Overview

Brief Summary

Biology

Like other members of this family, the Pacific angel shark spends its days lying partially buried in sand or mud, snapping up its head and protruding its jaws at a surprising speed to ambush prey, such as bottom-dwelling fishes and squids. Whilst it does not pose a great danger to humans, its habit of lurching out to grab prey with its powerful jaws and needle-sharp teeth, can also be employed if touched or provoked, inflicting a serious bite on the diver (2). The Pacific angel shark becomes active at night, although does not swim long distances, when it will forage under the cover of darkness, thus still retaining the advantage of ambushing prey (4). The Pacific angel shark is an ovoviviparous fish; the embryos develop inside eggs that remain within the mother's body for nine to ten months until they hatch. Females produce litters of six to ten pups, of which only 20 percent are likely to survive to reach maturity at 10 to 13 years old (4).
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Description

Superficially, the Pacific angel shark resembles a large ray more than a shark, due to its remarkably flat body and huge, wing-like pectoral fins. Its skin is pale beige, scattered with dense small, brown spots, offering perfect camouflage in sandy habitats (3). Small spines that are prominent in young sharks on the back and tail are small or absent on adults. Fleshy projections (nasal barbels) with broad, flat tips, hang down near the nostrils, and are used to taste and feel. The large head is concave between the eyes (2) (4).
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Comprehensive Description

Description

  Common names: shark (English), tiburón (Espanol), pez-ángel (Espanol)
 
Squatina californica Ayres, 1859


Pacific angel shark



Front half of body and head (including pectoral and pelvic fins) roughly diamond-shaped and greatly flattened; with distinct neck before pectorals; head angular, broad at rear; distance between nostrils greater than that between eyes; nostril barbel conical, with flattened tip; relatively large eyes (4.8 times in space between them) on top of head, with prominent spiracles behind them; mouth at front; pectoral and pelvic fins greatly enlarged; dorsal fins very small, of about equal size, situated near base of tail; lower lobe of tail larger; denticles on lower surface only along margins of the pectoral and ventral fins, and on the tail, with none on the chest and abdomen; young with thorns, but not adults.


Mottled brown or greyish, with small dark spots of various sizes scattered over body and fins; large paired dark blotches on back and tail form ocelli in young.

Maximum size about 152 cm; size at birth 21-26 cm.
  
Usually seen resting on sand bottoms.

Occurs in 1-205 m depth.

Temperate; Alaska to Gulf of California
   
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Biology

Found on the continental shelf and littoral areas (Ref. 247).A sluggish and inactive species that buries itself in sand or mud (Ref. 247). Also found around rocks, heads of submarine canyons, and sometimes near kelp forests (Ref. 247). Feeds on bottom and epibenthic fishes, including croakers, California halibut, and squid (Ref. 247). Ovoviviparous (Ref. 50449). Can whip up its head and snap very quickly when touched, provoked, harassed, or speared, and can inflict painful lacerations (Ref. 247).
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Distribution

National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Range Description

The Pacific Angelshark occurs off the coast of North America from Alaska to the tip of Baja California, Mexico (including the Gulf of California) and perhaps to Ecuador and southern Chile, but the taxonomy of the southern population has not yet been validated. It is relatively common in central and southern California (US) waters, especially off the coast of Santa Barbara (Natanson and Cailliet 1986, 1990, Leet et al. 1992, 2001). It lives in relatively shallow waters to depths of 100 m, but it is much more abundant in nearshore, coastal waters (Eschmeyer et al. 1983).
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Zoogeography

See Map (including site records) of Distribution in the Tropical Eastern Pacific 
 
Global Endemism: All species, East Pacific endemic, TEP non-endemic

Regional Endemism: All species, Tropical Eastern Pacific (TEP) non-endemic, Temperate Eastern Pacific, primarily, California province, primarily, Continent, Continent only

Residency: Resident

Climate Zone: North Temperate (Californian Province &/or Northern Gulf of California), Northern Subtropical (Cortez Province + Sinaloan Gap)
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Eastern Pacific: southeastern Alaska to Gulf of California; Costa Rica to southern Chile.
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Geographic Range

Squatina californica, commonly known as the Pacific angel shark but also referred to as the "monk fish" or "sand devil" is found in a fairly limited geographical range. Pacific angel sharks inhabit the Eastern Pacific ocean, ranging from Costa Rica to Southern Chile and also from Southeast Alaska to the Gulf of California (Baja), though it is unusual to encounter these sharks north of California between Oregon and Southern Alaska (Smith 2004). The Pacific angel shark is absent along the southern part of Mexico and most of Central America (i.e. Squatina californica is not found south of the Gulf of California or north of Costa Rica) (Bester 2004).

Biogeographic Regions: pacific ocean (Native )

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Eastern Pacific.
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Range

Occurs in the eastern Pacific, from south-eastern Alaska to the Gulf of California, and Ecuador to southern Chile (2).
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Depth

Depth Range (m): 1 (S) - 205 (S)
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Physical Description

Morphology

Dorsal spines (total): 0; Dorsal soft rays (total): 0; Analspines: 0; Analsoft rays: 0
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Physical Description

The Pacific angel shark is a dorsoventrally flattened ray-like shark, with broad, wing-like pectoral fins (which are separated from the head by deep notches) and slightly smaller, wing-like pelvic fins. A terminal mouth is located at the tip of the snout, the eyes and large spiracles are dorsal (on the top of the head), five pairs of gill slits are found from the side of the head to under the throat, and fleshy, nasal barbels and flaps are also located on the head. Pacific angel sharks have two, spineless dorsal fins, no anal fin, and a well-developed caudal fin with a decidedly longer lower lobe than upper lobe (as opposed to the “top-heavy” caudal fin with a longer upper lobe typical of most other sharks). It has been proposed that this tail shape characteristic of Pacific angel sharks is an evolutionary adaptation to the sudden, rapid lift off the bottom they need to ambush and capture unsuspecting prey (Martin 2003).

