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Takifugu obscurus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII TETRAODONTIFORMES TETRAODONTIDAE

Scientific Name: Takifugu obscurus
Species Authority: (Abe, 1949)
Synonym(s):
Fugu obscurus (Abe, 1949)
Sphoeroides ocellatus subspecies obscurus Abe, 1949

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2014
Date Assessed: 2014-07-16
Assessor(s): Hardy, G., Matsuura, K., Shao, K., Jing, L., Leis, J.L. & Liu, M.
Reviewer(s): Zapfe, G. & Lyczkowski-Shultz, J.
Contributor(s): Stump, E.
Facilitator/Compiler(s): Stump, E.
Justification:
Takifugu obscurus is known from the Yellow Sea, East China Sea and South China Sea to the Korean Peninsula. It is found in rivers in China. It is found at depths ranging from one to at least 20 m. This is a euryhaline species which lives in the bottom layer of inshore and inland waters. Spawning occurs in estuaries, and this species is known to migrate into freshwater to spawn. It is a commercial species which is considered highly-valued, however there is little information available to characterize the fishery. This species has been bred in captivity, and it is unclear whether or not this effort has been for the purposes of stock enhancement. There is little species-specific population information available. This species' dependence on freshwater systems to spawn and its predictable, seasonal mass spawning migrations into freshwater systems render it particularly vulnerable to overfishing. Seasonal fishing prohibitions and the presence of both fresh and marine water preserves in parts of its range may offer this species some protection. Takifugu obscurus is assessed as Least Concern.
History:
2009 Least Concern

Geographic Range [top]

Range Description: In the Western Pacific, Takifugu obscurus is known from the Yellow Sea, East China Sea and South China Sea south to the Korean Peninsula. It is found in rivers in China (Nakabo 2002). It is found to depths of at least 20 m, and may be found deeper.
Countries:
Native:
China; Japan; Korea, Democratic People's Republic of; Korea, Republic of
FAO Marine Fishing Areas:
Native:
Pacific – northwest; Pacific – western central
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There is little species-specific population information available for wild populations of T. obscurus.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology:

Takifugu obscurus is a demersal,  anadromous species which undergoes annual seasonal migrations into freshwater systems to spawn. In the Yangtze River basin, the spawning period for T. obscurus is from March until April. This species maintains a sex ratio of approximately 1: 1. This species reaches sexual maturity between 25 and 28 cm (SL). The ovaries and blood are extremely toxic, while the liver, skin, and intestine are highly toxic. The flesh and testes are innocuous (Nakabo 2002).

This species lives in the bottom layer of inshore and inland waters, and grows 20–40 cm in length. Most of the growth takes place in the sea but they spawn in brackish and fresh water. During the spawning season, which is from late spring to early summer, the sexually mature fish run into river estuaries and spawn in inland waters including rivers, lakes, and ponds. The fingerlings grow in the inland water and either return to the sea the next spring or they there for a few months before returning to the sea. In the sea they grow to sexually mature fish over several years, and then return to the inland water again to spawn (Kato et al. 2005).

Systems: Freshwater; Marine

Use and Trade [top]

Use and Trade:

Takifugu obscurus is a popular food fish in China and fetches a premium price owing to its high quality meat (Yang and Chen 2008). This is a species of interest for intensive aquaculture in China (Zhou and Jia-Xin 2003).

Aquaculture
Fishes of the genus Takifugu have become the focus of increasing aquaculture efforts throughout East Asia. Aquacultured Takifugu are used to meet increasing demand for pufferfish products and to enhance natural populations which have been depleted throughout the region (Kawata et al. 2012). Takifugu pufferfishes, principally represented by the tiger puffer, T. rubripes, are raised in floating net pens in Japan, Korea, and China (Belle and Nash 2009). The total wild catch of pufferfish species in Japan has been relatively stable, ranging from 7,800 to 11,000 tonnes from 1995 to 2002. The four most common species consumed in Japan areT. rubripesT. snyderi, T. chinensis, and T. porphyreus. Aquaculture efforts focus on T. rubripes, which ranks fifth among marine aquacultured species (the top aquacultured species in Japan are: Yellowtail (Seriola quinqueradiata), Red Sea Bream (Pagrus major), coho Salmon (Oncorhynchus kisutch) and Japanese flounder (Paralichthys olivaceus). Although highly valuable (the market price of T. rubripes is 1.5 times that of Japanese flounder, three times that of yellowtail or seabream), the value began to decrease rapidly from the late 1990s onwards due to importation of Tiger puffer from China. In Japan, the majority of fingerlings produced in commercial hatcheries are then raised in floating net cages for direct consumption. About 15 million fingerlings are produced by commercial hatcheries for aquaculture, 1.5 times higher than the amount produced for release for stock enhancement by semi-governmental hatcheries in 1999. One of the most serious problems in the net cage aquaculture of tiger puffer is high (over 50%) mortality from outbreaks of parasitic diseases (Ogawa and Inouye 1997).

