Acanthurus triostegus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Perciformes Acanthuridae

Scientific Name: Acanthurus triostegus (Linnaeus, 1758)
Common Name(s):
English Convict Surgeonfish, Convict Tang, Fiveband Surgeonfish
French Chirurgien à Raies Noires, Chirurgien Bagnard, Chirurgien Zèbre
Spanish Cirujano Convicto, Cirujano Rayado, Cirujano Reo, Lancero Convicto, Sangrador Carcelario
Acanthurus hirudo Bennett, 1829
Acanthurus pentazona Bleeker, 1850
Acanthurus subarmatus Bennett, 1840
Acanthurus triastegus (Linnaeus, 1758)
Acanthurus triostegus marquesensis Schultz & Woods, 1948
Acanthurus triostegus sandvicensis Streets, 1877
Acanthurus triostegust (Linnaeus, 1758)
Acanthurus triostegus triostegus (Linnaeus, 1758)
Acanthurus zebra Lacepède, 1802
Chaetodon couaga Lacepède, 1802
Chaetodon triostegus Linnaeus, 1758
Harpurus fasciatus Forster, 1801
Hepatus sandvicensis (Streets, 1877)
Hepatus triostegus (Linnaeus, 1758)
Rhombotides pentazona (Bleeker, 1850)
Rhombotides triostegus (Linnaeus, 1758)
Teuthis australis Gray, 1827
Teuthis elegans Garman, 1899
Teuthis sandvicensis (Streets, 1877)
Teuthis triostegus (Linnaeus, 1758)
Teuthis troughtoni Whitley, 1928
Taxonomic Notes: There is strong geographical pattern in the genetic structure of Acanthurus triostegus throughout the tropical Pacific but this does not warrant species recognition (Planes and Fauvelot 2002).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2010-05-04
Assessor(s): McIlwain, J., Choat, J.H., Abesamis, R., Clements, K.D., Myers, R., Nanola, C., Rocha, L.A., Russell, B. & Stockwell, B.
Reviewer(s): McClenachan, L., Edgar, G. & Kulbicki, M.
Acanthurus triostegus is widespread throughout the Indo-Pacific region. There is a strong geographical pattern in genetic structure throughout the Pacific, but this does not warrant species recognition. It is very abundant in some parts of its range. It is a targeted food and recreational species. There are no indications of global population declines through harvesting. It is found in a number marine protected areas in parts of its range. It is therefore listed as Least Concern. We recommend monitoring of the harvest levels and population status of this species.

Geographic Range [top]

Range Description:Acanthurus triostegus is widely distributed throughout the Indo-Pacific, including Yemen, but it is not found elsewhere in the Arabian Peninsula. In the eastern Pacific it occurs from the lower Gulf of California, El Salvador to Ecuador and all the oceanic islands.
Countries occurrence:
American Samoa; Australia; Bangladesh; British Indian Ocean Territory; Brunei Darussalam; Cambodia; Chile (Easter Is.); China; Christmas Island; Cocos (Keeling) Islands; Colombia; Comoros; Cook Islands; Costa Rica; Disputed Territory (Paracel Is., Spratly Is.); Djibouti; Ecuador (Galápagos); El Salvador; Fiji; French Polynesia; French Southern Territories (Mozambique Channel Is.); Guam; Honduras; Hong Kong; India (Andaman Is., Nicobar Is.); Indonesia; Japan; Kenya; Kiribati (Gilbert Is., Kiribati Line Is., Phoenix Is.); Macao; Madagascar; Malaysia; Maldives; Marshall Islands; Mauritius; Mayotte; Mexico; Micronesia, Federated States of ; Mozambique; Myanmar; Nauru; New Caledonia; New Zealand; Nicaragua; Niue; Norfolk Island; Northern Mariana Islands; Palau; Panama; Papua New Guinea; Philippines; Pitcairn; Réunion; Samoa; Seychelles; Singapore; Solomon Islands; Somalia; South Africa; Sri Lanka; Taiwan, Province of China; Tanzania, United Republic of; Thailand; Timor-Leste; Tokelau; Tonga; Tuvalu; United States (Hawaiian Is.); United States Minor Outlying Islands (Howland-Baker Is., Johnston I., Midway Is., US Line Is., Wake Is.); Vanuatu; Viet Nam; Wallis and Futuna; Yemen
FAO Marine Fishing Areas:
Atlantic – southeast; Indian Ocean – western; Indian Ocean – eastern; Pacific – southeast; Pacific – eastern central; Pacific – western central; Pacific – southwest; Pacific – northwest
Additional data:
Lower depth limit (metres):90
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Acanthurus triostegus was recorded as the most abundant species of surgeonfish in the Hawaiian Islands (Randall 1961b). It is an abundant inshore species (Randall 2001b). Marine recreational catch surveys administered by the Hawaii Marine Recreational Fishing Survey in 2006 recorded 432,182 individuals (Friedlander et al. 2006). It is the 3rd most commercially landed acanthurid in Hawaii, with an average of 5,800 kg from 1997-2005 (Hawaii Division of Aquatic Resources unpub. data).

It was recorded as occasional in Raja Ampat, Indonesia, where it is usually found in shallow, wave affected areas (Allen 2003b). It is locally abundant in the Philippines (B. Stockwell pers. comm. 2010).  In Calamianes Islands, El Nido and San Vicente, Palawan, it is moderately common in shallow, wave affected areas near shore (Werner and Allen 2000, Palawan Council for Sustainable Development unpub. data).  In Moorea, French Polynesia, the Acanthuridae family was dominant on the barrier reef (2.30 ind. m-2) and on the outer slope, (1.61 spec. m-2). On the barrier reef, this species accounted for 37% of the total density (Moussa 2009).