The ability of Pacific angel sharks to maintain a stationary position on the bottom of the ocean for a sustained period of time is attributed to specific muscles that pump water over the gills and through the spiracles. This feature allows these sharks to breath without having to move through the watery meduim (Monteray Bay Aquarium 2004).

The teeth of Pacific angel sharks are pointed and conical with broad bases, smooth edges, and large gaps at each symphysis. The upper jaw has 9-9 teeth and the lower jaw has 10-10 teeth (Bester 2004).

Pacific angel sharks are typically whitish with red, brown, and grey splotches but certain individuals have been recorded as dark brown to black with blotches of black and brown shades (Bester 2004). The particular coloration of Pacific angel sharks allows them to camouflage themselves with muddy and sandy bottoms.

These sharks do not exceed lengths of 60 in. (152 cm) and weights of 60 lbs. (27 kg) (Bester 2004). Males grow to a maximum length of 118 cm TL while females grow even larger to a maximum length of 152 cm TL (Natanson 1984, cited in Pacific Shark Research Center, 2004).

Range mass: 27 (high) kg.

Range length: 152 (high) cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: female larger

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Size

Length max (cm): 152.0 (S)
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Size

Maximum size: 1520 mm TL
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Max. size

152 cm TL (male/unsexed; (Ref. 247)); max. reported age: 35 years (Ref. 6147)
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Ecology

Habitat

Habitat Type: Marine

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Habitat and Ecology

Habitat and Ecology
Pacific Angelsharks are relatively small, bottom-dwelling elasmobranchs, which commonly remain partially buried on flat, sandy bottoms during the daytime, but which can become active at night (Leet et al. 1992, 2001). They are primarily piscivores, apparently waiting for vulnerable prey to swim overhead. In southern California, they are reported to eat croakers, damselfish and squid (Leet et al. 1992, 2001), but their diet extends to pelagic fishes as well. Numerous techniques of ageing and age verification have been used on Pacific angelsharks, but none except tag-recapture have been successful at estimating their growth rates or age-specific processes (Natanson and Cailliet 1990, Cailliet et al. 1992). These tag-recapture data, however, allowed an estimate of von Bertalanffy growth and demography parameters that predicted relatively slow growth and moderate fecundity, with maturity occurring relatively late in life. Reproduction starts in both males and females at about 90?100 cm TL or ~13 years of age, with gestation taking approximately 10 months, resulting in up to 11 pups (mean of six) per female born between March and June.

Systems
  • Marine
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Environment

demersal; marine; depth range 3 - 205 m (Ref. 9253), usually 3 - 46 m (Ref. 54903)
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Inhabiting marine temperate and tropical environments, Pacific angel sharks are generally found in shallow waters at depths of 10 to 328 ft (3 to 100 m) off the coast of California but they have also been found as deep as 610 ft (185 m) in the Sea of Cortez (Bester 2004). These bottom-dwelling (benthic) sharks partially bury themselves in sandy or muddy environments during the day (where they may reside camouflaged for weeks until a decent-sized desirable prey enters their domain), while at night they often take a more active approach and cruise over the bottom. This species of shark generally does not move far beyond its chosen territory. These sharks are often found on the continental shelves of western North and South America, in littoral zones, in shallow bays, in sand channels by rocky reefs and outcrops, at the edges of submarine canyons and in kelp forests.

Range depth: 3 to 185 m.

Habitat Regions: temperate ; tropical ; saltwater or marine

Aquatic Biomes: benthic ; coastal

Other Habitat Features: estuarine ; intertidal or littoral

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Depth range based on 8 specimens in 1 taxon.
Water temperature and chemistry ranges based on 2 samples.

Environmental ranges
  Depth range (m): 2 - 120
  Temperature range (°C): 14.764 - 18.831
  Nitrate (umol/L): 0.440 - 26.018
  Salinity (PPS): 33.781 - 34.996
  Oxygen (ml/l): 1.055 - 5.364
  Phosphate (umol/l): 0.411 - 2.035
  Silicate (umol/l): 2.488 - 19.912

Graphical representation

Depth range (m): 2 - 120

Temperature range (°C): 14.764 - 18.831

Nitrate (umol/L): 0.440 - 26.018

Salinity (PPS): 33.781 - 34.996

Oxygen (ml/l): 1.055 - 5.364

Phosphate (umol/l): 0.411 - 2.035

Silicate (umol/l): 2.488 - 19.912
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Depth: 3 - 205m.
From 3 to 205 meters.

