Raja pulchra

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA CHONDRICHTHYES RAJIFORMES RAJIDAE

Scientific Name: Raja pulchra
Species Authority: Liu, 1932
Common Name(s):
English Mottled Skate
Taxonomic Notes: This species is assigned in a new genus of "North Pacific Raja Assemblage" of family Rajidae (McEachran and Miyake 1986, 1990; McEachran and Dunn 1998).

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2bcd+3cd+4cd ver 3.1
Year Published: 2009
Date Assessed: 2004-09-07
Assessor(s): Ishihara, H., Wang, Y., Tanaka, S., Nakaya, K. & Jeong, C-H.
Reviewer(s): Haywood, M., Valenti, S.V. & Fowler, S.L. (Shark Red List Authority)
Justification:
The Mottled Skate (Raja pulchra) is a northwest Pacific skate, occurring from Japan to China, usually in coastal waters although it has been recorded to 100 m depth. This species is a targeted skate in both Japan and South Korea. There is evidence to support a decrease in population size throughout the range of this species. Catch data from South Korea shows a 90% decline over a ten year period. There are no specific data for reductions of catch numbers in Japan, although there are many reports of decline from fishermen. In China, there has been an overall reduction in all fish biomass due to over-exploitation and heavy trawling within the Mottled Skate's range, as well as habitat degradation as a result of the fishing activities. The overall decline in numbers of this species has certainly exceeded 30% over the last 15 years (three generation period) and it is listed as Vulnerable. Further investigation is required into the decline of this species, as it is suspected that these may in fact be more serious than can be supported with current information and this species may prove to be Endangered.

Geographic Range [top]

Range Description:Northwest Pacific: China, from Bohai Sea to Shanghai, Taiwan; Korea, Baereungdo Islands, uppermost of the Yellow Sea to Heuksan-do Islands; Japan; from northern Hokkaido to off Kyushu; Yellow Sea, East Sea (Sea of Japan), Sea of Okhotsk, East China Sea (Ishihara 1990b, Jeong 1999). This species is especially abundant in coastal waters around the Daecheong and Heuksando Islands, Korea, and around Hokkaido Island, Japan (Ishiyama 1958, Jeong 1999).
Countries:
Native:
China (Shanghai); Japan (Hokkaido, Honshu, Kyushu, Nansei-shoto); Korea, Republic of; Taiwan, Province of China (Taiwan, Province of China (main island))
FAO Marine Fishing Areas:
Native:
Pacific – northwest
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: This species was extremely common about twenty years ago in the northern Yellow Sea (especially around Daecheong-do Islands of Korea) and southern Yellow Sea (especially around Heuksan-do Islands of South Korea) and off the coast of Hokkaido, northern Japan, in historical reports (H. Ishihara pers. comm.).Although data are lacking, the decline of Raja pulchra in the Yellow Sea (South Korea) even exceeds that around northern Japan, where declines have been reported by fishermen (Nakaya, pers. comm, C.H. Jeong unpublished data).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: A temperate water skate found on the shelf, and apparently especially abundant in coastal waters in some areas of Korea and Japan. It is usually caught in coastal waters from about 5m-30m depth (Sea of Okhotsk) to 100m (off the central main island of Japan to the East China Sea)(Chyun 1977, Ishiyama 1958, Ishihara 1990, Ueda et al. 2003). Inhabits waters at 5-15 in the Yellow Sea (Yeon et al. 1997).

Males mature at 47.3 cm DW (Yeon et al. 1997), and females at 68.5 cm disc width (DW) (Yeon et al. 1997). Maximum size is reported at 111.9 cm total length (TL) (female) (Ishiyama 1958). Size at birth is at least 9.5 cm (Ishiyama 1967).

Like other skates, reproduction is oviparous. An adult female produces about 240 eggs (98-556) annually (Yeon et al. 1997). Breeding season is year round, mainly spring (April to June) and November to December, except middle of summer. Egg-capsules measure 14-18.8 cm in length, 70-9.4 cm in width and are rectangular with deep notches on the middle portion of lateral sides, with short flattened horns on anterior and posterior corners. Each egg-capsule usually encloses more than one embryo (C.H. Jeong et al. unpublished data), varying from one to five (Ishiyama 1958). A lot of egg-capsules were found in the culturing cage of scallop farm in Hokkaido, Japan (Ueda et al. 2003).

The stomach contents of 564 specimens of Raja pulchra, caught monthly from July 1991 to December 1995 by the large pair bottom trawl fishery in the Yellow Sea off Korea showed that this species mainly feeds on shrimps, fishes, cephalopods and crabs. The most important prey group was shrimp, which has an index of relative importance value of 93.1 %. Two species of shrimps, Crangon affinis (88.4 %) and Trachypenaeus cuvirostris (3.9 %), and the sandlance, Ammodytes personatus (3.9 %), were major food organisms (Yeon et al. 1999).
Systems: Marine

Use and Trade [top]

Use and Trade: It is one of the most expensive fishes sold in South Korea (Chyung 1977, Jeong et al. 1995; Jeong 1999). The market price reaches US $10 to US $ 30 per kilogram in South Korea. This species is valued for its fermented sliced raw flesh and in soup as food in Korea (C.H. Jeong unpublished data). In northern Japan, skate wing are usually dried and utilized and the meat is made into jelly (Ishihara 1990; Ueda et al. 2003).

