Squalus montalbani

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Philippines spurdog
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S. montalbani from the original description of the species in 1912.
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Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Squaliformes
Family: Squalidae
Genus: Squalus
Species:
S. montalbani
Binomial name
Squalus montalbani
Whitley, 1931
Synonyms

Squalus philippinusSmith and Radcliffe 1912 (see text)

Contents

The Philippine spurdog or Indonesian greeneye spurdog (Squalus montalbani), is a relatively large species of dogfish shark native to waters off the coast of Australia, the Philippines, and Indonesia. The species was identified in 1912 from a specimen caught off the coast of Luzon Island, and has been both bycatch and a targeted species in fisheries since. Its taxonomy is complex, having been renamed in 1931, being misidentified as a type of shortspine spurdog, [2] then being revived as a species in 2007. [3]

It is classified as vulnerable by the International Union for Conservation of Nature (IUCN) due to past and present threats from fisheries. It is morphologically similar to several other species, which makes identification difficult. The species is identified as a member of the mitsukurii group, a species complex [3] The similarity to other species has posed problems in identifying trends in the species, and thus, in its conservation. [1]

Biology, anatomy, and appearance

S. montalbani is relatively large, in comparison to other dogfish sharks. Females, with a maximum total length of 94.5 centimetres (37.2 in) are generally larger than males, which have a maximum total length of 84.0 centimetres (33.1 in). [4] The spines on the dorsal fin are low, like others in the mitsukrii species complex.

Coloration patterns are similar to others in the mitsukrii group: The dorsal surface is a light grey, and the ventral surface is white. [3] [5] The caudal bar is a dark bar found on the caudal fin of some species, including some sharks. Like other sharks in the mitsukurii group, the Philippines spurdog has a caudal bar which is dark and almost upright, however the caudal bar extends further in S. montalbani than S. mitsukurii, allowing visual differentiation of the species. [3] An additional coloration pattern distinguishes the two species: a dark blotch on the upper lobe of the caudal fin appears in both S. montalbani and S. mitsukurii, however the placement and shape differs. [3]

Like most sharks, the species is yolk-sac viviparous. [4] The species has been observed with litter sizes of 4-16 pups, with pups developing a yolk sack in utero. [6]

Diet is described in White et al. 2006 [6] "primarily of small fishes, cephalopods and crustaceans," which is repeated by the IUCN. [1]

Taxonomy

The "Philippines spurdog" was first described in 1912 by Hugh McCormick Smith and Lewis Radcliffe, [7] however the binomial name they choose, S. philippinus, is identical to a name previously given to the Port Jackson shark (Heterodontus portusjacksoni). Although S. philippinus is a junior synonym for the accepted binomial name for the Port Jackson shark, and thus is not valid, it is also not valid as a name for the Philippines spurdog either. The species was renamed by Gilbert Percy Whitley in 1931. [8] Thus, although the name S. philippinus predates the accepted name S. montalbani, S. philippinus is considered a junior synonym for the Philippines spurdog and a junior homonym for an invalid name of the Port Jackson shark. [3] [9]

The species was identified as synonymous with S. mitsukurii in several important taxonomic lists, including the first edition of Sharks and Rays of Australia in 1994. [6] and the 1984 Sharks of the World. [2] [3] The conspecificity of S. mitsukurii and S. montalbani was based on overlapping ranges and a substantial morphological similarity. In 2006, a description of the Indonesian greeneye spurdog was given in Economically Important Sharks and Rays of Indonesia and given the temporary binomial name Squalus sp. 1 [10] pending clarification of the classification of the species. The species name S. montalbani was revived and applied to this species after further analysis in 2007, based on morphometric differences and differences in the coloration pattern. [3]

The holotype specimen for the species was collected by Smith and Radcliffe in 1908, during the Philippine expedition. It is a juvenile male, taken from a depth of 432 metres (1,417 ft) off the coast of Sombrero Island in the Philippines. The specimen deposited at the Museum of Natural History (USNM Cat No. 70256). [7]