Habitat: demersal. Found on the continental shelf and littoral areas. Buries itself in sand or mud where it remains sluggish and inactive. Also found around rocks, heads of submarine canyons, and sometimes near kelp forests. Feeds on bottom and epibenthic fishes, including croakers, California halibut, and squid. Ovoviviparous. Can inflict painful wounds when it whips up its head due to provocation, harassement, by being speared or by merely being touched.
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The Pacific angel shark inhabits cold to warm-temperate waters, at depths down to 200 meters. It generally occurs in waters over sandy and muddy bottoms, and is also often observed around rocks, and sometimes near kelp forests (2) (4).
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Salinity: Marine, Marine Only

Inshore/Offshore: Inshore, Inshore Only

Water Column Position: Bottom, Bottom only

Habitat: Macroalgae, Reef associated (reef + edges-water column & soft bottom), Soft bottom (mud, sand,gravel, beach, estuary & mangrove), Soft bottom only, Mud, Sand & gravel

FishBase Habitat: Demersal
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Migration

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Trophic Strategy

Also in Ref. 9137. A carnivor (Ref. 9137).
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Food Habits

Pacific angel sharks are carnivores that primarily feed on bony fish and cephalopods (squid and octopus) but are known to consume crustaceans and other types of mollusks as well. Of the bony fish, Pacific angel sharks attack croakers (Scianidae, Atractoscion nobilis and Seriphus politus); flatfish (Pleuronectiformes); corbina (Menticirrhus undulatus); sea basses (Serranidae, Paralabrax clathratus); blacksmith (Pomacentridae, Chromis punctipinnis); mackerels, tunas, and bonitos (Scombridae); hake and halibut (Hippoglossus stenolepis); Pacific sardines (Clupeidae, Sardinops sagax) and also peppered shark (Galeus piperatus)(Fouts and Nelson 1999 and Ebert 2003, cited in Pacific Shark Research Center, 2004; Martin 2003).

Animal Foods: fish; mollusks; aquatic crustaceans

Primary Diet: carnivore (Piscivore )

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Feeding

Feeding Group: Carnivore

Diet: octopus/squid/cuttlefish, bony fishes
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Associations

Ecosystem Roles

Pacific angel sharks are predators that eat a variety of other smaller marine predators. They are, in return, preyed upon by bigger sharks. Parasites associated with Squatina californica include tapeworms (1 family, 1 species), flukes (1 family, 1 sp.), marine leeches (1 family, 1 sp.), and protozoans (1 family, 1 sp.) (Love and Moser 1983, cited in Pacific Shark Research Center, 2004).

Commensal/Parasitic Species:

  • Love, M., M. Moser. 1983. A checklist of parasites of California, Oregon, and Washington marine and estuarine fishes. NOAA Technical Report NMFS SSRF-777, 777: 577.
  • Cortés, E. 1999. Standardized diet compositions and trophic levels of sharks. ICES Journal of Marine Science, 56(5): 707-717.
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Predation

Pacific angel sharks are only preyed upon by some larger sharks, including white sharks (Carcharodon carcharias) (Bester 2004; Ebert 2003, cited in Pacific Shark Research Center, 2004). Humans, through the booming trawl and gillnet fishery in the early 1980’s, also posed a threat to the survival of Pacific angel sharks. Many of these fisheries are now either regulated or closed in order for the depleted population of Pacific angel sharks to increase again.

Known Predators:

Anti-predator Adaptations: cryptic

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Life History and Behavior

Behavior

Communication and Perception

There is little known about communication and perception among Pacific angel sharks. Squatina californica principally utilizes its eyes (on the top of the head) and sense of feel while it camly lies in wait at the bottom of the sea floor for prey. These sharks are known to be electroreceptive, utilizing electric fields to locate prey. While many species of sharks must move/swim in order to breath, Pacific angel sharks have muscles that pump water over the gills and through the spiracles so that it is not necessary for them to move, an adaptation crucial to their ambush style of feeding.

Perception Channels: visual ; tactile ; electric

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Life Cycle

Ovoviviparous, embryos feed solely on yolk (Ref. 50449).
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Development

Though there is little known about the development and life cycle of Squatina californica, it has been observed that males grow and reach maturity at a length of 30 to 31 in. (75 to 80 cm) and an age of 8 years whereas females develop and reach maturity at a length of 35 to 39 in. (90 to 100 cm) and the age of 13 years.

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Life Expectancy

Lifespan/Longevity

The maximum reported age of a Pacific angel shark is 35 years (Natanson 1984, cited in Pacific Shark Research Center 2004).

Range lifespan

Status: wild:
35 (high) years.

Average lifespan

Status: captivity:
35 years.

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Lifespan, longevity, and ageing

Maximum longevity: 35 years (wild)
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Reproduction

We have no information about the mating systems of the Pacific angel shark.

The reproductive cycle of the Pacific angel shark is typically annual (the fecundity ranges from approximately 1 to 10 ovarian eggs produced with an average of 7) with a gestation period of approximately 10 months and the births occurring primarily between March and June in the northern part of the species' range (Natanson and Cailliet 1986, cited in Pacific Shark Research Center, 2004). Pacific angel sharks reproduce by aplacental vivipary (ovovivipary), which means that the eggs hatch inside of the mother’s body and there is no nourishing placenta to sustain the young. Instead, nutrition is provided by an external yolk which shrinks as the pups grow and shifts into an internal sac when the embryo reaches 150 mm TL. The stored yolk is then transferred from the internal sac to the intestine of the embryo where is it absorbed (Bester 2004). Though the litter size can range from 1 to 13, the number of pups per pregnancy is generally between 8 and 13. At birth, the pups are on average, 9 in. (23 cm) long. Males tend to reach sexual maturity earlier than females at the age of 8 years, while females reach sexual maturity around the age of 13 years (Bester 2004).

Breeding interval: Pacific angel sharks breed once per year

Breeding season: S. californica breeds from May to August in the northern portion of its range

Range number of offspring: 1 to 13.

Average number of offspring: 6.

Average gestation period: 10 months.

Average age at sexual or reproductive maturity (female): 13 years.

Average age at sexual or reproductive maturity (male): 8 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); ovoviviparous

Average age at sexual or reproductive maturity (female)

Sex: female:
3650 days.

Little has been recorded regarding parental investment in Pacific angel sharks but the long gestation period (approx. 10 months) and the development of the embryo inside the mother’s body indicate that a significant amount of time and energy is invested in ensuring the growth and immediate survival of the young pups. There is no known dependence of the pups on their parents: once the pups are born they are on their own.

