Pangasianodon gigas

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	ACTINOPTERYGII	SILURIFORMES	PANGASIIDAE

Scientific Name:

Pangasianodon gigas

Species Authority:

Chevey, 1930

Common Name/s:

English	–	Giant Catfish, Mekong Giant Catfish
French	–	Silure De Verre Géant
Spanish	–	Siluro Gigante

Synonym/s:

Pangasius gigas (Chevey, 1931)

Assessment Information [top]

Red List Category & Criteria:

Critically Endangered A4bcde ver 3.1

Year Assessed:

2003

Assessor/s

Hogan, Z.S.

Evaluator/s:

Darwall, W. (Freshwater Biodiversity Assessment Programme) & Kottelat, M.

Justification:
P. gigas is endemic to the Mekong River Basin area. It is known from the Tonle Sap Lake, Tonle Sap River, and the Mekong River. It is not known to occur in the upper 2,000 km of the Mekong River. The current extent of occurrence is estimated at around 4,150 km².

Historical reports indicate that the species was abundant in the early 1900s. However, in the 1970's, local fisheries began to report the disappearance of the species. Current population size is unknown, but a decline of more than 80% over the last thirteen years can be estimated from past and current annual catch records, qualifying the species for Critically Endangered under criterion A. Generation length for the species is thought to be between 10 and 15 years.

Fishing effort in the Mekong Basin area in general is increasing. Fishing effort specifically for P. gigas in the Mekong River remains constant, although it may be increasing in some areas, such as Tonle Sap Lake. Habitat loss and degradation are also serious threats to P. gigas. There has been increasing siltation of the Mekong mainstream through past deforestation practices in the northern parts of the Mekong River area. The planned destruction of rapids in the stretch of the Mekong River in the northern Lao PDR, northern Thailand and southern China may also pose a serious threat to the species' spawning habitat. The loss of migratory routes through the construction of dams (for example, the Pak Mun Dam in Thailand) may also have a negative impact on fish abundance in the river.

The Thai Department of Fisheries has been releasing captive-bred individuals since 1985. Since 2000, approximately 10,000 captive-bred fish have been released into the Mekong. The fish have also been hybridized with P. hypophthalmus.

Given the ongoing threats to the species and its habitat, the population decline rate seen over the last thirteen years is not expected to diminish over the next two generations (approximately 30 years). Therefore, the species is assessed as Critically Endangered A4bcde.

History:

1996	–	Endangered (Baillie and Groombridge 1996)
1994	–	Vulnerable (Groombridge 1994)
1990	–	Vulnerable (IUCN 1990)
1988	–	Vulnerable (IUCN Conservation Monitoring Centre 1988)
1986	–	Vulnerable (IUCN Conservation Monitoring Centre 1986)

Geographic Range [top]

Range Description:	Pangasianodon gigas is a Mekong endemic (Rainboth 1996). Historically, it was distributed throughout the Mekong River Basin from the coast of Viet Nam to northern Lao PDR. Past reports of the species occurring as far north as southern Yunnan Province in China (Smith 1945, Roberts and Vidthayanon 1991) remain unconfirmed. The species' migration patterns are unknown. However, based on catch information provided by Roberts (1993) and others, it is believed that P. gigas migrates from the Tonle Sap Lake in Cambodia, upstream into northeast Cambodia and possibly up to Lao PDR or Thailand to spawn (Hogan et al. 2001). At least one spawning site is known (northern Thailand/Lao PDR), with a further possible spawning area in northeast Cambodia (Z. Hogan pers. comm.). There may have been other (lost) spawning sites in the middle and lower reaches of the Mekong (M. Kottelat pers. comm.). The extent of occurrence is estimated at around 4,150 km² (Z. Hogan pers. comm.).
Countries:	Native: Cambodia; Lao People's Democratic Republic; Thailand; Viet Nam Presence uncertain: China; Myanmar

Range Description:

Pangasianodon gigas is a Mekong endemic (Rainboth 1996). Historically, it was distributed throughout the Mekong River Basin from the coast of Viet Nam to northern Lao PDR. Past reports of the species occurring as far north as southern Yunnan Province in China (Smith 1945, Roberts and Vidthayanon 1991) remain unconfirmed. The species' migration patterns are unknown. However, based on catch information provided by Roberts (1993) and others, it is believed that P. gigas migrates from the Tonle Sap Lake in Cambodia, upstream into northeast Cambodia and possibly up to Lao PDR or Thailand to spawn (Hogan et al. 2001). At least one spawning site is known (northern Thailand/Lao PDR), with a further possible spawning area in northeast Cambodia (Z. Hogan pers. comm.). There may have been other (lost) spawning sites in the middle and lower reaches of the Mekong (M. Kottelat pers. comm.). The extent of occurrence is estimated at around 4,150 km² (Z. Hogan pers. comm.).

