[Coral-List] Humphead parrotfish and Napoleon Wrasse

[Crawdaddy Hale]

Dear Coral List: In response to the recent posting about humphead parrotfish and Napoleon wrasse, humphead parrotfish chew coral with their big chomper (beaver looking teeth) and Napoleon wrasse disturb coral by nosing around looking for critters hidden amongst the coral heads. At least this is very common on the reefs of Palau.  In Palau, where both fish are protected from any take whatsoever, the population is coming back, despite pressure from illegal fishing.  It is not unusual to see herds of humphead parrotfish feeding.  In fact you can usually hear the scraping ruckus before you actually see the animals.  What is left in their wake is coral with lots of tooth marks. Napoleon wrasse are different, they tend to go for critters, like crabs and other crustaceans.  Relative to other reef fish, they are huge armored tanks.  In Palau, at popular dive sites like Blue Corner, you can see Napoleons pounding into reef crevices sending sand and pieces of coral flying up into the water column.  You can hear "boom, boom" as the fish pound their way into the rocks and coral.  Then whitetip sharks weasel their way in.  A perimeter is controlled by giant trevallies and the occasional marbled grouper or red snapper. These fish have an impact.  Whether the impact is negative is another matter.  It probably isn't.
 
You should look at the David Bellwood (et al.) article on the ecosystem role played by the humphead.  Ecology Letters (2003) 6:281-285.
 
Interesting discussion.
 
Thanks,
 
Christopher L. Hale
crawdaddyhale at hotmail.com