Parental Investment: female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)

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Egg Type: Live birth, No pelagic larva, No pelagic phase
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Molecular Biology and Genetics

Molecular Biology

Barcode data: Squatina californica

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


There are 36 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.

ACCCTTTATTTAATTTTTGGTGCATGAGCAGGAATGGTAGGTACTGCCCTA---AGTTTACTTATCCGAGCAGAATTAAGCCAGCCCGGAACACTACTTGGGGAT---GATCAAATTTACAATGTAATTGTTACTGCCCACGCTTTCGTAATAATCTTTTTTATGGTAATACCAATCATAATTGGTGGATTTGGAAATTGATTAGTTCCATTAATA---ATTGGTGCACCAGATATAGCCTTTCCACGAATAAATAATATAAGCTTCTGACTTTTACCTCCTTCCCTATTATTATTACTTGCTTCAGCTGGAGTTGAAGCAGGGGCCGGCACTGGTTGAACAGTATATCCTCCTCTTGCAGGAAATTTAGCTCACGCCGGAGCATCAGTAGATTTA---GCAATTTTTTCCCTACACTTAGCTGGTATCTCTTCAATTTTAGCCTCTATTAATTTCATTACAACTATTATTAACATAAAACCCCCAGCTATTTCTCAATATCAAACACCACTCTTTGTTTGATCAATCTTGGTAACTACTGTACTTCTCCTCCTTTCTCTCCCAGTTCTAGCAGCT---GCAATTACAATATTATTAACTGACCGTAATCTAAATACAACATTTTTTGACCCTGCAGGAGGTGGAGACCCAATCCTTTACCAACACTTA------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------TTC
-- end --

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Statistics of barcoding coverage: Squatina californica

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 39
Specimens with Barcodes: 43
Species With Barcodes: 1
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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: NNR - Unranked

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NatureServe Conservation Status

Rounded Global Status Rank: GNR - Not Yet Ranked

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IUCN Red List Assessment


Red List Category
NT
Near Threatened

Red List Criteria

Version
3.1

Year Assessed
2005

Assessor/s
Cailliet, G.M.

Reviewer/s
Musick, J.A. & Fowler, S.L. (Shark Red List Authority)

Contributor/s

Justification
This assessment is based on the information published in the 2005 shark status survey (Fowler et al. 2005).

This once abundant eastern Pacific coastal shark is relatively slow-growing, late maturing and moderately fecund, reaching maturity at ~13 years and producing up to 10 pups per year. Because of its rather limited geographical range and life history, resident stocks of Pacific Angelshark (Squatina californica) may be particularly vulnerable to heavy localised fishing pressure. Commercial catch data in recent decades demonstrated a peak, followed by an almost complete collapse in the central California gillnet fishery for California halibut. This fishery is now closed under California law.
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Due to the large regulated trawl and gillnet fishery off the California coast, which was primarily instituted by Santa Barbara fish processor Michael Wagner in 1978, the number of Pacific angel sharks significantly decreased (Martin 2003). Landings for Pacific angel sharks jumped from 366 lbs. in 1977 to more than 700,000 lbs. in 1984. It became the leading shark food from 1985 to 1986 until size limits were imposed and near shore fishing (i.e. gillnetting inshore of 3 miles) was banned by a voter initiative (Smith 2004). The gillnet fisheries of California are now closed because of the severely depleted populations of Pacific angel sharks. Renewal of gillnetting could potentially threaten the future survival of Pacific angel sharks off of the U.S. coast. The IUCN red list currently indicates that Squatina californica is tagged as “Near Threatened” (LR/nt).

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: near threatened

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Status

Classified as Near Threatened (NT) on the IUCN Red List (1).
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IUCN Red List: Listed, Near threatened

CITES: Not listed
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Population

Population Trend
Unknown
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Threats

Major Threats
The growth and demography parameters from the tag-recapture study indicated that Pacific Angelsharks grew slowly enough and had relatively few offspring relatively late in life to indicate that they could not handle strong exploitation (see Richards 1987). There was a rapid increase in angel shark landings between 1983?1986 (Richards 1987), leading to concern that stocks could be over-exploited. Even though a minimum size was proposed for the gillnet fishery targeting both California Halibut (Paralichthys californicus) and Pacific Angelsharks, this measure proved not to be effective at reversing the declining population levels along the Santa Barbara/ Ventura coast and Channel Islands areas, California (Richards 1987, Cailliet et al. 1993). Because of the gillnet fishery ban (Proposition 132) voted into law by Californians in 1990, there is now a reduced threat to the California population of Pacific Angelsharks. However, little is known about the effect of fisheries on the overall stock of this population, which is being heavily fished along both the Pacific and Gulf coasts of Baja California (C. Villavicencio pers. comm.).

