Creature of the Month

courtesy of Scuba News

Napoleon Wrasse, (Cheilinus undulatus)
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The Napoleon Wrasse, also known as the Maori or Humphead
Wrasse, is found throughout the warm waters of the Red Sea,
the Indian and Pacific Oceans. An extremely large fish, it
grows to over 2 m and weighs up to 191 kg (420 lb or
30 stone)!

Living between 1 and 60 m down, you can easily identify the
fish by its large size and the prominent bulge on its
forehead.  Usually solitary, it feeds primarily on
invertebrates and will even take toxic animals like
crown-of-thorns starfish, boxfish or sea hares.

Like others in the wrasse family, the Napoleon Wrasse
doesn't usually move its tail when swimming but flaps its
pectoral fins. The species can live for at least 30 years,
and becomes sexually mature at between 5 and 7 years.

Napoleon Wrasse are particularly vulnerable to fishing, as
they grow slowly, mature late, and are uncommon.  They
are traded on the live reef food fish market, which serves
luxury restaurants in, amongst others, Hong Kong, China,
and Singapore. There is evidence of decline throughout its
range, but particularly in Southeast Asia.  Historical
information shows Cheilinus undulatus was common in the
1950s and 1960s, and that declines have coincided with
increased fishing activity.

To compound its problems, the species changes sex from
female to male, which, if a fishery selects for larger
fish, may make it even more vulnerable to over-fishing.
It is estimated that less than 1% reach maturity
as males.

For a photo of a Napoleon Wrasse, taken in the Red Sea,
see
http://www.scubatravel.co.uk/humphead.html

Further Reading:
IUCN, The world conservation union
http://www.iucn.org/webfiles/doc/SSC/CoP12/Analyses/1238.pdf

Coral Reef Fishes (Collins Pocket Guides),
Ewald Lieske and Robert Myers
http://www.scubatravel.co.uk/fishbook.html