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Overview

Comprehensive Description

Biology

A little-known angelshark found on the outer continental shelf. Possibly larger. Ovoviviparous (Ref. 50449).
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Distribution

Range Description

Northwest Pacific: East China Sea (Compagno et al. 2005a, Walsh and Ebert 2007), continental waters surrounding northern Taiwan, Province of China, and East Taiwan Strait (Shuyuan 1994).

Specimens from the Philippines previously identified as this species were misidentified. These specimens are likely an undescribed species (J.H. Walsh and D.A. Ebert pers. obs. 2007).
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North Western Pacific: East coast of Taiwan and Ryuku Islands to SE Japan to Izu Peninsula (Ref. 84150); misidentifiction of S. caillieti in the Philippines (Ref. 86399).
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Western North Pacific.
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Physical Description

Morphology

Dorsal spines (total): 0
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Size

Max. size

55.4 cm TL (male/unsexed; (Ref. 84150))
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Diagnostic Description

Taiwan angelshark Squatina formosa has broad pectoral fins with outer corner more obtuse and free rear tips narrowly subangular; nasal barbels apparently simple, narrow and tapered. Anterior nasal flaps smooth to weakly fringed; dermal folds on sides of head possibly with a triangular lobe. Rear tip of inner margin of pelvic fins reaching little beyond origin of first dorsal. Very short hypocercal tail. Rows of small spines on midline of back and tail, and on snout and between eyes. Color: no ocelli (eye-like spot) on body (Ref. 247, 31369).
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Squatina formosa, Shen & Ting 1972 : 23, Figure 4, valid, holotype: NTT7213130. Figure 2.

 

Common name. Taiwan angelshark.

 

Diagnosis. A squatinid with the following distinctive characters: upper lip arch semi-circular, height greater than other WNP squatinids (3.8-5.1% in width, 1.4-2.1% TL in height); pectoral fins broadly rounded, especially posterior free tip; pelvic girdle moderately broad, pelvic anterior margin slightly curved, angle of lateral apex considerably more obtuse than 120°, pelvic fin tips reaching first dorsal origin; dorsal fins lobe-like with slightly rounded anterior margin, first dorsal fin base slightly larger than second dorsal base; caudal fin lobed, especially dorsally, with a curvilinear caudal posterior ventral margin.

 

Description. Dorsal surface, except for posterior portion of caudal fin, covered with denticles of moderate roughness. Ventral surface smooth except for narrow bands of denticles on the pectoral and pelvic fins anterior margins.

 

Head rounded, length about 0.2 times total length, maximum width occurring just anterior of gill openings. Moderately rough tubercles interspersed above mouth and eye crests. Eyes almond-shaped, widely set, interorbital space 8.2 (7.7-8.9). Eye-spiracle space short. Spiracles are crescent shaped without large papillae. Interspiracle space (7.8-8.2) slightly less than interorbital space. Center of upper lip exposed at midpoint of upper jaw, exposure semi-circular in shape, extending dorsally approximately 0.6-0.7 of upper jaw space, upper lip height (1.2-2.1), upper lip arch width (3.8-5.1). Labial furrows conspicuous, roughly equal in length, extending from corners of mouth medially, with upper labial furrow partially covered with dermal folds. Distinct nasal flaps protruding from dermal folds above mouth, two barbels protruding from each flap. Inner nasal barbel rod-like with a spatulate tip, inner basal portion contains little if any fringe. Outer nasal barbel narrow. Nostrils large, slightly protruding. Dermal folds along exterior of head, one small lobe present at corners of mouth extending ventrally. Mouth length about 0.3 times as long as mouth width. Dentition consisting of small, dagger-like teeth, conical without cusplets on a broad base, in 3 orderly longitudinal rows, no teeth at symphysis, teeth by row 9 - 10 - 9 - 10 / 10 - 10.

 

Pectoral fins large, broadly rounded, originating just behind gills. Anterior margin of pectoral fin slightly convex and about three quarters as long as pectoral length, extending to a lateral apex. Angle of lateral apex slightly more obtuse than 120°. Margin from lateral apex to most posterior lobe slightly concave. Posterior lobe broadly convex. Pectoral inner margin convex, about one half of pectoral length.

