Takifugu ocellatus 

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Tetraodontiformes Tetraodontidae

Scientific Name: Takifugu ocellatus (Linnaeus, 1758)
Common Name(s):
English Ocellated Puffer
Fugu ocellatus (Linnaeus, 1758)
Fugu ocellatus ssp. ocellatus (Linnaeus, 1758)
Spheroides ocellatus (Linnaeus, 1758)
Takifugu ocellatus ssp. ocellatus (Linnaeus, 1758)
Takyfugu ocellatus (Linnaeus, 1758)
Tetraodon ocellatus Linnaeus, 1758
Tetrodon ocellatus Linnaeus, 1758
Taxonomic Notes:

Takifugu ocellatus (Linnaeus, 1758)

Vietnamese named: Cá Nóc ch?m.

Diodon  ocellatus (Linnaeus, 1758); Tetraodon ocellatus Chevey & Lemasson, 1937; Fugu ocellatus Matsubara, 1955
Discrible by Mai, 1978: L = 78-123mm, Lo = 63 - 102mm. D = 4,11; A = 3,10; P = 2,16; V = 0; C = 1+8+2. Lo = 3,47 H = 3,62 T; T = 3,62 O = 4,61 OO.

Round, flat side and long body, large dorsal and head. Many flaxes on body. Flaxes of dorsal distributed from back 2 nostrils to front dorsal fin. Round caudal peduncle, high body, small mouth and strong teeth. Large eyes on 2 sides head. Lateral line has 3 sections. Dorsal fin put off body. Draw anal fin. Has not pelvic fin, large pectoral fin. Brown dorsal, silver abdomen. Has 2 large points eyes after pectoral fin. And 1 large point on dorsal fin.

Specimens have been keeping at the Museum of Animals of Natural Sciences University - Hanoi National of Universtity.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2014
Date Assessed: 2011-06-10
Assessor(s): Hardy, G., Leis, J.L., Liu, M., Jing, L. & Matsuura, K.
Reviewer(s): Zapfe, G. & Lyczkowski-Shultz, J.
Contributor(s): Stump, E.
Facilitator/Compiler(s): Comeros-Raynal, M., Carpenter, K.E., Sanciangco, J. & Harwell, H.
Takifugu ocellatus is distributed in the northwest Pacific in coastal areas of China south to Viet Nam and South Korea at depths ranging from very shallow waters to 20 metres. It is an anadromous species which undergoes seasonal annual migrations to freshwater to spawn. It does not appear to be overly common, and is considered rare in parts of its range. Takifugu ocellatus is a highly-valued food fish, and has been the subject of artificial breeding efforts in China and South Korea for the purposes of stock enhancement and in order to supply fish for human consumption. This species' dependence on freshwater systems to spawn and its predictable, seasonal mass spawning migrations into freshwater systems render it particularly vulnerable to overfishing. Habitat modification in estuaries is occurring in parts of its range and we infer that these events are contributing to population declines in parts of its range. Some authors have noted population declines in this species, which are currently unquantifiable. This high-value species occupies a shallow depth range (<20 m) and undergoes mass-spawning migrations to freshwater systems, factors which render it particularly vulnerable to increasing anthropogenic pressures on coastal areas as well as to overfishing. It is inferred that this species is dependent on fisheries management, such as off-fishing seasons, restrictions on minimum body size, support for stock enhancement programs, improvements to fishing grounds, protected areas, and the increasing reliance on species-specific aquaculture to meet increasing consumer demand which can not be met by wild stocks alone. Takifugu ocellatus is conservation dependent and is therefore assessed as Near Threatened. Due to the economic importance of the Takifugu genus, and the prevalence of taxonomic uncertainty within this group, we recommend further taxonomic studies utilizing both molecular and morphological methods in addition to habitat and population monitoring.

Geographic Range [top]

Range Description:

Takifugu ocellatus is known from coastal areas and large estuaries in South Korea, China, Taiwan (Liu Jing pers. comm. 2011) and Viet Nam. It has been reported from the coasts of the South China Sea, and the middle and lower reaches of the Pearl River, East China Sea, and lower reaches of Jiulong River and Yangzi River and Yellow Sea (Su and Li 2002). This species can be found a considerable distance up rivers, and is known from the Yangtze river basin. It is found at depths of 1–25 metres.

Countries occurrence:
China; Japan; Korea, Republic of; Philippines; Taiwan, Province of China; Viet Nam
FAO Marine Fishing Areas:
Pacific – western central; Pacific – northwest
Additional data:
Lower depth limit (metres):25
Upper depth limit (metres):1
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Due to their relatively recent divergence times, Takifugu interspecific crosses produced by artificial and natural fertilization in both natural and laboratory settings were found to be viable (Fujita 1967, Masuda et al. 1991, Miyaki et al. 1995, Kai et al. 2005). Each combination of Takifugu species is expected to produce fertile hybrid crosses (Yamanoue et al. 2008). Molecular analyses of the whole mitochondrial genome of the genus Takifugu revealed that the genetic differences between T. variomaculatus and T. ocellatus, are not significantly different from the genetic differences between individuals within the species T. ocellatus, reinforcing the need for further taxonomic studies of the genus using molecular and morphological techniques (Yamanoue et al. 2008). 

