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Squatina japonica

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES SQUATINIFORMES SQUATINIDAE

Scientific Name: Squatina japonica
Species Authority: Bleeker, 1858
Common Name(s):
English Japanese Angelshark
French Ange de Mer Kasuzame
Spanish Angelote Japonés
Taxonomic Notes: Diagnostic features include pelvic fin tips which do not reach the first dorsal origin, and spines along the midback line. This species like other regional Squatinids are poorly known taxonomically and are often misidentified. See Walsh and Ebert (2007) for recent revision of this genus in the western North Pacific.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2d+4d ver 3.1
Year Published: 2009
Date Assessed: 2008-12-01
Assessor(s): Walsh, J.H. & Ebert, D.A.
Reviewer(s): Valenti, S.V., Gibson, C.G. & Fowler, S.L. (Shark Red List Authority)
Justification:
The Japanese Angelshark (Squatina japonica) is a medium-sized angel shark found in the Northwest Pacific on the continental shelf to a depth of 300 m from the Sea of Japan to Taiwan, Province of China. It is caught as bycatch in fisheries, which operate down to 300 m, and in particularly large numbers in demersal trawl fisheries. It is not known to be targeted, but is a retained bycatch, with individuals recorded in local fish markets in northern Taiwan, Province of China and Japan, although this species, like other Northwest Pacific angel sharks, has frequently been misidentified. This species' generation period may be between 8-15 years, based on biological information from better known angel sharks. Other angel shark populations (for example Squatina squatina and Squatina guggenheim) have proved particularly vulnerable to trawl and gillnet fishing gear, resulting in significant population depletion because of their low reproductive potential and low potential for re-colonisation. Where population data are available for other angel sharks, declines greater than 80% have been observed in less than three generations within areas where target or bycatch fisheries take place. Although trend data are not available for Japanese Angelshark, there is concern that it has already declined significantly as a result of fisheries, which possibly operate throughout its range. Based on current knowledge of fishing pressure in this region, these trends are likely to continue. This species, however, has a fairly wide geographic and bathymetric range, which may offer some areas of refuge from fisheries. It is therefore assessed as Vulnerable A2d+A4d, based on suspected declines approaching 50%, but it may prove to have been more seriously depleted than this. Further research into this species' abundance, distribution, life-history and population trends is urgently needed.

Geographic Range [top]

Range Description: Endemic to the northwest Pacific including the Sea of Japan, along the south eastern Japan coast, Yellow Sea, East China Sea, waters surrounding northern Taiwan, Province of China, and the Taiwan Strait (Shuyuan 1994, Randall and Lim 2000, Compagno et al. 2005a, Walsh and Ebert 2007).
Countries:
Native:
China; Japan (Honshu, Kyushu, Shikoku); Korea, Democratic People's Republic of; Korea, Republic of; Taiwan, Province of China
FAO Marine Fishing Areas:
Native:
Pacific – northwest
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Population size for this species is unknown. Little data exist due to a total lack of known catch records for this species and confusing taxonomic information used to distinguish individuals of this species from other Northwest Pacific angel sharks (D. Ebert pers. obs. 2007).
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: Little is known of the habitat of this species, but as it is taken as bycatch in trawl fisheries, it can be assumed to be found over soft substrate on or near the bottom on the continental shelf down to 300 m deep (D. Ebert pers. obs. 2007).

Though life history parameters are unknown, this species is thought to be slow growing and late maturing like other angel sharks. Other species of angel sharks are known to bury themselves in the sediment and ambush their prey. Reproduction is aplacental viviparity. The species may grow up to 150 cm in length (D. Ebert pers. obs. 2007).

Size at maturity in females is reported at 80 cm total length (TL) (Yamada et al. 2007). Size at birth is reported at 22 cm TL (Yamada et al. 2007). They reproduce in spring and summer, with litter sizes of two to ten pups (Yamada et al. 2007).

