Saturday, February 10, 2007
Goblin Shark: Rare Video of a 'Living fossil' (Japan, February 2007)
Reports say the primitive shark - also known as the Elfin Shark - was subsequently displayed in an aquarium until it expired some days later.
More info on Mitsukurina owstoni is available from Biology of Sharks and Rays:
"As depicted in most shark books, the Goblin Shark (Mitsukurina owstoni) looks quite unlike any other lamnoid (see The Evolution of Lamnoid Sharks) - more like a snaggle-toothed, beaked gargoyle with a carpenters' trowel projecting forward from its 'forehead'. But this unwieldy headgear is actually an artifact of the goblin shark's extremely protrusile ('Capable of being thrust outward') jaws."
Media coverage has been sparse compared to that given to the capture, also in January and also in Japan, of another 'living fossil' called the Frilled Shark (see "Rare Video of Prehistoric Frilled Shark").
Information on the Goblin Shark from the International Union for Conservation of Nature and Natural Resources Red List of Threatened Species*:
Justification: This species is assessed as Least Concern because although apparently rare, it is widespread in the Atlantic, Indian and Pacific Oceans and is only infrequently taken in deepwater fisheries. It has a sporadic distribution with most records from the Northwest Pacific (Japan, Taiwan) on the upper continental slope. May also be mesopelagic. It is likely to be found in more locations than previously known as deepwater surveys are undertaken in other regions or as deepwater fisheries expand globally. Taken in deep bottom-set gillnet, bottom longline and trawl fisheries; rarely surface drift nets. Also entangled in deepwater fishing gear. Recorded from depths of =30 m (occasional) to greater than 1,000 m with reported landings of adults rare suggesting most of the adult population is unavailable to existing deepwater fisheries.
Range: Most goblin shark records come from Japan. All Japanese records have been made between Tosa Bay and Boso Peninsula (including Sagami Bay, Suruga Bay, Izu Islands), despite similar fishing gear being used throughout the Japanese Archipelago (Yano 2003). In April 2003 an exceptionally large number of goblin sharks (reportedly 100-300) were captured off northwest Taiwan, an area they had been previously unknown from.
The species is likely to occur in more locations than presently known as surveys are undertaken in other regions or as deepwater fisheries expand globally.
Population: Reported landings from Tokyo Canyon show no trend in abundance (Yano 2003).
Habitat and Ecology: This is an apparently rare and consequently poorly known upper slope, possibly mesopelagic species. Maximum size is estimated to be 540 - 617 cm total (TL) using regression analysis based on photographs of a specimen taken in the Gulf of Mexico (Parsons et al. 2002). Males are mature at 264 cm TL; female size at maturity is unknown. Pregnant females are unknown but like other Lamniformes the embryos are probably oviphagous and litter size is likely to be small. The smallest known free-swimming individual was about 88 cm TL.
Individuals less than 300 cm TL are occasionally reported inshore or near the surface over deepwater at depths =30 m, and occur to at least 979 m depth. Individuals larger than 300 cm TL have not been collected shallower than about 270 m depth. Maximum reported depth is 1,300 m, however, it is unclear if the specimens referred to in this record were taken on the bottom or in the water column as the trawl was deployed and/or retrieved. The largest reported specimen was tangled in a crab pot at about 1,000 m depth. Most reported captures are of small juveniles taken on or near the bottom over the outer shelf and upper slope. In Tokyo Canyon peak catches of goblin sharks in bottom-set gillnets occur between 200-300 m depth. A seasonal peak in catches occurs between December and April, with secondary peaks reported in July and September in some years (Yano 2003). Total catch is low with a maximum of about 30 individuals a year reported. The fishery takes mainly small juveniles less than 150 cm TL. The largest specimens taken in this fishery exceeded 200 cm TL and were also immature (Yano 2003). Goblin sharks collected at similar depths off New Zealand, South Africa and France (Bay of Biscay) have also been juveniles suggesting that the bulk of the adult population occurs outside the depth range, or is otherwise unavailable to most deepwater fisheries.
Their anatomy suggests goblin sharks are a non-vertical migrating mesopelagic species. Although poorly known their diet also suggests a mesopelagic habitat. A large goblin shark taken near the surface off California had been feeding on squid. Juveniles (= 150 cm TL) taken off Kaikoura, New Zealand, and KwaZulu-Natal, South Africa, had been feeding on midwater crustacea (including Macrocypridina castanea rotunda), unidentified teleosts, and squid (including juvenile Teuthowenia pellucida).
Goblin sharks were unknown from Taiwan until 2003, when an exceptionally large number (greater than 100) were reportedly caught off the northwest coast over two weeks in April by a number of fishers. These captures were reportedly made around 600 m depth, following a strong earthquake centred in the area. One fisher reportedly stated that most of these sharks were male. No measurements or other data are known to have been recorded; however, an unconfirmed length estimate of 350-400 cm TL for some specimens was reportedly based upon the size of several jaws (M. and M. Kazmers posting on the Archives of SHARK-L AT RAVEN.UTC.EDU, 12 July 2003).
Threats: The goblin shark is a rare bycatch of deepwater fisheries with most captures around Japan. In an unusual occurrence, an exceptionally large number (greater than 100) were reportedly caught off the northwest coast of Taiwan over two weeks in April 2003 by a number of fishers.
Taken in deep bottom-set gillnet, bottom longline and trawl fisheries; rarely surface drift nets. Also entangled in deepwater fishing gear. Most reported captures are juveniles suggesting that the bulk of the adult population occurs outside the depth range of, or is otherwise unavailable to most deepwater fisheries.
The jaws are sought after by collectors. The jaws of most of those goblin sharks landed in Taiwan during April 2003 were reported exported to the USA. Prices vary with the size and quality of the jaw, and range from 1,500–4,000 US dollars.
Conservation Measures: No conservation measures are in place for this species.
Citation: Duffy, C.A.J., Ebert, D.A. & Stenberg , C. 2004. Mitsukurina owstoni. In: IUCN 2006. 2006 IUCN Red List of Threatened Species.
The following 1909 paper from the American Museum of Natural History Research Library contains two interesting images:
A new goblin shark, Scapanorhynchus jordani, from Japan. Bulletin of the AMNH ; v. 26, article 19.
Four specimens of the rare Japanese shark Scapanorhynchus (Mittukurina) have recently come into my hands for study. Two were generously placed at my disposal by Professor Bashford Dean, one belongs to the American Museum collection, and the fourth (a head only) was secured for me in Japan by my friend Dr. N. Yatsu of the Imperial University at Tokyo. On comparing these specimens among themselves and with the description and figures of S. owstoni (Jordan),' it was seen that they differed markedly in certain regards from that species, though agreeing entirely among themselves. Since the type species is known from at least two carefully figured specimens- one a male 42 inches long (type), the other2 a female 11 feet long-the characters of the four specimens in hand, three females and one (head only) apparently a male, are not to be regarded as mere sex or age variants, but as indicating a distinct species. This may be defined as follows.
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