Countries:

Native:

Cambodia; Lao People's Democratic Republic; Thailand; Viet Nam

Presence uncertain:

China; Myanmar

Population [top]

Population:	Current population size is unknown. A rate of population decline of over 80% can be estimated from combining annual catch data over the last thirteen years in the Mekong River Basin area: In Chiang Khong (Northern Thailand), the catch has declined from a peak of 69 fish in 1990 to just seven fish in 1997 (Srettacheua 1995, Hogan 1998). In 1999, 20 fish were captured in Chiang Khong, however no fish were caught in the area in 2001 (Hogan et al. 2001) or in 2002. In Nong Khai Province (Northeast Thailand) 40-50 fish were caught per year in the early 1900's. However, since that time the number of fish caught has declined. In 1967, fishermen captured 11 fish in the area (Pookaswan 1969), and by 1970, P. gigas occurred only rarely as by-catch of beach seine fisheries (Pholprasith and Tavarutmaneegul 1998). Today, very few P. gigas are reported from Nong Khai Province (Hogan et al. 2001). In Luang Prabang (Lao PDR) the catch declined from 12 fish per year to just three fish caught in 1968. No fish were caught in 1972, 1973, or 1974 (Davidson 1975) and there has been no significant catch of the species reported since that time (Hogan et al. 2001). In Khone Falls (southern Lao PDR), a few fish were reported by fishermen each year prior to 1993, almost all of them in the first half of the year. No fish were reported in 1993. The status of P. gigas in the Khone Falls area has not been assessed since 1993 (Baird, pers. comm.). In the Tonle Sap River (Cambodia), four fish were captured in the bagnet fishery in 1999 and eleven fish reported in 2000. Fishermen report that they catch a few P. gigas each year (Pengbun et al. 2001, Hogan et al. 2001). Anecdotal information suggests that the species was once present in the Mekong Delta (Viet Nam), but is now reported as being very rare. One fish was caught close to, but not in, Viet Nam in 2003 (Z. Hogan, pers. comm.). No significant fishery for the species exists in Viet Nam (Lenormand 1996). Overall annual catch data for the Mekong River area indicate that around ten years ago 40-50 fish were caught each year. The figure has now dropped to approximately 5-8 catches per year (Z. Hogan, pers. comm.). The Tonle Sap River is one of the last places where the fish is caught in appreciable numbers. Although the species has been disappearing from Lao, Thailand , and Viet Nam, there is little information on population trends in Cambodia (Hogan et al. 2001). In 2001 and 2002, no P. gigas were caught in northern Thailand. Annual catch figures for the Tonle Sap River in Cambodia over recent years were, four in 2000, 11 in 2001 and five in 2002. Generation length has been reported as less than 10 years, however this is difficult to verify. The best estimate of generation length is between 10 and 15 years (Z. Hogan, pers. comm.).
Population Trend:	Decreasing

Population:

Current population size is unknown. A rate of population decline of over 80% can be estimated from combining annual catch data over the last thirteen years in the Mekong River Basin area:

In Chiang Khong (Northern Thailand), the catch has declined from a peak of 69 fish in 1990 to just seven fish in 1997 (Srettacheua 1995, Hogan 1998). In 1999, 20 fish were captured in Chiang Khong, however no fish were caught in the area in 2001 (Hogan et al. 2001) or in 2002. In Nong Khai Province (Northeast Thailand) 40-50 fish were caught per year in the early 1900's. However, since that time the number of fish caught has declined. In 1967, fishermen captured 11 fish in the area (Pookaswan 1969), and by 1970, P. gigas occurred only rarely as by-catch of beach seine fisheries (Pholprasith and Tavarutmaneegul 1998). Today, very few P. gigas are reported from Nong Khai Province (Hogan et al. 2001).

In Luang Prabang (Lao PDR) the catch declined from 12 fish per year to just three fish caught in 1968. No fish were caught in 1972, 1973, or 1974 (Davidson 1975) and there has been no significant catch of the species reported since that time (Hogan et al. 2001).

In Khone Falls (southern Lao PDR), a few fish were reported by fishermen each year prior to 1993, almost all of them in the first half of the year. No fish were reported in 1993. The status of P. gigas in the Khone Falls area has not been assessed since 1993 (Baird, pers. comm.).