Because of its rather limited geographical range and evidence of only limited exchange among regional stocks within this range, resident stocks near large population centres may be particularly vulnerable to heavy localised fishing pressure. This is especially true since past commercial catch data have exhibited a typical elasmobranch fisheries pattern. Angel shark landings in California increased from about 45.4 t in the late 1970s, to >545 t in 1985 and 1986. This was followed by a rapid decline in total catch to <90t in 1989 and an almost complete collapse by the early 1990s (Richards 1987, Cailliet et al. 1993).
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Near Threatened (NT)
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Around 1980 the Pacific angel shark became the subject of an expanding gillnet fishery off southern California. The shark was captured for its meat for human consumption, and became a highly sought after food (2). Catches peaked in 1985 and 1986, and then declined rapidly (5). This fishery not only threatened the survival of the Pacific angel shark, but also impacted many other marine species that are incidentally caught in the drift gillnets, including large numbers of California sea lions, harbour seals, and cormorants (6). Restrictions on gillnet fishing in the region, implemented in the early 1990s, are thought to have prevented a total population collapse of the Pacific angel shark (4) (5). Elsewhere, the Pacific angel shark is taken as by-catch, such as in the shrimp bottom-trawl fishery, where it ends up being processed with other fishes for fishmeal (2). The slow reproductive rate and late maturation of the Pacific angel shark makes it particularly vulnerable to such exploitation.
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Management

Conservation Actions

Conservation Actions
The Pacific Angelshark is considered to be overfished. The fishery is now indirectly regulated, mainly through the ban on nearshore gillnet fisheries in southern California, which originally targeted the California halibut (Cailliet et al. 1992, Leet et al. 1992). Nevertheless, an interest still remains in commercially exploiting this species and conservation measures should be implemented to protect its populations in the future.
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Conservation

In 1991, depth restrictions were implemented in central Californian fisheries, which banned fishing inshore of 55 meters, and in 1994, area closures restricted set gillnets to waters greater than 5.5 kilometres from the southern California mainland. A year-round ban on gill nets inshore of 110 meters was implemented between Point Reyes and Point Arguello, California, in 2002; however this closure is currently being challenged by fishermen. These measures have resulted in a discernible decrease in fishing effort in the angel shark fishery, and may allow depleted populations a chance to recover (6). By-catch is a global problem that continues to threaten the Pacific angel shark and many other marine species. Many organizations are working to stop the use of particularly damaging fishing methods, develop technology to reduce by-catch, and create marine reserves where marine species are safe from this ubiquitous threat (7).
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Relevance to Humans and Ecosystems

Benefits

Importance

fisheries: commercial
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Economic Importance for Humans: Negative

Since Pacific angel sharks spend most of their time buried in sand or mud at the bottom of estuaries, bays or the ocean where they reside, these sharks are considered relatively peaceful if left alone. But if these sharks are provoked (by being trodden on, pulled by the tail, approached head on, captured, etc.) their extremely sharp teeth and aggressive bite can inflict severe and painful lacerations. Consequently, close encounters with these sharks can often adversely affect human health and safety.

Negative Impacts: injures humans (bites or stings)

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Economic Importance for Humans: Positive

Until the late 1970’s Pacific angel sharks were not marketed. In 1978, the trawl and gillnet fisheries off the California coast expanded and Pacific angel sharks, caught both commercially by the fisheries and recreationally by divers and sportfishers, became an important shark food for human consumption. Primarily during the early and mid 1980’s, the abundant Pacific angel shark flesh was both frozen and marketed fresh for humans to enjoy.

Positive Impacts: food

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Wikipedia

Pacific angelshark

The Pacific angelshark (Squatina californica) is a species of angel shark, family Squatinidae, found in the eastern Pacific Ocean from Alaska to the Gulf of California, and from Ecuador to Chile, although those in the Gulf of California and southeastern Pacific may in fact be separate species. The Pacific angelshark inhabits shallow, coastal waters on sandy flats, usually near rocky reefs, kelp forests, or other underwater features. This species resembles other angel sharks in appearance, with a flattened body and greatly enlarged pectoral and pelvic fins. Characteristic features of this shark include a pair of cone-shaped barbels on its snout, angular pectoral fins, and a brown or gray dorsal coloration with many small dark markings. It attains a maximum length of 1.5 m (4.9 ft).

An ambush predator, the Pacific angelshark conceals itself on the sea floor and waits for approaching prey, primarily bony fishes and squid. Prey are targeted visually and, with a quick upward thrust of the head, snatched in protrusible jaws. Individual sharks actively choose ideal ambush sites, where they stay for several days before moving on to a new one. This species is more active at night than during the day, when it stays buried in sediment and seldom moves. Reproduction is viviparous, with the embryos hatching inside the mother's uterus and being sustained by a yolk sac until birth. Females give birth to an average of six young every spring.

Pacific angelsharks are not dangerous to humans unless provoked, in which case their bite can cause a painful injury. They are valued for their meat and are captured by commercial and recreational fishers across their range. A targeted gillnet fishery for this species began off Santa Barbara, California in 1976 and ended in 1994, after overfishing and new regulations led to its near-collapse. This species is now mainly fished in Mexican waters. The International Union for Conservation of Nature (IUCN) has assessed this species as Near Threatened, as the Californian population is largely protected and recovering, while the impact of Mexican fisheries is unknown.

Taxonomy and phylogeny[edit]

The Pacific angelshark was first scientifically described in 1859 by William Orville Ayres, the first Curator of Ichthyology at the California Academy of Sciences.[2] He gave it the specific epithet californica, as the originally-described specimen was caught off San Francisco. Locally, this species may also be referred to as angel shark, California angel shark, or monkfish.[3]

The Chilean angelshark (Squatina armata) of the southeastern Pacific was synonymized with this species by Kato, Springer and Wagner in 1967, but was later tentatively recognized as a separate species again by Leonard Compagno.[4][5] The taxonomic status of angel sharks in the southeastern Pacific – whether they are S. californica, S. armata, or if there is more than one Squatina species in the region – remains unresolved. The angel sharks inhabiting the Gulf of California may also represent a different species, as they mature at a much smaller size than those from the rest of their range.[4]





Squatina dumeril



Squatina californica





Squatina occulta



Squatina guggenheim





Squatina armata



Phylogenetic relationships of the Pacific angelshark.[6]

A phylogenetic study based on mitochondrial DNA, published by Björn Stelbrink and colleagues in 2010, reported that the sister species of the Pacific angelshark is the sand devil (S. dumeril) of the western North Atlantic. The two species are estimated to have diverged approximately 6.1 Ma, close to when the Isthmus of Panama first began to form. The authors also found that Pacific angelsharks from the Gulf of California differed genetically from those elsewhere, though they were equivocal as to whether this represented a species-level distinction.[6]

Distribution and habitat[edit]

Pacific angelsharks are found in cold to warm-temperate waters from the southeastern corner of Alaska to the Gulf of California, including the entire Baja peninsula, and are most common off central and southern California. It may also occur from Ecuador to the southern tip of Chile (see taxonomic uncertainty above). This bottom-dwelling shark prefers habitats with soft, flat bottoms close to shore, such as estuaries and bays, and are often found near rocky reefs, submarine canyons, and kelp forests. On occasion, they have been seen swimming 15–91 m (49–299 ft) above the sea floor.[3] Off California, the Pacific angelshark is most common at a depth of 3–45 m (9.8–148 ft), but has been reported from as deep as 205 m (673 ft).[7]

A number of genetically discrete subpopulations have been identified across the northern range of the Pacific angelshark. Several subpopulations exist along the coast from Point Conception northward to Alaska. In the Southern California Bight, there are at least three separate subpopulations off the mainland and northern and southern Channel Islands. The subpopulation along the Pacific coast of Baja California are distinct from those in the Gulf of California.[3] These subpopulations have diverged from one another over time because Pacific angelsharks do not undertake long migratory movements outside of their preferred home areas, and deep waters serve as effective geographical barriers to population mixing. Heterozygosity, a measure of genetic diversity, is higher in the Pacific angelshark than in other shark species that have been examined.[8]

Description[edit]

The Pacific angelshark has dorsally placed eyes, a terminal mouth, and nasal barbels.

With its flattened body and wing-like pectoral fins, the Pacific angelshark superficially resembles a ray. Unlike in rays, its five pairs of gill slits are located on the sides of the head rather than underneath, and the expanded anterior lobes of its pectoral fins are separate rather than fused to the head. The eyes are located on top of the head, with the spiracles behind. There are folds of skin without triangular lobes on the sides of head. The mouth is very wide and placed terminally (at the front of the snout); a pair of cone-shaped barbels with spoon-like tips are located above.[3][4] There are 9 tooth rows on either side of the upper jaw and 10 tooth rows on either side of the lower jaw, with toothless gaps at the middle of both jaws. Each tooth has a broad base and a single narrow, smooth-edged cusp.[2]

The pectoral and pelvic fins are broad and angular with pointed tips. The two dorsal fins are located far back on the body, and there is no anal fin. The lower lobe of the caudal fin is larger than the upper. A row of small thorns runs down the middle of the back and tail; thorns are also present on the snout and over the eyes.[4] As the shark ages, the thorns decrease in size and may disappear. The dorsal coloration is gray, brown, or reddish brown with scattered dark markings: large blotches surrounded by a ring of tiny spots in adults, and pairs of ocelli in juveniles. The underside is white, extending to the margins of the pectoral and pelvic fins.[9] This species measures up to 1.5 m (59 in) long and weighs up to 27 kg (60 lb).[2]

Biology and ecology[edit]

During the day, Pacific angelsharks are almost never seen in the open, instead resting motionless on the sea floor buried under a thin layer of sediment that disguises their outlines. At night some individuals remain motionless, waiting for prey, while others may be encountered on the bottom unburied or actively swimming.[10] Large sharks, including the great white shark (Carcharodon carcharias) and the broadnose sevengill shark (Notorynchus cepedianus), and the northern elephant seal (Mirounga angustirostris) are known to consume Pacific angelsharks.[3][11] Known parasites of this species include the copepod Trebius latifurcatus, which infests the skin, the myxosporidian Chloromyxum levigatum, which infests the gall bladder, and the tapeworm Paraberrapex manifestus, which infests the spiral valve intestine.[12][13][14] The leech Branchellion lobata may be attached around this shark's cloaca, inside the intestine, and even inside the uterus and on developing embryos.[15]

Feeding[edit]

The Pacific angelshark's cryptic dorsal coloration enables it to ambush prey.

A sedentary ambush predator, the Pacific angelshark feeds mainly on bony fishes, including kelp bass, croakers, flatfishes, damselfishes, mackerels, and sardines. During the winter and early spring, spawning squid are abundant and become the primary source of food.[3] In the southern Gulf of California, the most important prey species are, in descending order, the mackerel Decapterus macrosoma, the toadfish Porichthys analis, the lizardfish Synodus evermann, the soldierfish Myripristis leiognathus, and the shrimp Sicyonia penicillata.[16] At Catalina Island, this species feeds mainly on the blacksmith (Chromis punctipinnis) and the queenfish (Seriphus politus).[10] Adults and juveniles have similar diets.[16]

Individual sharks choose sites giving them the best ambush success. They prefer junctions of sandy and rocky substrates near reefs (used by many fishes for shelter) usually orienting themselves either toward or parallel to nearby vertical structures. They tend to face upslope, which may facilitate burying via falling sediment, bring more fish swimming downstream from the reef, or ease targeting by silhouetting prey against the sunlight.[10]

Once settled at a successful site, an angelshark may remain there for ten days, re-burying itself on or near the same spot after every strike. As the local prey eventually learn to avoid the stationary predator, the shark periodically shifts at night to a new site several kilometers away. One study off Santa Catalina Island found that over 13–25 hours, nine sharks together used only 1.5 km2 (0.6 mi2). A later, longer-term study found that the sharks' sporadic position changes covered as much as 75 km (47 mi) over three months, almost circling the island. Single individuals swam up to 7.3 km (4.5 mi) in a night.[10][17]

