Elasmobranchii (sharks and rays) >
Squaliformes (Sleeper and dogfish sharks) >
Squalidae (Dogfish sharks)
Etymology: Squalus: Genus name from Latin 'squalus' meaning shark (Ref. 6885, 27436); formosus: The epithet formosus is based on the Portuguese word Formosa, an alternative name for Taiwan, in allusion to the type locality of this species.
Environment: milieu / climate zone / depth range / distribution range
Ecology
Marine; pelagic-oceanic. Subtropical
Distribution
Countries | FAO areas | Ecosystems | Occurrences | Point map | Introductions | Faunafri
Pacific Ocean: Taiwan and Japan. Type specimens were collected from the fish landing site at Tashi (c. 24‹ 50Œ S) in north-eastern Taiwan, but depth of capture unknown. Also recorded from waters off Kyushu (c. 32‹ N) and Shikoku (c. 33‹ 20Œ N) (Chen et al., 1979).(Ref. 87791).
Size / Weight / Age
Maturity: Lm ? range ? - ? cm
Max length : 73.4 cm TL male/unsexed; (Ref. 87791); 81.4 cm TL (female)
Short description
Identification keys | Morphology | Morphometrics
A medium-sized species of Squalus of the ‘highfin megalops group’ is characterized by the following combination of characters: snout relatively short; first dorsal fin tall and upright, upper posterior margin almost straight; caudal fin with broad white posterior margin, no dark caudal bar; flank denticles tricuspid. These characters clearly differentiate this species from the three other sympatric Squalus species. Squalus formosus is morphologically closest to S. albifrons from eastern Australia but differs in the following characters: first dorsal fin with a distinct, broad white anterior margin (v. no distinct white marking); second dorsal fin height 5.7–6.4 v. 4.3–5.1% LT; first dorsal fin height 9.0–10.5 v. 7.7–8.9% LT, anterior margin 12.4–14.6 v. 10.9–12.7% LT; eye slightly larger 4.8–5.3 v. 4.4–4.8% LT. Squalus formosus can be further distinguished from other Squalus species in the following combination of characters: pre-second dorsal length 3.7–4.4 times pectoral-fin anterior margin; preoral length 2.2–2.3 times horizontal prenarial length; head length 4.0–4.7 times eye length; interorbital width 1.4–1.6 times horizontal preorbital length; posterior margin of second dorsal fin deeply concave; second dorsal-fin spine with a broad base; dorsal surface of head dark, sharply demarcated from paler ventral surface; 45–46 monospondylous centra, 94–95 precaudal centra, 123–124 total centra; adult maximum size at least 73 cm LT (Ref. 87791).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Distinct pairing with embrace (Ref. 205).
White, W.T. and S.P. Iglésias, 2011. Squalus formosus, a new species of spurdog shark (Squaliformes: Squalidae), from the western North Pacific Ocean. J. Fish Biol. 79:954-968. (Ref. 87791)
IUCN Red List Status (Ref. 130435: Version 2024-1)
Threat to humans
Harmless
Human uses
Fisheries: of potential interest
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Estimates based on models
Phylogenetic diversity index (Ref.
82804): PD
50 = 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00347 (0.00165 - 0.00730), b=3.09 (2.92 - 3.26), in cm total length, based on LWR estimates for this Genus-body shape (Ref.
93245).
Trophic level (Ref.
69278): 4.3 ±0.3 se; based on size and trophs of closest relatives
Fishing Vulnerability (Ref.
59153): Moderate to high vulnerability (53 of 100).
