Overview

Comprehensive Description

Biology

Found mainly on muddy bottom (Ref. 26999). Feeds on small sharks and jacks. Ovoviviparous (Ref. 50449). Utilized dried salted and fresh for human consumption; liver oil and hide also utilized (Ref. 247).
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Distribution

Range Description

Eastern Atlantic: Morocco and western Sahara coasts, Mauritania, Senegal, Guinea to Nigeria, Gabon to southern Angola and Namibia (Compagno in prep).

Mediterranean: western and central basins, Ionian Sea and Egyptian coasts. Its occurrence in the Adriatic has not been reported (Notarbartolo di Sciara and Bianchi 1998).
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Eastern Atlantic: western Mediterranean, Morocco, Senegal, Guinea to Nigeria, Gabon to Angola.
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Mediterranean Sea, eastern Atlantic: Morocco to Angola.
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Physical Description

Size

Maximum size: 1880 mm TL
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Max. size

188 cm TL (male/unsexed; (Ref. 247))
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
Squatina aculeata is an offshore angel shark of the outer continental shelf and uppermost slope of the warm-temperate and tropical eastern Atlantic. It lives on or near the seabed at depths of 30 to 500 m. It apparently prefers muddy bottoms.

The biology of S. aculeata is sketchily known. The estimated average length of this shark at maturity is 124 cm (Compagno in prep). Maximum sizes are estimated at around 188 cm (Compagno in prep). Its size at birth, longevity, age at maturity, rate of population increase and mortality are unknown. It is ovoviviparous, but the reproductive age, gestation time, reproductive periodicity, fecundity and the rate of population increase are also all unknown.

Diet in the Mediterranean includes small sharks, herring (Clupeidae), jacks (Trachurus, Carangidae), picarels (Centracanthidae), flatfish (Citharus linguatula, Citharidae) sole (Solea solea, Soleidae), cuttlefish (Sepia officinalis), and crustaceans including shrimp, manis shrimp, and crabs (Alpheus dentipes, A. ruber, Peneus keraturus, Squilla mantis, Parapeneus longirostris, Dorippe lanata, Goneplax rhomboides, Liocarcinus sp., Atelecyclus sp.) (Compagno in prep).

Systems
  • Marine
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Environment

demersal; marine; depth range 30 - 500 m (Ref. 247)
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Depth range based on 2 specimens in 1 taxon.

Environmental ranges
  Depth range (m): 207.5 - 255

Graphical representation

Depth range (m): 207.5 - 255
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Depth: 30 - 500m.
From 30 to 500 meters.

Habitat: demersal. Found on the continental shelf and uppermost slopes. Feeds on small sharks and jacks. Ovoviviparous. Utilized dried salted and fresh for human consumption. Its liver oil is also taken as well as hides for leather.
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Life History and Behavior

Life Cycle

Ovoviviparous, embryos feed solely on yolk (Ref. 50449).
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Squatina aculeata

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There are 2 barcode sequences available from BOLD and GenBank.  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.

ACCCTTTACTTAATCTTCGGTGCATGAGCAGGAATAGTAGGCACCGCCCTA---AGTTTACTTATCCGAGCAGAATTAAGCCAGCCCGGTACTCTTCTTGGAGAT---GATCAAATTTACAATGTAATCGTTACTGCCCACGCCTTAGTGATAATCTTTTTTATGGTAATGCCAATCATAATTGGAGGATTTGGAAATTGATTAGTCCCCTTAATA---ATTGGCGCACCAGATATAGCTTTTCCACGAATAAATAATATAAGTTTCTGACTTTTACCTCCTTCACTACTTTTACTACTTGCCTCAGCCGGAATTGAAGCAGGGGCCGGCACTGGTTGAACGGTTTATCCTCCTCTTGCAGGAAATTTAGCTCACGCCGGAGCATCTGTAGATTTA---GCAATTTTTTCCCTACATTTAGCCGGTATCTCTTCAATCCTAGCCTCTATTAATTTCATTACAACCATTATTAATATGAAACCACCAGCTATCTCCCAGTATCAAACACCACTCTTCGTTTGATCAATCCTTGTAACTACTGTCCTCCTCCTCCTCTCTCTCCCAGTCCTCGCAGCT---GCAATCACAATATTGTTAACCGACCGTAACCTAAACACAACATTTTTTGACCCTGCAGGGGGTGGGGACCCAATCCTTTATCAACACTTA------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------TTC
-- end --

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Statistics of barcoding coverage: Squatina aculeata

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 2
Specimens with Barcodes: 4
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
CR
Critically Endangered

Red List Criteria
A2bcd+3cd+4cd

Version
3.1

Year Assessed
2007

Assessor/s
Morey, G., Serena, F., Mancusi, C., Coelho, R., Seisay, M., Litvinov, F. & Dulvy, N.