 

Overall pelvic fin shape somewhat triangular with rounded fintips. Pelvics originating anterior to pectoral fin free rear tips. Pelvic fin length approximately two thirds as long as pectoral fin length. Pelvic fin base approximately 1.2 times broader than pectoral base. Anterior margin slightly curvilinear, extending at roughly a 45° angle from trunk to rounded apex lateral of body, anterior margin 0.5 times as long as pelvic fin length. Pelvic girdle width (26.3-29.8) between pelvic fin apexes moderately broad, about 1.4 times head length. Posterior margin of pelvic fin, approximately 0.8 times pelvic fin length, straight to posterior free tip. Pelvic inner margin concave and short, only about 0.4 times as long as pectoral fin length. Pelvic insertion furrows on ventral extend in a narrow ellipse to anterior apogee of vent in most specimens, vent is within ellipse. Pelvic fin tips reach origin of first dorsal.

 

Dorsal fins lobed and nearly equal in size, with denticles covering the whole of fins. Interdorsal space about 0.8 times as long as dorsal caudal finspace. Anterior margin of dorsals slightly convex, nearly equidistant. First dorsal base slightly shorter than second, first dorsal base 15.2 (10.0-11.8), second dorsal base 17.4 (13.0-15.0). Apex of dorsals lobed. Posterior margins slightly convex, about 0.7 times as long as anterior margins. Inner margins of dorsals slightly convex, approximately 0.7 times as long as anterior margins.

 

Caudal peduncle compressed dorso-ventrally with lateral longitudinal ridges, tapering posteriorly. Caudal fin lobe-like, markedly at dorsal apex. Caudal dorsal margin broadly rounded, about 0.8 times as long as preventral caudal fin margin. Subterminal caudal fin margin approximately half as long as caudal upper post ventral margin. Caudal lower postventral margin convex, approximately 0.8 times as long as caudal upper post ventral margin.

 

Total vertebrae 137-139; total precaudal vertebrae 107-110; monospondylous vertebrae 48-52; diplospondylous vertebrae 58-59; caudal vertebrae 29-30.

 

Coloration. Dorsal surface of specimens prior to preservation are light to dark brown throughout with numerous black and white spots of varying sizes. Black blotches laterally at origin of dorsals. Ventral surface pale white with some black mottling on abdomen, pectoral and pelvic fin ventral margins with denticles colored similar to dorsal. Color after preservation tends to fade to a lighter brown or pale yellow with spots becoming indistinct.

 

Distribution. Endemic to western North Pacific including the East China Sea (Compagno et al, 2005a), waters surrounding northern Taiwan, and East Taiwan Strait (Shuyuan 1994).

 

Etymology. Named in allusion to the known geographic range (Formosa Strait, Taiwan) where the holotype was collected.

 

Remarks. Examination of the holotype (labeled NTT7213130 in Shen & Ting 1972, now labeled NTUM 01329) and non-type comparison material revealed that S. formosa is distinct from other WNP squatinids through four characters (Fig 2). First, S. formosa possesses a lobed caudal fin, especially in the dorsal lobe, and has a more curved postventral caudal margin. Second, S. formosa has lobed dorsal fins with a curvilinear anterior margin. Third, the pelvic girdle distance in S. formosa is more narrow than other WNP squatinids, at 1.4 or less the head length (where both measurements are standardized by total length). Fourth, S. formosa has an upper lip arch which is semicircular in shape, where the upper lip arch height is greater than 1.5% of the total length.

 

Comparison of the three S. formosa paratypes (originally labeled as NTU7041631, NTU7041632, NTU7222433 in Shen and Ting 1972; now labeled as NTUM 01327(x2) and NTUM01328) with the holotype reveals differences among these four characters (Table 2). The paratypes possess angular caudal fins without curved postventral caudal margins, angular dorsal fins with straight anterior margins, a wider pelvic girdle distance, and upper lip arches which are more semi-oval in shape (Fig 3A-C). Therefore, our contention is that these paratypes of S. formosa are, in fact, a different species. Furthermore, these characters are most consistent with the S. nebulosa comparison material we examined.

 

An apparent change in designation of one of the paratypes for unknown reasons has also added to the confusion in the type series. At present, one of the paratypes (NTUM 01328) has been designated as the holotype, and the true holotype (NTUM 01329) now has a question mark on its catalogue card next to its holotype designation, as documented by the junior author (DAE) who examined the type material of S. formosa in May 1988 and again in May 2005. However, comparison of the type material with photos of the holotype within the original species description (Shen & Ting, 1972) confirms that the NTUM 01329 specimen is the actual holotype.

 

A squatinid reported from the Philippines as S. formosa (Compagno et al., 2005b) is also not likely this species. Examination of photographs of the Philippines specimen, provided by L.J.V. Compagno, revealed several characters inconsistent with S. formosa . These characters include pelvic fins which do not reach the first dorsal base, a wider pelvic girdle, a more shallow upper lip arch and distinctly different coloration than observed in S. formosa . Therefore, the Philippines specimen most likely represents a different, possibly undescribed, squatinid species from true S. formosa .

 

Comparative material: DAE 881805, immature male, Tahsi, Taiwan , May 1988 , collected by David A. Ebert ; DAE 052105, immature male, Tahsi, Taiwan , May 2005 , collected by David A. Ebert ; DAE 052305-2, immature female, Tahsi, Taiwan , May 2005 , collected by David A. Ebert .

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
A little known species, caught at or near the bottom on the continental shelf, usually at depths of 100?300 m, although it is likely to occur in shallower depths also (D.A. Ebert unpublished data). Other angel sharks are known to bury themselves in sediment and ambush their prey.

Though life history parameters are unknown, this species is thought to be slow growing and late maturing like other species of angel shark. Reproduction is aplacental viviparity (D.A. Ebert unpublished data). Size at maturity is unknown, but large, in excess of 100 cm total length (TL) (D.A. Ebert unpublished data). Maximum recorded size is 150 cm TL and size at birth is ~30?40 cm TL (D.A. Ebert unpub. data).

Systems
  • Marine
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Environment

bathydemersal; marine; depth range 183 - 220 m (Ref. 54905)
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Depth: 183 - 220m.
From 183 to 220 meters.

Habitat: bathydemersal. A little-known angelshark found on the outer continental shelf. Possibly larger.
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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 formosa

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


There are 8 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.

ACCCTTTACTTAATCTTCGGTGCATGAGCAGGAATAGTAGGTACTGCCCTA---AGTTTACTTATCCGAGCAGAGTTAAGCCAGCCCGGAACACTCCTTGGTGAC---GATCAAATTTACAATGTAATCGTTACTGCCCACGCTTTAGTAATAATCTTCTTTATAGTGATACCAATTATAATTGGAGGGTTTGGAAATTGATTAGTCCCCTTAATA---ATTGGCGCACCAGATATAGCTTTCCCACGAATAAATAATATAAGTTTCTGACTTTTACCTCCTTCCTTACTTTTACTACTTGCCTCAGCCGGAGTTGAAGCAGGGGCCGGCACTGGTTGAACAATTTACCCTCCTCTTGCAGGAAATTTAGCTCATGCCGGAGCATCAGTAGATTTA---GCAATTTTTTCCTTACATTTAGCTGGTATCTCTTCAATCCTAGCCTCTATTAACTTCATTACAACCATTATTAACATAAAACCCCCAGCTATTTCCCAGTATCAAACACCGCTCTTTGTTTGATCAATCCTTGTAACTACTGTCCTTCTCCTCCTTTCTCTCCCTGTCCTCGCAGCT---GCAATCACAATATTATTAACCGACCGAAACCTTAACACAACATTTTTTGACCCTGCAGGAGGCGGGGACCCAATCCTTTATCAACACCTT------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------TTC
-- end --

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Statistics of barcoding coverage: Squatina formosa

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 8
Specimens with Barcodes: 11
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
EN
Endangered

Red List Criteria
A2d+4d

Version
3.1

Year Assessed
2009

Assessor/s
Walsh, J.H. & Ebert, D.A.

Reviewer/s
Valenti, S.V., Gibson, C.G. & Fowler, S.L. (Shark Red List Authority)

Contributor/s

Justification
The Taiwan Angelshark (Squatina formosa) is a medium-sized angel shark found in the northwest Pacific on the continental shelf surrounding Taiwan, Province of China. Usually it occurs at depths of 100?300 m, although it is likely also to occur in shallower depths. It is caught as bycatch, particularly in large numbers in demersal trawl fisheries. The species is not known to be targeted, but is a retained bycatch, with individuals recorded in local fish markets in northern Taiwan, although this species, like other northwest Pacific angel sharks, frequently has been misidentified. Taiwan's main fisheries (including longline, trawl and gillnet gear), operate throughout this species? entire limited known range. The Taiwan Angelshark's generation period may be between 8?15 years, based on biological information from better known angel sharks. Other angel shark populations (for example Squatina squatina and Squatina guggenheim) have proved particularly vulnerable to trawl and gillnet fishing gear, resulting in significant population depletion because of their low reproductive potential and low potential for re-colonisation. Where population data are available for other angel sharks, declines greater than 80% have been observed in less than three generations within areas where target or bycatch fisheries take place. Although trend data are not available for the Taiwan Angelshark, there is concern that it has already declined significantly as a result of fisheries, which operate throughout its entire known range. Based on current knowledge of fisheries in this region, these trends are likely to continue. Given that it is fished throughout its range with no refuges from fishing pressure, it is assessed as Endangered A2d+A4d, based on continuing suspected declines of 50?80%.Further research into this species? abundance, distribution, life-history and population trends is urgently needed.
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Population

Population
No details are available on the population of this species. Individuals are found in local fish markets in Taiwan. Little data exist due to a total lack of known catch records for this species and problems distinguishing individuals of this species from other northwest Pacific angel sharks.

