 ft) and males 1.8 m (5.9 ft); the maximum reported weight is 80 kg (180 lb). This species shares in common with other angel sharks a flattened body and large, wing-like pectoral fins whose anterior lobes are not fused to the head. The head and body are very broad and stocky, with small eyes positioned dorsally and followed by a pair of larger spiracles. There are a pair of unadorned barbels in front of the nares, as well as a smooth or weakly fringed flap. Folds of skin with single triangular lobe are present on the sides of the head. The teeth are small, sharp, and of similar shape in both jaws.
The pectoral and pelvic fins are wide with rounded tips; the two dorsal fins are positioned on the muscular tail behind the pelvic fins. The anal fin is absent, and the caudal fin has a larger lower lobe than upper. The dermal denticles are small, narrow, and pointed, and cover the entire upper and most of the lower body surface. There are patches of small spines on the snout and over the eyes. Small individuals have a row of thorns down the middle of the back. The coloration is gray to reddish or greenish brown above, with many small black and white spots, and white below. Juveniles are more ornately patterned than adults, with pale lines and darker blotches. The dorsal fins have a darker leading margin and lighter trailing margin. Some individuals have a white spot on the back of the "neck".
Distribution and habitat
Historically, the angelshark occurred in the temperate waters of the northeastern Atlantic, from southern Norway and Sweden to the Western Sahara and the Canary Islands, including around the British Isles and in the Mediterranean and Black Seas. In recent times it has been extirpated from the North Sea and large portions of the northern Mediterranean. This benthic shark inhabits the continental shelf, preferring soft substrates such as mud or sand, and can be found from near the coast to a depth of 150 m (490 ft). It sometimes enters brackish environments. Northern angelshark subpopulations migrate northward in summer and southward in winter.
Biology and ecology
During daytime, the angelshark usually lies motionless on the sea floor, buried under a layer of sediment with only its eyes showing. At night it becomes more active, and may sometimes be seen swimming above the bottom. Aggregations numbering up to a hundred have been observed off Gran Canaria in the summer. Known parasites of this species include the tapeworms Grillotia smaris-gora, G. angeli, and Christianella minuta, the fluke Pseudocotyle squatinae, the monogenean Leptocotyle minor, and the isopod Aega rosacea.
The angelshark is an ambush predator that feeds mainly on bottom-dwelling bony fishes, especially flatfishes, though it also preys on skates and invertebrates. Prey reported taken include the hake Merluccius merluccius, the bream Pagellus erythrinus, grunts in the genus Pomadasys, the flatfishes Bothus spp., Citharus linguatula, and Solea solea, the squid Loligo vulgaris, the cuttlefishes Sepia officinalis and Sepiola spp., and the crabs Medorippe lanata, Geryon trispinosus, Dromia personata, Goneplax rhomboides, Liocarcinus corrugatus, and Atelecyclus rotundatus. The stomachs of some examined specimens have also contained seagrass or birds (in one case an entire cormorant). Individual sharks select sites that offer the best ambush opportunities, and if successful may remain there for several days.
Angelsharks are aplacental viviparous, meaning the young hatch inside the mother's uterus and are nourished by a yolk sac until birth. Females have two functional ovaries, with the right ovary containing more oocytes and the right uterus correspondingly containing more embryos; this functional asymmetry is not present in other angel shark species. Unlike most sharks, in which vitellogenesis (yolk formation) occurs concurrently with pregnancy, in the angelshark the onset of vitellogenesis is delayed until halfway through the gestation period. The mature ova measure 8 cm (3.1 in) across and are not enclosed in a capsule. The reproductive cycle has been estimated at 2 years with ovulation taking place in spring, though this periodicity is ill-defined. The litter size ranges from 7 to 25 and is correlated with the size of the mother; the young are gestated for 8–10 months. Parturition occurs from December to February in the Mediterranean and in July off England, with the newborns measuring 24–30 cm (9.4–11.8 in) long. Males and females mature at lengths of 0.8–1.3 m (2.6–4.3 ft) and 1.3–1.7 m (4.3–5.6 ft), respectively.
The angelshark is generally unaggressive towards humans, though it can deliver a severe bite if disturbed. When approached underwater the angelshark usually remains still or swims away, though there is a record of one circling a diver with its mouth open. Fishery workers in particular should treat it with caution; in the 1776 edition of British Zoology, Thomas Pennant wrote that it is "extremely fierce and dangerous to be approached. We know of an instance of a fisherman, whose leg was terribly torn by a large one of this species, which lay within his nets in shallow water, and which he went to lay hold of incautiously."
Humans have utilized the angelshark for thousands of years. Ancient Greek authors, such as Diphilus and Mnesitheus, described its meat as "light" and "easily digestible", and Pliny the Elder noted in his Naturalis Historia (77–79 AD) that its rough skin was valued by craftsmen for polishing wood and ivory. Aristotle recorded elements of its natural history, including that it bore live young, and correctly recognized that it was a shark despite its resemblance to rays and skates. The use of this species for food has continued into modern times; it is sold fresh or dried and salted, often under the name "monkfish" (which also refers to the goosefishes of the genus Lophius). The angelshark may also be a source for shark liver oil and fishmeal.
Sources from the 19th and early 20th centuries indicate that the angelshark was once abundant all around the coasts of Western Europe. Yarrell (1836), Day (1880–04), and Garstang (1903) all noted that the angelshark was common around the British Isles, and Rey (1928) recorded that this species was common around the Iberian Peninsula and in the Mediterranean. However, from the latter half of the 20th century onwards the angelshark has come under intense pressure from commercial fisheries operating across much of its range. Due to its benthic, near-shore habits, individuals of all ages are susceptible to incidental capture by bottom trawls, trammel nets, and bottom longlines; the low reproductive rate of this shark limits its capacity to withstand population depletion.
Angelshark numbers have declined precipitously across most of its range; it is now believed to be extinct in the North Sea and most of the northern Mediterranean, and has become extremely rare elsewhere. During the comprehensive Mediterranean International Trawl Survey (MEDITS) program from 1995 to 1999, only two angelsharks were captured from 9,905 trawls. Similarly, another survey by the Italian National Project (National Group for Demersal Resource Evaluation) around the same period caught angelsharks in only 38 of 9,281 trawls. Fishery data compiled by the Working Group for Elasmobranch Fishes (WGEF) show that no angelsharks have been landed in the Northeast Atlantic since 1998. Fewer than a dozen angelsharks are thought to remain in Irish waters. Healthy subpopulations of angelsharks are thought to still persist in areas off North Africa and around the Canary Islands, though a more thorough assessment is urgently needed.
As a result of these steep population declines and the ongoing threat from demersal fisheries, the IUCN has assessed the angelshark as Critically Endangered. It is listed on Annex III of the 1976 Barcelona Convention, which aims to limit pollution in the Mediterranean Sea. This species is protected within three marine reserves in the Balearic Islands, although it has not been reported from this area since the mid-1990s. In 2008, the angelshark also received full legal protection from human activities in the waters off England and Wales from the coast to a distance of 11 km (6.8 mi), under the UK Wildlife and Countryside Act. The United Kingdom and Belgium have pushed, unsuccessfully, for this species to be listed on the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) Priority List of Threatened and Endangered Species. A captive breeding program has been initiated at Deep Sea World, North Queensferry, with the first live pups born in 2011.
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