Chlorurus bowersi 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Actinopterygii Perciformes Labridae

Scientific Name: Chlorurus bowersi (Snyder, 1909)
Common Name(s):
English Bower's Parrotfish, Orange-blotch Parrotfish
Callyodon bowersi Snyder, 1909
Scarus bowersi (Snyder, 1909)
Taxonomic Notes: Westneat and Alfaro (2005) recognize the Scarini as a tribe within the family Labridae.

The genera Chlororus and Scarus are two distinct monophyletic lineages (Smith et al. 2008). The sister pair C. bleekeri and C. bowersi share particularly distinctive cheek patches of green/white (C. bleekeri) to solid green/blue (C. bowersi), a double chin strap of blue, and nearly identical fin colourations (Smith et al. 2008). C. troschelii is also likely a member of this clade (Choat and Randall 1986).

Assessment Information [top]

Red List Category & Criteria: Near Threatened 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.
This species has a relatively restricted range and occurs in low densities in the Indo-Pacific. In over 90% of its distribution, it is subject to heavy fishing pressure and it is expected that this pressure is likely to increase. It has experienced 50–60% declines in the past 20–30 years in at least one part of its range in the central Philippines. Fishing pressure will undoubtedly continue to increase throughout its range. Although declines in other parts of its range are not well-known, based on estimates in the central Philippines, it is estimated that over the next 15 years (three generation lengths), global population declines will approach 30%. It is therefore listed as Near Threatened.

Although there are numerous marine reserves in the Coral Triangle Region at the present time, most reserves are not very well managed. However, in well-managed reserves parrotfishes tend to recover comparatively quickly and therefore increased management in protected areas and potentially fishery protection might offset the overexploitation of this species. More research is needed on this species' habitat specific behaviour, population biology, and population status.
Previously published Red List assessments:

Geographic Range [top]

Range Description:This species is found in the central west Pacific from the Philippines to Indonesia: northwestern Java, Komodo (Beger and Turak 2008), Halmahera (Green and Muljadi 2009) and western Papua (Raja Ampat, Fak-Fak and Kaimana) (Allen and Erdmann 2009), northwards to Taiwan and the Ryukyu Islands and eastward to Chuuk, Micronesia. It was also recorded in Hong Kong as Scarus sp. 2 (Sadovy and Cornish 2000).
Countries occurrence:
Disputed Territory (Spratly Is.); Hong Kong; Indonesia; Japan; Micronesia, Federated States of ; Palau; Philippines; Taiwan, Province of China
FAO Marine Fishing Areas:
Indian Ocean – eastern; Pacific – western central; Pacific – northwest
Additional data:
Lower depth limit (metres):25
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is solitary and relatively rare in central Philippines (Stockwell et al. 2009). Abundance estimates record 0.5–1 kg per 500 m² (Stockwell et al. 2009). This species is occasionally found in Raja Ampat (Allen 2003).

There was a slight decrease observed in Karimunjawa, Indonesia from 2005–2007. In Karimunjawa this species was observed to be common but not abundant (S. Pardede pers comm. 2009).
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species is similar to sister species Chlorurus bleekeri. It inhabits sheltered to moderately exposed reef flats and fronts (J.H. Choat pers comm. 2009). It is a small, solitary excavating parrotfish generally found in pairs. It inhabits coral reefs and adjacent rubble bottoms (G. Allen pers comm. 2009).

Generation length justification: 14 (longevity) - 2 (age of maturity) = 7/2 = 3.5 or 4 years
Generation Length (years):4

Use and Trade [top]

Use and Trade: This species is not targeted specifically but is taken by spearfishing both diurnally and nocturnally. It has been found in aquariums (John Birch Aquarium in San Diego) (R.F. Myers pers comm. 2009).

Threats [top]

Major Threat(s): This species is caught for food and is heavily fished throughout its range along with other parrotfishes. Increased fishing pressures and habitat disturbance are its major threats. Moreover, its rarity makes it susceptible to overfishing. In the Philippines, it is exploited to at least the same level as C. bleekeri, which has experienced 50–60% declines (Stockwell et al. 2009) over a period of approximately 20–30 years.

Fishing pressure has increased and will undoubtedly continue to increase throughout its range. Based on estimates in the central Philippines (Stockwell et al. 2009), it is estimated that over the next 15 years, population declines will approach 30%.

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. Its distribution overlaps several marine protected areas within its range. However, unlike its sister species C. bleekeri, its range does not include reef areas which are well protected by marine reserves and it generally does not exist in areas where it is not exploited.

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 bowersi. The IUCN Red List of Threatened Species 2012: e.T190711A17796625. . Downloaded on 19 October 2017.
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