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Overview

Brief Summary

Biology

The gregarious humphead parrotfish is always found in small shoals, sometimes consisting of up to 75 individuals (1). It feeds on a diet of live corals and algae that grow on the ocean bottom, and uses its large bulbous head to ram the coral to break it into smaller, more easily digested pieces (1). Its beak-like front teeth and pharyngeal teeth at the back of the throat adeptly grind down this food, reducing the hard coral to a paste and breaking down the algae (3). Any hard, un-nutritious material is passed out in the fish's faeces (3). As a consequence, adult humphead parrotfish, which are estimated to consume five to six tonnes of coral each year, produce substantial amounts of sediment and influence the structure of coral reefs, thus playing an important role in the coral reef ecosystem (2). Humphead parrotfish aggregate to spawn at a certain time each month, often around the time of the full moon, in reef channels and passages. Spawning often takes place in early morning (2) (5), when females release eggs to be fertilized in the water by the sperm released by the male. These large spawning aggregations may consist of around 100 individuals. Large groups of humphead parrotfish are also found when they are sleeping. These large fish can live to an age of at least 40 years (1).
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Description

The largest of all parrotfish, the humphead parrotfish is an olive or blue-green to slate-grey fish, with a yellowish to pink head (2). Its most distinctive feature, and the reason for its common name, is the prominent bulbous forehead which develops in adults (2). Juvenile humphead parrotfish do not have this bulging head and also differ slightly in colour, being green or brown with five vertical rows of small, whitish spots (2). Parrotfish get their name from their peculiar teeth, which are fused into a parrot-like beak. They also have teeth at the back of the throat which grind food (3).
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WhyReef - Lifestyle

You will almost always find green humphead parrotfish in a small group with other humphead parrotfish. During the day they swim and eat, and at night they sleep in caves or even shipwrecks. Most humphead parrotfish live to be at least 40 years old!
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Comprehensive Description

Biology

Juveniles found in lagoons; adults in clear outer lagoon and seaward reefs up to depths of at least 30 m (Ref. 9710). Usually in small groups. Feeds on benthic algae, live corals (Ref. 9710) and shellfishes (Ref. 58784). May ram its head against corals to facilitate feeding (Ref. 9710). Sleeps in caves and often in shipwrecks at night (Ref. 48636). The largest and wariest of the parrotfishes. Vulnerable to overfishing (Ref. 9710).
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WhyReef - Fun Facts

As you might guess from its name, the green humphead parrotfish has a big head, and for good reason! It rams its head into coral to break it up into smaller pieces, and then eats it. It also has a very strong beak-like mouth that it uses to grind the coral into a paste. The humphead parrotfish can eat 10,000 pounds of coral every year! This might seem like a bad thing for the coral, but it can help new coral to grow.
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Distribution

Range Description

Recorded from the Red Sea east to the Line Islands and Tuamotu Archipelago (French Polynesia), north to Taiwan, the Yaeyama Islands (Japan), and Wake Island (United States Minor Outlying Islands), south to northwest Australia, the Great Barrier Reef and New Caledonia (Randall et al. 1990, Myers 1999).
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Indo-Pacific: Red Sea and East Africa to Samoa and the Line Islands, north to the Yaeyama and Wake islands, south to the Great Barrier Reef and New Caledonia.
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Red Sea, Indo-West Pacific: East Africa, Mascarenes (Mauritius and Rodrigues) and Maldives east to Wake Atoll, Marshall Islands, Line Islands and Gambier Islands, south to Western Australia, Queensland (Australia), New Caledonia and Tonga.
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Range

The humphead parrotfish can be found in tropical and subtropical coral reefs in the central and western Pacific, Indian Ocean and Red Sea (2).
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Physical Description

Morphology

Dorsal spines (total): 9; Dorsal soft rays (total): 10; Analspines: 3; Analsoft rays: 9
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Size

Maximum size: 1300 mm NG
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Max. size

130 cm TL (male/unsexed; (Ref. 9710)); max. published weight: 46.0 kg (Ref. 2334)
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Diagnostic Description

