The namesake of the film Blueback is a curious and lovable Western Blue Groper that the main character, Abby, meets and befriends on her first dive on her 8th birthday. It's no surprise that she falls in love with him when you learn how sociable and sweet these magnificent creatures are. Let's find out a bit more about this spectacular species of fish.
The Western Blue Groper (Achoerodus gouldii) is the largest carnivorous bony fish species found living on reefs. They reach lengths of up to 1.7 metres and can weigh up to 40 kilograms!
As well as being big characters, they can also live to the ripe old age of 70 years. Researchers have found this by counting the rings in the otoliths (ear bones) of the Western Blue Groper, which add a growth ring each year, just like tree trunks do. They're truly the wise elders of the reef!
Western Blue Gropers are found all the way from Geraldton, down the west coast of WA and all along the south coast of Australia, almost as far east as Melbourne! They hang out in waters from five to 65 metres deep.
This is one very likeable fish! Western Blue Gropers are known as an incredibly inquisitive and docile species, often swimming right up to divers to say hello! Sadly, this friendly behaviour can make them vulnerable to spearfishing.
Baby Western Blue Gropers are actually born a bright green colour! And they all start out life as female. Some (but not all) change their sex to male later in life. This change takes about 14 days in total, and usually the female is between 30-35 years of age when she changes to male.
Western Blue Gropers prefer to live in small groups or "harems", consisting of one male, one or two females and several juveniles. If the male fish dies or is removed from the group, the dominant female will take the male fish's place by changing sex and colour. But she won't do this until after she's already bred as a female.
The separation of the Western Blue Groper and the Eastern Blue Groper can be traced back to the Ice Age, when temperate waters became colder and the blue groper population probably split and moved up the west and east coasts, so they could stay warm and in their preferred temperature range.
The Western Blue Groper isn't part of the groper (Serranidae) family at all, but actually a member of the wrasse (Labridae) family! Wrasses are generally much smaller than gropers, so it's thought that the blue groper's large size is the reason behind its 'groper' name.
The Western Blue Groper uses its strong, peg-like teeth to prise off reef organisms such as sea urchins, molluscs and crustaceans to eat. Adults can also dislocate their own jaws to bite off large pieces of reef algal mat and then filter out and eat the tiny crustaceans that live in it. Talk about a strong appetite!