Range and habitat

S. montalbani, like most other sharks, is exclusively a marine species. It is found in Pacific and Eastern Indian Ocean waters of SE Asia, the Philippines, and Australia. [4] The range in Australian waters extends around the continent, [4] however is most frequently found off the coasts of New South Wales, Queensland, Western Australia. [1] It is found throughout waters of the Philippines and Indonesia. It inhabits water which is warm to temperate. [4] Its range overlaps with other species in the mitsukurii group. [3]

The species is found primarily in deep waters, generally close to the bottom. Specimens of the species have been recovered from depths as deep as 1,370 metres (4,490 ft), and as shallow as 154 metres (505 ft), however the species is usually caught in depths from 383 to 670 metres (1,257 to 2,198 ft). The species has been caught along the upper continental shelf or near islands. [4]

Conservation and human interaction

The species fished in bathydemersal longline fisheries in Indonesia, either as a targeted species or by-catch of other dogfish fisheries. [1] [6] It is eaten, and the fins and liver oil are both economically valuable. [4] The species was also caught in a short-lived fishery based in Esperance, Western Australia during the 1990s, however rapidly declining catches closed the fishery since 1999. [1]

The species was listed as "vulnerable" by the IUCN in 2008 due to threats from fisheries. [1] The similarity of the species to others in the mitsukurii group, and related uncertainty in its taxonomic classification, has posed problems for conservation of the species. Records of the species specifically do not exist, however morphologically similar dogfish underwent a massive collapse in the 1970s off the coast of Australia. Populations probably underwent declines of as much as 97% in some parts of New South Wales as the result of fishing. [1] The IUCN estimated global population of the species to have declined more than 30% from unfished levels and with a decreasing population trend. [1]

Related Research Articles

Squalidae, more commonly known as dogfish, dog sharks, or spiny dogfish, are one of several families of sharks categorized under Squaliformes, making it the second largest order of sharks, numbering 119 species across 7 families. Having earned their name after a group of fishermen reportedly observed the species chasing down smaller fish in dog-like packs, dogfish have slender, streamlined bodies, usually more compact in comparison to other species, and a pointed snout. Dogfish likewise have two dorsal fins, each with smooth spines, but no anal fin, and their skin is generally rough to the touch. As the species reaches adulthood, males usually measure a maximum of 100 cm, while females typically measure 125 cm long. The species therefore exhibits female-dominant sexual dimorphism.

<span class="mw-page-title-main">Spiny dogfish</span> Species of shark

The spiny dogfish, spurdog, mud shark, or piked dogfish is one of the best known species of the Squalidae (dogfish) family of sharks, which is part of the Squaliformes order.

<span class="mw-page-title-main">Little gulper shark</span> Species of shark

The little gulper shark is a small, deepwater dogfish of the family Centrophoridae.

Squalus is a genus of dogfish sharks in the family Squalidae. Commonly known as spurdogs, these sharks are characterized by smooth dorsal fin spines, teeth in upper and lower jaws similar in size, caudal peduncle with lateral keels; upper precaudal pit usually present, and caudal fin without subterminal notch. In spurdogs, the hyomandibula is oriented at a right angle to the neurocranium, while in other sharks, the hyomandibula runs more parallel to the body. This led some to think that the upper jaw of Squalus would not be as protractile as the jaws of other sharks. However, a study that compared different jaw suspension types in sharks showed that this is not the case and that Squalus is quite capable of protruding its upper jaw during feeding.

<span class="mw-page-title-main">Borneo shark</span> Rare species of requiem shark

The Borneo shark is a species of requiem shark, and part of the family Carcharhinidae. Extremely rare, it is known only from inshore waters around Mukah in northwestern Borneo, though it may once have been more widely distributed. A small, gray shark reaching 65 cm (26 in) in length, this species is the only member of its genus with a row of enlarged pores above the corners of its mouth. It has a slender body with a long, pointed snout and a low second dorsal fin placed posterior to the anal fin origin.