The Pacific angelshark is primarily a visual hunter; experiments in nature show that they strike at fish-shaped targets without any electrical, chemical, vibrational, or behavioral cues. At night, they are guided by the bioluminescence of planktonic dinoflagellates and ostracods disturbed by moving prey.[17] This species' visual system is attuned to the wavelengths of light emitted by these planktonic organisms, showing the importance of night hunting. Pacific angelsharks are more likely to strike at prey approaching from the front.[10] It usually waits until the prey approaches to 15 cm (5.9 in), as its attack is less accurate beyond this distance.[3] The strike is a stereotyped behavior in which the shark presses the forward lobes of its pectoral fins against the bottom and thrusts its head upwards at up to a 90° angle. Its mouth forms a tube when opened, creating a suction force, while its jaws protude forward to secure the prey between sharp teeth. During the strike, the eyes roll backward into the head for protection. The strike is often completed in under a tenth of a second.[10]

Life history[edit]

The Pacific angelshark is aplacental viviparous with the unborn young nourished by a yolk sac; reproduction occurs on an annual cycle. Most females have a single functional ovary (on the left side), though some have two; the oviducts are often filled with yolk, which has been speculated to be from unfertilized eggs being resorbed. Young embryos 35 mm (1.4 in) long have translucent skin, protruding eyes, and exposed gill filaments. Spots of pigment have developed when the embryo is 70 mm (2.8 in) long, and the first row of teeth have appeared when the embryo is 110 mm (4.3 in) long. By the time the embryo is 150 mm (5.9 in) long, the mouth has migrated to a terminal position and the color pattern has fully developed; the external yolk sac begins to shrink as the yolk is transferred to an internal yolk sac, which holds it until it can be transferred to the intestine for digestion. The internal yolk sac is fully resorbed before birth; if the pup is released prematurely, it does not feed until this process is complete.[18]

Off Santa Barbara, birthing takes place from March to June after a gestation period of ten months, and the females mate again shortly afterward. The average litter size is 6 with a range of 1–11 (rarely 13); there is no correlation between female size and number of offspring.[18] The young are born in water 55–90 m (180–300 ft) deep, probably to protect them from predators.[17] Pacific angelshark embryos grow at 45 mm (1.8 in) per month when young, slowing down to 10 mm (0.39 in) per month just before birth, and are born at a length of 25–26 cm (9.8–10 in). Newborn pups in captivity grow at a rate of around 14 cm (5.5 in) per year, while adults in the wild grow at around 2 cm (0.79 in) per year. Both sexes mature at 90–100 cm (3.0–3.3 ft) long, corresponding to an age of 8–13 years.[18][19] Gulf of California sharks, which may be another species, mature at 78 cm (2.56 ft) long for males and 85 cm (2.79 ft) long for females.[3] About 20% of newborns survive to maturity.[20] The maximum lifespan has been estimated at 25–35 years.[19] Unlike other sharks, the growth rings on the vertebrae of this species are deposited in proportion to the shark's size rather than yearly, making age determination difficult.[17]

Human interactions[edit]

Although usually sedate and approachable underwater, Pacific angelsharks are quick to bite if touched, captured, or otherwise provoked, and can inflict severe lacerations.[3] Commercial fisheries for this species exist off Baja California and to a lesser extent off California (see below); the meat is considered excellent and is sold fresh or frozen. This species is captured in limited numbers by recreational fishers using hook-and-line, spears, or even by hand, particularly off southern California. It is also taken as bycatch in shrimp trawls operating in the Gulf of California, and processed into fishmeal.[4] The capacity of this species to withstand a focused fishing effort is limited, due to its low rates of reproduction and movement.[20]

In 1976, the commercial gillnet fishery for the California halibut (Paralichthys californicus), operating off Santa Barbara, expanded to include the Pacific angelshark as well. The sharks had become valuable due to their promotion as a substitute for the seasonally available common thresher shark (Alopias vulpinus), and the development of new processing techniques. Around 50% of the shark was used, while the skin, cartilage, and offal were discarded. In the 1980s, rising demand led to the introduction of gillnets with a medium-sized mesh, designed specifically for this species. Fishery landings increased from a dressed (post-processing) weight of 148 kg (326 lb) in 1977, to 117,000 kg (258,000 lb) in 1983, to 277,000 kg (611,000 lb) in 1984. The fishery peaked in 1985 and 1986, when 550,000 kg (1.2 million lbs) were taken annually, making this species the number one shark fished off California. This level of exploitation was unsustainable, and despite a minimum size limit imposed in 1986, catches fell to 112,000 kg (247,000 lb) in 1990.[20][21]

In 1991, the use of gillnets in nearshore Californian waters was banned by a voter initiative (Proposition 132); the restricted area included much of the Pacific angelshark's habitat and reduced fishing pressure on the species. As a result, Pacific angelshark landings dropped further to 10,000 kg (22,000 lb) dressed in 1994, when the central Californian halibut/angel shark fishery was closed completely, and have remained low since. The decline of the Californian fishery led to the industry shifting to Mexico, where gillnet pangas (artisanal fishing vessels) targeting this species now meet most of the angel shark demand in California.[20][21] The International Union for Conservation of Nature (IUCN) has assessed this species as Near Threatened; Pacific angelshark numbers off California appear to be increasing and demographic modeling suggests the stock is healthy.[19] However, the impact of the intense, unregulated Mexican fishery on the global population is yet undetermined. There is continuing interest in California for a resumption of the commercial fishery, though conservation concerns have thus far taken precedence.[20]

