The Great Barrier Reef marine park is home to 1625 different species of fish that come in all manner of shapes, colours and sizes. 1400 of these species live on the coral reefs and one of the largest of these species is the hump head Maori wrasse, also known as the Napoleon wrasse. The wrasse family, labridae, is one of the largest in the fish world with over 600 species, most of which are beautifully, brightly coloured. The humphead Maori wrasse is no exception and is the largest extant member of this family. These are quite curious, inquisitive and friendly fish and as a result have become attractions and resident characters at many popular dive and snorkel sites around the world. They also have a high level of intelligence and have been known to form bonds with divers that they see and interact with regularly.
This large species can be found in tropical waters across the Indo-West and Central Pacific oceans including east Africa, Asia, New Caledonia and Australia. Here in Australia they can be found on the offshore reefs of the northern parts of Western Australia and on the east coast we are lucky enough to be able to find these giants across the whole length of the Great barrier Reef in Queensland, where they inhabit shallow inshore waters and coral reefs and also on outer reef shelves at depths of up to 100 meters.
Bright colours is a characteristic of most fish in the wrasse family and adult male Maori wrasse dazzle with beautiful blues and greens worked through with intricate, geometric patterns that are reminiscent of traditional Maori tattoos, which is where their name comes from. Females of this species also exhibit these stunning patterns although their colouring is much more subdued and have more of a greyish tone, sometimes with a russet colour on the dorsal (top) side. The males are also much larger and can reach lengths of over 2 meters and weigh up to 180 kilograms. An interesting thing about humphead Maori wrasse is that they all begin their lives as females and then have the ability to transition to male as they mature. The transition from female to male is where the “humphead” part of their name comes into play. As the females begin. To change their forehead will start to become more humped and this hump will become more prominent as the new male fish matures. These guys can live for up to 30 years in the wild however they don’t reach sexual maturity until they are about 7 years old and have a quite low reproductive rate.
Humphead Maori wrasse are carnivorous and enjoy a wide variety of marine critters in their diet. They have strong, thick teeth which allows them to crush through hard shelled animals such as molluscs, echinoderms (like sea urchins), and crustaceans. They are also one of the only predatory species of the coral destroying crown of thorns starfish (also an echinoderm) and will even feed on highly poisonous species like the yellow box fish. Their affinity for “reef eaters” makes the humphead Maori wrasse an extremely important part of healthy coral reefs as they keep reef ecosystems in balance by helping to prevent coral predator populations from increasing outside healthy levels.
Here in the Whitsundays humphead Maori wrasse are quite a common site on snorkels and dives. The best place to meet one is Manta Ray Bay on Hook island. This bay is home to a local Whitsundays celebrity, a humphead Maori wrasse named George. George is very accustomed to humans and will approach boats and snorkelers alike which can be an incredible experience. He even has a harem of smaller females who can be just as friendly. Although as tempting as it may be to reach out and give these friendly fish a pat it is important that we keep our hands to ourselves. This is because humphead Maori wrasse, like most other fish species, have a mucus coating over their scales which protects them from outside infections and touching them can remove this protective layer. Due to their willingness to approach humans and lack of fear paired with low reproductive rates, this species is now protected in Australia and is a no take species when it comes to fishing, which wasn’t always the case . Currently the IUCN has the humph Maori wrasse listed as endangered so it is important we do what we can to ensure these gents giants can continue living on coral reefs around the world.