<span class="mw-page-title-main">Sicklefin weasel shark</span> Species of shark

The sicklefin weasel shark is an uncommon species of ground shark in the family Hemigaleidae. It is native to southern India, southern China, and parts of Southeast Asia, living in shallow waters down to a depth of 170 m (560 ft). This lightly built shark is characterized by its very short mouth, broad upper teeth with serrations only on the trailing edge, and strongly sickle-shaped fins with obvious white tips on the two dorsal fins. It is light grey or bronze in colour, often with small white blotches on its sides; it reaches a maximum known length of 1.1 m (3.6 ft).

<span class="mw-page-title-main">Blacktailed spurdog</span> Species of shark

The blacktailed spurdog is a dogfish, a member of the family Squalidae, found around New Caledonia in the central Pacific Ocean, at depths from 320 to 320 m. Its length is up to 75 cm.

<span class="mw-page-title-main">Shortspine spurdog</span> Species of shark

The shortspine spurdog is a dogfish, a member of the family Squalidae, found on continental shelves off Japan in temperate waters, from the surface to 950 m. Its length is up to 75 cm.

<span class="mw-page-title-main">Velvet belly lanternshark</span> Species of shark

The velvet belly lanternshark is a species of dogfish shark in the family Etmopteridae. One of the most common deepwater sharks in the northeastern Atlantic Ocean, the velvet belly is found from Iceland and Norway to Gabon and South Africa at a depth of 20–2,490 m (66–8,169 ft). A small shark generally no more than 45 cm (18 in) long, the velvet belly is so named because its black underside is abruptly distinct from the brown coloration on the rest of its body. The body of this species is fairly stout, with a moderately long snout and tail, and very small gill slits. Like other lanternsharks, the velvet belly is bioluminescent, with light-emitting photophores forming a species-specific pattern over its flanks and abdomen. The ventral photophores are thought to function in counter-illumination, which camouflages the shark against predators and prey. The bioluminescent flank markings may play a role in intraspecific communication.

Squalus crassispinus, the fatspine spurdog, is a dogfish of the family Squalidae, found on the continental shelf off the northern coast of Western Australia, at depths of 180 to 200 metres. The length of the longest male specimen measured is 56 centimetres (22 in).

Squalus nasutus, the western longnose spurdog, is a dogfish of the family Squalidae, found on the continental shelf off the northwest and southwest coasts of Western Australia, at depths between 300 and 510 m. Its length is at least 55 cm.

<span class="mw-page-title-main">Indonesian angelshark</span> Species of shark

The Indonesian angelshark is a rare species of angelshark, family Squatinidae, known only from a few specimens collected from fish landing sites in southern Indonesia. It is thought to inhabit the deep waters of the continental slope. Reaching at least 1.34 m (4.4 ft) long, this species has a flattened, ray-like shape and a well-developed tail and caudal fin. It is characterized by the absences of fringes on its nasal barbels and thorns down the midline of its back, as well as by its relatively plain grayish-brown dorsal coloration with dark saddles beneath the dorsal fin bases and a black leading margin on the underside of the pectoral fins. The International Union for Conservation of Nature (IUCN) has classified it as Critically Endangered due to significant fishing pressure.

The Taiwan spurdog is a species of shark in the genus Squalus. It was accidentally found in Taiwan's Tashi fish market by William Toby White and a colleague of the CSIRO in Hobart, Australia. They named it S. formosus. It has also be recorded from the coast of Japan, near Kyushu and Shikoku.

<span class="mw-page-title-main">Bighead spurdog</span> Species of shark

The bighead spurdog is a rare and little-known species of dogfish shark in the family Squalidae. It is found in deep water south of New Caledonia, and over the Norfolk Ridge. Reaching at least 90 cm (35 in) in length, this stocky shark is brown above and light below, with a broad head and two dorsal fins with long spines. It is the only member of its genus with both one- and three-pointed dermal denticles. An infrequent bycatch of longline fisheries, this species is listed under Data Deficient by the International Union for Conservation of Nature (IUCN).

