Chlorurus microrhinos 

Scope: Global
Language: English

Translate page into:

Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Perciformes Labridae

Scientific Name: Chlorurus microrhinos (Bleeker, 1854)
Common Name(s):
English Steephead Parrotfish, Blunt-head Parrotfish, Gibbus Parrotfish, Heavybeak Parrotfish, Pacific steephead Parrotfish
French Perroquet bleu
Callyodon microrhinus (Bleeker, 1854)
Callyodon ultramarinus Jordan & Seale, 1906
Pseudoscarus microrhinos (Bleeker, 1854)
Scarus microrhinos Bleeker, 1854
Taxonomic Notes: This species is one of a clade of three large Chlorurus with an eastwest distribution: C. gibbus in the Red Sea, C. strongylocephalus in the Indian Ocean, C. microrhinos in the extreme east Indian Ocean and Pacific Ocean (Myers 1999, Parenti and Randall 2000, J.H. Choat pers comm. 2010). Up until 2000, all species were called C. gibbus. Records of Pacific C. gibbus refer to C. microrhinos (J.H. Choat pers comm. 2009).

Westneat and Alfaro (2005) recognize the Scarini as a tribe within the family Labridae. The genera Chlororus and Scarus are two distinct monophyletic lineages. The sister species is C. capistratoides (Smith et al. 2008).

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2009-09-16
Assessor(s): Choat, J.H., Carpenter, K.E., Clements, K.D., Rocha, L.A., Russell, B., Myers, R., Lazuardi, M.E., Muljadi, A., Pardede, S. & Rahardjo, P.
Reviewer(s): McIlwain, J. & Craig, M.T.
Although this species is heavily exploited at least half of its range, it is one of the most widespread parrotfishes. It is not subject to any form of exploitation in the southern limits of its distribution, and occurs in remote oceanic environments with no human habitation. It is the most abundant large parrotfish in Great Barrier Reef Marine and Western Australia marine parks. It occurs in a number of marine protected areas in parts of its range. It is therefore listed as Least Concern.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is found in the Ryukyu and Ogasawara Islands to Indonesia and Australia, Lord Howe Island and New Caledonia, and eastwards to Oceania (except Hawaiian Islands and Easter Island) (G. Allen pers comm. 2009). In the southerm hemisphere it extends south of coral reef formations. It is not found in Cocos Keeling Islands.
Countries occurrence:
American Samoa; Australia; China; Christmas Island; Cook Islands; Disputed Territory (Spratly Is.); Fiji; French Polynesia; Guam; Hong Kong; Indonesia; Japan; Kiribati (Kiribati Line Is., Phoenix Is.); Malaysia; Marshall Islands; Micronesia, Federated States of ; Nauru; New Caledonia; Niue; Northern Mariana Islands; Palau; Papua New Guinea; Philippines; Pitcairn; Samoa; Solomon Islands; Taiwan, Province of China; Timor-Leste; Tokelau; Tonga; United States Minor Outlying Islands (Howland-Baker Is., Wake Is.); Vanuatu; Viet Nam; Wallis and Futuna
FAO Marine Fishing Areas:
Indian Ocean – eastern; Pacific – eastern central; Pacific – southwest; Pacific – western central; Pacific – northwest
Additional data:
Lower depth limit (metres):50
Upper depth limit (metres):1
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is one of the more abundant and widely distributed Indo-Pacific parrotfishes. It is moderately common especially at the southern limits of its range. This species is rare in the Philippines and is not commonly found in markets in the Coral Triangle region. There have been abundance declines in Indonesia but elsewhere it is locally abundant. It is unknown if its rarity in markets in the Coral Triangle is due to past overfishing or a natural phenomenon.

This species shows substantial changes in abundance over its distributional range. Numbers are mean abundance per 1,000 m2:

Great Barrier Reef: 9-12
Middleton reef: 3-13
Coral Sea reefs: 17-2.3
West Australia (Rowley Shoals): 2.3
Kavieng, Papua New Guinea: 1.7
Samoa: 0.9
Tuvalu: 5.5.

This species is heavily fished in Pacific Islands eg: Samoa but at Tuvalu this species is inedible due to ciguatera. The Great Barrier Reef has naturally very high densities 9-12 as opposed to the West Australia reefs at 2-3. Both areas sampled are marine reserves. High abundances are recorded at the southern limit of coral reef formation (Middleton Reef). Both fishing and natural processes modify abundances in C. microrhinos (J.H. Choat pers comm. 2009).


Abundance data from 2005-2007 showed a decrease from 800 individuals per hectare to 80 individuals per hectare (S. Pardede pers comm. 2009).

Underwater fish visual census in Kofiau, Raja Ampat in April 2009 recorded biomass estimates of 2,000 kg per hectare (M.E. Lazuardi and A. Muljadi pers comm. 2009). It is moderately common in Raja Ampat (Allen 2003).
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This is a large excavating parrotfishes reaching 80 cm (TL) and forming schools of up to 40 individuals on reef fronts and crests. It is a rapidly growing species with maximum age of 15 yrs (identified as C. gibbus) (Choat et al. 1996). It is found in a wide range of habitats from inshore reefs to exposed oceanic reef fronts (Russ 1984).

Use and Trade [top]

Use and Trade: C. microrhinos is the primary food species over most of its central and western Pacific range. In the Solomon islands and Papua New Guinea, it is increasingly taken for local commerce to supply mining and logging camps. It is a major component in Taiwan fish markets (J.H. Choat pers comm. 2009).

Threats [top]

Major Threat(s): As a large parrotfish, this species is targeted for food in at least half of its range. It is also commonly taken by spearfishing at night and also during daytime including the Great Barrier Reef. It is heavily fished at some locations in Guam with declines of 86% in numbers landed since 1985 (Division of Aquatic and Wildlife Resources unpub. data). It is present in most markets observed including Palau and the Society Islands where it is heavily targeted in the Tuamotos. Fishing pressure is increasing in parts of its range such as in the Solomon Islands and Papua New Guinea (J.H. Choat pers comm. 2009). Destructive fishing practices and habitat destruction are prevalent in parts of its range (Indonesia, Malaysia, and Philippines).

Parrotfishes show varying degrees of habitat preference and utilization of coral reef habitats, with some species spending the majority of their life stages on coral reefs, while others primarily utilize seagrass beds, mangroves, algal beds, and /or rocky reefs. Although the majority of the parrotfishes occur in mixed habitat (primarily inhabiting seagrass beds, mangroves, and rocky reefs) approximately 78% of these mixed habitat species are experiencing greater than 30% loss of coral reef area and habitat quality across their distributions. Of those species that occur exclusively in coral reef habitat, more than 80% are experiencing a greater than 30% of coral reef loss and degradation across their distributions. However, more research is needed to understand the long-term effects of habitat loss and degradation on these species populations.   Widespread coral reef loss and declining habitat conditions are particularly worrying for species that depend on live coral reefs for food and shelter 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. Furthermore, coral reef loss and declining habitat conditions are particularly worrying for some corallivorous excavating parrotfishes that play major roles in reef dynamics and sedimentation (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. In Samoa, night spearfishing using SCUBA has been banned.

Citation: Choat, J.H., Carpenter, K.E., Clements, K.D., Rocha, L.A., Russell, B., Myers, R., Lazuardi, M.E., Muljadi, A., Pardede, S. & Rahardjo, P. 2012. Chlorurus microrhinos. The IUCN Red List of Threatened Species 2012: e.T190728A17783512. . Downloaded on 21 September 2018.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided