Green humphead parrotfish

Green humphead parrotfish
Conservation status
Vulnerable  (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Perciformes
Family:	Scaridae
Genus:	Bolbometopon J. L. B. Smith, 1956
Species:	B. muricatum
Binomial name
Bolbometopon muricatum (Valenciennes, 1840)

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). 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

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

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

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

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).

External links

• "Bolbometopon muricatum". Integrated Taxonomic Information System. Retrieved 11 March 2006.
• "Green humphead parrotfish" at the Encyclopedia of Life