Where population data are available for other angel sharks, declines greater than 80% have been observed in less than three generations, within areas where target or bycatch fisheries take place. For example, Squatina squatina has been extirpated from several parts of its range in the northeast Atlantic and Mediterranean, where it is taken as bycatch, as a result of continued intense fishing pressure (Morey et al. 2006, ICES 2004).

Population Trend
Unknown
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Threats

Major Threats
Taiwan?s main fisheries operate throughout the entire known range of this species (D.A. Ebert pers obs. 2007). It is caught in bottom trawl fisheries, which operate between 50 and 300 m (D. Ebert pers. obs. 2007). This species is utilized and is found in local fish markets, but it is unknown whether this species is truly targeted by fishing operations.

The East China Sea is intensively exploited, with several stocks declining due to overfishing and pollution (NOAA 2004). Heavy fishing mortality has resulted in a shift from an older, traditional fishery based on high-value demersal species to faster-growing, smaller, and lower-value species such as shrimp and cephalopods (NOAA 2004). Fishing pressure from trawl vessels is intense off China, despite bans on bottom trawling in various areas. China has the largest number of fishing vessels and fishers in the world with a marine fishing fleet consisting of 279,937 motorized vessels in 2004 (1,996 of which were confined to distant waters), showing little change from 1999 (FAO 2007). Catches have declined as a result, leading to catches of immature, small-sized and low value organisms (FAO 2007). In 2004, the most common fishing gear used was the trawl net (in terms of production, trawlers accounted for 47.6% of catches in 2004 (FAO 2007). In February 2006, the Government of China issued the Programme of Action on Conservation of Living Aquatic Resources of China. This states that by 2010 they aim to reduce the size and power of the motorized marine fishing fleet and the corresponding domestic marine capture catch in China from 220,000 vessels with a total power of 12.7 million kW and catching 13.06 million tonnes marine organisms in 2002, to 192,000 vessels, 11.43 million kW (FAO 2007). This represents a decline in fishing power of only 10%.

Other angel shark populations (e.g. Squatina californica, S. squatina, S. argentina) have proved particularly vulnerable to fishing pressure due to their low reproductive potential, vulnerability to trawl and gillnet fishing gear and low potential for recolonisation (due to their sedentary habit) (Gaida 1997, ICES 2004, Morey et al. 2006, Vooren and Klippel 2005). Squatina guggenheim and Squatina occulta, which occur in the Southwest Atlantic Ocean, have a triennial reproductive cycle, with a litter size of only two to eight pups. This extended breeding cycle means that they have a very low intrinsic rate of population growth. Consequently, these sharks are generally highly vulnerable to extirpation through bycatch in fisheries that are managed to sustain production of other, more productive, fishes (Musick et al. 2000, C. Vooren pers. comm. 2007).
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Endangered (EN) (A2d+4d)
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Management

Conservation Actions

Conservation Actions
No known specific conservation actions exist.

According to the Law of Fisheries of China, bottom trawling is banned within certain areas of Chinese waters (Y. Wang pers. comm. 2007). Bottom trawling is restricted in certain zones and at different times in shallow water. Individual Provinces are responsible for applying national regulations within China. They also can apply their own regulations, on basis of national regulations, but no specific information is available on the areas or timings involved or the effectiveness of enforcement.

Catch levels need to be accurately quantified and monitored. Resolution of the taxonomic issues and identification problems associated with this genus in the northwest and western central Pacific should be a high priority to achieve this (Walsh and Ebert 2007). Management action will most likely be required to reduce bycatch of this species.
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Relevance to Humans and Ecosystems

Benefits

Importance

fisheries: of no interest
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Wikipedia

Taiwan angelshark

The Taiwan angelshark, Squatina formosa, is an angel shark of the family Squatinidae found around Taiwan between latitudes 24° N and 22° N, at depths of between 185 and 220 m. Its length is up to 46 cm for an immature female - there are no adult specimens.

Reproduction is ovoviviparous.

References

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