Description

Occur in schools on clear outer lagoon and seaward reefs at depths of 1 to at least 30 m. Usually in small groups. Feeds on benthic algae and live corals. The largest and wariest of the parrotfishes.
  • Anon. (1996). FishBase 96 [CD-ROM]. ICLARM: Los Baños, Philippines. 1 cd-rom pp.
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Median predorsal scales 2 to 4 (may be obscured by hump); scales on cheek scale rows 1(4-6), 2(3-6), 3(1-2) (Ref. 9793). Sometimes confused with the humphead wrasse or other 'humphead' parrotfishes (Ref. 1602). Unlike the wrasse, it has a vertical head profile, and unlike other parrotfishes, it is uniformly covered except for the leading edge of the head which is often light green to pink, and has a nodular outer surface to its beak (Ref. 1602). The primary phase is a dull gray with scattered white spots, gradually becoming uniformly dark green (Ref. 1602).
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This species is gregarious and occurs in aggregations of up to several (> 75) individuals on seaward and clear outer lagoon reefs at depths of 1 to 30m; also enters outer reef flats at low tide to forage. Pelagic spawning on a lunar cycle; utilises resident spawning aggregations sites (Johannes 1981, Gladstone 1986). Eggs and larvae are pelagic. Primarily a corallivore, but also feeds upon benthic algae; this species uses its large gibbus head to ram corals and break them into pieces that are more easily ingested. Aggregations of this species are important producers of coral sand on reefs and may be important in the maintenance of ecosystem resilience (Bellwood et al. 2003). Reportedly wary on reefs near human settlement or use. This species sleeps in large groups, thus rendering them highly vulnerable to exploitation by spearfishers (mainly in the Pacific region) and netters at night (Myers 1999).

Additional notes, as follows:

Exposed reef crests are the primary habitat of B. muricatum (J.H. Choat, pers. comm. on 4th Jan 2007).

In unfished areas, B. muricatum may enter outer reef flats at depths of 1 to at least 30 m (Myers 1991).

Lieske and Myers (1994) observed that juveniles can be found in lagoons, while adults are in clear outer lagoon and seaward reefs at depths of at least 30 m.

Very small individuals are restricted to the shallow inner lagoon in Solomon Islands (Aswani and Hamilton 2004).

At Roviana Lagoon, Solomon Islands, juveniles are limited to the shallow inner lagoon environment, while larger individuals occur predominantly in passages (Hamilton 2004).

B. muricatum feeds substantially on live coral (Gladstone 1986, Myers 1991, Bellwood et al. 2003) and benthic algae (Randall et al 1990).

Gladstone (1986) described B. muricatum as generally timid and difficult to approach.

Bellwood et al (2003) reported that B. muricatum produces significant bioerosion in the Indo-Pacific. Based on 132 timed transects (20-min long, 5 m wide) at 9 reefs in the Great Barrier Reef, schools of 30 to 50 huge (up to 120 cm TL) specimens with each individual removing 2.33 m³ or 5.69 tonnes of structural reef carbonate each year.

Spawning
Spawning behaviour in a tightly packed school of about 100 individuals (pair spawning activities among this mobile group) was observed from the seafloor (15 m deep) to about 2 m below the surface on the morning of January 15, 1985 in Great Barrier Reef (Gladstone 1986). None of the B. muricatum in the spawning school was smaller than about 60 cm TL (Gladstone 1986). Choat and Randall (1986) recorded a group spawning (40 to 50 fish) on the outer face of Yonge reef in Great Barrier Reef during December 1983.

Sexual Pattern
Randall and Bruce (1983) had suggested sex inversion occurs in B. muricatum. J.H. Choat, pers. comm., 18 September 2006) stated that this species does not appear to be diandric; there is an extended prereproductive period of sexual differentiation from which males are produced.

Fecundity and Recruitment
Information not available

Systems
  • Marine
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Environment

reef-associated; marine; depth range 1 - 30 m (Ref. 9710)
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Depth range based on 4 specimens in 1 taxon.
Water temperature and chemistry ranges based on 3 samples.

Environmental ranges
  Depth range (m): 0.5 - 48
  Temperature range (°C): 26.287 - 28.954
  Nitrate (umol/L): 0.068 - 0.822
  Salinity (PPS): 34.131 - 34.753
  Oxygen (ml/l): 4.525 - 4.549
  Phosphate (umol/l): 0.108 - 0.189
  Silicate (umol/l): 1.579 - 3.817

Graphical representation

Depth range (m): 0.5 - 48

Temperature range (°C): 26.287 - 28.954

Nitrate (umol/L): 0.068 - 0.822

Salinity (PPS): 34.131 - 34.753

Oxygen (ml/l): 4.525 - 4.549

Phosphate (umol/l): 0.108 - 0.189

Silicate (umol/l): 1.579 - 3.817
 
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Depth: 1 - 30m.
From 1 to 30 meters.

Habitat: reef-associated.
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This coral reef fish inhabits shallow fringing and barrier reefs, between depths of one and thirty metres (1) (2). While adult parrotfish are most often found in outer lagoons and seaward reefs, juveniles are more often found inside lagoons, in seagrass beds (4). At night, this parrotfish can be found resting in caves or on the sandy flats of shallow lagoons (2).
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Trophic Strategy

Occur inshore (Ref. 75154). Juveniles found in lagoons; adults in clear outer lagoon and seaward reefs up to a depths of at least 30 m (Ref. 9710). Usually in small groups. Feed on benthic algae and live corals (Ref. 54301). May ram their heads against corals to facilitate feeding (Ref. 9710). Sleep in caves and often in shipwrecks at night (Ref. 48636). The largest and wariest of the parrotfishes.
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Associations

WhyReef - Menu

Green humphead parrotfish eat coral and turf algae. They spend all day munching on coral and chomping turf algae that grow on the bottom of the reef. Because it eats both animals and plants, the humphead parrotfish is an omnivore.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Bolbometopon muricatum

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 4
Species With Barcodes: 1
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
VU
Vulnerable

Red List Criteria
A2d

Version
3.1

Year Assessed
2012

Assessor/s
Chan, T., Sadovy, Y. & Donaldson, T.J.

Reviewer/s
Choat, J.H., Dulvy, N. & Hamilton, R.

Contributor/s
Raynal, M.

Justification
Donaldson and Dulvy (2004) stated that B. muricatum was common or abundant throughout much of its range historically. This species is now considered rare globally, with local densities negatively correlated with fishing pressure across six Indo-Pacific locations, and with suspected local extinctions at some localities (Dulvy and Polunin 2004). Underwater surveys across its range in suitable habitats, even at remote localities, have either failed to detect this species or have detected only rare individuals (Dulvy and Polunin 2004, T.J. Donaldson unpublished data of timed "long-swim"/gps transects). Otherwise, it is abundant only on the Great Barrier Reef and at Rowley Shoals in northwestern Australia; juvenile B. muricatum appear to be very rare in the Great Barrier Reef, Australia (Bellwood and Choat 1989) but adults achieve their highest abundance on the Great Barrier Reef (mean = 31 fish per hectare) over the recorded range of this species (J.H. Choat pers. comm.). Based on rapid visual census from a series of transects of 50x5 m at depth of 12 m on individual reefs at Coringa-Herald National Nature Reserve (located east of Cairns, Australia), the abundance of B. muricatum was estimated to range from 1 to 25 fish in northeast and southwest Herald (Oxley et al. 2003).

Elsewhere, it is relatively abundant in the Solomon Islands, Papua New Guinea, and a few other oceanic islands, and is common locally at Samoa, Sipidan Island (Malaysia), Wake Island, the Red Sea and New Caledonia. Choat and Randall (1986) described B. muricatum as widely distributed in West Indian and Pacific Oceans, and was most commonly observed on reef fronts, reef crests and flats. At other locations, it is now uncommon or rare, and is virtually extinct in Guam, Marshall Islands, parts of Fiji and East Africa, and is declining rapidly in Palau (Myers 1991, Donaldson and Dulvy 2004, Dulvy and Polunin 2004, Donaldson unpubl. data). This species is naturally rare in some parts of its range (e.g., Christmas Island, Amirantes and Farqhuar Atoll, Seychelles, and elsewhere in the Indian Ocean), a fact which cannot be attributed to over-fishing.(J.H. Choat pers. comm.). B. muricatum was rare around most the US Pacific Islands and was seen typically only at 1 or 2 islands of a region (e.g., US Line Islands, US Phoenix Islands, Marianas Archipelago, or American Samoan Islands) (R.H. Schroeder, Coral Reef Ecosystem Division of the NOAA, pers. comms. on 14th Aug 2006; 23rd and 29th Dec 2006).

See the attached PDF for the fishery-independent data. No fishery-dependent data is available either regionally or by country.

