The humphead wrasse (Cheilinus undulatus) is a large species of wrasse mainly found on coral reefs in the Indo-Pacific region. It is also known as the Māori wrasse, Napoleon wrasse, Napoleon fish, so mei 蘇眉 (Cantonese), mameng (Filipino), and merer in the Pohnpeian language of the Caroline Islands.
The humphead wrasse is the largest living member of the family Labridae. Males, typically larger than females, are capable of reaching up to 2 meters and weighing up to 180 kg, but the average length is a little less than 1 meter. Females rarely grow larger than one meter. This species can be easily identified by its large size, thick lips, two black lines behind its eyes, and the hump on the foreheads of larger adults. Its color can vary between dull blue-green to more vibrant shades of green and purplish-blue. Adults are usually observed living singly, but are also seen in male/female pairs and in small groups.
The humphead wrasses can be found on the east coast of Africa around the mouth of the Red Sea, and in some areas of the Indian and Pacific Oceans. Juveniles are usually found in shallow, sandy ranges bordering coral reef waters, while adults are found mostly in offshore and deeper areas of coral reefs, typically in outer-reef slopes and channels, but also in lagoons.
Very opportunistic predators, C. undulatus preys primarily on invertebrates such as mollusks (particularly gastropods, as well as pelecypods, echinoids, crustaceans, and annelids) and fish. Because half of echinoids and most pelecypods hide under the sand, wrasses may rely on fish excavators like stingrays, or they themselves may excavate by ejecting water to displace sand and nosing around for prey. Like many other Red Sea wrasses, humphead wrasses often crack sea urchins (echinoids) by carrying them to a rock in their mouths and striking them against the rock with brisk, sideways head movements.
They sometimes engage in cooperative hunting with the roving coral grouper.
Adults are commonly found on steep coral reef slopes, channel slopes, and lagoon reefs in water 3 to 330 ft (0.91 to 100.58 m) deep. The species actively selects branching hard and soft corals and seagrasses at settlement. Juveniles tend to prefer a more cryptic existence in areas of dense branching corals, bushy macroalgae, or seagrasses, while larger individuals and adults prefer limited home ranges in more open habitat on the edges of reefs, channels, and reef passes.
The humphead wrasse is long-lived, but has a very slow breeding rate. Individuals become sexually mature at five to seven years, and are known to live for around 30 years. They are protogynous hermaphrodites, with some becoming male at about 9 years old. The factors controlling the timing of sex change are not yet known. At certain times of year, adults move to the down-current end of the reef and form local spawning aggregations (groups). They likely do not travel very far for their spawning aggregations.
The pelagic eggs and larvae ultimately settle on or near coral reef habitats. Eggs are 0.65 mm in diameter and spherical, with no pigment.
In 1996, following a decade of rapid population decline, the humphead wrasse was placed on the IUCN Red List of endangered species. The wrasse's genomes must be analyzed to help keep the species alive.
Since so little was known about the wrasse's genetic relationships at a geographical scale, researchers utilized a test using microsatellite loci to facilitate population genetic studies. (DNA markers could not be used for testing, as the humphead wrasse lack such markers.) Of the 15 microsatellite loci used in the test, only four seemed to have different outcomes than the other 11. These loci were all prone to null alleles. However, with the presence of these null alleles, the results may have been slightly biased, or they may be related to a particularity of the C. undulatus, which are highly restricted to coral reef habitats.
The humphead wrasse is listed as endangered on the IUCN Red list and in Appendix II of CITES. Its numbers have declined due to multiple threats, including:
Unsustainable and severe overfishing within the live reef food fish trade is the primary threat. Sabah, on Borneo Island, is a major source of humphead wrasses. The fishing industry is vital to this state because of its severe poverty. The export of humphead wrasses out of Sabah has led to a roughly 99% decline in the area's population. In an effort to protect it, export of the humphead wrasse out of Sabah has been banned; however, it has not prevented illegal, unreported and unregulated activities. Protection by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) is managed in this area by the federal Department of Fisheries Malaysia,, which issues permits to regulate fishing activity. Two pieces of legislation have also been implemented to protect the species: The Fisheries Act 1985 controls the transport of live fish and prohibits destructive fishing techniques; and the International Trade in Endangered Species Act 2008 supports Malaysia's adoption of CITES.
The humphead wrasse is considered an umbrella species, which means many other species are sympatric with it and have much smaller ranges—thus the conservation of the humphead wrasse's habitat would benefit these other species as well. Understanding the concept of an umbrella species can lead to a better understanding of endangered species protection.
The humphead wrasse has historically been fished commercially in northern Australia, but has been protected in Queensland since 2003 and in Western Australia since 1998.
In Guangdong Province, southern mainland China, permits are required for the sale of the species. Indonesia allows fishing only for research, mariculture and licensed artisanal fishing. The Maldives instituted an export ban in 1995; Papua New Guinea prohibits export of fish over 2 ft (61 cm); and Niue has banned all fishing for this species.
The U.S. National Marine Fisheries Service has classified the humphead wrasse as a species of concern—one about which it has concerns, but for which it has insufficient information to list under the Endangered Species Act.
In Taiwan it is a protected species with fines of between NT$300,000 and $1.5 million and jail sentences of between 6 months and 5 years under the Wildlife Conservation act for hunting or killing of the species having been added to the protection list in 2014.
