Friday, March 19, 2010

Unusual Marine Sightings

It has been another great couple of weeks diving here in the Seychelles. We have been out around the north west of the island on our dive boat ‘Manta’ completing fish and invertebrate monitoring surveys.

On more than one occasion recently some of the volunteers have been fortunate enough to encounter a Humphead Wrasse (Cheilinus undulata). Also known as the Maori Wrasse or Napoleon Wrasse it is the largest of the wrasse species exceeding 2m and 420lbs.

Found throughout the Indian Ocean and the Indopacific, Humphead Wrasse are uncommon to rare in the locations where they are found and can live for over thirty years. They are one of the few reef fish that feed upon the coral predators Crown of Thorns Seastars, helping to keep numbers in check.

Globally, population numbers of Humphead Wrasse are declining with local extinctions having occurred in Hong Kong and areas of the Philippines. This can be directly attributed to their harvest for the live fish food trade. Sodium Cyanide is often used when capturing this species destroying large areas of reef in the process. Due to decreasing natural stocks, focus is now shifting towards aquaculture to supply the growing international demand. Unfortunately, this does nothing to alleviate the problem as juvenile Humphead Wrasse are taken from the wild and placed in floating net cages until they reach a saleable size.

Luckily there are still Humphead Wrasse in the waters around the Seychelles and we have been lucky enough to have two encounters in the past week. While undertaking a fish monitor survey at Conception Island a large adult Humphead appeared out of the blue, swimming right over the fish belt. We also observed a juvenile Humphead with it’s distinctive black lines under the eye at one of the sites on the mainland.

It is reassuring to know that this magnificent species is still at home here in Seychelles waters and we are privileged to be able to dive and see what is one of the most magnificent of all reef fish.