Donaldson and Dulvy (2004) showed that the large-sized, long-lived B. muricatum, but with low replacement rates and high vulnerability to fishing pressure, appears to be of considerable functional importance (as a major bioeroder on coral reefs and maintain ecosystem resilience) which should be protected.

Hamilton (2003) pointed out that the introduction of simple but new technologies coupled with small scale economic restructuring (from the mid 1970s till the end of 1980s, there were no cash markets for B. muricatum; greater financial development in late 1980s ended up in the development of fisheries projects; by the mid 1990s, fillets of B. muricatum were bought at a higher price than any other fish - commercialization) of the B. muricatum fishery in Solomon Islands has overexploited its stock which is in need of management.

As parrotfish are the only fish group capable of consuming reef carbonate, Bellwood et al. (2003) indicated that B. muricatum plays a crucial role in reef ecosystem processes, and its absence highlights the potential for marked changes in ecosystem function (shifting from steady-state reef calcification to carbonate accumulation).

Dulvy and Polunin (2004) revealed that informal methods of inferring whether a species is naturally rare or has declined or disappeared as a result of human activity could aid efforts to provide a more accurate estimate of the contemporary marine extinction rate in such data-poor situations.

In the Solomon Islands, Aswani and Hamilton (2004) stated that protection of the highly fecund large females would enhance the sustainability of the Roviana fishery.

Donaldson and Dulvy (2004) recommended (1) implementing a moratorium on commercial fishing and export; (2) educating stakeholders and the general public on the importance of conserving B. muricatum; (3) creating and enforcing larger marine reserves that incorporate key habitat; and (4) carrying further research on its population ecology and behaviour.

D. Fenner (pers. comm., 22nd Oct 2006) suggested that it is important to protect and monitor B. muricatum, a coral predator, because its removal might have effects on coral reef ecosystem with unknown consequences.

Gillett and Moy (2006) suggested that B. muricatum (a species that is inherently not very resilient to fishing pressure) should be a conceptual issue for consideration on the control of the fishing gear selectivity (especially selectivity of spearfishing).

Russ and Alcala (1998) suggested that the small size of most marine protected areas in heavily fished regions would show little positive effects on reef-bioeroding parrotfish abundances.

G.R. Allen (pers. comm. 16 January 2007) recommended blanket protection of this species, offering the "chance for the numerous immature fish to grow and form the nucleus of the globally exceptional concentration" of this giant reef fish.

For this historically abundant species, more information on its present abundance, biology, age-and-growth and management practices is recommended before it disappears due to unsustainable exploitation.

Given all the above information it seems reasonable to infer at least a 30% population reduction of the Humphead Parrotfish in the last three generations (the last 30 years) due to over-exploitation in parts of its range.

History
  • 2007
    Vulnerable
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Status

Classified as Vulnerable (VU) on the IUCN Red List 2007 (1).
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Population

Population
B. muricatum are locally patchily distributed, adults always found in small shoals (<= 40 individuals) (Donaldson and Dulvy 2004).

Choat and Randall (1986) stated B. muricatum does not display sex-associated patterns of colour change, maintaining a uniform body colouration in adult females and males. Juvenile shows a distinct colour pattern.

Hamilton (2003) described B. muricatum is the largest of all parrotfish, reaching over 50 kg and living to an age of at least 40 years.

Gladstone (1986) revealed that B. muricatum individuals usually occur as part of schools containing 20 to almost 100 fish which often move into shallow waters during feeding around Lizard Island in Great Barrier Reef.

Based on a histological analysis of gonad collected from 169 females in Solomon Islands in 2000-2001, the size of maturity was found to be 620 mm FL, in which some specimens as small as 610 mm FL showed significant gonad development (Hamilton 2003).

Hamilton and Adams (unpubl. data) showed that 100% female maturity occurs at 650 mm SL.

FishBase 2006 (www.fishbase.org) estimates that the minimum population doubling time ranges from 4.5 to 14 years; this estimate is derived from a formula that utilizes length and infinity (Linf), length at maximum yield (Lopt), time at length "0" (t0) and K (= 0.10), and may need to be recalculated given the maximum age of this species (J.H. Choat, pers. comm., 18 September 2006). FishBase (2006) calculates that the decline threshold equals 0.85; this species is vulnerable to extinction if this threshold value is exceeded over the longer of 10 years or three generations.

Sex composition
Information not available

Length-age relationship
Information not available.

Population Trend
Decreasing
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Threats

Major Threats
B. muricatum forms mixed sized schools and is extremely vulnerable to overfishing (Hamilton 2003).

Shoaling and group resting behaviour render B. muricatum highly vulnerable to spearfishing, particularly at night-time (Donaldson and Dulvy 2004) and mainly in the Pacific region (J.H. Choat pers. comm.). Spearfishing at night has reduced the numbers of B. muricatum (Gladstone 1986, D. Fenner pers. comm. on 27th July 2006).

In Roviana Lagoon (Solomon Islands), artisanal spear fishers use their sophisticated indigenous knowledge of the spawning behaviour and ecology of B. muricatum to catch as many fish as possible in a night (Hamilton 2003).

The belief that B. muricatum predominantly aggregate at night around the new moon period and that catch rates are far greater during the new moon was not supported by field survey done in 2000-2001 (Aswani and Hamilton 2004).

Dulvy and Polunin (2004) suggested that the decline of B. muricatum in the Lau Group in Fiji was mainly due its nocturnal aggregative behaviour in shallow lagoon water or in reef caves and the daytime foraging of shoals in depth accessible by spearfishermen.

B. muricatum was often captured for ceremonial events, indicating this species has a high cultural significant value in the Lau Island group, Fiji (Dulvy and Polunin 2004).

Low priority to enforcing legislation related to spearfishing in Fiji (Gillett and Moy 2006).

In 2001, the Samoa Fisheries Projected reported that SCUBA spearfishing activities at night had been increased rapidly in the past 12 months, in which B. muricatum was one of the target species (Gillett and Moy 2006).

Gillett and Moy (2006) pointed out that sleeping B. muricatum was one of the three main types of fish to be targeted by spearfishing.

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).
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Vulnerable (VU) (A2d)
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The habit of feeding, resting and spawning in groups makes the humphead parrotfish highly vulnerable to fishing, particularly by spear-fishing during the night (1) (2). This has resulted in a decline in numbers of the humphead parrotfish in some areas (1), and this once abundant fish is now virtually extinct in Guam, the Marshall Islands, parts of Fiji and East Africa (2).
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WhyReef - Threats

Overfishing is a big problem for the humphead parrotfish! Overfishing means too many fish are being caught by humans. Green humphead parrotfish are very easy to catch at night when they are sleeping. Because of this, they are almost extinct in Guam, the Marshall Islands, Fiji and East Africa.
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Management

Conservation Actions

Conservation Actions
Two marine protected areas (MPAs) ["no-take" zones] were established in Baraulu Village and Nusa Hope Village, Solomon Islands in 2002 to protect B. muricatum and other lagoon species (Aswani and Hamilton 2004).

There are no direct protective practices for B. muricatum.

Fiji
The Fisheries (Restrictions on Use of Breathing (Apparatus) Regulations, 1997 ban the use of underwater breathing apparatus to "collect, take, or dive for fish", except for those with appointment from the Permanent Secretary or any person appointed by him in writing. And the Sixth Schedule of the Fisheries Regulation establishes minimum sizes for 21 tpes of fish, including many that are often caught by spearfishing (Gillett and Moy 2006).

Besides, traditional fisheries rules (e.g,. a ban on night diving, and a ban on the use of SCUBA for fishing) in most of the 410 traditional fishing areas in Fiji have their own local fishing rules and many of those are applicable to spearfishing (Gillett and Moy 2006).

Samoa
The Fishing (Scuba Fishing) Regulations 2003 states no person shall scuba fish without a license (Gillett and Moy 2006).

Many different types of traditional rules (e.g., establishing small protected areas, minimun size limits, and restricting the use of underwater torches for spearfishing at night) governing fisheries exist in the 324 villages of Samoa (Gillett and Moy 2006).

Solomon Islands
Regulations 29 of the Fisheries Act, which enacted in January 2004, states "any person using under-water breathing apparatus for the purpose of harvesting any marine resource shall be guilty of an offence and liable to a fine not exceeding five thousand dollars or six months imprisonment or both such fine and imprisonment" (Gillett and Moy 2006).

Many villages regulate spearfishing (e.g. bans on night diving) by themselves (Gillett and Moy 2006).

Although traditional leader's ability to manage marine resource was found to be effective in some of the tribes in Solomon Islands, the existence of non-member (e.g., institutional context) and enforcement of harvest restriction rules are crucial so as to enhance management and minimize the public contest over natural resources (Aswani and Hamilton 2004).

Russ and Alcala (1998) suggested that the small size of most marine protected areas in heavily fished regions would show little positive effects on parrotfish abundances.

Aswani and Hamilton (2004) suggested that the prohibition on spearfishing within passage habitats in Roviana Lagoon, Solomon Islands, would provide a measure of protection the remaining important spawning stocks of B. muricatum in the Indo Pacific region.

Aswani and Hamilton (2004) recommended that any lunar ban on spearfishing should focus at late full moon quarter during which B. muricatum spawns.
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Conservation

There are no protective measures specifically in place for the humphead parrotfish (1), but a number of fishing regulations should afford this vulnerable fish some protection (2). For example, in some regions, restrictions on night-time spear-fishing or spear-fishing with compressed air are in place (1) (2), measures which will help protect the parrotfish when it is at its most vulnerable. Marine Protected Areas (MPAs), in which fishing is prohibited, protects numerous species; two MPAs were established in the Solomon Islands in 2002 (Baraulu Village and Nusa Hope Village) to protect the humphead parrotfish and other reef species (1).
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Relevance to Humans and Ecosystems

Benefits

Importance

fisheries: commercial; aquarium: commercial
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Wikipedia

Green humphead parrotfish


The green humphead parrotfish, Bolbometopon muricatum, is the largest species of parrotfish, growing to lengths of 1.3 m (4.3 ft) and weighing up to 46 kg (101 lb).[1] It is found on reefs in the Indian and Pacific Oceans, from the Red Sea in the west to Samoa in the east, and from the Yaeyama Islands in the north to the Great Barrier Reef, Australia, in the south.

Other common names include bumphead parrotfish, humphead parrotfish, double-headed parrotfish, buffalo parrotfish, and giant parrotfish.

It is the only species in the monotypic genus Bolbometopon.

Species description[edit]

Unlike wrasses, it has a vertical head profile, and unlike other parrotfishes, it is uniformly covered with scales except for the leading edge of the head, which is often light green to pink. Primary phase colouration is a dull gray with scattered white spots, gradually becoming uniformly dark green. This species does not display sex-associated patterns of color change. The adult develops a bulbous forehead and the teeth plates are exposed, being only partly covered by lips. The species is slow-growing and long-lived (up to 40 years), with delayed reproduction and low replenishment rates.

This species is gregarious and usually occurs in small aggregations, but group size can be quite large on seaward and clear outer lagoon reefs, exceeding 75 individuals.

Reproduction[edit]

The fish spawn pelagically near the outer reef slope or near promontories, gutters, or channel mouths during a lunar cycle, and they use spawning aggregation sites.

Ritualized headbutting of males at Wake Atoll

Ecology[edit]

The juvenile green humphead parrotfish is found in lagoons, often in seagrass beds, and the adult is found in clear outer lagoons and seaward reefs up to a depth of 30 m. It feeds on benthic algae and live corals. It may ram its head against corals to facilitate feeding. Each adult fish ingests over five tons of structural reef carbonates per year, contributing significantly to the bioerosion of reefs. The fish sleeps in caves and shipwrecks at night, usually in large groups.

Conservation[edit]

This species is highly sought after by fishermen throughout its range, and it has declined from overharvesting. Habitat degradation and destruction has sped the decline. Spearfishers and netters target the large groups as they sleep at night. This is a NOAA Species of Concern, thought to be threatened, but for which insufficient data are available to justify a listing under the Endangered Species Act.

Spearfishing while scuba diving was banned in American Samoa in 2001, but enforcement is limited. The waters surrounding Wake Island, Johnston Atoll, and Palmyra Atoll from the shoreline out to 50 fathoms (91 m) are protected as low-use marine protected areas, which means any person of the United States fishing for, taking, or retaining this fish must have a special permit. Also, it may not be taken by means of spearfishing with SCUBA gear from 6 pm to 6 am in the US Exclusive Economic Zone waters around these territories. The population of the fish in Palau is now protected by an export ban and a national minimum size restriction of 25 in (640 mm).

References[edit]

  1. ^ Froese, Rainer and Pauly, Daniel, eds. (2006). "Bolbometopon muricatum" in FishBase. March 2006 version.
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