Threats [top]

Major Threat(s): The species is targeted by commercial fisheries in South Korea. It is both targeted by gillnet fisheries and also as taken as bycatch of gillnets targeting flounder. In Japan, this species is also targeted by a fishery localized around Hokkaido (H. Ishihara pers. comm. 2005). Although specific data on population size and catch size in fisheries is lacking, there have been reported declines in capture rates by fishermen (H. Ishihara pers. comm. 2007).

Landings of skates in Korea, taken by fisheries from adjacent waters, have abruptly declined. In Korea, "skates" are known as "Hong-eo", and is usually the species Raja pulchra (Jeong 1999). The average annual catch from 1991-1993 was 2,700 metric tonnes, but the catch in 2001-2003 was 220 metric tonnes (data from homepage of MOMAF of Republic of Korea 2004), reflecting a serious decline in the biomass collected.

This species is one of the most expensive fishes sold in South Korea (Chyung 1977, Jeong et al. 1995; Jeong 1999), reaching US $10 to US $ 30 per kilogram. Skates are also valued in Japan, for their dried wings and meat, but are less expensive than in South Korea (US $ 5). This species of Skate is often served at weddings in South Korea as a traditional feast (Ishihara, pers. comm.).

This species is not targeted in China, although it is still taken as bycatch in fisheries operating there.

Conservation Actions [top]

Conservation Actions: There are no conservation measures in place for this species. Further assessment and monitoring of catches in fisheries and population trends is required.

Bibliography [top]

Chyung, M.K. 1977. The Fishes of Korea. IlJisa Publ. Co, Seoul.

Ishihara, H. 1987. Revision of the Western North Pacific species of the genus Raja. Japanese Journal of Ichthyology 34: 241-285.

Ishihara, H. 1990. Studies on the systematics and resources of the skates (Rajidae) in the North Pacific Ocean. PhD. Thesis, Tokyo University.

Ishihara, H. 1990. The skates and rays of the western North Pacific: an overview of their fisheries, utilisation and classification. In: H.L. Pratt, S.H. Gruber and T. Taniuchi (eds), Elasmobranchs as living resources: advances in biology, ecology, systematic and the status of fisheries. NOAA Technical Report NMFS 90. U.S. Department of Commerce, Springfield, Virginia.

Ishiyama, R. 1958. Studies on the rajid fishes (Rajidae) found in the waters around Japan. Journal of the Shimonoseki College of Fisheries 7: 193-394.

Ishiyama, R. 1967. Fauna Japonica. Rajidae (Pisces). Biogeographic Society of Japan, Tokyo.

IUCN. 2009. IUCN Red List of Threatened Species (ver. 2009.2). Available at: www.iucnredlist.org. (Accessed: 3 November 2009).

Jeong, C.H. 1999. A review of taxonomic studies and common names of rajid fishes (Elasmobranchii, Rajidae) from Korea. Korean Journal of Ichthyology 11(2): 198-210.

Jeong, C.H., Lee, Y.C., Kim, J.H. and Yang, S.Y. 1995. Systematic study on the fishes of the genus Raja (Pisces, Rajidae) from Korea. [in Korean with English abstract]. Korean Journal of Systematic Zoology 11(2): 207-221.

McEachran, J.D. and Dunn, K.A. 1998. Phylogenetic analysis of skates, a morphologically conservative clade of elasmobranchs (Chondrichthyes: Rajidae). Copeia 1998: 271-290.

McEachran, J.D. and T. Miyake. 1986. Inter-relationships within a putative monophyletic group of skates (Chondrichthyes, Rajoidei, Rajini). In: T. Uyeno, R. Arai, T. Taniuchi and K. Matsuura (eds), Indo-Pacific fish biology: Proceedings on the Second International Conference of Indo-Pacific Fishes, pp. 281-290. Tokyo.

McEachran, J.D. and T. Miyake. 1990. Phylogenetic inter-relationships of skates: a working hypothesis (Chondrichthyes, Rajoidei). In: H.L. Pratt Jr., S.H. Gruber and T. Taniuchi (eds), Elasmobranchs as living resources: advances in the biology, ecology, systematics and the status of the fisheries. NOAA.

Ueda, Y., K. Maeda, H. Shimada and T. Takami. 2003.. Fisheries and Aquatic in Hokkaido. Hokkaido Central Fisheries Experimental Station,, Hokkaido.

Yeon, I.J., Hong, S.H., Cha, H.K. and Kim, S.T. 1999. Feeding habitats of Raja pulchra in the Yellow Sea. [In Korean with English abstract]. Bulletin of the National Fisheries Research Development Instute Korea 57: 1-11.


Citation: Ishihara, H., Wang, Y., Tanaka, S., Nakaya, K. & Jeong, C-H. 2009. Raja pulchra. In: The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 29 November 2014.
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