|Scientific Name:||Squatina tergocellatoides Chen, 1963|
|Taxonomic Source(s):||Chen, J. T. F. 1963. A review of the sharks of Taiwan. Biological Bulletin, Tunghai University, Department of Biology, College of Science, Ichthyology Series 1: 1-102.|
|Taxonomic Notes:||This species needs additional material collected to critically compare it in greater detail to other angel sharks (Walsh and Ebert 2007). Diagnostic features include pelvic fin tips which do not reach the first dorsal origin, and distinct large ocelli on the pelvic fins (Walsh and Ebert 2007). Nasal barbels also appear particularly ornate compared to other Northwest and Western Central Pacific Squatinids (Walsh and Ebert 2007).|
|Red List Category & Criteria:||Vulnerable A2d+4d ver 3.1|
|Assessor(s):||Walsh, J.H. & Ebert, D.A.|
|Reviewer(s):||Valenti, S.V., Gibson, C.G. & Fowler, S.L. (Shark Red List Authority)|
The Ocellated Angelshark (Squatina tergocellatoides) is found in the South China Sea, waters surrounding northern Taiwan, Province of China and northwestern Malaysia, at depths of 100-300 m. 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 Taiwan, Province of China, although this species, like other Northwest Pacific angel sharks, has frequently been misidentified. Market observations of Taiwan fish markets indicate that it is less frequently observed than the Taiwan Angelshark (Squatina formosa) and the Clouded Angelshark (Squatina nebulosa). In Malaysia, it is rarely taken as bycatch of trawl fisheries and not found in local markets. 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 recolonisation. 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 Ocellated 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+4d, 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.
|Range Description:||Northwest and western central Pacific: South China Sea, waters surrounding northern Taiwan, Province of China (Compagno et al. 2005a), and northwestern Malaysia (Yano et al. 2005, Walsh and Ebert 2007).|
Native:Malaysia; Taiwan, Province of China (Taiwan, Province of China (main island))
|FAO Marine Fishing Areas:|
Pacific – northwest; Pacific – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Population size for this species is unknown. Market observations of this species in Taiwan, Province of China indicate that it is not as common as S. formosa and S. nebulosa, but was not uncommon at some fish markets surveyed (D.A. Ebert pers. obs. 2007).|
The one known record of this species from northwestern Malaysia was by a Department of Fisheries Malaysia Research Vessel in 1998. However, the species was not recorded once throughout market surveys in Sarawak, Sabah (in Borneo) Brunei Darussalam, and Peninsular Malaysia from 2000 to 2004.
Like other Northwest Pacific Angel sharks, it is misidentified. Little data exist due to a total lack of known catch records and problems with misidentification.
|Current Population Trend:||Unknown|
|Habitat and Ecology:||Found on the continental shelf. Very little is known about this species as few catalogued specimens exist. Individuals are caught at or near the bottom, at depths of between 100 and 300 m (D. Ebert unpub. data), often in sandy substrate (Compagno 1984). Other angel sharks are known to bury themselves in sediment and ambush their prey.|
Reproduction is aplacental viviparity. Size at maturity is unknown, but mature males can reach at least 85.4 cm total length (TL) (Yano et al. 2005) and females may grow to 100 cm TL or more (D.A. Ebert unpub. data). The holotype was a female, measuring 63 cm total length (TL) (Chen 1963). Size at birth is ~30 cm TL (D.A. Ebert unpub. data).
This species is a retained bycatch of demersal fisheries within its range off China and Taiwan, Province of China. 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. In Malaysia, it is rarely taken as bycatch of trawl fisheries and not found in local markets.
The East China Sea is intensively exploited, with several stocks declining due to overfishing and pollution (NOAA 2004). 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 2004). 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 2007). Catches have declined as a result, leading to catches of immature, small-sized and low value organisms (FAO 2007). 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 2007). 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 2007). 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).
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 tergocellatoides. The IUCN Red List of Threatened Species 2009: e.T161525A5443604.Downloaded on 12 December 2017.|
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