In the Tonle Sap River (Cambodia), four fish were captured in the bagnet fishery in 1999 and eleven fish reported in 2000. Fishermen report that they catch a few P. gigas each year (Pengbun et al. 2001, Hogan et al. 2001).

Anecdotal information suggests that the species was once present in the Mekong Delta (Viet Nam), but is now reported as being very rare. One fish was caught close to, but not in, Viet Nam in 2003 (Z. Hogan, pers. comm.). No significant fishery for the species exists in Viet Nam (Lenormand 1996).

Overall annual catch data for the Mekong River area indicate that around ten years ago 40-50 fish were caught each year. The figure has now dropped to approximately 5-8 catches per year (Z. Hogan, pers. comm.). The Tonle Sap River is one of the last places where the fish is caught in appreciable numbers. Although the species has been disappearing from Lao, Thailand , and Viet Nam, there is little information on population trends in Cambodia (Hogan et al. 2001). In 2001 and 2002, no P. gigas were caught in northern Thailand. Annual catch figures for the Tonle Sap River in Cambodia over recent years were, four in 2000, 11 in 2001 and five in 2002.

Generation length has been reported as less than 10 years, however this is difficult to verify. The best estimate of generation length is between 10 and 15 years (Z. Hogan, pers. comm.).

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	P. gigas is one of the world's largest freshwater fish, measuring up to three meters in length and weighing in excess of 300 kilograms (Smith 1945, Roberts and Vidthayanon 1991). It is a migratory species. From October to December each year, the species moves out of the Tonle Sap Lake (Cambodia) into the mainstream of the Mekong River. From there, it is believed to migrate upstream into northeastern Cambodia and possibly Lao PDR, or Thailand to spawn (Hogan et al. 2001). The fish was bred in captivity for the first time in 2001. Individuals artificially spawned from wild-caught parents have been released into the Mekong since 1985. The fish almost certainly spawns upstream of Chiang Khong, Thailand. Possible spawning sites include the Kok River near Chiang Saen, Thailand
Systems:	Freshwater

Habitat and Ecology:

P. gigas is one of the world's largest freshwater fish, measuring up to three meters in length and weighing in excess of 300 kilograms (Smith 1945, Roberts and Vidthayanon 1991). It is a migratory species. From October to December each year, the species moves out of the Tonle Sap Lake (Cambodia) into the mainstream of the Mekong River. From there, it is believed to migrate upstream into northeastern Cambodia and possibly Lao PDR, or Thailand to spawn (Hogan et al. 2001).

The fish was bred in captivity for the first time in 2001. Individuals artificially spawned from wild-caught parents have been released into the Mekong since 1985. The fish almost certainly spawns upstream of Chiang Khong, Thailand. Possible spawning sites include the Kok River near Chiang Saen, Thailand

Systems:

Freshwater

Threats [top]

Major Threat(s):	Alongside overfishing, main threats to the species include habitat loss and degradation (for example, as a result of damming of the Mun River and clearance of flooded forest in the Tonle Sap Great Lake), and genetic introgression with cultured stocks.

Major Threat(s):

Alongside overfishing, main threats to the species include habitat loss and degradation (for example, as a result of damming of the Mun River and clearance of flooded forest in the Tonle Sap Great Lake), and genetic introgression with cultured stocks.

Conservation Actions [top]

Conservation Actions:	This species has been listed on CITES Appendix I since 1975. The species occurs in a Biosphere Reserve in the Tonle Sap Lake, and a RAMSAR site in northeastern Cambodia, although neither of these sites offers real protection for the species. In Cambodia, it is illegal to capture, sell, or transport P. gigas, although bagnet fisheries in the area still catch and sell the species. It is also illegal to catch the species in Thailand, however the species is still caught there and tourists and the media are attracted to fishing sites there every year. P. gigas is also protected in Laos (Kottelat, pers comm.) although this does not prevent the species being fished there.

Conservation Actions:

This species has been listed on CITES Appendix I since 1975. The species occurs in a Biosphere Reserve in the Tonle Sap Lake, and a RAMSAR site in northeastern Cambodia, although neither of these sites offers real protection for the species. In Cambodia, it is illegal to capture, sell, or transport P. gigas, although bagnet fisheries in the area still catch and sell the species. It is also illegal to catch the species in Thailand, however the species is still caught there and tourists and the media are attracted to fishing sites there every year. P. gigas is also protected in Laos (Kottelat, pers comm.) although this does not prevent the species being fished there.

Citation:	Hogan, Z.S. 2003. Pangasianodon gigas. In: IUCN 2008. 2008 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 07 January 2009.
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