Reviewer/s
Cavanagh, R.D., Ducrocq, M. & Valenti, S.V. (Shark Red List Authority)

Contributor/s

Justification
This large stocky angel shark was formerly a common and important demersal predator over large areas of its coastal and outer continental shelf sediment habitat in the Mediterranean sea and eastern Atlantic. Most of this region is now subject to intense demersal fisheries, and the species is highly vulnerable from birth onwards to bycatch in the benthic trawls, set nets and bottom longlines operating through most of its range and habitat. As a result of its limiting life history characteristics and bycatch in fisheries with steadily increasing effort and capacity, its abundance has declined dramatically during the past 50 years to the point where it has been apparently been extirpated from large areas of the northern Mediterranean and parts of the West African coasts. It is now extremely uncommon throughout most of the remainder of its range. Along the West African coasts this species is taken as bycatch of industrial trawl and artisanal gillnet fisheries, and was reported as common in Russian surveys during the 1970s and 1980s. Portuguese landings data from the fleet operating off Morocco and Mauritania, aggregated for S. aculeata, S. oculata and S. squatina combined indicates a 95% decline in CPUE from 1990 to 1998, but nothing is known of the fishing effort associated with these landings. The available data from this region indicate that there are very few recent records, and none since 2002. Industrial and artisanal fishing pressure is intense and often unregulated in this region and it is suspected that this will continue at the current level or increase in the future. The species is therefore categorized as Critically Endangered on the basis of observed and suspected past declines and suspected future declines.

History
  • 2006
    Endangered
    (IUCN 2006)
  • 2006
    Endangered
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Population

Population
This species is known to be caught off Tunisia and is possibly a component of catches off other countries throughout the Mediterranean including those that report angel sharks to FAO: Albania, France, Malta, Turkey (Compagno in prep.).

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 1898-1905, to 95 between 1906 and 1913, and down to 15 between 1914 and 1922. This early decline probably marks the beginning of trawling activity.

Off the Balearic Islands Squatina spp. were historically documented in checklists (Barceló y Combis 1868, Fage 1907). Captures of Squatina spp. were relatively frequent until the 1970s, becoming increasingly sporadic during the 1980s in coastal artisanal fisheries (trammel nets and gillnets), trawls and bottom longline fisheries. For example, records from a Balearic lobster gillnet fishery show that it was common to capture angel sharks on a daily basis until the mid 1980s (presumably of S. aculeata or S. oculata, judging by the depth and substratum where this fishery operates). But since the mid 1990s no reports of Squatina spp. have been reported in the area (G. Morey pers. comm). Recently, Massutí and Moranta (2003) reported no captures of Squatina ssp. from four bottom trawl fishing surveys (131 hauls, at a depth range of 46-1,800 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.

Relini et al. (2000), did not report any captures of S. aculeata from 9,281 hauls during 22 trawl surveys from 1985-1998 as part of the Italian National Project in the northern Mediterranean. During the MEDITS program (1995-1999), a broad scale survey of the north Mediterranean coastline, spanning from W. Morocco to the Aegean Sea in depths of 10 to 800 m, S. aculeata appeared in only one of a total of 9,095 tows (Baino et al. 2001). Indeed, it appears that angel sharks are now absent from most of the northern Mediterranean coastline.

The species may be more common off the North Africa coastline than in the northern Mediterranean, for example, as reported for the Tunisia (Gulf of Gabès) coast (Quignard and Ben Othaman 1978). However, more recently, Bradai (2000) considered S. aculeata to be a very rare species off Tunisia.

There are little species specific data from the West African coasts, however, this species was previously reported as common in Russian surveys in this region during the 1970s and 1980s (F. Litvinov pers. comm. 2006). Artisanal Senegalese fishermen also remember this species as common and frequently caught by lines and gillnet 30 years ago; however it is appears to have been strongly depleted to the point where it has almost disappeared, now occurring very rarely (M. Ducrocq pers. comm. 2006). Catches are now very rare according to both artisanal fishermen and observers of the industrial demersal trawl fleets (M. Ducrocq pers. comm. 2006).

Although reported in Turkish waters (Bilecenoglu et al. 2002), the species is considered very rare in the eastern part of the Mediterranean and absent in the Black Sea (Serena 2005).

Population Trend
Decreasing
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Threats

Major Threats
Angel sharks are highly susceptible to bycatch in trawls as they lie on the bottom. Benthic trawl effort has increased in both intensity and efficiency on the shelf and slope area Mediterranean over the last 50 years. The species is also bycaught in trammel nets and bottom longlines throughout its range. Human disturbance by habitat degradation and tourism are also possible threats to its preferred sandy nearshore habitat.

There is evidence for dramatic declines from historic data from a tuna trap operating in the Northern Tyrrhenian Sea with catches of the genus Squatina reported at an average of 134 specimens from 1898 to 1905, down to 15 from 1914 to 1922 (Vacchi et al. 2002). This early decline probably marks the beginning of trawling activity in the area, to which angel sharks are highly susceptible. A low rate of exchange between Squatina populations makes them prone to local depletion and means that recolonisation will be extremely low.

