PHILIPPINE SPURDOG
Spurdog found in the Philippines with a confusing and difficult identification
The Philippine spurdog (Squalus montalbani) or sometimes called Indonesian Greeneye spurdog (not to be confused with the Greeneye Spurdog Squalus chloroculus), is a dogfish in the family Squalidae, and somewhat a larger dogfish. It is 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 was renamed in 1931 and revived in 2007. It is a member of the complex mitsukurii group.
Family: Squalidae – Dogfish Sharks
Genus: Squalus
Species: montalbani
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Common Name– Dogfish Sharks
Family– Squalidae
Common Name– Dogfish Sharks
Genus– Squalus
Species– montalbani
Status: IUCN Red List VULNERABLE
Average Size and Length: Females reach a maximum total length of 3.1 feet. Males have a maximum total length of 2.8 feet.
Teeth and Jaw: The snout is broadly triangular, with a mouth width of 1.69-2.32 (1.85) times the horizontal prenarial length.
Denticles: The flank denticles are tricuspid.
Tail: The Philippine spurdog has a caudal bar which is dark and almost upright and extends further than S. mitsukurii. It extends broadly from the caudal fork up the poster or margin of the upper lobe for about 0.6 of its length in immature specimens. There is upper caudal fringe forming a deep saddle along mid-length of the lobe. There is a dark blotch on the upper lobe of the caudal fin.
Demographic, Distribution, Habitat, Environment and Range: The Philippine spurdog can be found in the waters of the Pacific and Eastern Indian Ocean and is endemic to waters off the coast of Australia, the Philippines, and Indonesia. It is most frequently found off the coasts of New South Wales, Queensland, Western Australia. They prefer warm to temperate deep water, generally close to the bottom along the upper continental shelf or near islands. They are bathydemersal and have been recovered from depths as deep as 4,490 feet and as shallow as 505 feet, however they are usually caught in depths ranging from 1,257 to 2,198 feet.
Diet: They mostly eat small fish, cephalopods and crustaceans.
Aesthetic Identification: The dorsal surface is a light grey, and the ventral surface is counter-shaded white. The body is considered elongated to robust and the trunk depth is 8.9-13.4% of the total length. The spines on the dorsal fins are low. The dorsal fins are low raked. The pre-first dorsal length is 26.5-30.7 (29.0)% of the total length. The pre-second dorsal length is 57.6-62.8 (60.8)% of the total length. The interdorsal space is 21.7-25.9 (23.7)% of the total length. The second dorsal-fin length is 11.1-13.9 (12.4)% of the total length. The height is 3.4-4.6 (4.0)% of the total length. The inner margin length is 4.0-5.9 (4.8)% of the total length. The second dorsal-fin base is 15.8-21.3 (20.8) times the base of second dorsal spine. The pre-pectoral length is 20.8-22.9 (22.0)% of the total length. The pelvic-caudal space is 22.9-26.0 (24.0)% of the total length.
Biology and Reproduction: The Philippine spurdog is ovoviviparous. They have litter sizes between 4-16 pups. The monospondylous centra is 41-47 (mainly 42-44), and the precaudal centra is 79-85, the total centra is 105-114.
Behavioral Traits, Sensing and Intelligence: Unknown.
Philippine Spurdog Future and Conservation: It has been both bycatch and a targeted species in bathydemersal fisheries using longlines. It is hard to identify and can be confusing and a member of the mitsukurii group, so it remains in vulnerable status.
Philippine Spurdog Recorded Attacks on Humans: Not a threat to humans.
Ref: Last, P.R., W.T. White and H. Motomura. (2007).