References[edit]

  1. ^ Cailliet, G.M. (2005). "Squatina californica". IUCN Red List of Threatened Species. Version 2010.1. International Union for Conservation of Nature. Retrieved April 24, 2010. 
  2. ^ a b c Bester, C. Biological Profiles: Pacific Angelshark. Florida Museum of Natural History Ichthyology Department. Retrieved on June 22, 2009.
  3. ^ a b c d e f g h i Ebert, D.A. (2003). Sharks, Rays, and Chimaeras of California. University of California Press. pp. 76–80. ISBN 0-520-23484-7. 
  4. ^ a b c d e Compagno, L.J.V. (2002). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date (Volume 2). Rome: Food and Agriculture Organization. pp. 144–145. ISBN 92-5-104543-7. 
  5. ^ Lamilla, J. & Romero, M. (2004). Squatina armata. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved June 22, 2009.
  6. ^ a b Stelbrink, B., T. von Rintelen, G. Cliff, and J. Kriwet (2010). "Molecular systematics and global phylogeography of angel sharks (genus Squatina)". Molecular Phylogenetics and Evolution 54 (2): 395–404. doi:10.1016/j.ympev.2009.07.029. PMID 19647086. 
  7. ^ Froese, Rainer and Pauly, Daniel, eds. (2009). "Squatina californica" in FishBase. June 2009 version.
  8. ^ Gaida, I.H. (December 9, 1997). "Population Structure of the Pacific Angel Shark, Squatina californica (Squatiniformes: Squatinidae), around the California Channel Islands". Copeia (American Society of Ichthyologists and Herpetologists) 1997 (4): 738–744. doi:10.2307/1447291. JSTOR 1447291. 
  9. ^ Compagno, L.J.V., Dando, M. and Fowler, S. (2005). Sharks of the World. Princeton University Press. pp. 140–141. ISBN 978-0-691-12072-0. 
  10. ^ a b c d e f Fouts, W.R. and Nelson, D.R. (May 7, 1999). "Prey Capture by the Pacific Angel Shark, Squatina californica: Visually Mediated Strikes and Ambush-Site Characteristics". Copeia (American Society of Ichthyologists and Herpetologists) 1999 (2): 304–312. doi:10.2307/1447476. JSTOR 1447476. 
  11. ^ Sinclair, E.H. (1994). "Prey of juvenile northern elephant seals (Mirounga angustirostris) in the Southern California Bight". Marine Mammal Science 10 (2): 230–239. doi:10.1111/j.1748-7692.1994.tb00267.x. 
  12. ^ Deets, G.B. and Dojiri, M. (March 1989). "Three species of Trebius Krøyer, 1838 (Copepoda: Siphonostomatoida) parasitic on Pacific elasmobranchs". Systematic Parasitology 13 (2): 81–101. doi:10.1007/BF00015217. 
  13. ^ Jameson, A.P. (December 1931). "Notes on Californian Myxosporidia". The Journal of Parasitology (The American Society of Parasitologists) 18 (2): 59–68. doi:10.2307/3271964. JSTOR 3271964. 
  14. ^ Jensen, K. (2001). "Four New Genera and Five New Species of Lecanicephalideans (Cestoda: Lecanicephalidea) From Elasmobranchs in the Gulf of California, Mexico". Journal of Parasitology 87 (4): 845–861. doi:10.1645/0022-3395(2001)087[0845:FNGAFN]2.0.CO;2. PMID 11534651. 
  15. ^ Moser, M. and Anderson, S. (1977). "An intrauterine leech infection: Branchellion lobata Moore, 1952 (Piscicolidae) in the Pacific angel shark (Squatina californica) from California". Canadian Journal of Zoology 55 (4): 759–760. doi:10.1139/z77-098. 
  16. ^ a b Escobar-Sanchez, O., Abitia-Cardenas, L.A. and Galvan-Magnan, F. (2007). "Food habits of the Pacific angel shark Squatina californica in the southern Gulf of California, Mexico". Cybium 30 (4): 91–97. 
  17. ^ a b c d Martin, R.A. Sandy Plains: Pacific Angel Shark. ReefQuest Centre for Shark Research. Retrieved on June 22, 2009.
  18. ^ a b c Natanson, L.J. and Cailliet, G.M. (December 23, 1986). "Reproduction and Development of the Pacific Angel Shark, Squatina californica, off Santa Barbara, California". Copeia (American Society of Ichthyologists and Herpetologists) 1986 (4): 987–994. doi:10.2307/1445296. JSTOR 1445296. 
  19. ^ a b c Cailliet, G.M., Mollet, H.F., Pittenger, G.G., Bedford, D. and Natanson, L.J. (1992). "Growth and demography of the Pacific Angel Shark (Squatina californica), based upon tag returns off California". Australian Journal of Marine and Freshwater Research 43 (5): 1313–1330. doi:10.1071/MF9921313. 
  20. ^ a b c d e Fowler, S.L., Cavanagh, R.D., Camhi, M., Burgess, G.H., Cailliet, G.M., Fordham, S.V., Simpfendorfer, C.A. and Musick, J.A. (2005). Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. International Union for Conservation of Nature and Natural Resources. pp. 233–234. ISBN 2-8317-0700-5. 
  21. ^ a b Leet, W.S., Dewees, C.M., Klingbeil, R. and Larson, E.J., ed. (2001). "Pacific Angel Shark". California's Living Resources: A Status Report (fourth ed.). ANR Publications. pp. 248–251. ISBN 1-879906-57-0. 
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