In Guam, A. triostegus accounts for 6% of acanthurid landings and less than 1% in Saipan (Guam Division of Aquatic and Wildlife Resources unpub. data). After a hurricane in Reunion Is. in January 1989, the density of Acunthurus triostegus, decreased six months after the hurricane, and later increased. Abundance estimates record 19 ind/200 m2 (LeTourner et al. 1993).

In Kenya, landings during 1978-2001 for families that are less important in commercial catches (e.g., scarinae and Acanthuridae) showed rising catches (1978-1984) followed by a general decline during the 1990s (Kaunda-Arara et al. 2003).

Visual census surveys in the Iboih coast, Weh Island, Indonesia recorded fish densities of 18 individuals/750 m2 at Pantai Sirkui, 11 individuals/750 m2 at Teupin Layeu and 12 individuals/750 m2 at Teluk Pelabuhan (Faculty of Mathematics and Natural Science 2007). It was recorded as occasional in terms of relative abundance in Milne Bay Province, Papua New Guinea, usually in shallow wave-affected areas (Allen 2003).

This species is very abundant on offshore islands other than the Galapagos (where it is uncommon), and common in clear water environments along the tropical eastern Pacific continental coast and Gorgona Island, Colombia. According to Robertson and Allen (1996), this fish was frequent enough to have a resident population in Clipperton Atoll. In Cabo Pulmo, Gulf of California, this species was considered scarce (Villarreal-Cavazos et al. 2000).
Current Population Trend:Stable
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology: This reef-associated species occurs in lagoons and seaward reefs with hard substrate. It is usually seen in reef crests in shallow exposed reef fronts (J.H. Choat pers. comm. 2010). The young are abundant in tide pools (Randall 1986, Kuiter and Tonozuka 2001) In the Gulf of Chiriqui, Panama, this species can be found over zones of madreporic branching corals, in sheltered areas (Dominici-Arosemena and Wolff 2006). In Hawaii, this species occurs in bays, harbours, and exposed reef areas. It abounds in tide pools and shallow water, yet is also known in depths of at least 100 ft (Randall 1961b). It is often observed feeding near freshwater run-offs where certain algae grow on rocks (Kuiter and Tonozuka 2001). Adults are often observed in large feeding aggregations, it may also be seen as solitary or in small groups. Large aggregations may be dense and cover areas more than 50 ft in diameter (Randall 1961b). It feeds on algal turfs (Choat et al. 2004).  It is classified as a grazer (Green and Bellwood 2009).
It rarely achieves sizes above 20 cm (TL).


The sexes are separate among the acanthurids (Reeson 1983). Acanthurids do not display obvious sexual dimorphism, males assume courtship colours (J.H. Choat pers. comm. 2010). This species spawns year-round in equatorial waters, but seasonally in Hawaii, coinciding with the colder part of the year (February-March) (Randall 1961b). It recruits year-round in Guam (J. McIlwain unpub. data).

It was observed to form spawning aggregations on the Great Barrier Reef (Randall 1961a, 1961b; Johannes 1981; Robertson 1983). In Palau it spawns from May-August after the new moon (Randall 1961b). At Aldabra Atoll it spawns from November-December (Robertson 1983). During midday to dusk fish migrate in dense streams to aggregation sites, reaching tens of thousands to spawn (Randall 1961a, 1961b; Robertson 1983; Randall et al. 1990). Males displayed a spawning colour phase. Spawning takes place in pulses by sub-groups of 10-20 fish (Randall 1961a, 1961b; Robertson 1983). Pair spawning has also been observed in this species. A. triostegus aggregations are resident spawning aggregations (Domeier and Colin 1997). Its size during metamorphosis, from the post-larval stage to juvenile, is 3.2 cm (Krupp 1995). The eggs and larvae are pelagic. The smallest running ripe female found on Oahu was 10.1 cm (SL); the smallest male 9.7 cm (SL) (Randall 1961b).

Use and Trade [top]

Use and Trade: Acanthurus triostegus  is utilized as a food source (Titcomb 1972), and is important in commercial fisheries in some parts of its range. It is a popular recreational fish in Hawaii. It is also collected for the aquarium trade (Global Marine Aquarium Database accessed 19 March 2010). Online prices range from $22.95-$49.99 per individual (L. Rocha pers. comm. 2010).

Threats [top]

Major Threat(s): Localized fishing for artisanal and recreational fisheries is a threat in some areas.

Surgeonfishes show varying degrees of habitat preference and utilization of coral reef habitats, with some species spending the majority of their life stages on coral reef while others primarily utilize seagrass beds, mangroves, algal beds, and /or rocky reefs. The majority of surgeonfishes are exclusively found on coral reef habitat, and of these, approximately 80% are experiencing a greater than 30% loss of coral reef area and degradation of coral reef habitat quality across their distributions. However, more research is needed to understand the long-term effects of coral reef habitat loss and degradation on these species' populations. Widespread coral reef loss and declining habitat conditions are particularly worrying for species that recruit into areas with live coral cover, especially as studies have shown that protection of pristine habitats facilitate the persistence of adult populations in species that have spatially separated adult and juvenile habitats (Comeros-Raynal et al. 2012).

Conservation Actions [top]

Conservation Actions: There are no species-specific conservation measures in place for this species. However, its distribution overlaps several marine protected areas within its range.

Citation: McIlwain, J., Choat, J.H., Abesamis, R., Clements, K.D., Myers, R., Nanola, C., Rocha, L.A., Russell, B. & Stockwell, B. 2012. Acanthurus triostegus. The IUCN Red List of Threatened Species 2012: e.T177965A1504553. . Downloaded on 15 October 2018.
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