Mediterranean countries that report 'angelsharks' to FAO with this species as part of the catch include Albania, Turkey, Malta and France.

Squatina aculeata has virtually disappeared from most of its former Mediterranean range where its habitat over the outer continental shelf and uppermost slope (30 to 500 m depth), is subject to intense demersal fisheries, especially off the northern coasts. Declines have also been reported from studies off the Balearic Islands where this species, previously common, may now be absent. A type of fishing net for capturing Angel sharks previously existed in the Balearics called ?escatera' (?escat' meaning angel shark in Catalan), suggesting that the species used to be common in the area. Anecdotal evidence from interviews with fishermen in the Balearics indicates that in the last 20 years all species of Squatina have diminished drastically (G. Morey pers. comm.). There are only very few records from the Island of Menorca, where an intensive lobster gillnet fishery exists. Demersal fishing pressure is very high in this area, with bottom trawls operating from very shallow waters to about 800 m for shrimp (G. Morey pers comm).

Despite the scarcity of ancient numerical data, the species seems to have experienced a dramatic decline in most of its range of distribution, becoming extremely rare in the northern part of the Mediterranean.

Along the West African coasts, there are no directed fisheries for this species but it is taken as bycatch of major international industrial demersal trawl fisheries and inshore bottom set gillnets.

Portuguese landings data from the fleet operating off Morocco and Mauritania, aggregated for S. aculeata, S. oculata and S. squatina combined indicates a 95% decline in CPUE from 1990-1998, but nothing is known of the level of fishing effort associated with these landings. Landings increased to a peak of 35 t in 1990 and when the fishery was closed in 1998 the total landings were 1.7 t. This represents a decline of 95% in landings in 8 years, however nothing is known of the pattern of effort associated with these landings.

This species was previously reported as common in Russian surveys in this region during the 1970s and 1980s (F. Litvinov pers. comm. 2006). Artisanal Senegalese fishermen also remember this species as common and frequently caught by lines and gillnet 30 years ago; however it is appears to have been strongly depleted to the point where it has almost disappeared, now occurring very rarely (M. Ducrocq pers. comm. 2006). Catches are now very rare according to both artisanal fishermen and observers of the industrial demersal trawl fleets (M. Ducrocq pers. comm. 2006).

In Sierra Leone, Squatina species were periodically caught by demersal trawlers in the 1980s, but are now caught very infrequently in Sierra Leone (M. Seisay pers comm. 2006). Few individuals (19) have been caught in FIAS research surveys (FIAS unpub. data), and none have been captured since 1998. Only one specimen was caught in Guinea (year unknown) and one individual caught in Gambia in 1998. In Senegal at total of 13 individuals were caught from 1970 to 1998 and none have been seen in recent FIAS surveys (FIAS unpub. data). In Mauritania four were caught between 1988 and 1989, and none have been caught since.
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Critically Endangered (CR) (A2bcd+3cd+4cd)
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Management

Conservation Actions

Conservation Actions
The genus Squatina is protected within six Balearic Island marine reserves, where fishing for these species is forbidden and accidental captures must be released. There are no known specific conservation measures for this species throughout the rest of its range.
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Relevance to Humans and Ecosystems

Benefits

Importance

fisheries: minor commercial; price category: medium; price reliability: very questionable: based on ex-vessel price for species in this family
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Wikipedia

Sawback angelshark

The sawback angelshark, Squatina aculeata, is an angel shark of the family Squatinidae

Contents

Measurements

Mature ~ 100.0–124 cm TL; Max ~ 188 cm TL.

Identification

Colour: Are a dull grey to a light brown on back that has scarcely scattered with small irregular white spots and also with regular small dark brownish spots. No ocelli. Obtains dark blotches on head, back, the fin bases and tail. Body: Obtains large thorns atop its head in a row down its back. Has concave between eye, eye spiracle distance <1.5 x eye length. Has heavily fringed nasal barbels and including anterior nasal flaps.

Distribution & Range

Eastern Atlantic: western Mediterranean, Morocco, Senegal, Guinea to Nigeria, then Gabon to Angola. 43°N - 19°S, 18°W - 30°E.

Climate & Habitat

Subtropical; Offshore species, outer continental shelf and upper slope, demersal, marine. Usually found on a muddy bottom. 30 - 500m down.

Behaviour

Unknown.

Biology

Diet: feeds on small sharks, bony fishes, cuttlefish, and crustaceans. Reproduction: are ovoviviparous.

Status

IUCN Red List: Critically Endangered.

Threat to Humans

Harmless.

Resilience & Vulnerability

Low, minimum population doubling time: 4.5 – 14 years; high to very high vulnerability.

References

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