This species is frequently recorded from trawl surveys in Hong Kong. However, it appears in low numbers (Yu 2003, M. Liu pers. comm. 2011). It is rarely found in Viet Nam (K. Matsuura pers. comm. 2011) and is also rare in Taiwan (Shao pers. comm. 2011). Subpopulations of this species are currently declining because of over-exploitation and environmental pollution, which has prompted interest in the large-scale aquaculture of this species (Chen 2005), however the extent of the decline is currently not quantifiable. Takifugu ocellatus is moderately common in museum collections. It is represented by 13 lots (FishNet2 Database searched December 2013).

Current Population Trend:Decreasing
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:Takifugu ocellatus is anadromous, migrating into freshwater rivers for reproduction during the spawning season. The newly hatched larvae remain in freshwater for several months before migrating back to the sea. This species is dependent on estuaries and freshwater system for spawning. In China, T. ocellatus spawns from March to June every year, migrating to the Yangtze estuary (Yu 2003).

The male to female sex ratio is approximately 1:1 (Yang and Chen 2008). In the lower reaches of the Yangtze River, T. ocellatus reaches reproductive maturity between 22 and 26 cm SL (Yang and Chen 2008), with most females entering the maturing phase in March and increasing proportion of ripe individuals in April (Yang and Chen 2008). It reaches reproductive maturity in its second year (Yu 2003) and undergoes a migration to freshwater in April, May, and June (Yang and Chen 2008). This species is of interest to the aquaculture industry in China, and has been induced to spawn in captivity only with hormone treatments for the purposes of commercial fish culture and stock enhancement (Chen 2005).

The genus Takifugu speciated and radiated in marine waters around China, Korea, and Japan. The highest species density is found in the Bohai Sea, Yellow Sea, and East China Sea, followed by the Sea of Japan and Pacific Coast of Japan, and finally by the South China Sea. Several species have been reported from the Indian Ocean (Yamanoue et al. 2008).

Tetraodontids are characterized by a tough skin that is often covered with small spinulous scales, a beak-like dental plate divided by a median suture, a slit-like gill opening anterior to the base of the pectoral fin, no pelvic fins, no fin spines, a single usually short-based dorsal fin, a single usually short-based anal fin, and no ribs. They are capable of inflating their abdomens with water when frightened or disturbed and are capable of producing and accumulating toxins such as tetrodotoxin and saxitoxin in the skin, gonads, and liver. The degree of toxicity varies by species, and also according to geographic area and season (Allen and Randall 1977, Allen and Erdmann 2012). Fishes in the family Tetraodontidae have the smallest vertebrate genomes known to date (Neafsey and Palumbi 2003).

Systems:Freshwater; Marine

Use and Trade [top]

Use and Trade: Takifugu ocellatus is a popular food fish in China and fetches a premium price owing to its high quality meat (Chen 2005). This species is also found in the ornamental aquarium trade. Takifugu ocellatus, like other fugu species, is primarily caught by bottom long-line fishing, a method which is highly effective at landing Takifugu spp. pufferfishes (K. Matsuura pers comm. 2011).

Mass culture of T. ocellatus has developed rapidly in China (Yang and Chen 2008) and in South Korea (Liu Jing and K. Matsuura pers comm. 2011), where this species is cultured primarily for local consumption (Yu 2003). 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). 

Threats [top]

Major Threat(s): There have been anecdotal population declines in T. ocellatus which have been attributed to overfishing and pollution. 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 longlines 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. ocellatus are unknown it has been suggested that populations are declining due in part to over-fishing. It is likely that spawning aggregations of this species, which are found in freshwater, are intrinsically vulnerable to over-exploitation.

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). Because 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 overfishing
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).

This species is anadromous and breeds in freshwater. Several of its known breeding and feeding grounds, including the estuaries of the lower Yangtze river and several downstream lakes have recorded declines in fish biodiversity and shifts in species composition which have been attributed to anthropogenic habitat alteration, river modification (i.e. dam construction), overfishing, heavy metal pollution, deforestation and land erosion (Fu et al. 2003, Zhang et al. 2008, Huang et al. 2010, Chen and Zhu 2008). The impact on this species is unknown.

Conservation Actions [top]

Conservation Actions:

There are no known species-specific conservation measures in place for T. ocellatus, however, it is possible that management efforts aimed at sustaining T. rubripes fisheries have benefited T. ocellatus. Additionally, T. ocellatus 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 ocellatus 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., Leis, J.L., Liu, M., Jing, L. & Matsuura, K. 2014. Takifugu ocellatus. The IUCN Red List of Threatened Species 2014: e.T167006A1162597. . Downloaded on 15 October 2018.
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