Feed on fishes, molluscs and crustaceans (Yamada et al. 2007). Research has identified a parasite living in the uterus of females (S. Tanaka pers. comm. 2007).
Systems: Marine

Threats [top]

Major Threat(s): This species is apparently taken in large numbers in demersal trawl fisheries and is also likely caught as bycatch in set net and gillnet fisheries throughout large areas of its distribution (Compagno in prep.). It is unknown whether this species is truly targeted by fishing operations, but it is retained and can been found in local fish markets in Taiwan Island and Japan (S. Tanaka and D. Ebert pers.obs. 2007).

The East China Sea and Yellow Seas are intensively exploited, with several stocks declining due to overfishing and pollution (NOAA 2004ab). Heavy fishing mortality has resulted in a shift from an older, traditional fishery based on high-value demersal species to faster-growing, smaller, and lower-value species such as shrimp and cephalopods (NOAA 2004a). The Yellow Sea was once one of the most intensively exploited Large Marine Ecosystems (LME) in the world and is considered severely impacted in terms of overfishing, with destructive fishing practices (NOAA 2004b).

Fishing pressure from trawl vessels is intense off China, despite bans on bottom trawling in various areas. China has the largest number of fishing vessels and fishers in the world with a marine fishing fleet consisting of 279,937 motorized vessels in 2004 (1,996 of which were confined to distant waters), showing little change from 1999 (FAO 2007b). Catches have declined as a result, leading to catches of immature, small-sized and low value organisms (FAO 2007b). In 2004, the most common fishing gear used was the trawl net (in terms of production, trawlers accounted for 47.6% of catches in 2004 (FAO 2007b). Progress is being made in the introduction of ecosystem based management in the Yellow Sea and a fisheries recovery plan requires the cooperative effort of all countries bordering it. The Yellow Sea LME Project will assess fish stocks and establish TACs (NOAA 2004b). In February 2006, the Government of China issued the Programme of Action on Conservation of Living Aquatic Resources of China. This states that by 2010 they aim to reduce the size and power of the motorized marine fishing fleet and the corresponding domestic marine capture catch in China from 220,000 vessels with a total power of 12.7 million kW and catching 13.06 million tonnes marine organisms in 2002, to 192,000 vessels, 11.43 million kW (FAO 2007b). This represents a decline in fishing power of only 10%.

Other angel shark populations (e.g., Squatina californica, S. squatina, S. argentina) have proved particularly vulnerable to fishing pressure due to their low reproductive potential, vulnerability to trawl and gillnet fishing gear and low potential for recolonisation (due to their sedentary habit) (Gaida 1997, ICES 2004, Morey et al. 2006, Vooren and Klippel 2005). Squatina guggenheim and Squatina occulta, which occur in the Southwest Atlantic Ocean, have a triennial reproductive cycle, with a litter size of only two to eight pups. This extended breeding cycle means that they have a very low intrinsic rate of population growth. Consequently, these sharks are generally highly vulnerable to extirpation through bycatch in fisheries that are managed to sustain production of other, more productive, fishes (Musick et al. 2000, C. Vooren pers. comm. 2007).

Conservation Actions [top]

Conservation Actions: No known specific conservation actions exist.

According to the Law of Fisheries of China, bottom trawling is banned within certain areas of Chinese waters (Y. Wang pers. comm. 2007). Bottom trawling is restricted in certain zones and at different times in shallow water. Individual Provinces are responsible for applying national regulations within China. They also can apply their own regulations, on basis of national regulations, but no specific information is available on the areas or timings involved or the effectiveness of enforcement.

Catch levels need to be accurately quantified and monitored. Resolution of the taxonomic issues and identification problems associated with this genus in the northwest and western central Pacific should be a high priority to achieve this (Walsh and Ebert 2007). Management action will most likely be required to reduce bycatch of this species.

Citation: Walsh, J.H. & Ebert, D.A. 2009. Squatina japonica. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 23 September 2014.
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