<span class="mw-page-title-main">Pacific spiny dogfish</span> Species of shark

The Pacific spiny dogfish is a common species of the Squalidae (dogfish) family of sharks and are among the most abundant species of sharks in the world. This species is closely related to Squalus acanthias and for many years they were treated as a single species. Recent research, using meristic, morphological and molecular data led to the resurrection of Pacific Spiny Dogfish as a separate species. The American Fisheries Society recommends the common name "Pacific Spiny Dogfish" for Squalus suckleyi over alternatives such as "Spotted Spiny Dogfish" and "North Pacific Spiny Dogfish" and "Spiny Dogfish" for Squalus acanthias.

The greeneye spurdog is a species of dogfish described in 2007. It is a member of the family Squalidae, found off the coast of southeastern Australia. The length of the longest specimen measured is 85.6 cm (33.7 in). It was considered conspecific with the shortspine spurdog.

Edmund's spurdog is a dogfish described in 2007. It is a member of the family Squalidae, found off western Australia and Indonesia. The length of the longest specimen measured is 70.0 cm (27.6 in).

The Indonesian shortsnout spurdog is a dogfish described in 2007. It is a member of the family Squalidae, found off Indonesia. The length of the longest specimen measured is 52.2 cm (20.6 in).

Squalus hawaiiensis, the Hawaiian spurdog, is a dogfish, a member of the family Squalidae, found in waters surrounding the Hawaiian Islands, from the surface to 950 m. Its length is up to 75 cm.

References

  1. 1 2 3 4 5 6 7 8 9 Graham, K.J. (2019). "Squalus montalbani". IUCN Red List of Threatened Species . 2019: e.T161404A68645208. doi: 10.2305/IUCN.UK.2019-1.RLTS.T161404A68645208.en . Retrieved 20 November 2021.
  2. 1 2 Compagno, L.J.V. (1984). FAO species catalogue. Sharks of the World. An annotated and Illustrated catalogue of shark species known to date. Part 1. Hexanchiformes to Lamniformes. FAO Fisheries Synopsis, No. 125, v. 4 (part 1).
  3. 1 2 3 4 5 6 7 8 9 Last, Peter R.; White, William T.; Motomura, Hiroyuki (2007), Last, P.R.; White, W.T.; Pogonoski, J.J. (eds.), Descriptions of new dogfishes of the genus Squalus (Squaloidea: Squalidae). (PDF), Hobart, Australia: CSIRO Marine and Atmospheric Research, pp. 55–69
  4. 1 2 3 4 5 6 7 Froese, Rainer; Pauly, Daniel (eds.) (2013). "Squalus montalbani" in FishBase . December 2013 version.
  5. ↑ Froese, Rainer; Pauly, Daniel (eds.) (2013). "Squalus mitsukurii" in FishBase . December 2013 version.
  6. 1 2 3 4 White, W.T.; Dharmadi (2010). "Aspects of maturation and reproduction in hexanchiform and squaliform sharks". Journal of Fish Biology. 76: 1362–1378. doi: 10.1111/j.1095-8649.2010.02560.x .
  7. 1 2 Smith, Hugh M. "The squalid sharks of the Philippine Archipelago, with description of new genera and species". Proceedings of the United States National Museum. 41 (1877): 677–685. doi:10.5479/si.00963801.41-1877.677 . Retrieved 1 January 2014.
  8. ↑ Whitley, George P. (1931). "New names for Australian fishes". The Australian Zoologist. 6: 310–334.
  9. ↑ Compagno, Leonard (2001). Sharks of the world : an annotated and illustrated catalogue of shark species known to date. Vol. 2, Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). Rome: Food and Agriculture Organization of the United Nations.
  10. ↑ White, W.T.; last, P.R.; Stevens, J.D.; Yearsley, G.K.; Fahmi; Dharmadi (2006). Economically Important Skates and Rays of Indonesia (PDF). Canberra: Australian Centre for International Agricultural Research. Retrieved 31 December 2013.
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