Tiger puffer (T. rubripes) was introduced to China from Japan (Lin and Huang 2007). To meet increasing demand for pufferfish, China began large-scale artificial breeding of pufferfish in the 1990s. An annual output of about 4,000 tonnes of T. rubripes, which was introduced from Japan to China (Lin and Huang 2007) is exported to Japan and South Korea. Additionally, an annual output of about 6,000 tonnes of T. obscurus was also produced for export in China. Pufferfishes are still landed in China, mostly in Zhejiang, Fujian, Guangdong and other places. Nationwide, the total output of pufferfish is now around 20,000 t per year (Ma et al. 2011)

Threats [top]

Major Threat(s): There have been no confirmed population declines in T. obscurus. However, it is likely to be impacted by the following:

Fugu fishery
The Fugu fishery is acknowledged to have undergone significant declines throughout East Asia. Highly effective fishing gear, including modified long-lines and nets with small mesh sizes, rather than excessive fishing effort, have been implicated in the depletion of Takifugu pufferfish resources in parts of East Asia. In Japan, initial efforts to regulate the fishery in the mid-2000s had not achieved desired results by 2010, and were subsequently re-evaluated (Kawata 2012). Although the species-specific effects of the Fugu fishery on T. obscurus are unknown, it is likely that populations of this minor commercial species are impacted by this fishery. 

Genetic effects of cultured fish on natural populations
Fishes of the genus Takifugu have become the focus of increasing aquaculture efforts throughout East Asia. Aquacultured Takifugu are used to meet increasing demand for pufferfish products and to enhance natural populations which have been depleted throughout the region (Kawata et al. 2012). As culture fish are genetically distinct from natural populations, the release of aqua-cultured fish can result in a range of genetic outcomes, from no detectable effect to complete introgression or displacement of wild populations (Hindar et al. 1991). Fishes of the genus Takifugu are relatively recently diverged, and each combination of Takifugu species is expected to produce fertile hybrid crosses (Yamanoue et al. 2008). It is therefore likely that the effect of intentional and unintentional release of cultured Takifugu on the genetic integrity of wild populations is significant.

Regional threats: environmental degradation and over-fishing
Major threats to biodiversity of the China seas include over-exploitation of fishery resources and environmental deterioration. The China Seas have faced severe environmental degradation due to a range of anthropogenic activities within a relatively recent and short time frame (Daoji and Daler 2004). The degradation of estuarine environments due to pollution and coastal production is of particular concern, as these areas are characterized by high productivity and represent spawning and nursery areas for many species (Liu 2013). Large areas of the China Seas (Liu 2013) and the Gulf of Thailand (Blaber 2000) are considered to be heavily overfished. Additionally, heavy bottom-trawling in the 1980s and the widespread use of modified driftnets for multi-species fisheries in the Bohai Sea, combined with other anthropogenic stresses, have been implicated in the steady decrease in fish landings in this area (Xianshi 2004). In the Yellow Sea, previously dominant large demersal species became the targets of heavy fishing pressure during the 1950s and 1960s and greatly declined in abundance. By the 1980s, many large pelagic species were also showing great declines in abundance, and since that time the dominant species in the Yellow Sea have been small, planktivorous pelagic species, such as anchovies and sardines (Jin and Tang 1996). In the Yellow Sea, all ecological indexes such as the species number, species richness, species diversity and the evenness were lower in the year 2000 than in the year 1985 (Lin et al. 2005).

Conservation Actions [top]

Conservation Actions:

There are no known species-specific conservation measures in place for T. obscurus, however, it is possible that management efforts aimed at sustaining T. rubripes fisheries have benefited T. obscurus. Additionally, T. obscurus has been bred in captivity to meet increasing demand and to enhance existing stocks.

Fugu fishery
The Fugu fishery is acknowledged to have undergone significant declines. Japan, South Korea and China previously operated their fisheries under a policy which prevented the regulation of foreign fishing vessels and treated the open sea in East Asia as common property. Since 1999, with the ratification of the United Nations (UN) Convention on the Law of the Sea and new fishery agreements between these nations, this policy has shifted to enable coastal countries to regulate foreign fishing vessels. As a result of this policy shift, Japan announced the Plan for Rebuilding Puffer Resources in April 2005, which set dates for an off-fishing season, restrictions on minimum body size, support for stock-enhancement programs, improvements to fishing grounds, and mandated the release of small fishes. As of 2010, stocks had not fully improved, prompting a re-assessment of the program. Several recommendations have been made in order to ensure its continued existence, particularly in light of socio-economic constraints which limit the possibility of developing alternative fisheries. Recommendations include gear restrictions and mandating that fishers catch older and heavier fish by postponing the beginning of the fishing season (Kamara 2012).

In order to sustain fisheries of the East China Sea, the government of China has implemented a number of management and conservation measures. These include establishing a prohibited-fishing zone along the 50-m depth contour, the establishment of seventeen national nature reserves and five special marine protected areas, the creation of fishery protected areas which are annually closed to trawling, and a summer closed-fishing areas, which prohibit trawling and have been extended to the South China Sea, Yellow Sea, and Bohai Sea (Cheng et al. 2007).

Takifugu obscurus can be found in both freshwater and marine protected areas. According to the protection regulations for wetlands in the Poyang Lake of Jiangxi Province (2004) and the implementation of Chinese Fishery Lawin Jiangxi Province (1987), fishing is is banned from March 20th to June 20th every year in Poyang Lake. This corresponds with the spawning migration of this species in China, although whether or not this species spawns in the lake is unknown. Fishing has also been banned for two months from June 1st to July 31st each year since 1987 along the Xiajiang reach, Xingan reach, Jishui reach and Jian reach of the Ganjiang River, where this species has been recorded. However, this does not correspond to the freshwater spawning migration of this species (Huang et al. 2010).

Further research
The economically important genus Takifugu has been recommended for further taxonomic studies based on morphological and molecular analyses (Yamanoue et al. 2008), and we support this recommendation.


Citation: Hardy, G., Matsuura, K., Shao, K., Jing, L., Leis, J.L. & Liu, M. 2014. Takifugu obscurus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 22 December 2014.
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