Humphead Wrasse: The Reef Defender

Humphead Wrasse_INFOG
Art by Dana Rose Salonoy

Download the humphead wrasse module and the full size minigraphics.

Introduction

  • Scientific name: Cheilinus undulatus
  • Like many reef fishes, a humphead wrasse can change its sex starting out as a female and becoming a male wrasse around the age of 9.
  • Protects coral reefs by eating the deadly crown-of-thorns starfish
  • Considered to be endangered by the International Union for Conservation of Nature (IUCN), listed under Convention on International Trade in Endangered Species of Wild Fauna and Flora CITES Appendix II

Distribution

The humphead wrasse is found within the Indo-Pacific region all the way to the coasts of East Africa.  Younger humphead wrasses typically live closer to the coast where dense coral reefs are located while adults can also be found further away from the coast in lagoons and channel slopes in depths up to 100 meters.

The species is naturally rare, with recorded maximum adult density of not more than 20 fish per 10,000 m². The population has reduced by 50% over the course of 30 years.

The Napoleon wrasse is found in the Southeast Asian countries in the Coral Triangle which are Indonesia, Malaysia, and the Philippines or CT3. In the Philippines, its common name is mameng.

Why they are important

Humphead wrasses are one of the defenders of the coral reef. They are one of the few species that can eat the Crown of Thorns (COT), a poisonous starfish that feeds on coral polyps.  An individual crown of thorns starfish can consume up to 6 square meters (65 ft) of living coral reef in a year; hence the need to protect predators of COT like the humphead wrasse and triton shell to control COT population.

Coastal communities benefit from the humphead wrasse because it is a popular species for dive tourism due to its size, gentle nature, and bright colors.

“DSCF1886 Napoleanfish” by Clifton Beard is licensed under CC BY-NC 2.0
DSCF1886 Napoleanfish” by Clifton Beard (CC BY-NC 2.0)

Biology

The fish is easily identified by its lips, the bump located on its head, and by 2 black lines that are typically located next to the eyes. The species can also come in a wide range of different colors from blue, green, or a red which makes them a spectacular fish to see.

The species has an estimate life span of at least 30 years and there have been humphead wrasses that have reached a length of 2 meters and weighed up to 190 kilograms. This long reproductive cycle makes them very prone to overfishing because it will take them a long time to recover. They are known to be protogynous hermaphrodites, which means that some of the female humphead wrasses will change their sex and become male.

Humphead wrasse feed primarily on molluscs, fish, sea urchins, crustaceans, echinoderms, and other invertebrates, using their strong teeth.

They demonstrate a reproductive strategy of spawning aggregation, whereby sexually mature adults from adjacent reefs gather at specific sites to mate.

Threats

Even before the species was overfished, the humphead wrasse was a naturally rare fish. They have a long reproductive cycle which takes at least five years to reach sexual maturity. The humphead wrasse is one of the popular species used in the live reef food fish trade (LRFFT), a lucrative but unsustainable industry where the fish are kept alive when caught and sold for high prices either for food or for the aquarium business. The humphead wrasse does not have a large market share in the LRFFT due to its rarity but it is one of the most valuable selling for over $100 USD per kilogram in the retail market.

In order to mate, the species would congregate in large numbers  which can easily reach more than 100 individual humphead wrasses. These spawning aggregations make them easy targets for fishermen.

The coral reefs, the preferred habitat of the humphead wrasses, are under threat from the effects of climate change and human pressures. One of the most prominent threats associated with the LRFFT is cyanide fishing. Cyanide stuns the fish which allows fishermen to easily catch them. However, cyanide is toxic to humans, coral polyps, and other reef residents and its prolonged use will end up destroying the reef ecosystem.

What we can do

Do not purchase groupers or humphead wrasses. Fishermen will continue to harvest groupers or humphead wrasses if there are people that are willing to pay for it. If you see it at the market, don’t buy it. If more people refrain from buying it then fishermen will have less incentives to harvest these species.

Do not use reef fish for an aquarium. The LRFFT isn’t only for food; fishermen are able to sell live reef fish for aquariums because of their visual qualities and size. Show your support for the protection of reef fish and let them live in their natural environment instead of an aquarium.

Share information about the importance and status of napoleon wrasse. Raise awareness by telling your friends and family to avoid eating groupers and humphead wrasses. Share any information including this article to spread awareness.

Laws that protect the humphead wrasse within the CT3 (Philippines, Indonesia, and Malaysia)

Quiz

Humphead wrasses and several other reef fishes have the ability to change their gender. Why does the humphead wrasse change its gender?

Answer by commenting on the Facebook post by CTI-Southeast Asia!

Download the Protected Philippine Aquatic Wildlife posters.

Article by Panji Brotoisworo. Art by Dana Rose Salonoy.

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