The humphead wrasse, Cheilinus undulatus:: synopsis of a threatened and poorly known giant coral reef.

The humphead wrasse, Cheilinus undulatus, is the largest living member of the family Labridae, with a maximum size exceeding 2 m and 190 kg. Its geographic range covers much of the Indo-Pacific. The species is not common, recorded maximum adult densities rarely exceeding 20 fish/10,000 m(2). Small individuals are typically associated with high coral cover; larger fish are found mainly on outer or deep reefs, steep slopes and passes, singly or in small groups and seagrasses. However, for reproduction the species forms small spawning aggregations of tens to more than one hundred fish. The diet of the humphead wrasse includes large invertebrates and small fishes. The species attains at least 30 years and reaches sexual maturation at about 35 - 50 cm total length and < 5 years of age. Most small adults are female while mainly males exceed 1 m and there is evidence of female to male sex change. The humphead wrasse is of considerable cultural value in some Pacific countries and is among the most prized in the live reef food fish export trade, for which it is often taken in its juvenile size range, either directly for sale or, increasingly, for grow-out to market size. It is also marketed chilled. The species is particularly sensitive to fishing pressure. In most. shed areas, density and body size have dropped substantially. It appears to be particularly heavily targeted and depleted in SE Asia and in some places faces extirpation. The humphead wrasse is often taken by night spear fishing and by cyanide, with protection typically weak or non-existent, despite regulations and a 'vulnerable' assessment on the 1996 IUCN Red List. The humphead wrasse has not been reared successfully in hatcheries. Other giant reef fish share many similar problems and detailed study of the humphead wrasse contributes to a better understanding and conservation of all such species. This review examines and evaluates published and gray literature, original unpublished research and correspondence with almost 50 knowledgeable workers. It examines the value of such sources for quickly, but adequately, assessing the conservation and management status and key data gaps in species that are little known, vulnerable, difficult and expensive to study and may require urgent management or conservation action.